Life-history theory suggests that the variation in the seasonal timing of reproduction within populations may be explained on the basis of individual optimization. Optimal breeding times would vary between individuals as a result of trade-offs between fitness components. The existence of such trade-offs has seldom been tested empirically. We experimentally investigated the consequences of alter...

Environmental influences on egg and clutch sizes in lenticand lotic-breeding salamanders. Recent research indicates that social and environmental factors influence egg and clutch sizes in amphibians. However, most of this work is based on the reproductively diverse order Anura (frogs and toads), whereas less research has been conducted on Caudata (salamanders) and Gymnophiona (caecilians). Rese...

Pathogen infection is typically costly to hosts, resulting in reduced fitness. However, pathogen exposure may also come at a cost even if the host does not become infected. These fitness reductions, referred to as "resistance costs", are inducible physiological costs expressed as a result of a trade-off between resistance to a pathogen and aspects of host fitness (e.g., reproduction). Here, we ...

Models of optimal clutch size often implicitly assume a situation with uniparental care. However, the evolutionary conflict between males and females over the division of parental care will have a major influence on the evolution of clutch size. Since clutch size is a female trait, a male has little possibility of directly influencing it. However, the optimal clutch size from a female's perspec...

The amount of parental provisioning is thought to reflect the need of offspring. This hypothesis was tested in the case of provisioning food mass to young with controlled clutch size using the maritime earwig, Anisolabis maritima Bonelli (Dermaptera: Anisolabididae). The female provisioned a constant mass of food to the young irrespective of the number of nymphs and the distance of food carryin...

The change in avian clutch size with latitude is a celebrated example of geographic variation in a vertebrate life-history trait. Alternative hypotheses for this pattern invoke nest predation, limited food for nestlings, or post-fledging juvenile mortality as selection pressures leading to small clutch size of tropical birds. We manipulated the clutch size of Spotted Antbirds (Hylophylax naevio...

Individuals of different quality may have different investment strategies, shaping responses to experimental manipulations, thereby rendering the detection of such patterns difficult. However, previous clutch-size manipulation studies have infrequently incorporated individual differences in quality. To examine costs of incubation and reproductive investment in relation to changes in clutch size...

The majority of species in the scincid genus Emoia (Squamata: Scincidae) have a fixed clutch size of two eggs per clutch and produce between two and four clutches per year. One lineage within Emoia, the Emoia samoensis species group, consists of 13 species occurring in Melanesia and the islands of the southwestern Pacific Ocean, and exhibits variation in clutch size, with previously reported cl...

Parasites have been argued to influence clutch size evolution, but past work and theory has largely focused on within-species optimization solutions rather than clearly addressing among-species variation. The effects of parasites on clutch size variation among species can be complex, however, because different parasites can induce age-specific differences in mortality that can cause clutch size...