TY - JOUR
T1 - Evolutionary genetics of genital size and lateral asymmetry in the earwig Euborellia plebeja (Dermaptera
T2 - Anisolabididae)
AU - Kamimura, Yoshitaka
AU - Iwase, Ryota
PY - 2010/9
Y1 - 2010/9
N2 - Male genitalia show several evolutionary characteristics, including rapid morphological divergence between closely related species and low within-species phenotypic variability. In addition, genital asymmetry is widespread despite the essentially bilaterally symmetric external morphology of insects. Several hypotheses, such as sexual selection and lock-and-key hypotheses, have been proposed to explain these characteristics of genital evolution. Although these hypotheses provide different predictions about the genetic basis of variation in genitalia, detailed quantitative genetic studies have been conducted in only three insect taxa: heteropterans, dung beetles (Scarabaeidae), and drosophilid flies. For an anisolabidid earwig, Euborellia plebeja, characterized by paired elongated intromittent organs, we estimated the heritabilities and genetic correlations of genital laterality, size of genitalia, and body size. No statistically significant additive genetic, dominance, maternal, or common environmental effects were detected for genital laterality (readiness to use either the left or the right intromittent organ). This result lends further support to the general rule that the direction of antisymmetric variations is randomly determined by non-genetic factors. Irrespective of the restricted phenotypic variation in genitalia compared with body size (allometric slope < 1), as observed in previous studies for other insects, these two traits showed a similar level of genetic variation, measured as the narrow sense heritability (h2) and the coefficient of additive genetic variation (CVA). Comparison suggests the causes of interspecific differences in genetic variability/correlation structures were developmental processes (holo- or hemimetabolous) and/or mode of sexual selection.
AB - Male genitalia show several evolutionary characteristics, including rapid morphological divergence between closely related species and low within-species phenotypic variability. In addition, genital asymmetry is widespread despite the essentially bilaterally symmetric external morphology of insects. Several hypotheses, such as sexual selection and lock-and-key hypotheses, have been proposed to explain these characteristics of genital evolution. Although these hypotheses provide different predictions about the genetic basis of variation in genitalia, detailed quantitative genetic studies have been conducted in only three insect taxa: heteropterans, dung beetles (Scarabaeidae), and drosophilid flies. For an anisolabidid earwig, Euborellia plebeja, characterized by paired elongated intromittent organs, we estimated the heritabilities and genetic correlations of genital laterality, size of genitalia, and body size. No statistically significant additive genetic, dominance, maternal, or common environmental effects were detected for genital laterality (readiness to use either the left or the right intromittent organ). This result lends further support to the general rule that the direction of antisymmetric variations is randomly determined by non-genetic factors. Irrespective of the restricted phenotypic variation in genitalia compared with body size (allometric slope < 1), as observed in previous studies for other insects, these two traits showed a similar level of genetic variation, measured as the narrow sense heritability (h2) and the coefficient of additive genetic variation (CVA). Comparison suggests the causes of interspecific differences in genetic variability/correlation structures were developmental processes (holo- or hemimetabolous) and/or mode of sexual selection.
KW - Allometry
KW - Genetic assimilation
KW - Genetic correlation
KW - Genital evolution
KW - Heritability
KW - Sexual selection
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U2 - 10.1111/j.1095-8312.2010.01491.x
DO - 10.1111/j.1095-8312.2010.01491.x
M3 - Article
AN - SCOPUS:77955975047
VL - 101
SP - 103
EP - 112
JO - Biological Journal of the Linnean Society
JF - Biological Journal of the Linnean Society
SN - 0024-4066
IS - 1
ER -