Effects of Environmental Variation at Multiple Scales on the Dark-eyed Junco (Junco hyemalis) in California

摘要: The selective pressures acting on phenotypes are complex and can vary over space time. To examine the effects of selection due to environmental conditions avian bill morphology, we explored spatial temporal variation in morphology a common generalist songbird, Dark-eyed Junco (Junco hyemalis). We measured length, width, depth, calculated surface area, for >800 museum specimens collected state California from 1905-1980. then examined which variables (precipitation, temperature, habitat type) at scales (seasonal, annual, hemi-decadal, decadal) could explain each measure morphology. Although predicted relationships consistent with foraging utility optimal thermoregulation, patterns found were more complex. factors varied season specific traits. Measures type strongly associated than individual climate variables, temperature was important predictor precipitation. Bill area displayed stronger did linear measures Of identified as our analyses, support strongest decadal variability. strong relationship between vegetative community models, longer-term importance variability suggests that natural systems, large-scale context—ecology climate—plays role is not seen by looking its component parts alone.Different produce different pressures. life history along an elevation gradient identify contributing this variation. monitored breeding Juncos Sierra Nevada mountains sites 1960 2660 m above sea level compared peak activity, clutch size, brood nestling quality, nest mortality among elevations. also maximum minimum daily snow monthly precipitation across elevations determine whether these abiotic small differences length pattern reproductive timing While intermediate activity observed low high be explained solely factors, but may related those birds' prey base or nesting sites, potentially exacerbated lower ongoing drought. no quality. Higher had greater mortality, possibly severe weather. A computer simulation constructed mimic field system differences, combination contribute substantial success difficult observe setting.We investigated climatic conditions, number offspring produced per populations junco led synchrony, extra-pair paternity, use sexually-selected male signal, amount white tail. tested genetic structure populations. Using 12 variable microsatellite loci, paternity rates populations, rate (20% nests) elevations, (57%) middle (38%) mean values tail asymmetry, honesty signal (the strength correlation either two indices quality). Despite well season, synchrony association presence brood's synchrony. detected differentiation indicating gene flow occurs Persistent lack despite potential sexual