GENETICS (Chapter 17)
Lead Author: Joseph A. Cook
Contributing Authors: Christian Brochmann, Sandra L. Talbot, Vadim B. Fedorov, Eric B. Taylor, Risto Väinölä, Eric P. Hoberg, Marina Kholodova, Kristinn P. Magnusson and Tero Mustonen
SUMMARY
The impact of climate warming on Arctic organisms is complex, and its interpretation will require a concerted effort. To mitigate the impact of climate-induced perturbations, an essential first step is to develop an understanding of how high latitude species and ecosystems were influenced by past episodes of dynamic environmental change. One of our best views of past change in Arctic populations is through molecular genetics (e.g. DNA studies). DNA-based views provide a basis for forecasting how biomes and individual species will respond in the future and thus are a key component of an advanced early-warning system for natural environments of the Arctic.
Species typically adapt to new conditions or shift into new areas, but a number of Arctic species are now experiencing a reduction in their distributions, abundance and ability to exchange individuals among populations. Molecular genetic approaches are used in a wide range of studies to provide comprehensive assessments of how species interact with their environments. Important insights have been gained related to the conservation status of high latitude species of concern, but because Arctic environments are remote and difficult to access, only limited information is available about most essential factors for organisms (e.g. contemporary genetic diversity, evolutionary history, modes of reproduction). A coordinated investment in biological infrastructure is needed now (similar to that already in place for monitoring the physical environment) if we are to apply and realize the powerful insights provided by molecular genetics.
Knowledge exists, we live it. But I do not think about that ever. It is just there. We still follow the old ways. Naturally. This is our way. Isak Påve, a Saami reindeer herder from northern Sweden; Hiltunen & Huovari (2004).
INTRODUCTION
Maintaining genetic variation in wild populations of Arctic organisms is fundamental to the long-term persistence of high latitude biodiversity. Variability is important because it provides options for species to respond to changing environmental conditions and novel challenges such as emerging pathogens or invasive species. As individual species decline in abundance and their geographic distributions shrink, genetic variability is also often eroded. It is important to realize that we have not yet developed a basic understanding of how genetic variability is partitioned across space or time in the Arctic. Furthermore, we lack information on how genetic variation, and the related concept of evolutionary potential, is generated and maintained for most Arctic organisms, whether free-living or parasitic. Fortunately, new technologies and analytical approaches now afford the possibility of much more comprehensive and refined views of genetic variation, but realizing the potential of these new approaches will foremost require a renewed effort to inventory and rigorously document Arctic diversity at all levels (Fig. 17.1). A revitalized effort to explore diversity will provide the foundation necessary for a variety of theoretical and applied endeavors, ranging from uncovering the history of diversification and extinction of organisms, to tracking and mitigating emerging pathogens and invasive species, to developing robust projections for the long-term security of subsistence or traditional foods in the Arctic.
Traditional ecological knowledge (TEK) should also be an integral part of Arctic biodiversity assessment (Usher 2000). In particular, this knowledge can help determine how to more effectively study Arctic fauna and flora. For example, rural coastal villages in Alaska have been instrumental in providing unprecedented sampling of marine mammal populations through subsistence harvests. In Canada, populations of the northern Dolly Varden Salvelinus m. malma are found in the western Arctic region (i.e. tributaries of the Mackenzie River largely along its western bank), and these are of tremendous significance to indigenous peoples of the region. The subspecies was recently assessed as a taxon of Special Concern by Canada’s Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2011). A key feature of the biology of this fish is habitat located within overwintering sites characterized by groundwater upwelling that maintains ice-free habitat, and where fish congregate in large numbers. Despite the vast extent of occurrence of the subspecies’ distribution across the western Arctic (e.g. ~ 227,000 km2), these essential overwintering sites number fewer than 20 and have a combined area of less than 1 km2. The locations and the limited numbers of these key habitats were obtained in large part from TEK which was, therefore, critical to the status assessment and subsequent derivation of a conservation management plan.
This chapter does not tackle the thorny issues related to bio-prospecting and commercialization of Arctic genomic resources or introduction of genetically modified organisms. Instead, we provide an overview of not-for-profit approaches to studying genetic diversity in the Arctic emphasizing that an understanding of the influence of deeper (evolutionary) time in structuring diversity is essential to predicting future responses and persistence of the incomparable fauna and flora of the northern high latitudes of our planet.
CONCLUSIONS
In this review we have touched on several topics for which non-commercial genetic approaches are providing key insights into changing conditions in wildlife and plant communities in the Arctic. We have not addressed concerns about genetic prospecting and commercialization of genetic resources in the Arctic. Instead, our overview of not-for-profit genetic approaches in the Arctic emphasizes that an understanding of the influence of deeper (evolutionary) time in structuring diversity is essential to predicting the future response and persistence of the incomparable fauna and flora of the northern high latitudes of our planet. In many ways, new technology and analyses available to investigate Arctic biota have led to unprecedented insight. Future assessments will be limited primarily by our ability to provide representative samples from remote Arctic environments. This situation emphasizes the growing need to work collaboratively with rural Arctic communities as we aim to assess changing conditions.
Climate warming is substantially changing the distribution and population dynamics of marine, aquatic and terrestrial organisms in the Arctic. Population responses include adapting to new conditions, tracking climate shifts into new ranges that may lead to new zones of contact between species, or even the possibility of extinction. To forecast the impact of climate-induced perturbations, an essential first step is to develop an understanding of how high latitude species and ecosystems were structured by past episodes of dynamic environmental change. Today, molecular genetic approaches are used in a wide range of studies and provide comprehensive assessments of how species interact with their environments. Important insights have been gained related to the conservation status of high latitude species of concern so that these wildlife populations can be sustained. A number of factors influence the contemporary patterns of genetic diversity in Arctic organisms including the geological history of the region, the evolutionary and biogeographic past of individual species, modes of reproduction, contemporary community composition and shifting environmental conditions including those influenced by humans (Brochmann et al. 2003, 2004, Hewitt 2004, Lister 2004, Brochmann & Brysting 2008, O’Corry-Crow 2008, Derry et al. 2009). Because Arctic environments are remote and difficult to access, limited information is available about most of these essential factors for most species. Overcoming this lack of knowledge will require a coordinated investment to build infrastructure to enable us to apply the powerful insights provided by molecular genetic analyses as we integrate data across species and complex species assemblages as one of the pillars of future research and monitoring efforts.