The Galapagos Symposium, 1999

Proceedings of the American Association for the Advancement of Science, Pacific Division, Volume 18, Part 1, June 19, 1999

Galapagos: Ecology, Evolution and Conservation in Darwin's Islands. June 22 and 23, 1999
80th Annual Meeting of the AAAS: Pacific Division
San Fransisco State University, California
June 22 and 23, 1999

Abstracts

On the Origin of Darwin's Finches

LUIS F. BAPTISTA, REBECCA CARSON, and SYLVIA HOPE (Dept. of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, CA 94118, and San Francisco State University, San Francisco, CA 94132)

The 13 species comprising the celebrated Darwin's Finches ("geospizines") have been classified variously as members of a unique family (Geospizinae), as members of the subfamily Emberizinae of the Emberizidae, and more recently as finch-billed Tanagers (Thraupinae).

The taxonomic affinities of Darwin´s Finches have been a matter of considerable controversy. Swarth considered the group so ancient that identification of its closest relatives would be impossible. Others have been more optimistic and based partly on their black plumages, various authors have put forth Coereba flaveola (with black morphs), Volatinia jacarina,Melanospiza richardsoni and members of the genus Tiaris as close relatives of Darwin's Finches.

Within Darwin's Finches, only the genus Geospiza sensu strictu possesses black plumage: the other geospizines are either olive or olive and black. It is possible that black plumage was attained after colonization of the Galapagos. In this study we reexamine the question of the affinities of Darwin's Finches by bringing together osteological, morphological (plumage, tarsal scutellation), syringeal, behavioral (epigamic and agonistic displays, foraging behavior), bioacoustical and nest characteristics and subjecting them to PAUP analysis. Various finches and emberizids are included in the analyses. We find Melanospiza to be the sister taxon to the geospizines.

Citation:
Baptista, L.F., Carson, R., and Hope, S. 1999. On the origin of Darwin's finches. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 41-42.

Impacts of El Niño on Galapagos Penguins Body Condition and Movement

P. DEE BOERSMA (Dept. of Zoology, Box 351800, University of Washington, Seattle, WA 98195)

Galapagos penguins during severe El Niños fail to breed and some individuals become emaciated and die. I examined the body condition of Galapagos penguins in 1972 and 1998, two severe El Niño years. Body condition of the penguins was significantly poorer in 1972 and 1998 than in 1971. In 1972 and 1998, males were in better condition than females. Body condition was poorer in 1998 than in 1972 suggesting 1998 was a more severe El Niño. Galapagos penguins can not avoid poor food conditions by migrating long distances because outside of the Galapagos there are no suitable foraging areas. However, when food conditions are poor Galapagos penguins should move more than when conditions are better. By banding birds and observing them I found Galapagos penguins rarely go farther than a few hundred meters from shore and they often remain near their breeding site year round. Very few Galapagos penguins moved from the site where they were banded. Of 432 penguins, 66% were resighted. Of 234 adults that were resighted only 2% were soon more than 10 km from where they were banded. Galapagos penguins rarely leave their breeding area, and limited data suggest they are more likely to move when food conditions are poor.

Citation:
Boersma, P.D. 1999. Impacts of El Niño on Galapagos penguins body condition and movement. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 43.

The Foremost Granddaddy of Modern Galapagos Research Expeditions

ROBERT I. BOWMAN (Dept. of Biology, San Francisco State University, San Francisco, CA 94132)

A summarial description of the beginnings of modern scientific research in the Galapagos Archipelago, with special emphasis on the 1964 Galapagos International Scientific Project.

Citation:
Bowman, R.I. 1999. The foremost granddaddy of modern Galapagos research expeditions. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 44.

Constraint and Selection in the Evolution of Booby Clutch Size

LESLIE D. CLIFFORD and DAVID J. ANDERSON (Box 7325, Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109)

Galapagos masked boobies lay one to two eggs, but never raise more than one chick to fledgling because of obligate siblicide. We tested the Insurance Egg Hypothesis (IEH) as an explanation for clutch size variation in this species. The IEH proposes that second eggs act as insurance against failure of first eggs or early death of first chicks. Pairs laying two-egg clutches should have higher reproductive success, and selection will favor multiple-egg clutches. One-egg clutches result when proximate constraints do not allow parents to lay second eggs. Clutch-size manipulations resulted in higher reproductive success for enlarged clutches than unmanipulated one-egg clutches, supporting the IEH. A separate supplemental feeding experiment was conducted to determine if availability of food resources acts as a proximate constraint in this species. Ninety-two percent of supplementally fed females produced two-egg clutches while only 69% of control females did. Therefore, directional selection driven by replacement value appears to favor two-egg clutches in the Galapagos masked booby, while proximate constraints such as food availability limit clutch size to one egg in some individuals.

Citation:
Clifford, L.D. and Anderson, D.J. 1999. Constraint and selection in the evolution of booby clutch size. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 46.

The Status of Endemic Rodents of the Galapagos Islands and Prospects for their Conservation

ROBERT C. DOWLER (Dept. of Biology, Angelo State University, San Angelo, TX 76909)

The endemic rodents of the Galapagos Islands form an interesting part of the unique fauna of that archipelago. Their history began with the discovery of the first species by Charles Darwin in 1835 and the last species was described as recently as 1979. Unfortunately, of the seven described species known to occur in the islands during the past 150 years, only two were known to be extant into the middle of this decade. I conducted two expeditions to the Galapagos Islands to survey endemic rodent populations. The 1995 expedition confirmed the existence of a small endemic rice rat, Nesoryzomys fernandinae, on Isla Fernandina known previously from pellet remains found in the 1970´s. In 1997, I conducted an expedition to Isla Santiago and discovered a population of the larger rice rat, N. swarthi. This species had last been collected alive in 1906 and has been considered extinct in all recent literature on the Galapagos Islands. Collecting efforts on Santa Cruz unfortunately resulted only in introduced rats (Rattus rattus, R. norvegicus, and Mus musculus). Based on this research the extant species of endemic rodents in the Galapagos Islands now number four: Isla Fernandina — N. narboroughi and N. fernandinae; Isla Santiago — N. swarthi; Santa Fe — Oryzomys bauri. Three of these four are on islands where no introduced rodents or cats occur, whereas only one (N. swarthi) coexists with R. rattus and M. musculus. Three species still are considered extinct: Isla Santa Cruz — N. indefessus and N. darwini; Isla San Cristobal — O. galapagoensis.

Citation:
Dowler, R.C. 1999. The status of endemic rodents of the Galapagos Islands and prospects for their conservation. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 49.

