Evolutionary and population ecology of large mammals

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My long-term research program seeks to understand how individual differences develop and how they affect population dynamics and evolutionary processes. Because the fitness consequences of changes in resource abundance vary according to individual characteristics, individual differences are key determinants of both evolutionary potential and population ecology. By monitoring individually-marked wild mammals from birth to death, my research group documents variation in morphology, genotype, reproductive success and survival. Using data on known individuals collected over several generations, we now can test hypotheses about how lifetime reproduction, a proxy of fitness, is affected by of early development or parental characteristics. Based on exceptionally detailed data on over 1300 bighorn sheep (54 years by 2023) and 1600 kangaroos (16 years), working with an international network of collaborators and innovative statistical techniques, over the next 5 years I will train 11 HQP. We will test hypotheses on life-history evolution, including the effects of growth patterns on reproductive success in both sexes and on reproductive allocation in females. Mixture models will identify clusters of both male and female bighorn sheep based on early growth. We will then determine if clusters are associated with different lifetime reproductive tactics. Bighorn mothers show much individual variation in allocation to lactation: I hypothesize that some of that variation can be explained by parental age and by early growth patterns. We will study age-specific allocation to reproduction in kangaroos: with indeterminate growth, the reproductive value of mothers may remain higher than that of offspring into old age, selecting against the greater allocation to reproduction with age predicted by the Terminal Investment Hypothesis. We will determine whether female kangaroo, bighorn sheep and mountain goats skip reproductive opportunities as part of a tactic, or are simply constrained by resource availability. Results on individual reproductive tactics will inform research on population dynamics. Kangaroos face an unpredictable environment: the flexible reproductive allocation of females according to forage abundance may drive changes in recruitment and explain the wide changes in population growth. In bighorn sheep, we will investigate the genetic and demographic consequences of an experimental translocation to rescue a population affected by inbreeding.