Like the formation of animal species, plant speciation is characterized by the evolution of barriers to genetic exchange between previously interbreeding populations. Prezygotic barriers, which impede mating or fertilization between species, typically contribute more to total reproductive isolation in plants than do postzygotic barriers, in which hybrid offspring are selected against. Adaptive ...

OBJECTIVES The purpose of the study was to investigate whether fertility therapy might contribute to subsequent cardiovascular disease. BACKGROUND Fertility medications are used for 1% of births yet may also lead to endothelial injury with long-term adverse consequences for the mother. METHODS A population-based cohort analysis was performed of women who gave birth in Ontario, Canada, betwe...

Objective To determine the effectiveness of achieving pregnancy with focused intercourse in the fertile window identified using natural fertility indicators. Methods 24-cycle prospective effectiveness study. Setting A North American web-based fertility monitoring service. Participants 256 North American women aged 20-43 (mean age 29.2 years) seeking to achieve pregnancy. Intervention Pa...

The purpose of this study was to test whether men perceive changes in their female partner's attractiveness as a function of her fertility status. We further tested how both male and female self-perception varies in relation to female fertility status. This study benefits from the use of transvaginal ultrasonography to detect fertility during the regular cycle and the use of a within-subjects d...

The (PD) peak day of cervical mucus is an important biologic marker for the self-determination of the optimal time of fertility in a woman's menstrual cycle. The purpose of this article is to provide evidence (literature and empiric) for the accuracy of the PD of cervical mucus as a biologic marker of peak fertility and the estimated day of ovulation. An analysis of data from four published stu...

age-1(hx546) is a recessive mutant allele in Caenorhabditis elegans that results in an increase in mean life span averaging 40% and in maximal life span averaging 60% at 20 degrees; at 25 degrees age-1(hx546) averages a 65% increase in mean life span (25.3 days vs. 15.0 days) and a 110% increase in maximum life span (46.2 days vs. 22.0 days for wild-type hermaphrodites). Mutant males also show ...

OBJECTIVE To investigate the influence of maternal working conditions on fertility and pregnancy outcomes. METHODS 8880 women were enrolled in a large prospective birth cohort during early (76%), mid (21%) or late pregnancy (3%) (61% participation). Complete questionnaire information was available for 6302 women (71% response). Outcomes were prolonged time to pregnancy (TTP) (> 6 months), pre...

The demographic transition is an ongoing global phenomenon in which high fertility and mortality rates are replaced by low fertility and mortality. Despite intense interest in the causes of the transition, especially with respect to decreasing fertility rates, the underlying mechanisms motivating it are still subject to much debate. The literature is crowded with competing theories, including c...