Male-biased predation and its effect on paternity skew and life history in a population of common brushtail possums (Trichosurus vulpecula).
Differences in predation risk may exert strong selective pressures on life history strategies of populations. We investigated the potential for predation to shape male mating strategies in an arboreal folivore, the common brushtail possum (Trichosurus vulpecula Kerr). We predicted that possums in a tropical population exposed to high natural levels of predation would grow faster and reproduce earlier compared to those in temperate populations with lower predation. We trapped a population of possums in eucalypt woodland in northern Australia each month to measure life history traits and used microsatellites to genotype all individuals and assign paternity to all offspring. We observed very high levels of male-biased predation, with almost 60% of marked male possums being eaten by pythons, presumably as a result of their greater mobility due to mate-searching. Male reproductive success was also highly skewed, with younger, larger males fathering significantly more offspring. This result contrasts with previous studies of temperate populations experiencing low levels of predation, where older males were larger and the most reproductively successful. Our results suggest that in populations exposed to high levels of predation, male possums invest in increased growth earlier in life, in order to maximise their mating potential. This strategy is feasible because predation limits competition from older males and means that delaying reproduction carries a risk of failing to reproduce at all. Our results show that life histories are variable traits that can match regional predation environments in mammal species with widespread distributions.
Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia; School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales, Australia.
Jane L
JL
DeGabriel
School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales, Australia.
Ben D
BD
Moore
Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
William J
WJ
Foley
School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia.
Christopher N
CN
Johnson
D000818:Animals; D005260:Female; D014644:Genetic Variation; D008018:Life Cycle Stages; D008297:Male; D018895:Microsatellite Repeats; D010334:Paternity; D012098:Reproduction; D048330:Trichosurus / Q000235:genetics