Sexual reproduction imposes risks on participating adults through increased probability of injury, predation pressure, or parasite exposure. Evolutionary theory predicts that animals will tolerate infection during at the expense load, resulting in individual trade-offs between temporary costs current against long-term evolutionary benefits form life-long production viable offspring. We tested t...

The mechanisms underlying honest signal expression remain elusive and may involve the integration of social and physiological costs. Corticosterone is a socially modulated metabolic hormone that mediates energy investment and behavior and may therefore function to deter dishonest signal expression. We examined the relationship between corticosterone and green badge coloration in male sand lizar...

migratory birds are most often responsible for the distribution of avian diseases in different areas and serve as hosts for most parasites, including ectoparasites. the aim of the present study was to record the distribution range of a mesostigmatic mite species, dermanyssus gallinae in barn swallow nests in urmia suburb, north west of iran. the samples were collected from 161 bird nests in 44 ...

argulus foliaceus (crustacea: branchiura), or the fish louse, is an ectoparasite of the skin or gill of the fresh water fish species. clinical signs in infected fish include scratching on aquarium walls, erratic swimming, and poor growth. it causes pathological changes due to direct tissue dam­age and secondary infections. in the present study, lionhead goldfish (carassius auratus ), taken from...