Visar resultat 1 - 5 av 127 avhandlingar innehållade ordet PaternAl.
Sammanfattning : In this thesis I explore how sexual selection, sexual conflicts, coevolution with parental care and an environmental selective agent (hypoxia) affect the evolution of different egg characteristics and embryo survival and size in pipefishes (Syngnathidae). In the broad-nosed pipefish, Syngnathus typhle Linnaeus, both sexes prefer to mate with large partners; large females produce more and larger eggs and large males can care for more young, and, as shown in this thesis, invest more per embryo and provide better oxygenation during brooding. LÄS MER
Sammanfattning : Sexual selection arises through variation in reproductive success. This thesis investigates different aspects important in sexual selection, namely nest building, sperm competition, paternity and paternal care, and their mutual interrelationships. LÄS MER
Sammanfattning : In the fifteen-spined stickleback, Spinachia spinachia, males provide females with direct benefits by fanning, cleaning and guarding the offspring. Males announce their parental skills through intense body shakes during courtship. Females preferred to mate with more intensely shaking males. LÄS MER
Sammanfattning : From an evolutionary and adaptive perspective, the occurrence and extent of parental care in animals (investment in offspring beyond the genetic contribution) is expected to depend on an optimal (fitness-maximizing) balance of its costs and benefits. Males of the sex-role reversed broad-nosed pipefish, Syngnathus typhle, which care for eggs and embryos and may perform brood reduction, are particularly interesting in this respect. LÄS MER
Sammanfattning : This thesis had two general aims. The first was to describe and compare the social-economic and reproductive characteristics and involvement in pregnancy and childbirth of fathers of children born to teenage mothers in Stockholm (Papers I and II). LÄS MER