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Evolutionary responses to harvesting in ungulates
Author(s) -
PROAKTOR G.,
COULSON T.,
MILNERGULLAND E. J.
Publication year - 2007
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1111/j.1365-2656.2007.01244.x
Subject(s) - biology , reproduction , population , density dependence , ecology , selection (genetic algorithm) , productivity , reproductive success , zoology , demography , macroeconomics , artificial intelligence , sociology , computer science , economics
Summary1 We investigate the evolutionary responses to harvesting in ungulates using a state‐dependent, stochastic, density‐dependent individual‐based model of red deer Cervus elaphus (L.) females subject to different harvesting regimes. 2 The population's mean weight at first reproduction shifts towards light weights as harvesting increases, and its distribution changes from a single peak distribution under very low or high harvest rates, to a bimodal distribution under intermediate harvest rates. 3 These results suggest that, consistent with previous studies on aquatic species, harvesting‐induced mortality may drive adaptive responses in ungulates by reducing the fitness benefits from adult survival and growth in favour of early and lightweight reproduction. 4 Selective harvesting for heavy animals has no additional effect on the evolutionarily stable strategy, suggesting that harvest rate is more important than the degree of selectivity in driving adaptive responses. However, selective harvesting of light females is positively associated with maturation weights even higher than those of a nonharvested population, probably due to the reduction in the fitness value of the offspring. 5 The average number of weight at maturation strategies in the population declines but the total number of strategies across all simulations increases with harvest rate, suggesting that harvesting‐induced selection on weight at maturity overcomes the increase in strategy diversity expected from density‐dependent release. 6 Yield initially increases with harvesting due to enhanced productivity of light females experiencing density‐dependent release. However, it crashes under intense harvesting resulting in a population skewed to light, young and, therefore, less reproductive animals.