Quality Males (quality + male)

Distribution by Scientific Domains

Selected Abstracts

Harem size and oviposition behaviour in a polygynous bark beetle

Abstract. 1. Harem polygyny can have fitness benefits and costs on females. In bark beetles of the genus Ips the latter may include within-harem competition between larvae. However, earlier competition between females for male care and mating opportunities may also influence oviposition behaviour. There has been relatively little investigation into the relationship between harem size and initial egg output. The present study investigated this relationship in the bark beetle Ips grandicollis. 2. The measure of egg output used was the number of eggs in the gallery with the most eggs in each harem. Mean (±SE) harem size of 242 observed harems was 3.25 ± 0.10. A curvilinear relationship was found between egg output and harem size, with females in smaller harems (one to four females) laying more eggs with increased harem size. However, females in larger harems (five to seven females) laid fewer eggs as harem size increased. The optimal harem size (in terms of number of eggs laid) was close to four females. 3. We found no evidence from a behavioural assay that females could preferentially choose unmated males over mated males with harems of two females. Additionally, the distribution of harem sizes suggests that females distribute themselves among males randomly. 4. The results suggest that harem size has effects on female reproduction that extend beyond larval competition and influence patterns of oviposition. The mechanism that determines why egg laying is greatest at intermediate levels is unknown. There is no evidence that smaller harems belong to lower quality males, but females may adjust egg-laying behaviour in large harems as a result of reduced male attendance or anticipated larval competition. [source]

Is Preening Behaviour Sexually Selected?

ETHOLOGY, Issue 12 2006
An Experimental Approach
Elaborate or colourful feathers are important traits in female mate choice in birds but little attention has been given to potential costs of maintaining these traits in good condition with preening behaviour. Recent studies indicate that the time and energy required to maintain ornamental plumage in good condition reinforces the honesty of plumage trait. It has been proposed that some behaviours, whose primary function is not to transfer information, can also evolve as signalling components. Here we investigate whether the preening behaviour intensity has a signalling component: we hypothesized that if only high quality males can invest a lot of time in preening, this behaviour may be used by females as a quality signal (attractive preening hypothesis). We tested this hypothesis by using female budgerigars in mate-choice tests in captivity. We tried to experimentally manipulate the preening behaviour of two groups of budgerigar males (treatment and control group). The proportion of time in which treated males preened in front of females was statistically higher than for control males, however, females spent similar amounts of time with treated males and control males. Moreover, males did not show significant quantitative changes in preening (for both groups) when females were present, suggesting that male budgerigars did not use this behaviour to convey information. These results are inconsistent with the ,attractive preening' hypothesis which predicts that preening behaviour itself provides information on condition and is used in female choice. [source]

Lack of evidence for improved immune response of extra-pair nestlings in collared flycatcher Ficedula albicollis

Tomasz Wilk
Extra-pair paternity is common in many socially monogamous bird species. Increasing evidence suggests that extra-pair copulations are female-driven, but benefits for females mating outside social pair-bonds are still poorly understood. The most influential explanation, "good genes" hypothesis, states that females mated socially with low quality males, engage in extra-pair copulations to obtain genetic benefits for their progeny. According to this model, enhanced performance of extra-pair offspring is expected. Here, based on 4-year study of collared flycatcher Ficedula albicollis, we compared the condition of extra-pair and within-pair young. We found no difference in immune response and body size between maternal half-siblings raised in the same nests. Additionally sex ratio was not biased among extra-pair nestlings, and paternity was not associated with hatching rank. Our results failed to reveal "good genes" effects in the studied population. These effects might be hard to detect, but other hypotheses should also be studied more thoroughly in the future. [source]

Mate selection in Litoria chloris and Litoria xanthomera: Females prefer smaller males

Clare Morrison
Abstract It is generally accepted that high quality males are those that succeed in male,male competition: in either aggression or rivalry to attract and be selected by females. Previous studies of amphibians have suggested that the main characters influencing male mating success include variation in call characteristics (e.g. call rate, call intensity), calling behaviour, body condition, age and chorus tenure. In the present paper, several of the characters influencing female mate choice (male body size, body condition, call rate, call frequency and chorus tenure) are investigated in two closely related, explosive breeding frog species Litoria chloris and Litoria xanthomera. Smaller males of both species are shown to be more successful than larger males and this success is attributed to the increased chorus tenure of smaller males in L. xanthomera. This increased chorus tenure was attributed to the lower total energy used per call by a small male calling at a higher frequency. Whether increased chorus tenure explains female mate choice in L. chloris is uncertain but is highly probable given the strong similarity between the two species in both ecology and call characteristics. [source]