Sex-specific rejection in mate-guarding pair formation in the intertidal copepod, Tigriopus californicus.

Satomi Tsuboko-Ishii,Ronald S Burton

doi:10.1371/journal.pone.0183758

Satomi Tsuboko-Ishii, Ronald S Burton

Open Access

https://doi.org/10.1371/journal.pone.0183758

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Abstract

Securing a potential mate is one of the most important processes in sexual reproduction of animals. Intertidal copepods of the genus Tigriopus show mate-guarding behavior where a male captures a female and continues to clasp her for up to two weeks prior to copulation. Although these copepods form a mate-guarding pair between a male and a female with high accuracy, interactions between the sexes in pair formation have not been well described and the mechanism allowing successful male-female pair formation is not yet understood. In this study, we performed experiments with Tigriopus californicus to analyze the behavior of both a capturer (male) and a captured individual (female or male) in formation of a guarding pair. While capturer males were attracted by both females and males, capture of virgin males was terminated in a significantly shorter time than that of virgin females. However, when presented freshly killed females or males, regardless of the sex of the body, capturer males continued to clasp the body for a comparable time as in an attempt on a living female. Our results suggest that a sex-specific rejection signal actively sent by captured males prevents male-male pair formation. Experiments also suggest that mated females reject an attempt of pair formation. To our knowledge, this is the first study to suggest involvement of active rejection by a captured individual in facilitation of reproductively successful male-female guarding pair formation in the genus Tigriopus.

Highlights

Reproducing animals employ various strategies for securing a mate
While no significant difference was detected in the frequency of attempts between malefemale pairs and male-male pairs (Fig 2A; p = 0.13, Mann-Whitney U test), a significant difference was detected in the average duration of capture. These results suggest that males can be attracted to both males and females and sex-specific interruption or continuation of capture are involved in the process of mate-guarding pair formation
To examine if a mature female is more attractive than a juvenile to males, we presented either an adult or a copepodid stage III (CIII) juvenile to individual males and examined if frequency of guarding attempts and average duration of capture changed depending on developmental stage of a target

Summary

Introduction

In a wide range of animal taxa including crustaceans [1], insects [2], teleosts [3], rodents [4], primates [5], and humans [6], sexually mature individuals perform mate-guarding behavior, where they physically contact or stay proximate to their potential mate to prevent it from copulating with other individuals. Mate-guarding pair formation in an intertidal copepod. Copepods of the genus Tigriopus, which are common inhabitants of high intertidal rock pools, show contact mate-guarding behavior prior to copulation: in a guarding attempt, an adult Tigriopus male utilizes his geniculate antennae to capture a guarding target (juvenile or adult) [1, 8,9,10]. Formed male-female guarding pairs are often maintained until copulation following the female’s terminal molt, which can be up to two weeks in T. californicus [1]

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