Although the amount of energy that males and females invest in reproduction is an integral component of theories explaining the evolution of particular mating strategies, few studies have actually determined the amount of energy that each sex allocates to reproduction. We compared how energy is expended by male and female Anolis carolinensis lizards during both the breeding and postbreeding sea...

It is proposed that where sexually selected vocal communication is an honest signal, the call production rate is predicted to change throughout the breeding season. Male leopard seals call underwater for many hours each day over their three- to four-month breeding season, and it is hypothesized that a decrease in calling rate would be associated with the declining body condition of smaller male...

When prey animals discover a predator close by, they mob it while uttering characteristic sounds that attract other prey individuals to the vicinity. Mobbing causes a predator to vacate its immediate foraging area, which gives an opportunity for prey individuals to continue their interrupted daily activity. Besides the increased benefits, mobbing behaviour also has its costs owing to injuries o...

in this study, the number of 1802 longevity records of ewes collected during 1989 to 2010 in breeding station of lori-bakhtiari sheep flocks were used to estimate of genetic, environmental and phenotypic trends for economic lifetime. the breeding values of a ewe’s lifetime were estimated by restricted maximum likelihood procedure under an animal model of univariate analysis. the best linear unb...

the aim of this study was to evaluate the reproductive efficiency of short and long term treatment with progestagens in addition to pregnant mare serum gonadotropin (pmsg) in arabian ewes during the non-breeding season. a total of 56 ewes were divided into three groups: in group i vaginal sponges (60 mg medroxy progesterone acetate; map) were applied and removed after 6 days; in group ii, vagin...

When prey animals discover a predator close by, they mob it while uttering characteristic sounds that attract other prey individuals to the vicinity. Mobbing causes a predator to vacate its immediate foraging area, which gives an opportunity for prey individuals to continue their interrupted daily activity. Besides the increased beneŽ ts, mobbing behaviour also has its costs owing to injuries o...

The habitat suitability index, which reflects spatial variability in species occurrence probability, has been shown to exhibit various contrasting relationships with local demographic performances (survival, productivity) in several species. One proposed explanation for these discrepancies is that the link between the habitat suitability index and demography is influenced by density-dependent, ...

The effect of gonadotropin releasing hormone (GnRH) treatment on the time of ovulation and the occurrence of follicular dominance during the non-breeding and breeding seasons (experiment 1), and on fertility after artificial insemination (AI) in the non-breeding season (experiment 2), was examined in Merino ewes. Oestrus was synchronized in 40 nulliparous ewes (experiment 1; n = 20, in the non-...

Timing of reproduction in a seasonal cycle is a life history trait with important fitness consequences. Capital breeders produce offspring from stored resources and, by decoupling feeding and reproduction, may bend the constraints caused by seasonality in food or predation. Income breeders, on the other hand, produce offspring from concurrent food intake, with the disadvantage of less flexibili...