Background: Male reproductive disorders that are of interest from an environmental point of view include sexual dysfunction, infertility, cryptorchidism, hypospadias and testicular cancer. Several reports suggest declining sperm counts and increase of these reproductive disorders in some areas during some time periods past 50 years. Materials and Methods: Except for testicular cancer this evide...

the main aim of this research was to estimate the genetic and phenotypic parameters for productive and reproductive traits of esfahan native chickens. traits included body weights at hatch (bw1), 8 weeks of age (bw8), 12 weeks of age (bw12), and at sexual maturity (wsm)], age at sex maturity (asm), egg number (en), average egg weight (aew) in the first 12 weeks of production, and egg production...

Studying biological and social determinants of mortality and fertility provides insight into selective pressures in a population and the possibility of trade-offs between shortand long-term reproductive success. Limited data is available from post-demographic transition populations. We studied determinants of reproductive success using multi-generational data from a large, population-based coho...

Epidemiology is one of the areas in biology to which mathematical modeling has been applied most successfully. It was through the mathematical concept of basic reproductive number that Ronald Ross gained the insight that malaria could be controlled if the mosquito population was sufficiently suppressed (Heesterbeek 2002). Later, similar concepts were applied to the eradication of smallpox and t...

Interactions between animals and their environment are fundamental to ecological research. Field studies of coyote (Canis latrans) reproductive performance suggest mean litter size changes in response to prey abundance. However, this relationship has been assessed primarily by using carcasses collected from trappers. The objective of this study was to assess whether nutritional manipulation pri...

Accepted: 29/09/2015 Abstract The control and manipulation of reproduction is the subject of scientific interest for many years. High level of reproductive performance can be achieved under optimum managemental conditions because reproduction is directly affected by various managemental factors. Manipulation of these factors causes changes in reproductive performance. Seasonal breeders are anim...

Members of some social insects adjust their behaviours depending upon social context. Such plasticity allows colonies to sustain efficiency of the whole without the cost of additional production of individuals or delayed responses to perturbations. Using the recently discovered social clonal stage of trematode parasites, we investigated whether members of the reproductive caste adjust their def...

In order to investigate drought stress and plant density the yield, yield components and protein of spotted bean grain (cultivar Talash), an experiment was carried out as split plots in randomized complete blocks with three replications in Yasouj, in 2012. Factors of the test including irrigation in three levels; without stress (control treatment), water stress in vegetative stage (interrupting...

Despite the many successes of cancer research, we lack the framework necessary to predict the ratio of familial (inherited) to sporadic (non-inherited) cancers. An evolutionary model of multistage carcinogenesis provides this framework by demonstrating that the number of tumour suppressor loci (TSLs) preventing cancer in a given tissue is expected to depend upon the tissue's vulnerability to pr...

In dioecious plants, reproductive efforts of male and female plants can be differentially affected by herbivory due to sex-specific allocation and re-modulation of resources. Here, we investigate the effects of foliar herbivory by the polyphagous species Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) on male and female reproductive traits of Silene latifolia (Poir.) (Caryophyllaceae...