Genetic and Environmental Change in the Arctic
One of the greatest uncertainties regarding the biotic impact of anticipated global warming is the influence of climatic change on the abundance of different genotypes and on their geographic distribution. Questions of biotic response to global warming are critical in the Arctic, as polar regions are particularly sensitive to climate change and are expected to experience continued warming and consequent displacements of species' ranges and biomes. The Pleistocene climatic and environmental history of the Arctic has been turbulent. Understanding mammalian responses to past climatic changes is important to predicting and potentially mitigating the impact of future climatic changes on extant species. In this study, we investigate relationships between genetic and environmental change during the late Pleistocene for caribou (Rangifer tarandus),an extinct Pleistocene horse (Equus lambei), and gray wolves (Canis lupus).
Reconstructions of past arctic environments and climates have generally used plant and animal macrofossil, palynological, paleolimnological and ice-core data. However, these approaches provide little or no information on genotypic changes that might have occurred during past periods of climatic change. In addition, continuous plant macrofossil, palynological or paleolimnological records extending through the last glacial cycle remain sparse and sometimes difficult to interpret. Recent ancient DNA studies have shown that brown bears (Ursus arctos) in Beringia experienced population turnovers in the period from 60 to 14 thousand years before present (ka BP), implying habitat changes and a genotypic response not revealed by other analyses. The causes for these Quaternary population turnovers are unclear. These studies demonstrate the great potential of ancient DNA analysis to illuminate the impact of environmental change on the diversity, geographic structure and ultimately, the fate of mammalian populations.
We explore the generality of these past turnover events by analyzing patterns of mitochondrial DNA sequence change over the past 40,000 years in more large mammal species with different ecological requirements. Because the habitat preferences differ, we might expect them to show unique responses to changes in late Quaternary climate and vegetation. DNA sequenced from bones of these species will provide a record of genetic variability and genetic turnover reflecting changes in population size and the frequency of extinction and recolonization events.
Participants
Jennifer Leonard
Robert-Jan den Tex
Major collaborators
Pam Groves, University of Alaska
Bob Wayne, University of California, Los Angeles
Glen MacDonald, University of California, Los Angeles
Paul Koch, University of California, Santa Cruz
Genetics and Ecology of wolves in British Columbia
The central coast of British Columbia is the largest intact coastal temperate rainforest in the world. The rugged landscape, comprised of innumerable islands separated by open ocean lies on the western side of the Coastal Mountain Range. Deep fjords punctuate the coastline. Its remote nature has protected it from the large-scale, industrial, clearcut logging that has severely altered the environment in adjacent southeast Alaska and Washington state. Because the “Great Bear Rainforest” is largely undeveloped and sparsely populated, it is supposed that this archipelago landscape still harbors large carnivores and their natural prey base in historical abundances. However, due to the inaccessibility of this habitat, basic parameters such as the distribution and density of large mammals, including wolves and their prey are unknown. With the help of the local Heiltsuk First Nations people, we explore this area by boat and collect data permitting an estimation of these fundamental parameters.
The island ecosystem may impose unique constraints on the activities of predator and prey. Based on data from adjacent areas, we believe that many of the islands are too small to support a sufficient number of deer to maintain a persistent population of wolves. Moreover, wolves have been observed swimming among islands, likely searching for areas where vulnerable prey has not been exhausted. The time lag between population recovery by deer and the island’s subsequent re-colonization by wolves defines a unique predator-prey system that has fundamentally different dynamics than terrestrial ecosystems. Classic survey techniques cannot easily be used to study patterns of abundance and movements among islands. Consequently, we utilize new non-invasive approaches involving systematic collection of feces across the region multiple times each year. Fecal typing has been shown to be a feasible and accurate method for monitoring activity of canids.
The data we will collect has important conservation as well as ecological implications. The coastal habitat, previously protected by ruggedness, is now being targeted by logging companies as the resources in the other areas are being exhausted. By comparing the ecological data we collect in this pristine forest with similar data collected previously in coastal southeast Alaska (which has been heavily impacted by logging and hunting), we will be able to assess potential impacts of logging on predator-prey dynamics.
Participants
Jennifer Leonard
Violeta Muñoz
Lotta Bohman
Frank Hailer
Martin Breed
Major collaborators
Raincoast Conservation Society
Chris Darimont, University of Victoria
Bob Wayne, University of California, Los Angeles
Paul Paquet, University of Calgary
Biogeography of the Sunda Shelf
Biological diversity is high in Southeast Asia, particularly in the vicinity of the Malayan Peninsula, the adjoining islands of Sumatra, Borneo, Java, numerous smaller islands of the Sunda Shelf, and the neighboring Philippine Islands. During the last glacial maximum, the Sunda Shelf was completely above water and many of these islands were connected to the mainland, becoming isolated only in the last 10,000-14,000 years. However, the vegetation during the last glacial maximum was undoubtedly very different from now, and the overall effect of climate and sea level changes on the distribution of the fauna and flora is unclear. We examine a particularly interesting genus of squirrels, Sundasciurus, using molecular techniques, to assess their diversity, determine their phylogeny, compare and contrast genetic and morphological differences, and attempt to understand them within the historical context of climate and sea level changes in the Malayan region.
Squirrels of the genus Sundasciurus include small brown, nondescript squirrels of the Sunda Shelf, and several species of larger, more colorful squirrels found on the Sunda Shelf and the southern islands of the Philippines. These two groups of squirrels were combined in one genus on the basis of a single morphological feature of the ear region (Moore, 1958), an assessment that has not been tested. The species diversity of the genus is unknown. It has been estimated variously to include nine species (Corbet and Hill, 1992) and 15 species (Hoffmann et al., 1993). The species distribution is also puzzling. No species of Sundasciurus is found on Java, although other tree squirrels occur there. Also, species of Sundasciurus reached the Philippines and the Mentawi Islands, which would appear to be at least as isolated as Java from the rest of the Sunda Shelf.
Participants
Jennifer Leonard
Robert-Jan den Tex
Major collaborators
Richard Thorington, National Museum of Natural History, Smithsonian Institution
Jesus Maldonado, Genetics Program, Smithsonian Institution