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...

Understanding how local environmental factors lead to temporal variability of vital rates and to plasticity of life history tactics is one of the central questions in population ecology. We used long-term capture-recapture data from five populations of a small hibernating rodent, the edible dormouse Glis glis, collected over a large geographical range across Europe, to determine and analyze bot...

Polymorphism often corresponds to alternative mating tactics in males, but much less is known about this relationship in females. However, recent work suggests that selection for alternative reproductive strategies in females can maintain genetic variation in important life-history traits. Brown anole lizards (Anolis sagrei) exhibit a genetically based polymorphism in dorsal pattern that is exp...

According to life-history theory, any organism that maximizes fitness will face a trade-off between female fertility and offspring survivorship. This trade-off has been demonstrated in a variety of species, but explicit tests in humans have found a positive linear relationship between fitness and fertility. The failure to demonstrate a maximum beyond which additional births cease to enhance fit...

BACKGROUND Late menarche, early menopause, high parity, and early first birth decrease the risk of development of breast cancer. The influence of these factors on the survival of breast cancer patients has not been explained. METHODS A group of 1885 patients with operable breast cancer was studied retrospectively. A univariate analysis was used to calculate 10-year overall survival (OS) and d...

BACKGROUND There are conflicting data regarding the role of sex hormones in colorectal cancer development. Whereas clinical trials data indicate that hormone therapy use reduces the risk of colorectal cancer, data from prospective cohort studies suggest that circulating estrogen levels are positively associated with colorectal cancer risk. A surrogate measure of lifetime estrogen exposure is re...

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Frequency-dependent selection may favour the evolution of mixed reproductive strategies, resulting in polymorphic life-histories within a population. Here I explore the theoretical and ecological possibilities for evolution of mixed reproductive strategies in two minimal age-structured life-history models. The first model addresses evolution of delayed maturity (i.e., competition between annual...

Oxidative stress, determined by the balance between the production of damaging reactive oxygen species (ROS) and antioxidant defences, is hypothesized to play an important role in shaping the cost of reproduction and life history trade-offs. To test this hypothesis, we manipulated reproductive effort in 94 breeding pairs of tawny owls (Strix aluco) to investigate the sex- and melanism-specific ...

BACKGROUND Ecological characteristics (growth, morphology, reproduction) arise from the interaction between environmental factors and genetics. Genetic analysis of individuals' life history traits might be used to improve our understanding of mechanisms that form and maintain a hybrid zone. METHODOLOGY/PRINCIPAL FINDINGS A fish hybrid zone was used to characterize the process of natural selec...