نتایج جستجو برای: reproductive history
تعداد نتایج: 441343 فیلتر نتایج به سال:
Understanding sources of reproductive variation can inform management and conservation decisions, population ecology and life-history theory. Annual reproductive variation can drive population growth rate and can be influenced by factors from across the annual cycle (known as carry-over effects). The majority of studies, however, focus solely on the role of current environmental events. Past ev...
Patterns of reproductive isolation between species may provide insight into the mechanisms and evolution of barriers to interspecific gene exchange. We used data from published interspecific hybridization experiments from 14 genera of angiosperms in order to test for the presence of asymmetrical barriers to gene exchange. Reproductive isolation was examined at three life-history stages: the abi...
OBJECTIVE The aim of the study was to understand the association between women's reproductive history and their risk of developing type 2 diabetes. We hypothesized that characteristics signifying lower cumulative endogenous estrogen exposure would be associated with increased risk. METHODS Prospective cohort analysis of 124,379 postmenopausal women aged 50 to 79 years from the Women's Health ...
Background and Objective: The1994 International Conference on Population and Development (ICPD) specifically identified “empowering women” as an essential ingredient for achieving desirable reproductive health and population outcomes. This study was done to determine the relation between women empowerment and reproductive behaviors. Materials and Methods: An analytical descriptive surv...
Plant strategy and life-history theories make different predictions about reproductive efficiency under competition. While strategy theory suggests under intense competition iteroparous perennial plants delay reproduction and semelparous annuals reproduce quickly, life-history theory predicts both annual and perennial plants increase resource allocation to reproduction under intense competition...
Plant reproduction yields immediate fitness benefits but can be costly in terms of survival, growth, and future fecundity. Life-history theory posits that reproductive strategies are shaped by trade-offs between current and future fitness that result from these direct costs of reproduction. Plant reproduction may also incur indirect ecological costs if it increases susceptibility to herbivores....
In many organisms survival depends on body size. We investigate the implications of size-selective mortality on life-history evolution by introducing and analysing a new and particularly flexible life-history model with the following key features: the lengths of growth and reproductive periods in successive reproductive cycles can vary evolutionarily, the model does not constrain evolution to p...
BACKGROUND Adolescent childbirth and elevated parity are relatively common in middle and low-income countries and they may be related to the higher prevalence and earlier onset of physical decline documented in these settings, especially in women. The aim of this paper is to investigate whether reproductive history is associated with physical function in middle-aged women from Northeast Brazil....
One of the current challenges of evolutionary ecology is to understand the effects of phylogenetic history (PH) and/or ecological factors (EF) on the life-history traits of the species. Here, the effects of environment and phylogeny are tested for the first time on the reproductive biology of South American xenodontine snakes. We studied 60% of the tribes of this endemic and most representative...
Life-history theory predicts that resource scarcity constrains individual optimal reproductive strategies and shapes the evolution of life-history traits. In species where the inherited structure of social class may lead to consistent resource differences among family lines, between-class variation in resource availability should select for divergence in optimal reproductive strategies. Evaluat...
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