Antennal asymmetry and sexual selection in a cerambycid beetle

Abstract

Abstract. Cerambycid beetles have exaggerated antennae that are usually sexually size-dimorphic. We investigated the relationship between antenna morphology and sexual selection in the species Stenurella melanura (L.) in which males on average have antennae that are 13% longer than those of females. Males and females aggregate at flowers near oviposition sites for feeding during June-August. We sampled both copulating and single individuals at these sites. Fluctuating asymmetry (a measure of developmental instability) in antennae was considerably larger than in tibia and elytra and males had larger degrees of asymmetry in their antennae than females. Mated individuals did not differ from unmated individuals with respect to any of three size variables, but antennal asymmetry was smaller in mated individuals of both sexes. When two males were released with a female on a flower, males with symmetric antennae more often won the fight over the female than expected by chance. When two females and a male were released on a flower, the male more often preferred the female with more symmetric antennae than expected by chance. These results suggest that antennal symmetry, but not length, is currently under sexual selection.

Tarsal Asymmetry, Nutritional Condition, and Survival in Water Boatmen (Callicorixa Vulnerata)

“…FA has been linked to decreased competitive ability in other insects (Thornhill 1992;Allen and Simmons 1996;Møller and Zamora-Munoz 1997;Blanckenhorn et al 1998). Tarsal FA was negatively correlated to survival of water boatmen in our feeding experiment, adding support to the hypothesis that the inverse relationship detected between FA and nutritional condition is due to differential feeding ability.…”

“…That these individuals maintained residual weights similar to fieldcaught individuals and individuals provided unlimited food suggests these individuals were able to feed effectively despite resource limitations. Previous studies have shown similar trends involving FA and competition for mates such as in Japanese scorpion flies (Thornhill 1992), cerambycid beetles (Møller and Zamora-Munoz 1997), and dung flies (Allen and Simmons 1996).…”

“…Levels of such fluctuating asymmetry (FA) may represent the ability of the genotype to buffer developmental errors, and thus to develop an optimal phenotype under suboptimal conditions (Møller and Thornhill 1997;Gangestad and Thornhill 1999;Shykoff and Møller 1999; but see Leamy 1997). Consequently, FA has been used as a measure of developmental stability (Van Valen 1962;Leary et al 1992;Palmer 1994), and elevated levels of asymmetry have been linked to reduced fitness and to poor phenotypic or genotypic quality (Moodie and Reimchen 1976;Møller 1991Møller , 1996Thornhill 1992;Allen and Simmons 1996;Møller and Zamora-Munoz 1997;Reimchen 1997;Hunt et al 1998;reviewed in Møller 1997; but see Clarke 1998). Such fitness reduction may arise from bad genes, where asymmetry is an indicator of poor overall genetic quality (Møller and Hoglund 1991;Møller 1994;Hunt et al 1998;Shykoff and Møller 1999), or from the performance costs of phenotypic asymmetry (Møller 1991(Møller , 1996Balmford et al 1993;Gummer and Brigham 1995).…”

Sexual Dimorphism Using Geometric Morphometric Approach

“…Most of the morphological variations between males and females in moth and buterflies are due to the effects associated with the environment, whether phenotypic responses (plasticity) or particularly those which act during ontogenetic development [64][65][66]. Females are generally larger than males; this gives them adaptive advantages such as greater fecundity and better parental care [14,15,63,67].…”

Asymmetry Analysis of Brontispa longissima Gestro, 1885 (Coleoptera: Chrysomelidae) Metasternum Using Symmetry and Asymmetry on Geometric Data (SAGE)

“…Palmer and Strobeck [2], [3] termed these deviations as 'developmental noise' which are environmentally or epigenetically induced stresses. Unlike the other types of (AS), fluctuating asymmetry (FA) have long been viewed as a measure of developmental instability [4] due to environmental stress [5]- [8], adaptation and coadaptation [9] and fitness or individual quality [10], [11]. There are several methods available in computing asymmetries.…”