Eastern Pacific Sea Surface Temperature since 1600 A.D: The (180 Record of Climate Variability in the Galapagos)

ROBERT B. DUNBAR (Dept. of Geological & Environmental Sciences, Stanford University, Stanford, CA 94305-2115); and GERARD M. WELLINGTON (Dept. of Biology, University of Houston, Houston, TX 77204-5513)

Comparisons of instrumental data sets show that sea surface temperatures (SST) in the Galapagos region are representative of a broad portion of the eastern equatorial Pacific. This site is especially well-suited for long-term studies of the El Niño/Southern Oscillation (ENSO) phenomenon, as it lies within the eastern Pacific "center of action" for thermal anomalies associated with ENSO. Cross spectral analysis shows that SST can explain greater than 80% of the variance in (180 at both the annual cycle and within the high frequency portion of the ENSO band (3-5 yr). The isotopic coral record for Pavona clavus is annual in resolution, extending from 1587-1953 A.D., and was obtained from a 10 m diameter colony preserved within the Urvina Bay uplift. The isotopic record appears to be a very good indicator of ENSO events and shows good correspondence with the historical record reconstructed by Quinn and Neal, 1995. Most interannual (180 variations between 1607 and 1953 represent annual average temperature excursions on 1° to 2.5°C. The dominant oscillatory modes, both within the ENSO and interdecadal frequency bands shift to shorter periods from the early to middle 1770´s and again from the middle to late 1800´s. This may reflect major reorganizations within the tropical ocean-atmosphere system and suggests that tropical climate variability is linked across timescales ranging from years to decadals.

Citation:
Dunbar, R.B. and Wellington, G.M. 1999. Eastern Pacific sea surface temperature since 1600 A.D: The ¹⁸0 record of climate variability in the Galapagos. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 49-50.

Nesting Ecology of the Galapagos Giant Tortoise during the 1997-8 El Niño

STEPHEN D. EARSOM, HOWARD L. SNELL (Charles Darwin Research Station, Puerto Ayora, Santa Cruz, Galapagos, and Dept. of Biology, University of New Mexico, Albuquerque, NM 87130); CRUZ MARQUEZ, and SOLANDA REA (Charles Darwin Research Station, Puerto Ayora, Santa Cruz, Galapagos)

In the 1980s, personnel of the Charles Darwin Research Station conducted a series of experiments to determine the optimal conditions for incubating eggs of captive giant tortoises. Parameters of interest included water potential of the nesting substrate and temperature of incubation. Research on Isabela Island from July 1997 to May 1998 extended this study to the field, resulting in a better understanding of how female tortoises attempt to control the nesting habitat, and how successful they are during an El Niño. This weather phenomenon´s destructive effects on marine life in Galapagos are well documented, while terrestrial organisms are generally assumed to prosper. Juvenile and adult giant tortoises reap the benefits of greatly increased food supply, but the bounty may not extend to the egg stage. Female tortoises successfully located patches of soil in a landscape dominated by lava, and the nesting process temporarily modified vegetation coverage, thereby maximizing insolation and nest temperature for the freshly buried eggs. Subsequent soil temperature decreases may have been due to increased soil moisture and shading from emergent vegetation. Though nesting sites were relatively well drained, a high level of egg mortality was associated with heavy rains and variable temperatures. Experimental and anecdotal data lend further support to the hypothesis that El Niño rains resulted in near total reproductive failure at the study site.

Citation:
Earsom, S.D., Snell, H.L., Marquez, C., and Rea, S. 1999. Nesting ecology of the Galapagos giant tortoise during the 1997-8 El Niño. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 50.

Retracing Darwin's Steps Through Galapagos

GREGORY B. ESTES and K. THALIA GRANT (Isla Santa Cruz, Islas Galapagos, P.O. Box 17-16-65, Quito, Ecuador)

Charles Darwin's visit to Galapagos in 1835 was key to his understanding of transmutation of species and his conversion to evolution. For this reason, it is surprising how little is known about Darwin's whereabouts on land while he was in the islands. Darwin visited four islands (Chatham, Charles, Albemarle and James) in five weeks, 19 days of which he spent on shore. In 1996 an expedition was put together to identify and retrace all the sites where Darwin explored on land on these four islands. The sites of his historic visit were identified using published Beagle record, Captain Fitzroy's charts, the Beagle log and Darwin's unpublished notes which first were transcribed from the originals. Fitzroy's charts are relatively accurate and detailed; there is little to distinguish his charts from those used today. Using Fitzroy's charts, which show the Beagle's course through the islands, it was possible to determine Darwin's route through Galapagos. Nautical bearings noted in the Beagle log indicate the ship's anchorages in the archipelago and hence helped to determine where Darwin landed. Darwin's eighty pages of unpublished geological notes on Galapagos were indispensable in finding the sites visited and geological formations examined by Darwin. The findings of this expedition greatly clarified Darwin's land route through Galapagos and enabled comparative site specific natural history observations to be made.

Citation:
Estes, G.B. and Grant, K.T. 1999. Retracing Darwin´s steps through Galapagos. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 51.

Foraging Behavior of Galapagos Albatrosses Revealed by Satellite Tracking and its Relationship to Reproductive Rate

A. PATRICIA FERNÁNDEZ and DAVID J. ANDERSON (Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109)

The low reproductive rates of pelagic seabirds have long been a cornerstone of evolutionary life history theory. The widely accepted "prey distance" hypothesis suggests that reproductive rates in pelagic seabirds are constrained by the distance of the food source (and its correlated effect on food delivery rate to the nest), with clutch size and intervals between broods inversely correlated with prey distance. We contrast the predictions of that hypothesis with an alternative, the "feeding site quality" hypothesis, suggesting that high prey densities at distant sites diminish or largely eliminate distance effects. We collected foraging data using satellite tracking from three species of albatrosses known to have an annual breeding and compared these results with those from biennially breeding albatrosses. Breeding Galapagos albatrosses (Phoebastria irrorata) traveled to the cold upwelling near the Peruvian coast known to have high productivity and high prey densities, located approximately 1,200 km south-east of the breeding colony, during the incubation period in 1995 and the chick rearing period in 1996. Black-footed albatrosses (P. nigripes) and Laysan albatrosses (P. immutabilis) nesting in the Hawaiian Islands and tracked during 1998 and ´99 breeding seasons also performed long foraging trips back to continental shelf areas off North America. Foraging trips by all three species often exceeded three weeks in duration and covered distances over 3000 km roundtrip, comparable to the biennial species. Phylogenetically controlled analysis indicated that foraging distances are uncorrelated with reproductive rates. However, the site quality hypothesis appears to be supported by our data.

Citation:
Fernández, A.P. and Anderson, D.J. 1999. Foraging behavior of Galapagos albatrosses revealed by satellite tracking and its relationship to reproductive rate. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 53.

