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The case for genetics in conservation…
Written in the DNA of every individual are not just the instructions for building the organism, but also the history of its ancestors. When populations of individuals are analyzed together, their DNA can tell an even larger story of population dynamics, demography and divergences, both recent and ancient. Genetic approaches allow us to interpret the historical information contained in DNA, which can provide insights difficult or otherwise impossible to obtain. The DNA of populations can also influence the future, as it is the genetic variation within populations and the resulting differential fitness that is the raw material on which natural selection acts.
The central goal in my research is to apply the principles of population genetics to provide information that is useful for conserving populations. |
Research Themes
Genetic Diversity Change over Time
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Monitoring the level of genetic diversity within a population provides critical information about how resilient the population is likely to be in the face of environmental change. But, even more informative is understanding how genetic diversity has changed over the recent past. Historical and ancient DNA samples can be used to provide information on baseline levels of diversity in the past, and measure directly how it has changed. See the recent publication in TREE highlighting how ancient and historical DNA can be used to inform conservation policy.
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Monitoring the Structure of Wildlife Populations |
Often there are invisible boundaries between populations within a species, where restricted gene flow or adaptation leads to genetic differentiation. By detecting and monitoring the strength and locations of these boundaries, we can identify factors impacting populations and delineate appropriate conservation units to target actions towards.
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Evaluating the Impacts of Conservation Actions |
Understanding how populations have responded to conservation interventions is important for justifying the costs and trade-offs associated with such actions. Genetic approaches can allow us to see the evolutionary impact of these initiatives and whether they are achieving their started goals, whether that is the maintenance of genetic diversity, or the restoration of gene flow.
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Informing the Scientific Management of Ex Situ Populations
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Although it is never the first choice, sometimes populations need to be conserved outside of their natural home. Captive breeding and head-starting can be effective tools for sustaining populations while the cause of their decline is addressed. It is important that ex situ initiatives are scientifically managed to maintain healthy, genetically diverse and representative populations.
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Research Highlights
Galapagos giant tortoises
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Galapagos tortoises are iconic emblems of both evolutionary biology and the fight to save species from the brink of extinction, making them a unique study system to study basic questions in ecology and evolution that has applied conservation implications and huge levels of public interest.
Recent projects include the discovery of a new extinct lineage of tortoise on San Cristobal Island (open access publication here, news coverage by Vice, Natural History Museum and the Heredity podcast), and population genomic analyses of whole genomes (publication here). |
BEARWATCH
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A large, collaborative group has been formed to work towards developing a more dynamic and real-time monitoring system for polar bears that includes northern people in the process. My role in this is to use population genomics to better understand how polar bear populations are structured in the Canadian Arctic today, worked published in Ecology and Evolution, available open access here, We next would like to understand how this structure has changed over the past two decades. We are working towards developing a set of genetic markers that will be used to identify individual polar bears from their scat as part of a community based monitoring project.
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Synthesis of Genetic Resources for Captive Species |
Despite the wide-spread recognition that captive populations must be scientifically managed, there has been resistance to the use of empirical population genetic data to guide breeding. Many arguments against it are "straw men", but one genuine barrier to the adoption of empirical genetic information within the captive population management community, is the availability of genetic resources from which to build a monitoring system, and a baseline understanding of the genetic structure of wild populations. Along with collaborators from the Toronto Zoo, we are conducted a systematic literature review of population genetic studies to synthesize published genetic resources for amphibian, bird, mammal and reptile species held in captivity and evaluating their availability, scale, limitations and potential for informing ex situ management across these taxonomic groups. This work was published in Zoo Biology, link here.
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Ex Situ Conservation
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I have worked on projects in collaboration with Dr, Yoamel Milián-García, helping to provide information for the management of captive breeding programs for Cuban Parrots and Cuban Crocodiles, and a central part of my Ph.D. thesis was evaluating a 50-year long head-start program for the Pinzón Island Giant Tortoise. I also co-wrote a book chapter with my Ph.D. advisor Dr. Michael Russello on the genomics of ex situ conservation, which will be available soon.
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Prioritizing Taxa
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I hate to admit it, but perhaps we can’t save every species from extinction. Resources for conservation are limited, and tough decisions about priories need to be made. One rational basis for determining priorities is ensuring that extinctions do not result in inordinate losses of evolutionary history; for it's intrinsic value perhaps, but also because we assume that it represents evolutionary potential and trait diversity (among other things). Numerous methods have been proposed to rank taxa based on the importance of the phylogenetic diversity they contribute, but these fail to take into account complementarity. Along with coauthors, including Dr. Arne Mooers, I proposed a new metric that integrates evolutionary isolation, probability of extinction and complementarity: I-HEDGE.
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Historical DNA
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Natural history collections throughout the world are filled with biological samples that represent a treasure trove for evolutionary studies. The arrival of the genomics era has opened the door for using historical specimens in conjunction with contemporary samples. Empirical evolutionary studies incorporating genomic data from several generations of even the most long-lived species are now possible, including the Galápagos Giant Tortoises. One of the most exciting parts of my PhD research was capturing RAD loci and whole mitochondrial genomes from 110-year old museum specimens of Pinzón and Española Tortoise. These data allowed us to peek into the past of these species to understand historical levels and patterns of genetic diversity and better appreciate what was lost when they became endangered, and what was saved by the head-start program. Aspects of this project have been published in the Journal of Heredity and Evolutionary Applications.
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Photograph by Josh Miller.
