نتایج جستجو برای: female broods
تعداد نتایج: 268087 فیلتر نتایج به سال:
In many socially monogamous animals, females engage in extrapair copulation (EPC), causing some broods to contain both within-pair and extrapair young (EPY). The proportion of all young that are EPY varies across populations and species. Because an EPC that does not result in EPY leaves no forensic trace, this variation in the proportion of EPY reflects both variation in the tendency to engage ...
BACKGROUND Animals use carotenoid-pigments for coloration, as antioxidants and as enhancers of the immune system. Carotenoid-dependent colours can thus signal individual quality and carotenoids have also been suggested to mediate life-history trade-offs. METHODOLOGY To examine trade-offs in carotenoid allocation between parents and the young, or between skin coloration and plasma of the paren...
Abstract Genes of the major histocompatibility complex (MHC) are crucial for adaptive immunity in jawed vertebrates, and theory predicts that there should be mate choice optimizing MHC constitution offspring. In a previous study, we demonstrated non-random female extra-pair males bluethroat ( Luscinia svecica ), yielding offspring was closer to an intermediate class II (MHCII) allele count than...
Chicks of the brood parasitic common cuckoo (Cuculus canorus) typically monopolize host parental care by evicting all eggs and nestmates from the nest. To assess the benefits of parasitic eviction behaviour throughout the full nestling period, we generated mixed broods of one cuckoo and one great reed warbler (Acrocephalus arundinaceus) to study how hosts divide care between own and parasitic y...
Food provisioning rates and chick growth rates of Common Terns Sterna hirundo and Arctic Terns S. paradisaea were studied in Northeast England. Adult terns ofboth species fed large broods more frequently than those containing fewer chicks. Energy supply per nestling declined slightly as brood size increased and as a result, chicks in large broods developed body mass at a slightly lower rate tha...
Commensurate with the decline in many crustacean populations has been an accumulation in reports of sexually ambiguous individuals within these populations. The cause of gynandromorphism or intersex among crustaceans is unknown. We show that gynandromorphism in the branchiopod crustacean Daphnia magna is initiated by the sex-determining hormone methyl farnesoate when levels of the hormone are i...
Objective: We develop the use of Bayesian logistic regression models for the analysis of sex ratio data for organisms with variable brood sizes. Background: Ant populations often exhibit ‘split sex ratios’, whereby most colonies produce strongly male-biased or female-biased broods. Furthermore, colony-level sex ratios may depend on brood size or other non-normally distributed covariates. The la...
Polyembryonic parasitoids clonally produce sterile soldier larvae in both sexes. Female soldier larvae of Copidosoma floridanum defend their siblings and host resources against heterospecific competitors as well as conspecific male embryos that results in female biased sex ratios. However, the male soldiers of the USA strain exhibit no aggressive behaviors against them, suspected to be a second...
Extra-pair copulation can increase genetic diversity and offspring fitness. However, it may also increase intra-nest variability in avian hosts of brood parasites, which can decrease the discrimination ability of host parents towards the parasite. In New Caledonia, the Fan-tailed Gerygone (Gerygone flavolateralis), which is parasitized by the Shining Bronze-cuckoo (Chalcites lucidus), has two n...
Superfetation, the ability of females to simultaneously carry more than one brood at different developmental stages, is an unusual reproductive strategy that has independently evolved several times in the livebearing fish family Poeciliidae. Why this strategy has evolved remains uncertain. One hypothesis is that superfetation is a response to selective pressures that constrain the physical spac...
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