Age and size at maturity: sex, environmental variability and developmental thresholds

Age and size at maturity: sex, environmental variability and developmental thresholds.

In most organisms, transitions between different life-history stages occur later and at smaller sizes as growth conditions deteriorate. Day and Rowe recently proposed that this pattern could be explained by the existence of developmental thresholds (minimum sizes or levels of condition below which transitions are unable to proceed). The developmental-threshold model predicts that the reaction n...

Developmental thresholds and the evolution of reaction norms for age and size at life-history transitions.

It is quite common in studies of life-history plasticity to find a negative relationship between the age at which various life-history transitions occur and the growth conditions under which individuals develop. In particular, high growth typically results in earlier transitions, often at a larger size. Here, we use a relatively general optimization model for age and size at life-history transi...

Maternal age and developmental variability.

Sex‐specific plasticity and genotype × sex interactions for age and size of maturity in the sheepshead swordtail, Xiphophorus birchmanni

Responses to sexually antagonistic selection are thought to be constrained by the shared genetic architecture of homologous male and female traits. Accordingly, adaptive sexual dimorphism depends on mechanisms such as genotype-by-sex interaction (G×S) and sex-specific plasticity to alleviate this constraint. We tested these mechanisms in a population of Xiphophorus birchmanni (sheepshead swordt...

Variability in hematology and plasma indices of common carp Cyprinus carpio, associated with age, sex and hormonal treatment

The purpose of this study was to determine changes in hematological and plasma indices of Common Carp Cyprinus carpio with regard to age, sex and hormonal treatment. Sixty fish were used to assess the age factor. Also, 20 fish including female and male were assigned to determine blood indices with regard to sex and hormonal treatment. The pituitary gland extract was used as hormone for males an...