Search

According to the genic capture hypothesis, genetic variance in costly sexual traits is maintained because their expression depends on many genes that affect resource acquisition ability. Hence, such traits should constitute a large mutational target and thus show high sensitivity to deleterious mutations. To test this, we exposed male guppies to a chemical mutagen that induces point mutations, and measured sexual display and ornamental traits in the progeny of the mutagenized fish. For comparison, we measured several life history and morphological traits. Compared with progeny of control males, sons of the mutants took a longer time to mature, and daughters of mutants gave birth to fewer offspring than daughters of control males. No significant effect of mutations on body size, eye size or offspring mortality was detected. Consistent with the genic capture hypothesis, induced mutations negatively affected the courtship display rate. However, the area and spectral characteristics of sexually selected orange spots were not significantly affected. Our results demonstrate that energetically costly courtship display, but not orange coloration, is a reliable indicator of mutation load. [ABSTRACT FROM AUTHOR]

In many species, the genetic quality of gametes is likely to decline with age of the male. Some form of discrimination against mating with old males, or against fertilization by their sperm, can be expected to evolve. We investigated the effect of male age on the probability of mating and on sperm competitiveness in the bulb mite, Rhizoglyphus robini. There was no significant difference between male age classes in the probability of mating with virgin females, but young males were more likely to mate with already mated females. Furthermore, young males won sperm competition against older males. This implies that polyandry may be an effective way of avoiding fertilization by the sperm of older males. It has also been suggested that polyandry insures females against the infertility of old males. Our results do not support this hypothesis: matings with older males did not result in female infertility significantly more often than matings with young males. [Copyright &y& Elsevier]

Examines the function of the prolonged mate association of the bulb mite, Rhizoglyphus robini. Prolonged mate association function as a form of post-copulatory mate guarding; Female mating history and male fertilization success; Increase in duration of pair association with the male-female ratio.

Looks at kin recognition in the acarid mite. Kin selection theory; No evidence for kin recognition; Intrageneric differences in kin or colony recognition.

Opinion. Comments on animal mating systems. Mark Pagel's explanation for the evolution of conspicuous estrus advertisement in primates; Pagel's usage of the notion spite; Female motivation for multiple copulation; Evolution of indiscriminate spite.

Mate-guarding strategies are known to evolve in response to changes in the environment, but little is known about the genetic and plastic components of this source of variation. Here, we investigated how risk associated with aggression shapes postcopulatory association time between mates in the bulb mite, Rhizoglyphus robini , a species in which aggressive, armoured fighters often coexist with unarmoured scramblers. In some populations, scramblers have been reported to prevent females remating by remaining in copula for over 6 h. In this study, we investigated whether mate guarding by scramblers is affected by the presence of aggressive fighters in populations. We investigated whether guarding is riskier in the presence of fighters and found that guarding males were more likely to be attacked. Our data allowed us to determine whether the presence of fighters can affect mate-guarding duration, by comparing guarding duration between populations (both natural and artificially selected). We found that in both types of population, males guarded longer when fighters were absent. Comparisons between lines selected for the presence of fighters, lines selected for the presence of scramblers and their source populations indicated that scrambler morphs evolved prolonged guarding. We also investigated whether males show plasticity and shorten guarding in response to the presence of fighters in a social group. Surprisingly, we found that males in a mixed-morph context copulated significantly longer than males from single-morph groups. Our results demonstrate that mate guarding may evolve in response to the presence or absence of fighters in populations, but males are not able to adjust guarding behaviour to the risk of being attacked by fighters. The study provides insight into the role of genetics and plasticity in guarding strategies. [ABSTRACT FROM AUTHOR]