نتایج جستجو برای: sexual reproduction
تعداد نتایج: 177469 فیلتر نتایج به سال:
Abstract Introduction: Teenagers (especially girls) who are going through puberty are among vulnerable populations whose sexual needs receive little attention. Objective: This study aimed to determine educational needs of 11-14 year old girls on sexual health in Dezful. Methods: This cross-sectional study was conducted on 810 middle school girls aging 11 to 14 in Dezful city in 2012....
Although sexual reproduction implies a cost, it represents an evolutionary advantage for the adaptation and survival of facultative sexual pathogens. Understanding the maintenance of sex in pathogens requires to analyse how host resistance will impact their sexual reproduction through the alteration of their life-history traits. We explored this experimentally using potato (Solanum tuberosum) a...
An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of th...
The near-ubiquity of sexual reproduction in animal species has long been considered a paradox because sexually reproducing individuals transmit only half of their genome to their progeny. Here, we show that the ant Cataglyphis cursor circumvents this cost by using alternative modes of reproduction for the production of reproductive and nonreproductive offspring. New queens are almost exclusivel...
Abstract Introduction: Teenagers (especially girls) who are going through puberty are among vulnerable populations whose sexual needs receive little attention. Objective: This study aimed to determine educational needs of 11-14 year old girls on sexual health in Dezful. Methods: This cross-sectional study was conducted on 810 middle school girls aging 11 to 14 in Dezful city in 2012....
Individuals who reproduce asexually have a two-fold advantage over their sexually-reproducing counterparts as they are able to reproduce twice as fast. Explaining why sexual reproduction is favoured over asexual reproduction therefore remains an important challenge in evolutionary biology. Various mechanisms involving resistance to parasites, adaptation to novel environments and helping to purg...
Using the idea that life-history parameters are subject to natural selection and should approach values that are stable optima, with the population immune to invasion by mutant individuals, we derive an analytic expression for the evolutionarily stable dispersal rate in a stochastic island model with random site extinction. The results provide interesting contrasts between three different optim...
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