Many chemicals introduced into the environment by humans adversely affect embryonic development and the functioning of the male reproductive system. It has been hypothesized that these developmental alterations are due to the endocrine-disruptive effects of various environmental contaminants. The endocrine system exhibits an organizational effect on the developing embryo. Thus, a disruption of ...

Assortative mating promotes reproductive isolation and allows allopatric speciation processes to continue in secondary contact. As mating patterns are determined by mate preferences and intrasexual competition, we investigated male-male competition and behavioral isolation in simulated secondary contact among allopatric populations. Three allopatric color morphs of the cichlid fish Tropheus wer...

We examined aerobic performance traits in male and female tarantulas (Aphonopelma anax). Reproductive fitness in these males relies heavily on locomotory searching to locate receptive females, which are fossorial and sedentary. Because of this dimorphism in life history, we predicted that selection in males would enhance their ability to sustain high levels of aerobic metabolism (compared with ...

The reproductive system is extremely susceptible to environmental insults, for example exogenous steroids during gestational development and differentiation. Experimental induction of androgen excess during prenatal life in female animal models reprograms their reproductive physiology, however the fetal programming of the male reproductive system by androgen excess has not been well studied. We...

BACKGROUND Lead exposure is known to be harmful to the male reproductive system, including impairment of fertility. However, it is unclear whether currently existing low levels of exposure have this effect. AIMS To study retrospectively current workers in lead using industries (battery manufacture, smelting, etc), and in non-lead using control industries, in four European countries, with Time...

Second-stage larvae of Meloidodera floridensis kept in tap water developed without feeding into small, slender males. They completed three molts, and the molted cuticles remained superimposed. All organ systems were well developed in third- and fourth-stage male larvae. Structures in the head region such as cephalic framework, styler and esophagus were smaller and differed morphologically from ...