Suicidal reproduction (semelparity) has evolved in only four genera of mammals. In these insectivorous marsupials, all males die after mating, when failure of the corticosteroid feedback mechanism elevates stress hormone levels during the mating season and causes lethal immune system collapse (die-off). We quantitatively test and resolve the evolutionary causes of this surprising and extreme li...

the populations of wild carp (cyprinus carpio carpio), as a commercially valuable species in the southeast iranian waters of the caspian sea, have been severely declined during last three decades, but there is no comprehensive research available on the biology of this species in this area. the age, growth and reproductive aspects of samples collected during 2009-2010 fishing season were measure...

Several nonexclusive, sometimes contradictory, hypotheses have been employed to explain age-related changes in reproduction and survival among vertebrates. We evaluated these hypotheses with observations collected from a 31-year study of individually marked Wood Thrushes (Hylocichla mustelina). Age-specific fledgling production, survival probabilities, and derived life table columns are present...

The performance of wild animals is impacted by diverse challenges imposed the environment and distinct life history stages such as breeding hibernation. Glucocorticoids (GCs) are hormonal mediators that reflect response to these challenges, exerting their far-reaching effects on numerous processes energy allocation, immunity behavior. Whereas short term elevations GC levels crucial for survival...

Growth, yield, and quality of 10 sweet potato selections and reproduction of the reniform nematode, Rotylenchulus reniformis, were studied in fumigated and nonfumigated plots in a naturally infested field. Nematode reproduction on the different selections in the field was similar to that reported in the greenhouse but was not related to the effect of the nematode on yield of the different selec...

In summer high temperatures are stress for sows mostly. This situation often affects the reproduction physiology in animals strongly. As a result of that the fertility and reproduction performance of sows can be reduced. High environmental temperatures and especially heat accumulation in body of the animals affect the metabolism in high performance sows. That is important in very sensitive phas...

'Fight-or-flight' stress responses allow animals to cope adaptively to sudden threats by mobilizing energy resources and priming the body for action. Because such responses can be costly and redirect behavior and energy from reproduction to survival, they are likely to be shaped by specific life-history stages, depending on the available energy resources and the commitment to reproduction. Here...

The basic reproduction number (R0) is an important quantity summarising the dynamics of an infectious disease, as it quantifies how much effort is needed to control transmission. The relative change in R0 due to an intervention is referred to as the effect size. However malaria and other diseases are often highly seasonal and some interventions have time-varying effects, meaning that simple rep...

Monochamus galloprovincialis (Olivier) is the vector of the pinewood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle, in Europe and Asia. Reproduction is probably the most important event in the life history of insects and may be affected by a number of factors, such as seasonal changes in larval or adult nutrition. In this study the effect of season on the reproductive potenti...

Life-history theory is fundamental to understanding how animals allocate resources among survival, development, and reproduction, and among traits within these categories. Immediate trade-offs occur within a short span of time and, therefore, are more easily detected. Trade-offs, however, can also manifest across stages of the life cycle, a phenomenon known as carryover effects. We investigated...