Differences in mating strategies in two closely related small ermine moth species (Lepidoptera: Yponomeutidae)

Aletta C Bakker,Wil E Van Ginkel,Peter Roessingh,Steph B.J Menken

doi:10.14411/eje.2008.031

Abstract

The degree of polyandry in a species is linked to other life history traits such as egg maturation, life span, and male ejaculate size and quality. The study of differences in mating strategies between closely related species can provide a better understanding of the evolution of these strategies and of sperm competition. Mating patterns of two closely related species of small ermine moths (Yponomeuta) were investigated in the laboratory. The average female age at first mating was higher in Y. cagnagellus than in Y. padellus. Both species mated more than once; however, Y. cagnagellus females were more likely to remate in a short time frame. Moreover, Y. cagnagellus had higher life time female mating frequencies than Y. padellus (viz., 3.0 versus 2.0). These differences in mating frequency were confirmed in the field by examining the presence of spermatophores (or their remains) in the bursa as well as sperm in the spermatheca of field-caught females.

Highlights

Theory predicts that male reproductive success should increase steadily with mating frequency, whereas females should increase their success by maximizing the number of viable eggs laid, for which usually 1–2 matings suffice (Bateman, 1948; Parker, 1970; Arnqvist & Nilsson, 2000)
Female mating patterns in the laboratory The laboratory experiment to test the remating frequency of once mated females during a 1-week period showed that 82.6% (i.e., 19 out of 23) of Y. padellus females did not remate after the first mating compared to 26.1% (i.e., 6 out of 23) of Y. cagnagellus
We investigated possible differences between the mating strategies of Y. padellus and Y. cagnagellus and assessed female mating frequencies for both species

Summary

Introduction

Theory predicts that male reproductive success should increase steadily with mating frequency, whereas females should increase their success by maximizing the number of viable eggs laid, for which usually 1–2 matings suffice (Bateman, 1948; Parker, 1970; Arnqvist & Nilsson, 2000). Few species mate only once or nearly only once, such as Erebia ligea (Nymphalidae) and Aphantopus hyperanthus (Nymphalidae; Wiklund, 1982; Svärd & Wiklund, 1989), and many mate 1–2 times (Drummond, 1984; Svärd & Wiklund, 1989). Others, such as Euxoa perolivalis (Noctuidae), mate more than ten times (Byers, 1978). Within species, individual female mating frequencies can differ widely; for example, in laboratory experiments with Pieris napi (Pieridae) females, which had mating opportunities with non-virgin males throughout their life span (about 15 days), females mated between two and more than ten times (see Bergström et al, 2002)

Methods

Results

Conclusion