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USGS Mendenhall Postdoctoral  Research Fellowship Program

14-22. Integrating habitat modeling and landscape genetics to understand impacts of climate change and energy development on species persistence and diversity in the desert southwest

Population genetic structure will play a role in the future response of species to large scale, systematic environmental changes predicted with global climate change. Persistence in the face of climate change will be determined by a species’ ability to migrate or disperse to suitable habitat, as well as to adapt to changing ecological conditions. For many species, these processes may be hindered by reductions in population size and range, local extirpation, and fragmentation caused by threats such as urbanization and other land use change. Genetic differentiation within a species’ range is ultimately determined by natural selection, genetic drift and gene flow. Selection and drift enhance genetic differences if populations are sufficiently isolated.  Although gene flow can preclude local adaptation, it can also introduce novel variation and facilitate widespread selective sweeps for strongly selected traits. Current modeling approaches for species responses to climate change rarely account for genetic structuring of populations, assuming either that gene flow is high enough that populations across a species’ range will respond similarly to the same environmental conditions, or that rates of migration will enable individuals to track changing abiotic factors (Neilson et al. 2005., Midgley et al. 2006.). However, natural and human created barriers to gene flow, such as mountains, roads and urbanization) may impede migration and gene flow across species’ ranges and impede range shifts and in situ adaptation to changing climate conditions, particularly if genetic variation is low at the leading edge of range shifts (Zakharov and Hellmann 2008).

Spatially explicit genetic data can provide information on the movement of individuals and genes across landscapes and relative levels of genetic connectivity and variability among sub-populations. Furthermore, recent advances in sequencing techniques and computing power are allowing geneticists to apply genomic approaches to conservation questions, and target both functional and neutral genetic variation. However, spatial genetic analysis tools are limited. Better analytical methods that can account for genomic data and integrate detailed environmental information are needed (Storfer et al. 2010.).  In combination with species distribution modeling, a landscape genetic approach can provide relative estimates of population genetic connectivity, and elucidate patterns of genetic diversity within a species that will affect its adaptive potential. This can aid in determining range shifts under differing climate change scenarios. Examining these patterns across multiple species can determine whether common movement corridors exist, and whether particular geographic regions contain higher than average levels of genetic diversity. Prioritizing populations with high genetic diversity or distinctiveness for protection may help retain the evolutionary potential within species in changing environments (Moritz 2002., Thomassen et al. 2011).

Such information is imperative for regional land use planning and management of adaptive potential: 1) it will identify locations where populations contain the highest levels of genetic diversity and likely have the greatest potential to evolve to environmental stressors induced by climate change, and 2) it will help to determine the most important connections between “core” preserved habitats that should be preserved and/or restored to allow for gene flow of adaptive traits.

We have begun investigating patterns of habitat suitability and intra-specific genetic diversity in animal species across the desert southwest. Human land use and modification in the arid lands of the western United States have intensified in recent decades (Leu et al. 2008.). In the Mojave Desert, for example, urbanization, agriculture, transportation networks, military operations and energy production have already altered sections of the landscape with impacts to native wildlife (Lovich and Bainbridge 1999., Webb et al. 2009.). Further land use change is projected in this region, particularly utility-scale renewable energy development (USRED) on federal lands in response to federal and state goals and mandates for renewable energy production (e.g., the American Recovery and Reinvestment Act of 2009, CA Executive Order S-14-08 and CA Senate Bill X1-2). Increasing production of renewable energy will have benefits in curtailing greenhouse gas emissions, and promoting energy independence and economic growth, but development of USRED facilities and their associated infrastructure may negatively impact local wildlife through habitat loss and fragmentation.

We seek a postdoctoral fellow with strong skills in landscape genetics/genomics, landscape ecology, geospatial statistics, or species distribution modeling that can apply innovative approaches to better understand how predicted climate and land use change will impact habitat suitability, and how changes to habitat suitability may further impact levels and distribution of genetic diversity across species ranges in the desert Southwest.  The overarching goal of our research program is to assess climate and land use impacts to intraspecific genetic diversity and biodiversity, and to develop science-based tools to inform decision-making in the desert southwest.  In our work to date, we have created habitat suitability models and mapped patterns of neutral genetic diversity for multiple animal species. We have analyzed these in combination to determine regions of high habitat suitability and high genetic diversity within species and for the species assemblage as a whole. In addition we are currently investigating potential habitat and genetic diversity loss due to projected renewable energy and other development (Nussear et al. 2009., Wood et al. 2012., Inman et al. 2013., Vandergast et al. 2013). This foundation will allow expansion to address impacts of climate change on this system.

Applicants may propose postdoc research projects centered on a number of themes including: 1) spatially explicit modeling of population processes  to predict changes to patterns of genetic diversity in target species under different land use and climate scenarios; 2) expanding methods to model species distributions under climate change and assess the significance of these changes, and 3) empirical hypothesis testing to understand environmental correlates and other landscape factors associated with high neutral and adaptive variation within select species.  Significant data have been amassed to support these research themes including species occurrence data, and genetic data for herpetofauna, small mammals and invertebrate species throughout the study region, and derivatives of downscaled Global Climate Models (e.g. climate water deficit and others, Flint and Flint 2012), and over 70 environmental data layers rasterized at the relevant spatial scales. Other resources include laboratory facilities and next generation sequencing capabilities, GIS and computing resources.

