Subsocial Cockroaches Nauphoeta cinerea Mate Indiscriminately with Kin Despite High Costs of Inbreeding.

Sofia Bouchebti,Virginie Durier,Cristian Pasquaretta,Colette Rivault,Mathieu Lihoreau,Peter Schausberger

doi:10.1371/journal.pone.0162548

Abstract

Many animals have evolved strategies to reduce risks of inbreeding and its deleterious effects on the progeny. In social arthropods, such as the eusocial ants and bees, inbreeding avoidance is typically achieved by the dispersal of breeders from their native colony. However studies in presocial insects suggest that kin discrimination during mate choice may be a more common mechanism in socially simpler species with no reproductive division of labour. Here we examined this possibility in the subsocial cockroach Nauphoeta cinerea, a model species for research in sexual selection, where males establish dominance hierarchies to access females and control breeding territories. When given a binary choice between a sibling male and a non-sibling male that had the opportunity to establish a hierarchy prior to the tests, females mated preferentially with the dominant male, irrespective of kinship or body size. Despite the lack of kin discrimination during mate choice, inbred-mated females incurred significant fitness costs, producing 20% less offspring than outbred-mated females. We discuss how the social mating system of this territorial cockroach may naturally limit the probability of siblings to encounter and reproduce, without the need for evolving active inbreeding avoidance mechanisms, such as kin recognition.

Highlights

Inbreeding–the reproduction of closely related individuals–increases homozygosity and the expression of deleterious recessive alleles, often resulting in a reduction of fitness traits in the progeny known as inbreeding depression [1,2]
We examined the influence of kinship on mate choice in the subsocial cockroach N. cinerea
We found that females mated preferentially with dominant males irrespective of their relatedness to them and despite significant costs of inbreeding on offspring production

Summary

Introduction

Inbreeding–the reproduction of closely related individuals–increases homozygosity and the expression of deleterious recessive alleles, often resulting in a reduction of fitness traits in the progeny known as inbreeding depression [1,2]. Post-copulatory mechanisms can reduce the fertilisation success of inbred matings, such as male-female gamete incompatibility [21,22] or cryptic female choice (e.g. when females prevent complete ejaculation, discard sperm, or reduce the number of offspring produced) [23,24,25,26]. These mechanisms are important in group-living animals, when individuals are the most likely to encounter close relatives and mate with them [2,8,9]

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