Environmental Conditions Influence Allometric Patterns in the Blow Fly, Chrysomya albiceps

The objective of this research was to study variations in allometry of body characters in females and males of two populations of blow flies, Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), under different environmental conditions to establish patterns of morphological variation. Body size of both males and females in the experimental population was significantly higher than in the individuals of the natural population, indicating an important influence of food on body size. All genitalic and non-genitalic characters in males and females of the two populations showed a trend towards negative allometry rather than isometry. Allometric patterns were modified in both sexes and between populations. The data show generally larger allometric slopes in females than in males. We confirmed that the environmental conditions have an important effect on allometric patterns and body size

Nest desertion is not predicted by cuckoldry in the Eurasian penduline tit

Engagement in extra-pair copulations is an example of the abundant conflicting interests between males and females over reproduction. Potential benefits for females and the risk of cuckoldry for males are expected to have important implications on the evolution of parental care. However, whether parents adjust parental care in response to parentage remains unclear. In Eurasian penduline tits Remiz pendulinus, which are small polygamous songbirds, parental care is carried out either by the male or by the female. In addition, one third of clutches is deserted by both male and female. Desertion takes place during the egg-laying phase. Using genotypes of nine microsatellite loci of 443 offspring and 211 adults, we test whether extra-pair paternity predicts parental care. We expect males to be more likely to desert cuckolded broods, whereas we expect females, if they obtain benefits from having multiple sires, to be more likely to care for broods with multiple paternity. Our results suggest that parental care is not adjusted to parentage on an ecological timescale. Furthermore, we found that male attractiveness does not predict cuckoldry, and we found no evidence for indirect benefits for females (i.e., increased growth rates or heterozygosity of extra-pair offspring). We argue that male Eurasian penduline tits may not be able to assess the risk of cuckoldry; thus, a direct association with parental care is unlikely to evolve. However, timing of desertion (i.e., when to desert during the egg-laying phase) may be influenced by the risk of cuckoldry. Future work applying extensive gene sequencing and quantitative genetics is likely to further our understanding of how selection may influence the association between parentage and parental care

Evidence that mating plug is related to null female mating activity in the scorpion Vaejovis punctatus

We document a case in which the mating plug of the scorpion Vaejovis punctatus seems correlated with a reduction in female sexual receptivity. We used two morphological and behavioral analyses. The mating plug was dissected and described from both males and females: it bears a set of spines and two enlarged terminations which possibly allow anchoring to the female inside and impede removal. Behavioral observations support this view: after sperm transfer ended, the female tried to remove the plug by rubbing the ventral side of her body using her second and third pair of legs. This pattern was also performed after mate separation. All females seemed unable to displace the plug and rejected male mating attempts. The mating plug suffered a progressive degradation into the female. This degradation was completed 2 or 3 mo prior to parturition, so that the plug did not seem a barrier for the emergence of embryos. Furthermore, females bearing mating plugs in different degradation stages did not accept another mating during the reproductive season, and sexual acceptance was reinitiated only after parturition. The mating plug therefore seems to correlate with a lost in mating activity. The comparison of this structure with that of other scorpion species allows us to hypothesize a sexual coevolutionary scenario in which the effectiveness of the plug to inhibit female remating may lie at the center of such interaction