Are Hunters Driving Natural Selection?
A few studies in the early 2000’s found that hunting was influencing directional selection
A few studies in the early 2000’s found that hunting was influencing directional selection. That is, by selecting for the largest animals with the biggest adornments (trophy selection), hunting pressure was selecting for the smaller animals. Over time, reports began to surface indicating this was occurring in vulnerable populations such as Bighorn Sheep in British Columbia (one of the more widely read studies).
A new study argues the effects of directional selection are not documented well enough to make wider assumptions about populations pressured by hunting. They argue that hunting intensity is more influential than general hunting pressure due to the varied animals hunters tend to take. Many hunters take animals for meat without caring much for large antlered animals, for example.
Read more about the study here.
The study is a literature review of near fifty sources in an attempt to draw a conclusion on the most recent data regarding directional selection. They make the argument that evidence of directional pressures by trophy selection is rare and that it may be possible to offset selection pressures by selecting for younger and smaller individuals along with trophy selection, thus mirroring a “natural population structure”.
After reviewing a few of the sources, the study is credible. If directional selection is occurring in areas valued for trophy animals, more research is needed to determine how widespread the phenomenon may be. Hunting can be a strong influence on selection under certain circumstances, but this study has shown that strong directional selection events appear to be rare. It is particularly interesting to note that populations of animals in areas of low trophy value may be selected in ways that maintain a diverse population structure and healthy herd.
(Bighorn Sheep photo sourced from Wikipedia Commons)