Abstract

The intensity of mating competition and the potential benefits for female of mating with certain males can be influenced by several extrinsic factors, such that behavioral decisions can be highly context-dependent. Short-lived species with a single reproductive season are a unique model to study context-sensitive mating decisions. Through exhaustive sampling in the field and simultaneous choice tests in the laboratory, we evaluated operational sex ratio (OSR) and female mate choice at the beginning and end of the reproductive season in the annual killifish Austrolebias reicherti. We found seasonal change in both OSR and female mate choice. At the start of the reproductive season the OSR did not deviate from parity, and females preferred larger males. Later in the reproductive season, while the proportion of males in the ponds decreased, females became unselective with respect to male size. The particular biological cycle of annual killifish, where both life expectancy and mating opportunities decline sharply over a short timescale, could account for the seasonal change in female choice. Reduction in choosiness could arise from diminished reproductive prospects due to a decline in male availability. Moreover, as the end of the season approaches, any benefits of choosiness are presumably reduced: a female’s fitness will be higher if she mates with any male than if she forgoes reproduction and dies. Future work will disentangle the mechanisms underlying seasonal changes in mating preferences, notably direct responses to demographic factors, environmental cues, or intrinsic changes during development.

Highlights

  • Sexual selection results in differential reproductive success among individuals of the same sex [1]

  • The interaction time that females spent in the choice zones did not differ significantly at the beginning and end of the reproductive season, and there was no relationship between time spent interacting with males and female size (Pearson correlation: r52 = 0.144, P = 0.310)

  • We found seasonal change in both operational sex ratio and female mate choice in the annual killifish Austrolebias reicherti

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Summary

Introduction

Sexual selection results in differential reproductive success among individuals of the same sex [1]. [3,4,5,6]) Animals that expend their entire reproductive effort over the course of a single season provide a distinctive opportunity to study context-sensitive mating decisions. We examined mate choice in the annual killifish Austrolebias reicherti (Teleostei: Rivulidae). These fish live in temporary ponds that dry out completely during the dry summer months; lifespan is restricted by the duration of the pond, usually between 4 and 6 months [7]. Individuals hatch, mature, reproduce, and die within the span of a very short season. They complete their life cycle in ,1 year, with no overlapping generations

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