Title

Changing costs of reproduction: age-based differences in reproductive allocation and escape performance in a livebearing fish

Keywords

reproductive value hypothesis, reproduction, fecundity, escape velocity

Abstract

The reproductive value hypothesis predicts that if residual reproductive value declines as a female ages, then young females should allocate less of available energy to current fecundity and more to future reproduction; whereas, older females should allocate more of available energy to current fecundity and less to future reproduction (i.e. survival). We test the prediction that older female Gambusia affinis exhibit higher levels of allocation to reproduction (i.e. fecundity) and consequently experience greater decline in escape performance (survival cost) during pregnancy compared to young females. Old females had relatively larger clutch wet masses and clutch wet mass increased more during pregnancy compared to young females. Correspondingly, old females exhibit a significant decline in escape velocity over the course of pregnancy; whereas young females show no change in escape velocity throughout pregnancy. Old females have higher escape velocities early in pregnancy and their performance only declines to about the level of performance of young females by the end of pregnancy. Thus, although old females exhibit a greater decline in performance they are better able to ameliorate the cost of decreased performance.

Original Publication Citation

Belk, M.C., and R.C. Tuckfield. 2010. Changing costs of reproduction: age-based differences in reproductive allocation and escape performance in a livebearing fish. Oikos 119:163-169.

Document Type

Peer-Reviewed Article

Publication Date

2009-12-23

Publisher

Oikos

Language

English

College

Life Sciences

Department

Biology

University Standing at Time of Publication

Full Professor

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