The observation that normal pathways of differentiation and development are invariably altered during the process of carcinogenesis implies an intrinsic relationship between these processes. This relationship is particularly evident in the breast, as exemplified by the existence of endocrine risk factors for breast cancer that are related to the timing of normal developmental events. Understand...

Individual reproductive behaviour and survival of Bombina variegata was studied in a dynamic habitat with a variety of rain-filled ponds from 1990 to 1992. Most animals reached sexual maturity at the age of two years. Annual adult survival was at least 62 %. Individual females, on average, laid between 40 and 70 eggs per ?clutch?. While about 12 % of the breeding females spawned a second time w...

Impulsivity has often been invoked as a proximate driver of different life-history strategies. However, conceptualisations of ‘‘impulsivity’’ are inconsistent and ambiguities exist regarding which facets of impulsivity are actually involved in the canalisation of reproductive strategies. Two variables commonly used to represent impulsivity were examined in relation to reproductive behaviour. Re...

Management of the few regulated ornamental fisheries relies on inadequate information about the life history of the target species. Herein, we investigated the reproductive biology of the most heavily traded marine invertebrate in the western Atlantic; the blue-legged hermit crab Clibanarius tricolor. We report on density, individual-level, and population-level reproductive parameters in 14 pop...

Recent advances in human life history theory have provided new insights into the potential selection pressures that were instrumental in the evolution of human and non-human primate males. However, gaps remain in our understanding of how primate males regulate and allocate energetic resources between survivorship and reproductive effort. Defense against parasitic infection is an important force...

Since the observation that snails exposed to trematode parasites bring forward their maturity and increase their fecundity to lessen the parasite's impact on their reproductive success (Minchella & Loverde, 1981; Minchella, 1985), several studies have considered modi®cations of a host's life history as its adaptive response to parasite pressure (Michalakis & Hochberg, 1994). The marine snail Ce...

Low food availability during early growth and development can have long-term negative consequences for reproductive success. Phenotypic plasticity in adult life-history decisions may help to mitigate these potential costs, yet adult life-history responses to juvenile food conditions remain largely unexplored. I used a food-manipulation experiment with female Trinidadian guppies (Poecilia reticu...

Seasonal changes in day length enhance or suppress immune function in individuals of several mammalian species. Siberian hamsters (Phodopus sungorus) are long-day breeders that adjust reproductive physiology and behavior, body mass, and immune function following exposure to short photoperiods. Photoperiods of intermediate-duration, encountered in nature by juvenile hamsters born in early-spring...

We develop a model for somatic growth in fishes that explicitly allows for the energy demand imposed by reproduction. We show that the von Bertalanffy (VB) equation provides a good description of somatic growth after maturity, but not before. We show that the parameters of the VB equation are simple functions of age at maturity and reproductive investment. We use this model to show how the ener...

Background: Nowadays, gamete and embryo donation is applied as effective process in treatment infertility problems. In order to participate in the process of donation, donors should complete an extensive questionnaire that details their personal and family medical history. Included in this questionnaire should be a detailed sexual history, substance abuse history, history of family disease, and...