In a diverse array of avian and mammalian species, experimental manipulations of clutch size have tested the hypothesis that natural selection should adjust numbers of neonates produced so as to maximize the number of viable offspring at the end of the period of parental care. Reptiles have not been studied in this respect, probably because they rarely display parental care. However, females of...

Reproductive success in many avian populations declines throughout the breeding season. Two hypotheses have gained attention to explain such a decline: the ‘‘timing’’ hypothesis proposes that deteriorating food availability causes the decline in reproductive success (causal effect of breeding time), whereas the ‘‘quality’’ hypothesis proposes that individuals of lower phenotypic quality reprodu...

Geographic variation in body size and reproductive traits has been reported in a wide range of organisms, including amphibians. Most studies have focused on latitudinal and/or altitudinal variation where differences in temperature and duration of the growing season are the main causes for population divergence. We describe a steep variation in body size and reproductive traits in two anuran spe...

We describe a method for the rearing of the oligophagous herbivore Hadena bicruris, and its gregarious koinobiont endoparasitoid Microplitis tristis under laboratory conditions. With flowers from the host food plant Silene latifolia available, female moths lay on average 414 eggs during their lifetime, starting at day 3 after eggression and with a peak number per night on day 8. Caterpillars ca...

The hormone melatonin is known to play an important role in regulating many seasonal changes in physiology, morphology and behaviour. In birds, unlike in mammals, melatonin has thus far been thought to play little role in timing seasonal reproductive processes. This view is mainly derived from laboratory experiments on male birds. This study tests whether melatonin is capable of influencing the...

Cooperatively breeding birds tend to exhibit high adult survival and relatively small clutch sizes. According to the life-history hypothesis for cooperative breeding, high survival creates conditions for philopatry based on difficulties that dispersers face when competing for territories in a landscape with slow territory turnover. However, this hypothesis evokes a puzzle because high fecundity...