The trade-off between offspring size and number can present a conflict between parents and their offspring. Because egg size is constrained by clutch size, the optimal egg size for offspring fitness may not always be equivalent to that which maximizes parental fitness. We evaluated selection on egg size in three turtle species (Apalone mutica, Chelydra serpentina and Chrysemys picta) to determi...

Forest fragmentation results in population declines and extinctions for many forest vertebrates, but little is known about the mechanisms causing declines in fragments. We investigated potential causes of declines in forest fragments for an Amazonian forest frog (Colostethus stepheni) at an experimental fragmentation study site in central Amazonian Brazil using field estimates of abundance and ...

Life history trade-offs are often hierarchical with decisions at one level affecting lower level trade-offs. We investigated trade-off structure in female side-blotched lizards (Uta stansburiana), which exhibit two evolved strategies: yellow-throated females are K-strategists and orange-throated are r-strategists. Corticosterone treatment was predicted to differentially organize these females' ...

Phenotypic plasticity and phenotypic stability are major components of the adaptive evolution of organisms to environmental variation. The invariant two-egg clutch size of Eudyptes penguins has recently been proposed to be a unique example of a maladaptive phenotypic stability, while their egg mass is a plastic trait. We tested whether this phenotypic plasticity during reproduction might result...

Processes of adaptation to urban environments are well described for relatively few avian taxa, mainly passerines, but selective forces responsible for urban colonization in ecologically different groups of birds remain mostly unrecognized. The aim of this article is to identify drivers of recent urban colonization (Łódź, central Poland) by a reed-nesting waterbird, the Eurasian coot Fulica atr...

1. With the aid of a novel survivorship model, an 8-year field study of social and maternal factors affecting duckling survival in eiders (Somateria mollissima) revealed that duckling survival probability varies in accordance with maternal brood-rearing strategy. This variability in survival provides compelling evidence of different annual fitness consequences between females that share brood-r...

Variation in egg size and shape of the Hooded Crow Corvus corone cornix was investigated in the National Park “Ujœcie Warty”, western Poland, in 2000 and 2001. Mean clutch size was 4.55±0.79 (n=40). Coefficients of variation for clutch means ranged from 2.00±1.16 (breadth) to 3.35±1.76 (elongation index). Mean repeatability estimates were 0.69, 0.71, 0.73, and 0.62 for length, breadth, volume, ...

Species in which males do not contribute to reproduction beyond the provision of sperm offer good opportunities to study the potential genetic benefits that females can obtain from polyandry. Here, we report the results of a study examining the relationships between polyandry and components of female fitness in the common lizard (Lacerta vivipara). We found that polyandrous females produce larg...

The evolution and development of complex morphological structures, and of body form, can now be addressed hierarchically, using diverse techniques from multiple theoretical perspectives. Such an ‘integrative’ or ‘holistic’ approach is likely to provide more complete insight into the origin of patterns and processes of evolution than the more traditional reductionist mode. Current work on the im...

Parasites can have dramatic effects on life-history decisions of hosts such as timing of reproduction, clutch size, and investment in individual offspring, depending on the timing of parasite effects on host fitness. Moreover, parasites may influence the optimum values of important life-history traits such as clutch size and brood size by having different fitness effects for large and for small...