Life history and mating systems select for male biased parasitism mediated through natural selection and ecological feedbacks.
tlsb-1%Males are often the 'sicker' sex with male biased parasitism found in a taxonomically diverse range of species. There is considerable interest in the processes that could underlie the evolution of sex-biased parasitism. Mating system differences along with differences in lifespan may play a key role. We examine whether these factors are likely to lead to male-biased parasitism through natural selection taking into account the critical role that ecological feedbacks play in the evolution of defence. We use a host-parasite model with two-sexes and the techniques of adaptive dynamics to investigate how mating system and sexual differences in competitive ability and longevity can select for a bias in the rates of parasitism. Male-biased parasitism is selected for when males have a shorter average lifespan or when males are subject to greater competition for resources. Male-biased parasitism evolves as a consequence of sexual differences in life-history that produce a greater proportion of susceptible females than males and therefore reduce the cost of avoiding parasitism in males. Different mating systems such as monogamy, polygyny or polyandry did not produce a bias in parasitism through these ecological feedbacks but may accentuate an existing bias.
IFISC(CSIC-UIB) Instituto de Física Interdisicplinar y Sistemas Complejos, Campus Universitat Illes Balears, E-07122 Palma de Mallorca, Spain. florabacelar@ifisc.uib-csic.es
Flora S
FS
Bacelar
Andrew
A
White
Mike
M
Boots
D000818:Animals; D015982:Bias; D005075:Biological Evolution; D018562:Disease Transmission, Infectious; D017753:Ecosystem; D025461:Feedback, Physiological; D005260:Female; D008018:Life Cycle Stages / Q000502:physiology*; D008297:Male; D010271:Parasites / Q000254:growth & development*; D012641:Selection, Genetic; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*