Long-term Studies on Scalesia, Opuntia and Bursera in the Galapagos: Mortality and Recruitment

OLE HAMANN (Botanic Garden, University of Copenhagen, Oester Farimagsgade 2 B, DK-1353 Copenhagen K, Denmark)

The study of permanent sample plots during 26 years in selected vegetation types on the islands of Santa Cruz, Santa Fe and Pinta has generated information on the dynamics of some characteristic woody plants. Data on growth, mortality and recruitment are presented for Scalesia pedunculata, S. helleri ssp. helleri, S. baurii ssp. hopkinsii, Opuntia echios var. gigantea, O. Echios var, barringtonensis, O. galapageia var. galapageia, and Bursera graveolens. The differences recorded are discussed in relation to conservation.

Citation:
Hamann, O. 1999. Long-term studies on Scalesia, Opuntia and Bursera in the Galapagos: Mortality and recruitment. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 56.

Are Darwin's Finches Opportunistic Breeders?

MICHAELA HAU, MARTIN WIKELSKI (Dept. of Ecology, Ethology & Evolution, 515 Morrill Hall, University of Illinois, 505 S. Goodwin Ave., Urbana, IL 61801); HELGA GWINNER, and EBERHARD GWINNER (Forschungsstelle für Ornithologie in der Max-Planck-Gesellschaft, Von-der-Tann-Str. 7, D-82346 Andechs, Germany)

Reproduction of Darwin's finches is closely associated with rainfall. Since rainfall on Galapagos is very variable, birds have been found breeding at many times of the year. The physiological basis of this breeding strategy is unknown. Three mechanisms are conceivable: (1) Birds maintain gonads in a semi-active or active state all the time ('opportunism'), (2) Birds maintain gonads in a regressed state all the time and reproductive activity is initiated with the beginning of the rains, (3) Birds show a regular seasonal pattern in gonadal recrudescence and regression. Thus, finches are responsive to stimuli associated with the rains only at certain times of the year; at other times they are refractory to these stimuli. A first step towards distinguishing between these three alternatives is to measure gonadal sizes in two years that differ in environmental conditions. Our data suggest that Small ground finches and Cactus finches completely regress their gonads in the non-breeding season, excluding opportunistic breeding in the strict sense. Theoretically, gonadal recrudescence could either result from rainfall-associated cues or gonads could re-grow as a response to an endogenous program or other environmental cues. Since gonadal development in the dry year '98/'99 was suppressed, it is likely that environmental cues directly trigger gonad growth. However, we can not yet exclude the possibility that Darwin's finches usually show regular seasonal patterns in gonadal development and the dry conditions either suppressed or delayed gonadal growth. In the future we will experimentally test whether rain or food cues stimulate reproductive activity of Darwin's finches.

Citation:
Hau, M., Wikelski, M., Gwinner, H., and Gwinner, E. 1999. Are Darwin's finches opportunistic breeders? Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 57.

Components of Fitness in Juvenile Survivorship of Masked Boobies

KATHRYN P. HUYVAERT and DAVID J. ANDERSON (Dept. of Biology, Box 7325, Wake Forest University, Winston-Salem, NC 27109)

Studies of selection parental care in birds frequently base estimates of reproductive success on number of offspring fledged, when survival to the age of recruitment may be a more informative parameter. Among factors thought to influence survival from fledging to pre-breeding adulthood in seabirds are the timing of breeding, brood size, and body condition at fledging. This study examines these influences on post-fledging survival in a population of Galapagos masked boobies (Sula dactylatra). As part of a long-term study of reproduction in this species, chicks were banded and a battery of measurements was taken at or near fledging. Recapture data were collected in subsequent years by intensive whole colony searches. Program MARK was used to estimate post-fledging survival probabilities and to construct age-dependent mark-capture models incorporating effects of measures of condition and timing of breeding on survival. The median age of post-fledging first appearance in the colony was four years but first appearances occurred as late as 12 years of age. Approximately 36% of birds examined in this study appeared again in the colony by seven years of age while the probability of survival from fledging to adulthood ranged from 30 to 40%. Preliminary analyses indicate that mass at fledging does not play a significant role in the probability of survival from fledging to pre-breeding first appearance in the colony while timing of breeding does appear to enhance post-fledging survival.

Citation:

Huyvaert, K.P. and Anderson, D.J. 1999. Components of fitness in juvenile survivorship of masked boobies. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 59.

Biogeography of Scalesia (Asteraceae) Endemic to the Galapagos Islands

SYUZO ITOW (Nagasaki University Menoto 2-34-12, Nagasaki 852-8144, Japan)

The genus Scalesia consists of 15 species, of which 12 are shrubs and three are trees. Regardless of their stature, the predominant trait is that of being herbaceous: fast growth, soft wood, large pith at the center of the trunk, and flowering (in greenhouse) in the first year after germination. The habit of the genus is heliophilous and of pioneering in open habitats. Plants of the tree-like species Scalesia pedunculata (Hook.f. 1847) reach maturity in approximately 15 years, reaching a height greater than 10 m and a trunk DBHOB (diameter at breast height outside bark) greater than 17 cm. The mature stand of trees is nearly a monoculture, without young generations under the canopy. It collapses synchronously during extremely dry or extremely wet conditions. Shortly after a collapse, a new cohort of seedlings germinates in the dieback stand. Thus succession in Scalesia-dominated regions is one of buildup and collapse, and can be described as being self-cyclic.

The above-ground tree biomass of Scalesia pedunculata can be approximated by the equations: Ww=0.079(DH)^1.209, & Wf=0.0141(DH)^0.571, where Ww and Wf are the biomass values (kg) of wood and foliage, respectively, and the values D and H are DBHOB (cm) and tree height (m), respectively. In a nearly-mature forest, where the tree density was approximately 2500/ha, the standing biomass was estimated as 58,600 kg/ha in wood and 1,500 kg/ha in foliage. These biomass values are approximately 1/4 to 1/6 of the values in comparable forest ecosystems.

Citation:
Itow, S. 1999. Biogeography of Scalesia (Asteraceae) endemic to the Galapagos Islands. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 59-60.

