Understanding the strength and demographic consequences of inbreeding depression in the wild, and the subsequent implications for conservation

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The negative fitness consequences associated with inbreeding, as well as their avoidance, represent some of the central factors shaping the biology of animal populations. These range from individual-based effects such as on behaviour and fitness, to population-wide effects such as on population growth rates and extinction probabilities. Inbreeding has therefore been a key topic of biological interest for over a century. Despite this long-term interest, our understanding of the strength and demographic consequences of inbreeding depression in the wild is still in its infancy. This situation results from two main constraints. First, much of our understanding still comes from studies of laboratory and captive populations, where conditions and selection pressures are relatively homogeneous and benign, resulting in underestimates of the effects of inbreeding depression. The second constraint is that, until recently, studies have had low power to quantify individual inbreeding coefficients with reasonable accuracy and precision. The main goal of the proposed work is to improve this understanding by overcoming these constraints through the combination of long-term individual-based field studies and high-density SNP genotypes to quantify the impacts of inbreeding on individual health, reproductive success, and survival in the endangered North Atlantic right whale (Eubalaena glacialis); and to assess how these individual effects combine to shape population growth rates and recovery potential. My approach will have five major components. The first will be to genotype individuals at tens of thousands of SNPs to provide dense marker panels required for estimating inbreeding coefficients with high precision and accuracy. For step 2 use these data to quantify the impact of inbreeding on reproductive performance. In step 3 we will quantify the impact of inbreeding on individual health and survival. For step 4 we will conduct individual-based population viability analyses to assess how the identified impacts of inbreeding on individual fitness scale-up to influence the recovery potential and viability of this species. Lastly, for step 5 we will conduct preliminary tests for "outlier loci" to see if one or more loci stand out as particularly strong drivers of these effects. This work will have substantial impacts at two different scales. At a narrow scale it will identify the degree to which inbreeding is shaping patterns of individual fitness, and how these individual effects combine to limit the recovery potential of this endangered species. At a broader scale, this work will provide much needed information on the strength and demographic consequences of inbreeding depression in the wild, the subsequent effects on recovery potential and population viability, and the implications for conservation.