Abstracts of Papers, Twenty-eighth Annual Albert L. Tester Memorial Symposium, 16-17 April 2003

Abstract

The Albert L. Tester Memorial Symposium is held in honor of Professor Albert Tester, who, at the time of his death in 1974, was Senior Professor of Zoology at the University of Hawai'i at Mānoa. The faculty and students of the Department of Zoology proposed an annual symposium of student research papers as a means of honoring, in a continuing and active way, Dr. Tester's lively encouragement of student research in a broad range of fields within marine biology. Papers reporting original research on any aspect of science are solicited from students at the university and these papers are presented at the symposium, which takes place during the spring semester. Income from contributions to the Albert L. Tester Memorial Fund of the University of Hawa'i Foundation is used to provide prizes for the three best papers, judged on quality, originality, and importance of research reported, as well as the quality of the public presentation. Judges include Department of Zoology faculty members and the previous year's student award winners. In addition, a distinguished scholar from another university or research institution is invited to participate in the Symposium as a judge and to present the major Symposium address. In 2003 the distinguished visitor and judge was Dr. William G. Eberhard, Staff Scientist at the Smithsonian Tropical Research Institute and Professor Catedratico at the Universidad de Costa Rica.

Barriers to Gene Flow in the Hawaiian Spinner Dolphin (Stenella longirostris)

In many cetacean populations, reproductively isolated subgroups exist within populations even when these subgroups live in the same geographic range or are capable of traveling to other subgroups' ranges. The factors that lead to reproductive isolation of these subgroups are often complex and can include such factors as food type and distribution, feeding behavior, social structure, migration patterns, philopatry, and learned behaviors. In the Hawaiian spinner dolphin (Stenella longirostris) population, there is variability throughout the Hawaiian Archipelago in geographic distance between suitable habitat, prey distribution, habitat type, availability of habitat, and social structure. To determine whether these factors have led to reproductive isolation, and therefore genetic distinction, between subgroups, I compared genetic structure, movement patterns, and social structure of the Hawaiian spinner dolphin using genetic analyses and available photographic identification data. I collected genetic samples from wild spinner dolphins throughout the Hawaiian Archipelago and sequenced part of the mitochondrial D-loop region to investigate genetic differentiation between dolphins at different islands and between different social groups at islands. Genetic diversity was lower for dolphins at islands with smaller populations and more stable social groups than at islands with larger populations and less stable social groups. In addition, dolphins at the main islands were genetically distinct from dolphins at the geographically distant Northwestern Hawaiian Islands. Different social groups inhabiting the same geographic region at Midway Atoll were also genetically distinct. These preliminary results indicate that geographic distance, habitat type, and social structure may be factors that lead to reproductive isolation between subgroups within the Hawaiian spinner dolphin population.

Type Ia Supernovae and the Accelerating Universe³

Five years ago two teams of astronomers revealed evidence indicating that expansion of the universe was accelerating rather than slowing down. The basis for this surprising result was studies of exploding stars known as Type Ia supernovae, which are believed to have a uniform peak brightness (therefore known as "standard candles") that allows their distance to be determined accurately and hence the structure of the universe to be probed. This unexpected discovery has implications for our understanding of the most fundamental physics of the universe and must be subject to extreme scrutiny. In...