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The potential for disruptive selection on growth rates across genetically influenced alternative reproductive tactics

Author

  • M. R. Morris
  • R. J. Friebertshauser
  • O. Rios-Cardenas
  • M. N. Liotta
  • J. K. Abbott

Summary, in English

A trade-off between survival to sexual maturity and mating success is common across alternative reproductive tactics (ARTs), and can lead to tactical disruptive selection on shared traits (i.e. positive selection gradient in one tactic, and negative selection gradient in another). We were interested in examining the theoretical possibility of tactical disruptive selection on intrinsic growth rate. The male ARTs in Xiphophorus multilineatus express two distinct life histories: “courters” optimize mating success by maturing later at larger size and coaxing females to mate, while “sneakers” optimize survival to sexual maturity by maturing earlier at a smaller size, using both coaxing and coercive mating behaviors. In addition to differences in mating behaviors, body length, body depth, and the pigment pattern vertical bars, courter males grow faster than sneaker males. We present a new hypothesis for differences in growth rates between genetically influenced ARTs. The “growth-maturity optimization” hypothesis suggests that ARTs with differences in the probability of surviving to sexual maturity may have different optimal growth rates, leading to tactical disruptive selection. We also present a simple model to suggest that when considering both a cost and benefit to faster growth, tactical disruptive selection on growth rates is theoretically possible. In our model, the value that determines when tactical disruptive selection on growth rate will occur is the increase in probability of survival to sexual maturity gained through faster growth multiplied by the cost of faster growth (reduced longevity). Finally, we present empirical evidence to support the prediction that faster growth has a cost in X. multilineatus: in a controlled laboratory setting, courter males that did not survive 1.2 years past sexual maturity grew faster as juveniles (14–70 days) than those that survived.

Department/s

Publishing year

2016-06-01

Language

English

Pages

519-533

Publication/Series

Evolutionary Ecology

Volume

30

Issue

3

Document type

Journal article

Publisher

Springer

Topic

  • Ecology

Keywords

  • Alternative reproductive tactics
  • Melanincortin-4 receptor gene
  • Mortality growth trade-off
  • Tactical disruptive selection
  • Xiphophorus
  • “Growth-maturity optimization” hypothesis

Status

Published

Research group

  • Genetics of Sex Differences

ISBN/ISSN/Other

  • ISSN: 0269-7653