Managing wildlife for ecological, socioeconomic, and evolutionary sustainability

Abstract

Selective harvesting of animals is widespread throughout the marine, freshwater, and terrestrial environments and affects a diverse list of species, including fish, mammals, birds, and reptiles (1). Such harvesting can cause changes in the distribution of phenotypic traits within target populations, often with undesirable biological and economic consequences. For example, selective harvesting has been linked to declines in the size of trophy horns in two antelope species in Zimbabwe (2) and of antlers in red deer (Cervus elaphus) in Europe (3, 4), as well as to earlier maturation in some fish species (5). However, the extent to which these changes are the result of ecological or evolutionary mechanisms has been much debated (1). In PNAS, Traill et al. (6) approach this question from a novel angle by developing stochastic two-sex integral projection models (IPMs) capable of differentiating between the ecological and evolutionary effects of selective harvest. Their finding that evolutionary mechanisms contribute relatively little to observed changes in the body mass of bighorn sheep (Ovis canadensis) is an intriguing contribution to the debate over the evolutionary consequences of selective offtake, contradicting earlier studies (7). In addition, Traill et al. (6) suggest that their method could be adopted more widely to allow wildlife managers and conservation practitioners to incorporate the potential evolutionary effects of selective harvesting into their management planning. Here, we explore this suggestion by discussing key challenges that would need to be addressed to translate the approach by Traill et al. (6) from a purely biological model to an effective management model, focusing particularly on issues of data availability and the incorporation of different forms of uncertainty

The evolutionary legacy of size‐selective harvesting extends from genes to populations

“…; Jørgensen et al. ; Andersen and Brander ; see also Bunnefeld and Keane ). Although exploited fish populations can consist of individuals of reduced average adult body size for both demographic and evolutionary reasons (Jørgensen et al.…”

An adaptive behavioural response to hunting: surviving male red deer shift habitat at the onset of the hunting season

“…Harvested populations have shown substantial alteration of morphological and life history traits with net documented changes in these types of traits averaging 18% and 25%, respectively (Darimont et al, 2009). Yet, distinguishing between ecological and evolutionary causes is neither a trivial nor a simple matter (Bunnefeld & Keane, 2014;Fenberg & Roy, 2008) and, in one recent study, demographic changes resulting from hunting explained observed phenotypic changes that were earlier attributed to evolution (Traill, Schindler, & Coulson, 2014). Still, potential evolutionary impacts of harvesting deserve consideration in applied management and conservation efforts, not least because they can be difficult to reverse (Bunnefeld & Keane, 2014;Coltman et al, 2003;Darimont et al, 2009;Fenberg & Roy, 2008).…”

“…Yet, distinguishing between ecological and evolutionary causes is neither a trivial nor a simple matter (Bunnefeld & Keane, 2014;Fenberg & Roy, 2008) and, in one recent study, demographic changes resulting from hunting explained observed phenotypic changes that were earlier attributed to evolution (Traill, Schindler, & Coulson, 2014). Still, potential evolutionary impacts of harvesting deserve consideration in applied management and conservation efforts, not least because they can be difficult to reverse (Bunnefeld & Keane, 2014;Coltman et al, 2003;Darimont et al, 2009;Fenberg & Roy, 2008). 'Unnatural' selection from hunting can potentially also affect heritable behavioural traits (Allendorf & Hard, 2009), but there is still limited knowledge of the link between harvesting by humans and animal behaviour.…”

Modeling the impact of selective harvesting on red deer antlers

“…Integral projection models offer a powerful tool for understanding the phenotypic and life‐history consequences of harvesting (Bunnefeld and Keane , Traill et al ). Our study offers valuable insights into how trophy hunting may influence reproductive value and mean antler size in red deer at unusually high hunting quotas (>50%).…”