REFERENCES.

Inman, R. D., T. C. Esque, K. E. Nussear, P. Lieitner, M. D. Matocq, P. J. Weisberg, T. E. Dilts, and A. G. Vandergast. 2013. Is there room for all of us? Renewable energy and Xerospermophilus mohavensis. Endangered Species Research 20:1-18.

Flint, L. E., and A. L. Flint. 2012. Downscaling future climate scenarios to fine scales for hydrologic and ecological modeling and analysis. Ecological Processes 1:1.

Leu, M., S. E. Hanser, and S. T. Knick. 2008. The human footprint in the west: A large-scale analysis of anthropogenic impacts. Ecological Applications 18:1119-1139.

Lovich, J. E., and D. Bainbridge. 1999. Anthropogenic degradation of the southern California desert ecosystem and prospects for natural recovery and restoration. Environmental Management 24:309–326.

Midgley, G. F., G. O. Hughes, W. Thuiller, and A. G. Rebelo. 2006. Migration rate limitations on climate change-induced range shifts in Cape Proteaceae. Diversity and Distributions 12:555-562.

Moritz, C. 2002. Strategies to protect biological diversity and the evolutionary processes that sustain it. Systematic Biology 51:238-254.

Neilson, R. P., L. F. Pitelka, A. M. Solomon, R. Nathan, G. F. Midgley, J. M. V. Fragoso, H. Lischke, and K. Thompson. 2005. Forecasting regional to global plant migration in response to climate change. Bioscience 55:749-759.

Nussear, K. E., T. C. Esque, R. D. Inman, L. Gass, K. A. Thomas, C. S. A. Wallace, J. B. Blainey, D. M. Miller, and R. H. Webb. 2009. Modeling habitat of the desert tortoise (Gopherus agassizii) in the Mojave and parts of the Sonoran Deserts of California, Nevada, Utah, and Arizona: U.S. Geological Survey Open-File Report 2009-1102, 18p.

Storfer, A., M. A. Murphy, S. F. Spear, R. Holderegger, and L. P. Waits. 2010. Landscape genetics: where are we now? Molecular Ecology 19:3496-3514.

Thomassen, H. A., T. Fuller, W. Buermann, B. Mila, C. M. Kieswetter, P. Jarrin, S. E. Cameron, E. Mason, R. Schweizer, J. Schlunegger, J. Chan, O. Wang, M. Peralvo, C. J. Schneider, C. H. Graham, J. P. Pollinger, S. Saatchi, R. K. Wayne, and T. B. Smith. 2011. Mapping evolutionary process: a multi-taxa approach to conservation prioritization. Evolutionary Applications 4:397-413.

Vandergast, A. G., R. D. Inman, K. R. Barr, K. Nussear, T. Esque, S. A. Hathaway, D. A. Wood, P. A. Medica, J. W. Breinholt, C. L. Stephen, A. D. Gottscho, S. B. Marks, W. B. Jennings, and R. N. Fisher. 2013. Evolutionary hotspots in the Mojave Desert. Diversity 5:293-319.

Webb, R. H., L. Fenstermaker, and J. S. Heaton. 2009 The Mojave Desert. University of Nevada Press, Reno, NV.

Wood, D. A., A. G. Vandergast, K. R. Barr, R. D. Inman, T. C. Esque, K. E. Nussear, and R. N. Fisher. 2012. Comparative phylogeography reveals deep lineages and regional evolutionary hotspots in the Mojave and Sonoran Deserts Diversity and Distributions DOI: 10.1111/ddi.12022:1-16.

Zakharov, E. V., and J. J. Hellmann. 2008. Genetic differentiation across a laditudinal gradient in two co-occurring butterfly species: revealing population differences in a context of climate change. Molecular Ecology 17:189-20.

Proposed Duty Station: San Diego, CA; Las Vegas, NV.

Areas of Ph.D.: Landscape genetics, population genetics, landscape ecology, spatial statistics, evolution, conservation biology, or related fields (candidates holding a PhD. in other disciplines but with knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications - Research Geneticist, Research Ecologist, Research Statistician.

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant’s background, education, and research proposal. The final classification of theposition will be made by the Human Resources specialist).

Research Advisors: Amy Vandergast, (619) 225-6445, avandergast@usgs.gov.; Kenneth Nussear, (702) 564-4515, knussear@usgs.gov.; Todd Esque (702) 564-4506 , tesque@usgs.gov.

Human Resources Office Contact: Lisa James, (916) 278-9405, ljames@usgs.gov.


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U.S. Department of the Interior, U.S. Geological Survey
URL: http://geology.usgs.gov/postdoc/opps/2014/14-22 Vandergast.htm
Direct inquiries to Rama K. Kotra at rkotra@usgs.gov
Maintained by: Mendenhall Research Fellowship Program Web Team
Last modified: 10:11:50 Wed 24 Jul 2013
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