Sexual maturity, temporal reproductive pattern, and recruitment of juveniles were examined for the penaeoid shrimp Artemesia longinaris sampled for five and a half years in a tropical locality off the coast of São Paulo (23o S), Brazil. Monthly samples were taken from January 1998 to June 2003 at depths between 5 and 45 m. Ovarian maturity was used to examine breeding in adult females. Recruitm...

Influenza epidemics in temperate regions show a characteristic seasonal pattern with peak incidence occurring in winter. Previous research has shown that low absolute humidity and school holidays can both affect influenza transmission. During an epidemic, transmission is strongly influenced by the depletion of susceptibles (i.e., increase in the number of those immune). To assess how much varia...

Animal reproductive cycles are commonly triggered by environmental cues of favourable breeding conditions. In arid environments, rainfall may be the most conspicuous cue, but the effects on reproduction of the high inter- and intra-annual variation in temperature remain poorly understood, despite being relevant to the current context of global warming. Here, we conducted a multiyear examination...

Every organism has a limited amount of energy that can be expended towards growth, personal maintenance, and reproduction. Once an organism has reached sexual maturity, life history theory predicts a trade-off to exist between self-maintenance and investment in offspring. This study examined the extent to which male and female parental care was affected by a decrease in female body condition in...

We documented vocalization activity of breeding shorebirds at two sites in northern and western Alaska, on the Colville River Delta and on the Yukon – Kuskokwim Delta. At both sites, number of calling individuals decreased throughout the season. Variation in vocalization activity was significantly higher at the Colville River Delta towards the end of the season, while weather variables affected...

The reproductive strategy of a species depends upon the interaction between intrinsic and extrinsic factors. Examining the population of Leporinus friderici in two reservoirs of the Upper Paraná River basin in reference to first gonadal maturation and breeding season and sites, the present investigation tested whether the environment formed by damming promoted spatial and temporal changes in th...

Seasonal dynamics of the abundance, sexual reproduction and genetic architecture in a Daphnia hyalina-galeata hybrid complex were studied in the large and deep Lake Constance. We found evidence for the occurrence of first and second order hybridization. Our study revealed strong differences between the parental species not only regarding their seasonal dynamics, genetic architecture and diversi...

For hibernators, being born late in the active season may have important effects on growth and fattening, hence on winter survival and reproduction. This study investigated differences in growth, fattening, energetic responses, winter survival and fecundity between early-born ('EB') and late-born ('LB') juvenile garden dormice (Eliomys quercinus). LB juveniles grew and gained mass twice as fast...

INVESTIGATIONS of seasonal changes in thyroid histology in wild birds have shown that increases in activity occur in the period preceding and during the annual molt (Davis and Davis, 1954; Assenmacher, 1958; Voitkevich, 1966) and in response to low temperature (Wilson and Farner, 1960; Kendeigh and Wallin, 1966). Involvement of th'e avian thyroid in migration and reproduction has also been sugg...

Animals restrict breeding to specific times of the year when reproductive success is most likely. In males, the most reliable method of reproductive inhibition is gonadal retrogression to an immature state. Depending on the species, the testes decrease in size by between 10 and 95% in response to environmental cues associated with the non-breeding season. An increased rate of apoptosis can occu...