Intraspecific variation in biology and ecology of deer: magnitude and causation (Plenary lecture)

PUTMAN, R; FLUCK, WT

Huilo Huilo

Congreso; 7th International Deer Biology Congress; 2010

It has been noted that the search for patterns in biology to assist our understanding, often leads toover-simplification. That is, we are satisfied with statements that ‘the species as a rule does this’ or, ‘males of thisspecies do that’. But within such generalisations are masked what are often important variations from that supposed normand in practice there is tremendous variation in morphology, physiology, social organisation and behaviour of any onespecies. The focus on a supposedly mean optimal phenotype has diverted attention away from variation around thatmean, which is regularly regarded as a kind of ‘noise’ stemming merely from stochastic effects, and thus irrelevant toevolution. Yet it is becoming increasingly clear that this variation is by converse extremely significant and of tremendousimportance both to evolutionary biologists and to managers. Such intraspecific variation (IV) may be directly due tounderlying genetic differences between individuals or populations within a species, but equally may include a degree ofphenotypic plasticity whether as ‘non-labile’, traits which are expressed once in an individual’s lifetime, as fixedcharacteristics inherited from the parents or as more labile traits which are expressed repeatedly and reversibly in amature individual according to prevailing conditions.Recognition of the extraordinary degree of IV which may be recorded within species has important consequences formanagement of cervids and conservation of threatened species. We review the extent of IV in diet, in morphology, maturebodyweight, reproductive physiology, in population demography and structure (sex ratio, fecundity, frequency ofreproduction) before also reviewing the striking variation to be observed in behaviour: differences between individualsor populations in ranging behaviour, migratory tendency, differences in social and sexual organisation. In each case weexplore the factors which may underlie the variation observed, considering the extent to which variation described has aprimarily genetic basis or is a more plastic response to more immediate social and ecological cues.