Mortality in relation to season, age, sex, and reproduction in Columbian ground squirrels (<i>Spermophilus columbianus</i>)
نویسندگان
چکیده
منابع مشابه
Senescence and age-related reproduction of female Columbian ground squirrels
1. Three hypotheses have been proposed to explain age-structured patterns of reproductive investment and somatic investment: residual reproductive value, senescence and evolutionary restraint. We evaluated these hypotheses for female Columbian ground squirrels ( Spermophilus columbianus ) by examining age-related patterns of somatic and reproductive investment. Females were designated as succes...
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Environmental factors influence the dynamics and regulation of biological populations through their influences on demographic variables, but demographic mechanisms of population regulation have received little attention. We investigated the demographic basis of regulation of Columbian ground squirrel (Spermophilus columbianus) populations under natural and experimentally food-supplemented condi...
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The influence of climate change on the fitness of wild populations is often studied in the context of the spring onset of the reproductive season. This focus is relevant for climate influences on reproductive success, but neglects other fitness-relevant periods (e.g., autumn preparation for overwintering). We examined variation in climate variables (temperature, rainfall, snowfall, and snowpack...
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Parasites play an important role in the evolution of host traits via natural selection, coevolution and sexually selected ornaments used in mate choice. These evolutionary scenarios assume fitness costs for hosts. To test this assumption, we conducted an ectoparasite removal experiment in free-living Columbian ground squirrels (Urocittelus columbianus) in four populations over three years. Adul...
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Reproductive success of females in iteroparous species usually increases early in life, then remains constant or declines. The restraint hypothesis suggests that primiparous females limit their 1st reproduction in order to avoid future costs to survival, reproduction, or both, whereas constraint indicates that primiparous females are limited in their 1st reproductive attempt either because they...
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ژورنال
عنوان ژورنال: Canadian Journal of Zoology
سال: 2001
ISSN: 1480-3283,0008-4301
DOI: 10.1139/cjz-79-3-465