Rollo Beck: A Glimpse into the Life of an Endangered Species

MATTHEW J. JAMES (Dept. of Geology, Sonoma State University, Rohnert Park, CA 94928-3609)

Rollo Howard Beck (1870 – 1950) made four collecting trips to the Galapagos Islands between 1897 and 1906, but it was his role as chief collector on the 1905-06 trip aboard the schooner Academy on behalf of the California Academy of Sciences that both cemented his position in Galapagos history and propelled him headlong into a long and productive life of scientific collecting for the Academy as well as the Museum of Vertebrate Zoology and the American Museum of Natural History. Beck's skill at collecting reptiles and his particular specialty, sea birds, was not matched by his record of publication. A particularly poignant event during the 1905-6 trip involved Beck's collecting the only specimen of giant tortoise from Fernandina Island. An ironic taxonomic counterpoint to Beck's indefatigable collecting efforts is the subspecific epithet of the race of giant tortoise that might prove to be the genetic talisman for the tortoise known as Lonesome George from Pinta Island. Beck was not only himself an endangered species in the world of scientific collectors (he was placed in a class by himself in this regard), but he also played an important role in our knowledge of endangered species in the Galapagos

Citation:
James, M.J. 1999. Rollo Beck: A glimpse into the life of an endangered species. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 60.

Phenotypic Plasticity in the Reproduction of Galapagos Lizards

MARK A. JORDAN and HOWARD L. SNELL (Dept. of Biology, University of New Mexico, Albuquerque, NM 87131, and Vertebrate Restoration Ecology & Ecological Monitoring, Charles Darwin Research Station, Galapagos Islands, Ecuador)

Seasonal environments often present individual organisms with temporally varying selective pressures. The population of Galapagos lava lizards (Microlophus delanonis) at Gardner Bay, Isla Española, exhibits a shift from small to large egg size that is correlated with wet-dry seasonality. Assuming that egg size determines neonate size, theory predicts that the cause of such plasticity is an increase in the strength of natural selection on neonate size late in the reproductive season. We tested this hypothesis by measuring natural selection on the body size of hatchling and juvenile lava lizards over a three and six week period of time, respectively. We predicted that individuals of large size would have a higher probability of survival during the late portion of the reproductive season. An increase in hatchling mortality, and a decline in the growth rate and body condition of juveniles late in the year suggested a seasonal decline in environmental conditions for young lizards. However, we found no indication of differential mortality in relation to body size in hatchlings or juveniles in either season. The short-term nature of our study does not allow us to reject the hypothesis that natural selection maintains the seasonal shift in egg size in lava lizards. Our results do suggest that the notion that "bigger is better" for offspring is an assumption that may not always be valid in studies of the evolution of egg size.

Citation:
Jordan, M.A. and Snell, H.L. 1999. Phenotypic plasticity in the reproduction of Galapagos lava lizards. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 60-61.

Setting the Stage for Darwin: Captain Porter and the Early 19^th Century Precursors to Darwin

EDWARD J. LARSON (Dept. of History, University of Georgia, Athens, GA 30602-7272)

Charles Darwin did not set foot on virgin scientific soil when he landed on the Galapagos Islands in 1835. He had been sent there as part of the Beagle expedition precisely because earlier naturalists and explorers to the islands had begun uncovering so much of interest to science there. In many ways, they anticipated Darwin's findings and set the stage for his work. This paper will review some of those predecessors to Darwin.

European and, to a much lesser extent, American scientists had begun actively exploring the Pacific in the mid-1700s, most notably with the three voyages of James Cook. Although Cook never visited the Galapagos Islands, two of his officers led scientific expeditions in the 1790s that did visit them: George Vancouver and James Colnett. Naturalists with these expeditions conducted the first formal scientific study on the archipelago. Three other British scientific expeditions also visited the Galapagos before Darwin, all bringing back reports of unknown and interesting biological species and geological phenomena. They urged further study of the place.

It was American Navy Captain David Porter, however, who cruised among the islands for months during the War of 1812, who contributed the most detailed scientific observations about the Galapagos of all Darwin's precursors there. Reflecting the latest scientific thought of James Hutton on volcanism and Georges Cuvier of zoology, Porter recognized the recent volcanic origins of the islands, appreciated that they changed over time, identified differences between tortoises on the various islands, noted the novelty of various Galapagos birds and reptiles, and assumed the appearance over time of biological species. His writings were well known and, with those of other late-18^th and early-19^th century visitors, helped set the stage for Darwin's momentous Voyage of the Beagle.

Citation:
Larson, E.J. 1999. Setting the stage for Darwin: Captain Porter and the early 19^th century precursors to Darwin. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 63-64.

Phylogenetic Relationships of the Galapagos Tortoise Geochelone nigra from Microsatellite and Mitochondrial DNA Data

EDWARD LOUIS (Center for Conservation & Research, Henry Doorly Zoo, 3701 S. 10^th St., Omaha, NE 68107-2200)

Although the Galapagos tortoise, Geochelone nigra has been recognized for 30 years as a single species with sub-specific populations distinguished on the basis of morphology, the taxonomic relationships of these geographically isolated subspecies have remained unresolved. Although morphological differences for carapace shape, maximum adult size, and neck and limb length have continued to form the basis for the Galapagos tortoise's taxonomy, in many cases, the plasticity variation cannot be classified to subspecies based on morphology alone (Fritts 1984). This study has addressed the taxonomic relationships between the populations of Galapagos tortoises by utilizing mitochondrial DNA (mtDNA) sequence data and microsatellite nuclear DNA data. Three main objectives are sought as follows: to characterize the extant and extinct populations of the Galapagos tortoises, Geochelone nigra, to determine the phylogenetic relationships of the extinct and extant populations, to determine whether the morphological forms are consistent, evolutionary lines, to evaluate man's role in promoting the historical taxonomy, and to determine if the mitochondrial and nuclear DNA data exhibit compatible phylogenies. From the genetic distance analysis of the nuclear DNA data, three major clades of extant Galapagos tortoise populations are defined. The Española population is the sole representive of the first clade, the most ancestral lineage of Galapagos tortoises. The second clade includes the Southern Isabela populations, along with the Volcán Alcedo and Volcán Darwin populations. The third major clade includes the Santa Cruz, Pinzón, Piedras Blancas, Puerto Bravo, Santiago,

Citation:
Louis, E.E., Jr. 1999. Phylogenetic relationships of the Galapagos tortoise Geochelone nigra from microsatellite and mitochondrial DNA data. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 64-65.

Charles Darwin the Geologist

ALEXANDER McBIRNEY (University of Oregon, Eugene, Oregon 97403)

About the only formal training Darwin had as a naturalist was a series of lectures on geology at the University of Edinburgh and a few weeks in the field with Adam Sedgwick, a foremost geologist of his time. During the cruise he relied heavily on Lyell's "Principles of Geology". Thus it is clear that he thought of himself as primarily a geologist. In a letter home, for example, he said, after alluding to the pleasures of collecting and studying marine animals: "But Geology carries the day! I am quite charmed with Geology, but like the wise animal between two bundles of day, I do not know which to like best: the old crystalline group of rocks or the softer and more fossiliferous beds."

