How Do Females’ Genetic Characteristics Influence Male Mate Preference in the Terrestrial Isopod Armadillidium vulgare?

Abstract

Genetic diversity is a key factor that can influence mate choice in many species. We experimentally determined the influence of this factor on mate preference in the crustacean terrestrial isopod Armadillidium vulgare. This biological model is gregarious which could increase the risk of inbreeding by mating with closely related partners. Mechanisms of inbreeding avoidance during mate choice can thus be expected. Moreover, previous studies predict that males would be the choosy sex. We performed Y-choice tests giving males the choice between two females presenting different levels of heterozygosity and genetic similarity to the male. Our results show potential inbreeding avoidance according to the genetic characteristics of females presented to males. The higher the variation in genetic similarity to the male between females is, the higher the preference of the male towards the most dissimilar female is. Hence, male preferences may only be detectable when the difference between females' genetic characteristics is large enough. If heterozygosity is associated with fitness in A. vulgare (as in many organisms), the patterns of mate preference we observe may be adaptive.

Producing offspring in Armadillidium vulgare: Effects of genetic diversity and inbreeding

“…If ever present, correlations between heterozygosity and genetic similarity are usually negative (Roberts, Hale, & Petrie, ). We did not detect such correlation in experiment 1, nor for female heterozygosity in experiment 2, or in other studies carried on this species using the same molecular markers (Durand et al, , ). Consequently, the correlation between male heterozygosity and parental genetic similarity is very unlikely to reflect any biological relationship, and might solely result from the random assignation of heterozygous males to more similar partners in experiment 2.…”

“…DNA from all the adult individuals (n = 82) was extracted using a phenol-chloroform extraction as in Durand et al (2015). DNA was diluted to 1/20th prior to PCR.…”

“…For each adult and pullus sample, eleven microsatellite markers (Giraud, Valette, Bech, Grandjean, & Cordaux, 2013;Verne et al, 2006) were gathered into three multiplexes using 5′ fluorescein labeled forward primers, and amplified in the same conditions as in Durand et al (2015) (Appendix S2). However, because the aim was not to obtain the full genotype of the individual but to determine whether the egg was fecundated (i.e., whether paternal alleles were present or not), only one multiplex was amplified for the egg samples.…”

“…Mating strategies expected to optimize offspring genetic diversity have already been highlighted in this species. Males presented to two unrelated females display a precopulatory preference toward the most genetically dissimilar female, provided both females offer a wide enough range of genetic similarity to the male (Durand, Beauché, Richard, & Beltran-Bech, 2015). Moreover, when two males are allowed to reproduce simultaneously with the same female, paternity success is higher for the most heterozygous male, and in cases where a single male produces offspring, this male is the most dissimilar to the female (Durand, Cohas, Braquart-Varnier, & Beltran-Bech, 2017).…”

Multiple paternity in a wild population of Armadillidium vulgare: influence of infection with Wolbachia?

“…All PCRs were carried out according to the manufacturer's standard microsatellite amplification protocol in a final volume of 10 μL and an annealing temperature of 57 °C, as described in Durand et al . (); 1 μL of PCR product was added to 9 μL formamide and 0.5 μL ROX standard (Life Technologies, Applied Biosystems, Foster City, CA, USA), and the amplified fragments were separated by electrophoresis on an ABI PRISM R_3130xl ® Genetic Analyzer. Fragment size was determined using GeneMapper ® version 3.7 (Applied Biosystems), followed by visual verification.…”