Construction of the Itaipu Dam, 150 km downstream from Sete Quedas Falls, resulted in the drowning of that natural geographic barrier, with consequent invasion of Serrasalmus marginatus in the upper stream. This event was followed by the reduction in the abundance of the native species, S. spilopleura. Analyzes of reproductive activity these species revealed that in lotic waters S. marginatus h...

Ensuring women’s need for sexual and reproductive healthcare are met should be a priority during disease outbreaks, say Maira L S Takemoto colleagues

  Objective(s): The adverse effects of pyridaben on reproductive system in male animals are not well established. This study was designed to elucidate how pyridaben can effects the histomorphometric, hormonal alternations and reproductive functions of BALB/c mice .   Materials and Methods : For this study, 80 adult and apparently healthy male BALB/c mice were divided into three groups Viz, cont...

The formal Darwinism project aims to provide a mathematically rigorous basis for optimisation thinking in relation to natural selection. This paper deals with the situation in which individuals in a population belong to classes, such as sexes, or size and/or age classes. Fisher introduced the concept of reproductive value into biology to help analyse evolutionary processes of populations divide...

Abnormalities are not uncommon in Taenia saginata and T. solium. After examining 328 mature proglottids from 2 adult worms from two experimentally infected hamsters, 13 (4.0%) were found to have no genital pore but with numerous testes and several vas efferents; 1 (0.3%) one genital pore with one reproductive system; 12 (3.7%) one on each side with two sets of reproductive system; 17 (5.2%) two...

Reproductive character displacement--the evolution of traits that minimize reproductive interactions between species--can promote striking divergence in male signals or female mate preferences between populations that do and do not occur with heterospecifics. However, reproductive character displacement can affect other aspects of mating behaviour. Indeed, avoidance of heterospecific interactio...

Sexual dimorphism in size (sexual size dimorphism; SSD) is nearly ubiquitous, but the relative importance of genetic versus environmental control of SSD is not known for most species. We investigated proximate determinants of SSD in several species of squamate reptiles, including three species of Sceloporus lizards and the diamond-backed rattlesnake (Crotalus atrox). In natural populations of t...

In many animals, male ejaculates coagulate to form what has been termed a copulatory plug, a structure that varies in size and shape but often fills and seals the female's reproductive tract. The first published observation of a copulatory plug in a mammal was made more than 160 years ago, and questions about its formation and role in reproduction continue to endear evolutionary and population ...

Training in genetics in Edinburgh in the 1950s led to a PhD on the developmental biology of mouse embryos with unusual chromosomal complements. Fundamental aspects of reproduction under study included ovulation induction, oocyte maturation and embryonic growth to blastocysts. It led to the introduction of embryo stem cells, preimplantation genetic diagnosis, the exact timing of human oocyte mat...

In recent times, infertility among both man and woman has become a major concern affecting about 20 per cent of the population worldwide and has been attributed in part to several aetiological factors such as changes in lifestyle, which includes sedentary life, dietary habits, sleep anomalies, environmental pollution, etc. Assisted reproductive technologies (ART) have come to the rescue of many...