Darwin made many perceptive geological observations. He witnessed the effects of a major earthquake in the Andes and reasoned that marine sediments found at high elevations could be the result of repeated earth movements of this kind. He deduced that although Galapagos plant and animal life came from South America, the islands had never been connected to the continent. He observed evidence of crystal segregation by gravity and speculated that this could explain the diverse compositions of igneous rocks, a concept that is now accepted as a primary mechanism of magmatic differentiation. Perhaps his most famous geological contribution was his theory for the origin of coral atolls as the result of subsidence.

What great things this extraordinary man could have done if he had just stuck with Geology!

Citation:
McBirney, A.R. 1999. Charles Darwin the geologist. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 67.

Genetic Diversity in Galapagos Penguins (Spheniscus mendiculus)

G.D. MILLER, B.V. HOFKIN, and R.D. MILLER (Dept. of Biology, University of New Mexico, Albuquerque, NM 87131)

Because of their restricted mobility compared with flying species and their natal site fidelity, penguins should show distinct spatial patterns of genetic variability that will be useful for population studies. The Galapagos Penguin is restricted to the Galapagos Islands where 1,700-8,500 individuals breed on 6 main islands and several other small islands. We used Randomly Amplified Polymorphic DNA (RAPDs) on a sample 109 individuals from 14 breeding sites to describe the genetic variability and spatial structuring of the world population of Galapagos Penguins. Within the context of genetic variation, we will discuss possible conservation problems faced by the species.

Citation:

Miller, G.D., Hofkin, B.V. and Miller, R.D. 1999. Genetic diversity in Galapagos penguins (Spheniscus mendiculus). Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 69.

Seabird Foraging Behavior in the Inshore Waters of the Galapagos Islands

KYRA L. MILLS (Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, CA 94970-9701)

I examined the species composition, frequency, distance offshore, and duration of multispecies seabird feeding flocks on two islands within the Galapagos Archipelago. Flocks were comprised of Galapagos Penguins (Spheniscus mendiculus), Flightless Cormorants (Campsohaelius [Nannopterum] harrisi), Brown Pelicans (Pelecanus occidentalis), Brown Noddies (Anous stolidus), Blue-footed (Sula nebouxii) and Masked Boobies (Sula dactylatra), Magnificent Frigatebirds (Fregata magnificens) and Audubon Shearwaters (Puffinus lherminieri). My results indicated that pursuit-divers, such as Galapagos Penguins and Flightless Cormorants, increase the longevity of flocks, and species such as boobies may tend to dissipate flocks. I also report on the diving behavior recorded from Time-Depth-Recorders deployed on two Galapagos Penguins.

Citation:
Mills, K.L. 1999. Seabird foraging ecology in the inshore waters of the Galapagos Islands. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 70.

Phylogenetic Relationships among Pacific Pterodroma Petrels

G.B. NUNN (PE Biosystems, 850 Lincoln Centre Dr., Foster City, CA 94404) and D. ANDERSON (Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109)

We report a molecular phylogeny of the avian genus Pterodroma (Order Procellariiformes: Family Procellariidae). We develop a finer-and-finer dissection of Pterodroma diversity focused on the "Dark-rumped Petrel" which faces complex conservation issues. Using genes encoded on opposite strands of the mitochondrial genome, our study supplied a framework for delimitation of phylogenetically distinct units of Pacific Ocean Pterodroma.

Firstly, our single gene data indicated these birds evolved diverse but discrete radiations between oceanic systems. In the Pacific Ocean we found rapid and early divergence of four taxa of "long-winged" Pterodroma at Juan Fernandez, Kermadec, Galapagos, and Hawaii archipelagoes.

Secondly, our multiple gene data focused on the sister-taxa, phaeopygia and sandwichensis, traditionally recognized as the "Dark-rumped Petrel" biological species found at the Galapagos and Hawaiian archipelagoes. The taxa diverged a relatively long time period ago and should be considered specifically distinct. Our data endorsed a higher conservation status on behalf of each species.

Other interesting facts emerged from the data. No genetic structure between islands of the Galapagos could be detected in phaeopygia, perhaps indicative of frequent gene-flow within the archipelago. We also found genetic variation, comparable to phaeopygia populations, present in the dwindling Maui sandwichensis population. The variation may be a "signature" of enormous populations once present at the archipelago before Polynesian contact.

Further studies of extant small populations at other Hawaiian islands and the inclusion of ancient DNA studies of lava-tube (pre-Polynesian) and midden-site (post-Polynesian) bones may prove interesting and help reveal the original diversity of Pterodroma in the region.

Citation:
Nunn, G.B. and Anderson, D.J. 1999. Phylogenetic relationships among Pacific Pterodroma petrels. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 72.

Habitats and Distribution Patterns of Galapagos Marine Mammals

DANIEL M. PALACIOS (College of Oceanic & Atmospheric Sciences, Oregon State University, 104 Ocean Admin. Bldg., Corvallis, OR 97331-5503)

A suite of atmospheric, oceanographic and geological processes converging around the Galapagos Islands bring about strong gradients and dynamic mesoscale features, making this a suitable area to investigate the influence of biogeophysical processes on marine mammal distribution. Distinct sectors can be recognized around the archipelago based on water mass types and on the topography of the sea floor. These waters also undergo a marked seasonal and inter-annual (i.e. El Niño) variability. Warm and less productive waters are found to the north of the islands, in the North Equatorial Countercurrent while cool and more productive waters are found to the south of the archipelago, in the South Equatorial Current. The upwelling of the Equatorial Undercurrent brings to the surface the coolest but most productive waters west of the westernmost islands, Isabela and Fernandina. Surveys indicate that marine mammal distribution patterns reflect this spatial heterogeneity: highest abundances for many species occur in the western part of the archipelago, downstream of the core of the upwelling. Bryde's whales (Balaenoptera edeni) and short-beaked common dolphins (Delphinus delphis) are the dominant species in this habitat. Bottlenose dolphins (Tursiops truncatus) are most frequently found in the inshore waters of the central archipelago. Short-finned pilot whales (Globicephala macrorhynchus) and Risso's dolphins (Grampus griseus) are mostly found in areas of steep bottom topography. Groups of female/immature sperm whales (Physeter macrocephalus) are seasonal around the Galapagos, converging around the islands during the warmer months of the year.

Citation:
Palacios, D.M. 1999. Habitats and distribution patterns of Galapagos marine animals. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 74-75.

