Leptin, a hormone secreted from adipose tissue, plays an important role in reproductive physiology. It has been shown to stimulate the reproductive system by rescuing the sterility of leptin-deficient mice and advancing the onset of puberty in normal mice. Although leptin is not critical for the biology of pregnancy in mice, its ability to reduce food intake is blunted in mid-gestation suggesti...

BACKGROUND Reproductive function is tightly regulated by nutritional status. Indeed, it has been well described that undernutrition or obesity can lead to subfertility or infertility in humans. The common regulatory pathways which control energy homeostasis and reproductive function have, to date, been poorly understood due to limited studies or inconclusive data. However, gut hormones and adip...

Seasonal changes in the reproductive activity of the adult male viscacha (Lagostomus maximus maximus) were investigated during the annual reproductive cycle. Assays of heterologous in vitro binding between compatible gametes were used to evaluate the ability of viscacha spermatozoa to achieve primary binding during its annual reproductive cycle. Sperm were collected by mincing cauda epididymis ...

Various theories have been posed to explain the fitness payoffs of hunting success among hunter-gatherers. 'Having' theories refer to the acquisition of resources, and include the direct provisioning hypothesis. In contrast, 'getting' theories concern the signalling of male resourcefulness and other desirable traits, such as athleticism and intelligence, via hunting prowess. We investigated the...

The colonization of reproductive tissues in infected laying hens is a pivotal stage in the production of contaminated eggs that can transmit Salmonella enteritidis infections to humans. In an earlier study, a series of passages through infected laying hens increased the frequency at which an S. enteritidis isolate was deposited inside eggs. The present study evaluated the effect of in vivo pass...

Acetamiprid (ACE) and imidacloprid (IMI) are two major members in the family of neonicotinoid pesticides, which are synthesized with a higher selectivity to insects. The present study determined and compared in vitro effects of ACE, IMI and nicotine on mammalian reproduction by using an integrated testing strategy for reproductive toxicology, which covered sperm quality, sperm penetration into ...

The degree of sexual size dimorphism (SSD) in the cichlid Lamprologus callipterus is the greatest recorded among species in which males exceed females in body size. Males collect and defend empty snail shells in which females breed. We report on the potential importance of different selection mechanisms and constraints on male and female body sizes. To test for the importance of sexual selectio...

Several time-discrete ecological models are formulated and analyzed. Common to these models is that a trade-off between reproductive effort and competitive ability is assumed. We investigate how behavioral adjustment (suppression of reproduction) affects the population dynamics.

Reproductive failure is ubiquitous. However, research on the mechanisms underpinning reproductive still lacking in most species. This gap our understanding has particularly strong repercussions for threatened species and it hinders ability to establish effective interventions improve survival. In this review, we focus why eggs fail hatch – one of critical understudied aspects bird reproduction....

Parthenogenesis - the ability to produce offspring from unfertilized eggs - is widespread among invertebrates and now increasingly found in normally sexual vertebrates. Are these cases reproductive errors or could they be a first step in the emergence of new parthenogenetic lineages?