Cook Inlet Belugas

1. Cook Inlet Belugas • ESA petition • “The Cook Inlet population of beluga whales is a small, geographically isolated and genetically differentiated population facing the imminent threat of extinction.” • Alaska Chapter of The Wildlife Society • “The Cook Inlet population of beluga whales is small, geographically isolated from all other beluga populations in Alaska, and genetically distinct.” • Marine Mammal Committee, ASM • “This small group of whales is geographically and genetically isolated from all other beluga populations.”

2. Cook Inlet Belugas • NMFS AFSC Quarterly Report, December 2000 • Beluga whales (Delphinapterus leucas) that inhabit Cook Inlet, Alaska, form a small, isolated stock that is geographically and genetically segregated from the other four stocks of belugas found in Alaskan waters. Genetic evidence indicates that beluga whales in Cook Inlet have not mixed with other beluga stocks for thousands of years. • Arctic Science Journeys • Beluga whales in Alaska's Cook Inlet near Anchorage are thought to be genetically unique among the 50,000 belugas that live in waters off Alaska.

3. Terms • Genetically isolated • no gene flow • geographic barriers • Genetically distinct • probabilistic difference in genetic characters • must define the level of analysis • Genetically unique • genetic characters that unambiguously identify membership in a population or other group

4. Original report • O’Corry-Crowe et al. 1997. Phlyogeography, population structure and dispersal patterns of the beluga whale Delphinapterus leucas in the western Nearctic revealed by mitochondrial DNA. Molecular Ecology 6:955-970. • Alaskan populations • mtDNA

5. Findings • 5 populations examined • 29 haplotypes found • 5 found in Cook Inlet • all CI haplotypes shared with at least one other population • all populations had at least one haplotype in common with CI • differed in frequency only

6. Findings • significant genetic structure among Alaskan populations • all populations differed significantly from all others • “Cook Inlet is the most genetically distinct of all geographical subpopulations with respect to mtDNA, an indication perhaps that the Alaska Peninsula may indeed be an effective barrier to genetic exchange or that drift in this small population offsets any homogenizing effects of gene flow.”

8. ABC Brown Bears • mtDNA (Talbot and Shields 1996) • distinct and ancient lineage • found nowhere else • represented earliest entry of bears into North America • differed from bears on SE mainland • nuclear microsatellites (Paetkau et al 1998) • evidence of gene flow between ABC and mainland • male-mediated • ancient DNA (Leonard et al. 2000) • all 3 lineages were present in eastern Beringia 35,000 years ago • indicated that there were no separate entries

9. Closer to Home • Brown Gladden, et al. 1999. Population structure of North American beluga whales (Delphinapterus leucas) based on nuclear DNA microsatellite variation and contrasted with the population structure revealed by mitochondrial DNA variation. Molecular Ecology 8:347-363. • populations from Norton Sound to St Lawrence River • found differences among populations

11. Take-home Message • mtDNA • likely to exhibit structure across populations • female philopatry • Nuclear loci • more likely to show total amount of gene flow

12. Implications for Cook Inlet Belugas • They may be genetically distinct • nuclear loci necessary for determination • mtDNA data are informative • no female immigration • population growth must come from within

13. Conservation Units • Management Unit • demography is determined by internal processes • natality • mortality • NOT immigration • all populations can be assigned to MUs • Evolutionarily Significant Unit • important component of the evolutionary legacy of a species • not all populations need to be included in ESUs