Galapagos Hawks: Ecological and Genetic Studies of Variation in Mating Behavior and Morphology

P.G. PARKER, J.L. BOLLMER (Dept. of Evolution, Ecology, and Organismal Biology, Ohio State University, 1735 Neil Ave., Columbus, OH, 43210); J.C. BEDNARZ, M. DONAGHY CANNON (Dept. of Biological Sciences, Arkansas State University, P.O. Box 599, State University, Arkansas 72467); T.J. DEVRIES, D. SANCHEZ, T. SANCHEZ, S.M. STRUVE (Departamento de Biología, Pontificia Universidad Católica del Ecuador, Avenida 12 de Octubre y Roca, Apartado 17-01-2184, Quito, Ecuador; and J.R. FAABORG (Div. Of Biological Sciences, 110 Tucker Hall, University of Missouri, Columbia, MO, USA 65211)

The Galapagos hawk (Buteo galapagoensis) is the only diurnal raptor with established populations in the Galapagos, where they inhabit nine islands. Their mating system varies between islands, from standard pairs on some to polyandrous groups comprising single females with multiple males on others. Because populations exhibiting polyandry are almost exclusively polyandrous, this species represents the most extreme example of this unusual mating system in birds. We are investigating variation in mating behavior and morphology between islands, examining ecological correlates of mating system, and using genetic markers to understand the reproductive dynamics of the mating system and differentiation between islands. Genetic evidence based on minisatellite DNA fingerprinting suggests that, within polyandrous groups on Santiago, cooperating males are not closely related, and paternity is distributed randomly, as predicted by behavioral observations. We present new data on differentiation among populations on Santa Fe, Santiago, Española, and Isabela (at Alcedo). The genetic variation between islands far exceeds that within islands, some of which appear practically clonal using DNA fingerprinting. Fst values range from 0.14 between Santiago and Isabela, large and centrally located, to 0.89 between the smaller and more remote islands of Santa Fe and Española. Thus our preliminary results suggest strong differentiation among these four islands, including moderate differentiation between Santiago and Isabela, despite their proximity. Ongoing work includes sampling the remaining four islands sustaining undisturbed populations, developing molecular techniques to confirm sex, investigating history of ancestry of populations by mitochondrial sequence data, and study of resource base associated with monogamy and polyandry.

Citation:
Parker, P.G., Bednarz, J.C., DeVries, Tj., Bollmer, J.L., Donaghy Cannon, M., Sanchez, D., Sanchez, T., Struve, S.M. and Faaborg, J.R. 1999. Galapagos Hawks: Ecological and genetic studies of variation in mating behavior and morphology. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 75.

There Are 2000 Species of Insects in the Galapagos

STEWART B. PECK (Dept. of Biology, Carleton University, 1125 Colonel By Dr., Ottowa, Ontario K1S 5B6 Canada

The Galapagos Islands insect fauna is now known to contain at least 1850 species: of which 735+ are endemic, 823+ are native, and 292+ were accidentally introduced by human activities. The indigenous species arrived mostly by aerial and sea-surface transport, over about 3.5 My and represent a colonization-speciation rate of one species per 2250 years. The main source of colonists was the western side of the Americas from Mexico to Ecuador. There are some island-evolved species swarms, but the mean is 1.13 descendant species per ancestral colonization. Species diversity is positively related to island area, elevation, and ecological complexity, but not island age. The fauna is now probably 90-95% known.

Citation:
Peck, S.B. 1999. There are 2000 species of insects in the Galapagos. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 75.

Patterns of Evolution in Darwin's Finches: Microsatellites Provide a New Perspective

KENNETH PETREN, B. ROSEMARY GRANT, and PETER R. GRANT (Dept. of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544-1003)

The evolutionary relationships among Darwin's finches have proved difficult to resolve with standard molecular techniques. To accomplish this task, we have studied length variation at 16 microsatellite loci. These nuclear genomic molecular markers provide an estimate of phylogeny that is largely in agreement with Lack's estimate based on morphology and Yang & Patton's estimate based on allozymes. The results indicate that the six ground finch (Geospiza) species are monophyletic, as are five of the tree finch (Camarhynchus, Cactospiza) species. Divergence of the vegetarian tree finch (Platyspiza), preceded the divergence of the ground finches from the tree finches. The Cocos Island finch diverged from Darwin's finches after the Galapagos radiation was underway. Populations on different islands generally cluster according to species classification with two notable exceptions. Divergence among warbler finch populations (Certhidea olivacea) preceded the divergence of any other species of Darwin's finch. Similarly, divergence among populations of the sharp-beaked ground finch (Geospiza difficilis) preceded the divergence of all other ground finch species. In two instances, once a novel beak shape was evolved, it is clearly followed by divergence in size. These evolutionary patterns are consistent with the view that divergence in allopatry is followed by reproductive isolation in sympatry (secondary contact), competition, and character displacement. The unusual finding that microsatellites resolve relationships among Darwin's finch species reinforces the notion that much of this adaptive radiation has occurred very recently.

Citation:
Petren K, Grant, B.R. and Grant, P.R. 1999. Patterns of evolution in Darwin's finches: Microsatellites provide a new perspective. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 76.

Why Did Darwin Collect All Those Plants?

DUNCAN M. PORTER (Dept. of Biology, Virginia Tech, Blacksburg, VA 24061, and Cambridge, University Library, Cambridge CB3 9DR, UK)

While on the Beagle voyage of 1831-1836, Charles Darwin collected 1,444 specimens of vascular plants: clubmosses, horsetails, ferns, gymnosperms, and angiosperms. In Chile, where he spent a total of 22 months, he made 248 collections (404 sheets). In the Galapagos Islands, where he spent about six weeks, he made 211 collections (330 sheets). This resulted in approximately 141 collections per month in the Galapagos and approximately 11 per month in Chile. What are the reasons for this discrepancy?

Darwin was not the first to collect plants in the Galapagos. His 1835 visit to the islands was preceded by those of Archibald Menzies (1795), David Douglas and John Scouler (1825), James McRae (1825), and Hugh Cuming (1829). However, Darwin's collections were the most important for Joseph Dalton Hooker's first flora of the archipelago (1847). Darwin's still remain the most important specimens collected in the islands by any one person.

Why did Darwin collect plants at all, since his interests at this time of his life were mainly with geology and zoology? What did he collect and where did he collect it? These and other questions will be addressed in the context of Darwin's visit to the archipelago in September and October 1835.

Citation:
Porter, D.M. Why did Darwin collect all those plants? Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 77.

