SPM Journal Club: Sex-selective Harvest and Trait Change in Males
Traditionally, population models are often built using only the female half of a population and males are considered nothing but "ecological noise". However, males do matter, and particularly so when there is sex-selective harvest going on.
We are discussing a recent paper that uses an Integral Projection Model to investigate the effects of sex-selective harvest on the demography of male Red deer, as well as the resulting changes in a characteristic, male-only trait: Antler size:
Hunting is a common component in the management of ungulate species. Despite its widespread use, the influence of selective harvesting on phenotypic trait change is still ambiguous, and represents a critical gap in our understanding of the responses of wild populations under harvest. Using the long-term red deer (Cervus elaphus) dataset (1972–2012) from the Isle of Rum National Nature Reserve, Scotland, we assessed the relationship between antler length and key demographic processes (i.e., survival, recruitment, antler growth, parent-offspring trait correlation) for the male component of the population. We then constructed the first integral projection model for this species to examine the effects of simulated trophy hunting on 2 population-level parameters: the stable antler size distribution and the relative reproductive value of males. When male mortality rates due to hunting were <20%, the effect on antler size distribution and the reproductive value function were relatively small. However, as mortality due to hunting increased to 50% in large individuals, the direct effects of hunting on mean antler size and reproductive value became evident. Our model acts as a useful starting point to investigate the ecological and evolutionary consequences of hunting in red deer. © 2016 The Wildlife Society.