Sexual dimorphism of life history strategies in the biparental burying beetle, Nicrophorus orbicollis
Abstract
Organisms are selected to maximize lifetime reproductive success by balancing the costs of current reproduction with costs to future survival and fecundity. However, as an organism ages its chances for an additional reproductive bout decrease, so it is expected to increase effort toward current reproduction. This is the Terminal Investment Hypothesis. An alternative life history strategy has been termed Reproductive Restraint. This idea predicts that bodily damage causes a decrease in an organism's level of effort as they age, and this decrease in effort may increase the organism's fitness through more reproductive opportunities. In this study we assess the cost of reproduction in male and female Nicrophorus orbicollis. By comparing males and females that reproduced normally with those that did not provide post-hatching care or never reproduced during their lifetimes, we are able to quantitatively determine the costs of reproduction for males and females in terms of several fitness characteristics. Our results show that there is a cost to reproduction in both males and females, but the sexes respond to these costs differently. Females are more negatively affected by reproduction on a large carcass and by over-reproduction than males. We found terminal investment in males and females, but we also found reproductive restraint in males when they reproduced on low-quality carcass. This study provides clear evidence for differences in the reproductive strategies of males and females and is the first study that is able to directly compare costs of reproduction between the sexes.
Degree
M.S.
Advisors
Creighton, Purdue University.
Subject Area
Behavioral Sciences
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