Genetics and Phylogenetics of Giant Galapagos Tortoises

JEFFREY R. POWELL and ADALGISA CACCONE (Dept. of Ecology & Evolutionary Biology, Yale University, 165 Prospect St., P.O. Box 208106, New Haven, CT 06520-8106)

We are engaged in a long-term research program examining the origin, phylogenetic relationships, and evolutionary genetics of Geochelone nigra, the giant Galapagos tortoises. We have amassed about 2,000 blood samples, as well as skin and bone samples from specimens collected up to 100 years ago. Our initial studies have involved understanding the origin of the Galapagos tortoise lineage and determining how genetically distinct are the recognized subspecies. Our DNA sequence data have produced several results: (1) The closest living relative of G. Nigra is G. chilensis, the Chaco tortoise from mainland S. America. The estimated time of separation of G. nigra and G. chilensis is six to ten mya, predating the oldest extant island. (2) Most named subspecies can be distinguished uniquely with DNA sequence data. This potentially allows us to identify the origin of captive animals of unknown origin. Estimated times of divergence of subspecies are consistent with in situ differentiation on extant islands. (3) We have not been able to find any genetic distinctness among the four named subspecies on Isabela's four southern volcanoes. This is consistent with previous suggestions calling into question the subspecific status of these populations. The named subspecies (becki) on the northern most volcano, Wolf, is genetically distinct and was probably founded by an independent colonization from Santiago. (4) Our data indicate that all the breeders used in the Española repatriation program, including the male from the San Diego Zoo, come from a single taxon.

Citation:
Powell, J.R. and Caccone, A. 1999. Genetics and phylogenetics of giant Galapagos tortoises. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 77.

The Realities and Distribution of Biological Diversity in the Galapagos

HOWARD L. SNELL (Charles Darwin Research Station, and Biology Dept., University of New Mexico, Albuquerque, NM 87131)

The Galapagos Archipelago is unique among oceanic islands of the 20^th century. Unlike other human-inhabited archipelagos that have experienced many extirpations, at least 96% of the original biological diversity of the Galapagos remains intact. Other oceanic centers of evolutionary radiations like Hawaii, New Zealand, and the Caribbean Islands have all lost great percentages of their native and endemic species. These losses can exceed 50%, and are caused by a complex set of direct and indirect effects of human activity. The most disastrous effects are habitat destruction and the introduction of alien species, although over-exploitation from hunting and fishing activities also has extirpated many unique species.

The Galapagos Archipelago contains at least 127 islands and the terrestrial biological diversity includes approximately 560 indigenous species of plants, 115 indigenous vertebrates, and an estimated 2,000 indigenous species of invertebrates. Rates of endemism vary among the different organismal groups from nearly 100% down to approximately 38%. Unfortunately the percentage of introduced alien species is also great - 500 introduced plants (47%), 24 introduced vertebrates (17%), and an unknown number of alien invertebrates have colonized the islands since 1535. There are fundamental differences in the distribution of indigenous and alien biological diversity within the Galapagos. Indigenous species tend to inhabit very few islands: 54% have ranges that encompass no more than four islands, and 19% have ranges restricted to single islands. Alien species have relatively broader ranges. These and other differences in the nature of indigenous and alien biological diversity complicate efforts to preserve the unique nature of Galapagos diversity and are likely to lead to increasing numbers of indigenous extirpations.

Citation:
Snell, H.L. 1999. The realities and distribution of biological diversity in the Galapagos. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 82.

A Six Thousand Year History of El Niño Events in the Galapagos: Evidence from Lake Cores

MIRIAM STEINITZ-KANNAN (Northern Kentucky University, Highlands Heights, KY 41099-0400); MELANIE RIEDINGER (Northeastern Illinois University, Chicago, IL 60625); WILLIAM LAST (University of Manitoba, Winnipeg, Canada R37 2N2); MARK BRENNER (University of Florida, Gainesville, FL 32606); and MICHAEL MILLER (University of Cincinnati, Cincinnati, OH 45221-0006)

Sediment cores from Galapagos lakes contain some of the oldest and most complete records of the frequency of intense El Niño events. El Niño brings torrential rains that lower the salinity of the surface water of saline lagoons. These changes can be detected by mineralogical, geochemical and diatom analyses of the sediments. A core from the saline lagoon of the crater of Bainbridge, south-east of Santiago Island, provides a detailed history of these salinity fluctuations. This core has been extensively radiocarbon dated (AMS) with a date at the bottom of 6170+ 55 years. The complex stratigraphy and the mineralogical and geochemical data suggest that the lagoon has stayed supersaturated with salts in all its history with several short periods of lower salinity that we attribute to increases in precipitation related to ENSO. Such periods are characterized by 83 thin bands (<2 mm) each, rich in organic material and containing species of diatoms that indicate lower salinity. Most of these bands appear in the last 2500 years and are more frequent in the last 800-1000 years. Data from the cores of Genovesa crater lake and El Junco lake also indicate increased frequency of precipitation in the last 2500 years. Genovesa shows fluctuations in the amount of phosphorus (coming from the guano of the red-footed boobies that nest around the crater) and of pollen of Bursera (a plant that flowers only when it rains). El Junco lake shows fluctuations in lake level based on fossil diatoms and water ferns (Azolla).

Citation:
Steinitz-Kannan, M., Riedinger, M., Last, W., Brenner, M. and Miller, M. 1999. A six thousand year history of El Niño events in the Galapagos: Evidence from lake cores. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 84.

Ecological Importance of Terrestrial Hermit Crabs in the Galapagos Islands

SALLY E. WALKER (Dept. of Geology, University of Georgia, Athens, GA 30602)

Terrestrial hermit crabs are ubiquitous on tropical islands; however, their ecology is poorly known. This research was undertaken under the auspices of the Charles Darwin Research Foundation and the Galapagos National Park to determine the species of terrestrial hermit crabs that occur on the Galapagos Islands and their ecology in relation to the human population on Santa Cruz Island. The human impacted sites of Director´s Beach and Tortuga Bay and the protected site of Puerto Nuñez were used in this study. Coenobita compressus was the only species encountered. Thais melones was the most commonly used shell at Director's Beach (54%) while Nerita scabricosta was used by 65% of the hermits at Tortuga Bay and by 75% at Puerto Nuñez. At the human-affected sites, C. compressus emerged 1 to 1.5 hours after sunset to forage on bananas, corn cobs, bread, and grapefruit which were discarded by tourists. Crabs were afraid of humans at these localities, stopping behavior upon approach. At the protected site, crabs appeared two hours before sunset and were not afraid of humans — continuing with mating, aggressive behavior and food foraging. They consumed the purple flowers of Sesuvium, leaves of Tiquilia galapagoa, and foraged within driftwood and mangrove litter. However, the crabs were attracted to the camp garbage and ate the plastic garbage bag, paper labels off the cans, and "papeles de higenico". In summary, these "Cangrejos de Basura" are indeed important organisms for maintaining the cleanliness of Galapagos beaches with their late night beach-sweeping activities.

