Evolution of Female Preference for Younger Males

Previous theoretical work has suggested that females should prefer to mate with older males, as older males should have higher fitness than the average fitness of the cohort into which they were born. However, studies in humans and model organisms have shown that as males age, they accumulate deleterious mutations in their germ-line at an ever-increasing rate, thereby reducing the quality of genes passed on to the next generation. Thus, older males may produce relatively poor-quality offspring. To better understand how male age influences female mate preference and offspring quality, we used a genetic algorithm model to study the effect of age-related increases in male genetic load on female mate preference. When we incorporate age-related increases in mutation load in males into our model, we find that females evolve a preference for younger males. Females in this model could determine a male's age, but not his inherited genotype nor his mutation load. Nevertheless, females evolved age-preferences that led them to mate with males that had low mutation loads, but showed no preference for males with respect to their somatic quality. These results suggest that germ-line quality, rather than somatic quality, should be the focus of female preference in good genes models

Nociceptors: a phylogenetic view

The ability to react to environmental change is crucial for the survival of an organism and an essential prerequisite is the capacity to detect and respond to aversive stimuli. The importance of having an inbuilt “detect and protect” system is illustrated by the fact that most animals have dedicated sensory afferents which respond to noxious stimuli called nociceptors. Should injury occur there is often sensitization, whereby increased nociceptor sensitivity and/or plasticity of nociceptor-related neural circuits acts as a protection mechanism for the afflicted body part. Studying nociception and nociceptors in different model organisms has demonstrated that there are similarities from invertebrates right through to humans. The development of technology to genetically manipulate organisms, especially mice, has led to an understanding of some of the key molecular players in nociceptor function. This review will focus on what is known about nociceptors throughout the Animalia kingdom and what similarities exist across phyla; especially at the molecular level of ion channels

Marine mammal and seabird summer distribution and abundance in the fjords of northeast Cumberland Sound of Baffin Island, Nunavut, Canada

Critical baseline population knowledge is required to properly assess the status of marine mammal and bird populations in the Canadian Arctic and the effects of climate trends on them. To address this need for one significant Arctic region, a boat-based marine mammal and seabird transect survey was conducted in Cumberland Sound fjords during summer 2008. During 173 km effort (20 h), 959 birds were recorded representing at least nine species which were dominated by Common Eiders (Somateria mollissima borealis), Iceland or Glaucous Gulls (Larus glaucoides or Larus hyperboreus), and Black Guillemots (Cepphus grylle), in addition to less common birds including Red-throated and Common Loons (Gavia stellata and Gavia immer), Northern Fulmars (Fulmarus glacialis), and Great or Lesser Black-backed Gulls (Larus marinus or Larus fuscus). Of these, 480 birds were observed on the water in one event consisting of eiders and gulls which may have biased encounter rates. Of 101 marine mammal sightings, four species were represented: 73 harp seals (Pagophilus groenlandicus), 13 beluga whales (Delphinapterus leucas), nine bowhead whales (Balaena mysticetus), five ringed seals (Pusa hispida), and one unidentified pinniped. A pod of four killer whales (Orcinus orca) was observed off-effort in Pangnirtung Fjord during the survey period. This pilot study provided the first estimates of relative abundance for marine mammals and seabirds in the study area to aid in developing future surveys. © 2010 Springer-Verlag