Citation:
Walker, S.E. 1999. Ecological importance of terrestrial hermit crabs in the Galapagos Islands. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 86.

The New Regime for Conservation in the Galapagos: Ensuring Effectiveness and Compliance

DAVID WESTBROOK (School of Law, 5210 Brian Hall, State University of New York, Buffalo, NY 14260)

Many scientists at work in the Galapagos have a professional interest in ecosystem integrity in the Galapagos, quite apart from whatever personal interest they may have in conservation. In March of 1998, under pressure from the international conservation community, the government of Ecuador promulgated a law substantially revising the conservation regime for the archipelago and its surrounding waters. While law reform is a necessary step, no law could of itself suffice to ensure the integrity of the Galapagos ecosystems. Ensuring such integrity also depends on the ongoing administration of the new legal regime, and on the compliance of the regulated parties. From a legal perspective, this presentation will consider the basic structure of the new regime, and will analyze possible weaknesses in the regime, i.e., forces tending to weaken administration or undermine compliance or both. This presentation should serve as a basis for discussion of roles that scientists might play in strengthening conservation efforts in the Galapagos.

Citation:
Westbrook, D.A. 1999. The new regime for conservation in the Galapagos: Ensuring effectiveness and compliance. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 87.S

Advances in Zoo Biology and its Application to Galapagos Conservation

DAN WHARTON (Wildlife Conservation Society, CPWC, 830 Fifth Ave., New York, NY 10021)

Over the last few decades, zoological gardens have experienced a revolution in their orientation to wildlife conservation. Zoo biologists are currently developing a number of sophisticated technologies and/or strategies for investigating issues in small population biology, systematics as applied to conservation, wildlife medicine, nutrition, behavior, re-population, and captive breeding. Meanwhile, naturalistic presentation of wildlife has increased educational content of wildlife exhibition, drawing over 120 million visitors annually to the 180 zoos accredited by the American Zoo and Aquarium Association (AZA). AZA zoos are finding new and exciting ways to link exhibits and programs to field conservation, including at-exhibit fundraising for field science and conservation. This paper examines the various ways in which zoological gardens could contribute to Galapagos conservation. Included are details on the history of zoological gardens and the Galapagos tortoise and a tentative proposal to work with Galapagos mammals, genus Nesoryzomys.

Citation:
Wharton, D. 1999. Advances in zoo biology and its application to Galapagos conservation. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 87-88.

Evolution of Body Size in Galapagos Marine Iguanas

MARTIN WIKELSKI (Dept. of Ecology, Ethology & Evolution, University of Illinois, 515 Morrill Hall, 505 S. Goodwin Ave., Urbana, IL 61801)

Body size is a central trait of organisms, as nearly all traits of organisms scale with it. It has been postulated that body size is determined by an interaction of natural and sexual selection. I quantified the selection pressures on body size in two island populations of marine iguanas. There was no predation and interspecific competition to confound the analysis. While natural (mortality) selection favors intermediate body sizes on both islands, the absolute values of adult body mass differ about threefold between islands. Natural selection acts through energy limitation, the strength of which differs between habitats and seasons. Sexual selection, on the other hand, always favors large body sizes, the effect being strongest in males. Sexual selection acts through the higher mating success for larger males. Large body size is the major determinant of territorial acquisition in the lek of marine iguanas, the first lek mating pattern described for reptiles. By knowing the quantitative amount of selection pressures and the mechanisms of selection, I can proximately explain body sizes in marine iguana island populations from just two environmental parameters, namely effective temperature and food supply.

Citation:
Wikelski, M. 1999. Evolution of body size in Galapagos marine iguanas. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 88.

Galapagos and the Five Journals of William Ambrosia Cowley

JOHN WORAM (45 Lakeside Dr., Rockville Centre, NY 11570)

Perhaps the first scientific expedition to the Galapagos Islands began in 1683 when a group of English buccaneers departed Virginia for a season of robbery and looting in the South Seas. Although not to be confused with an outing of the Literary Guild, at least four of their number recorded their observations for posterity, the most famous being William Dampier, whose New Voyage Round the World is a masterful combination of scientific observation and travel essay. But a less-celebrated shipmate named William Ambrosia Cowley also made an important contribution, as the first to chart and name the islands.

Although the two versions of Cowley's manuscript journal in the British Library are well known to researchers, there are in fact three others elsewhere that have not been widely studied. This paper offers a comparison of the Galapagos sections of the five manuscripts, along with a description of the author's attempt to place them in chronological order and relate them to Cowley's much abridged account published in William Hack's 1699 Collection of Original Voyages. The three versions of the Galapagos chart attributed to Cowley are also briefly described, as is a post-Cowley mixup by James Colnett a century later. As a result of his interpretation of Cowley's map, the modern island whose English name is "Charles" may not be the one that Cowley meant.

A few other cartographic mixups will be examined, along with a review of the more fanciful "facts" that are now part of the biographical legends of Cowley and Dampier.

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Citation:
Woram, J.M. 1999. Galapagos and the five journals of William Ambrosia Cowley. Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 89.

Experimental Evaluation of the Role of Cost of Reproduction in the Evolution of Masked Booby Brood Size

DAVID J. ANDERSON, CECILIA BETANCOURT, ILONKA VON LIPPKE, and LYNN LOUGHEED (Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109)

Masked boobies show obligate siblicide, fledging only one chick per brood, yet are capable of feeding and fledging two chicks if siblicide is suppressed. We tested the hypothesis that reproductive costs associated with two-chick broods render that strategy sub-optimal to a one-chick brood at a colony in the Galapagos Islands, Ecuador. An experimental regime suppressed siblicide among age-matched nestmates and caused the circumstances of chick mortality to resemble those of a facultatively siblicidal congener, the blue-footed booby. Experimental chicks had higher per capita mortality rates, but parents of experimental broods nonetheless fledged more young than did controls. Experimentals with two chicks provided approximately twice as much food as did controls, and so may have foraged with higher effort than did controls. Judging by the absence from the nest site, experimental mothers responded more to the increased demand for food than did experimental fathers. In the year after the experiment, when all parents bred without manipulation, experimental mothers were less likely to breed successfully than control mothers, apparently exhibiting an excess cost of reproduction, but experimental fathers did not exhibit such a cost. Costs of reproduction may be a sufficient selective effect to favor the evolution of a sub-maximal reproductive rate in this species.

Citation:
Anderson, D.J., Betancourt, C., Von Lippke, I., and Lougheed, L. 1999. Experimental evaluation of the role of reproduction in the evolution of masked booby brood size.

Proceedings of the American Association for the Advancement of Science, Pacific Division 18 (1): 4

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