Mammalian pelage color can vary among individuals of many species, although this intraspecific variation is oftenoverlooked by researchers, perhaps because of its sometimes subtle nature and difficulty in assessing it...Mammalian pelage color can vary among individuals of many species, although this intraspecific variation is oftenoverlooked by researchers, perhaps because of its sometimes subtle nature and difficulty in assessing it quantitatively. Thus, suchvariation is rarely studied in mammals, and this is especially true within the order Chiroptera, where there has been very little empiricalresearch. We examined museum specimens of red bats (Lasiurus borealis, family Vespertilionidae) from Georgia, USA, todetermine the extent of sexual dimorphism in pelage color and to explore possible associations between body size and pelagecolor. We photographed 54 specimens under uniform lighting, and used an image analysis program to measure pelage hue on theuropatagium region, which is fully furred in members of the genus Lasiurus. Statistical analyses of pelage hue scores showedmales had significantly redder pelage than females when considered alone, but when examined together with effects of body sizeand collection year, sex was not significant, and collection year and body size were. More recent specimens tended to be less redthan older specimens, which might indicate a wearing of the buffy tips of hairs from older specimens, and smaller bats of bothsexes tended to be more red. These interesting findings are encouraging and we suggest that future explorations into intraspecificvariation in pelage color of bats using this or similar approaches are warranted to clarify the significance of the patterns. Thisstudy also demonstrated that care must be taken in analyses of mammalian pelage color from older museum skins, or at least thatresearchers must take into account the age of the specimens .展开更多
Throughout the animal kingdom there are species that have two or more phenotypic forms or ‘morphs＇, and many of these are amphibians. In North America, the red-backed salamander Plethodon cinereus can have either a ...Throughout the animal kingdom there are species that have two or more phenotypic forms or ‘morphs＇, and many of these are amphibians. In North America, the red-backed salamander Plethodon cinereus can have either a red dorsal stripe or no dorsal stripe （lead-phase form）, and evidence to date indicates the lead-phase form incurs a greater number of attacks from predators. In a recent collection of 51 P cinereus, blood smears of both color morphs （35 red-stripe, 16 lead-phase） were examined to obtain numbers of circulating leukocytes （via light microscopy）, which can be used to indirectly estimate levels of stress hormones in vertebrates via a ‘hematological stress index＇, which is the ratio between the number of two leukocyte types （neutrophils and lymphocytes）. Our results showed that lead-phase salamanders tended to have greater numbers of circulating neutrophils and lower numbers of circulating lymphocytes than red-stripe morphs, leading to higher average neutrophil-lymphocyte ratios in lead-phase individuals. Since the salamanders were held （refrigerated） for 7 days before sampling, we cannot be certain if this effect is a stress reaction to the captivity or the normal level for this morph. However comparison with two sets of related salamanders that were captured and sampled immediately indicates the red-stripe salamanders were either not stressed from the captivity at all, or their white blood cell distributions had returned to normal after 7 days of captivity. Taken together, our results indicate that lead-phase forms of P. cinereus have higher stress levels than the red-stripe forms, which may be a consequence of their higher exposure to, and/or attacks from, predators. They may also indicate that the lead-phase form is less-suited to captivity than the red-stripe form of this species.展开更多
基金supported by a grant rrom the Morris Animal Foundation
文摘Mammalian pelage color can vary among individuals of many species, although this intraspecific variation is oftenoverlooked by researchers, perhaps because of its sometimes subtle nature and difficulty in assessing it quantitatively. Thus, suchvariation is rarely studied in mammals, and this is especially true within the order Chiroptera, where there has been very little empiricalresearch. We examined museum specimens of red bats (Lasiurus borealis, family Vespertilionidae) from Georgia, USA, todetermine the extent of sexual dimorphism in pelage color and to explore possible associations between body size and pelagecolor. We photographed 54 specimens under uniform lighting, and used an image analysis program to measure pelage hue on theuropatagium region, which is fully furred in members of the genus Lasiurus. Statistical analyses of pelage hue scores showedmales had significantly redder pelage than females when considered alone, but when examined together with effects of body sizeand collection year, sex was not significant, and collection year and body size were. More recent specimens tended to be less redthan older specimens, which might indicate a wearing of the buffy tips of hairs from older specimens, and smaller bats of bothsexes tended to be more red. These interesting findings are encouraging and we suggest that future explorations into intraspecificvariation in pelage color of bats using this or similar approaches are warranted to clarify the significance of the patterns. Thisstudy also demonstrated that care must be taken in analyses of mammalian pelage color from older museum skins, or at least thatresearchers must take into account the age of the specimens .
基金Funding for AKD during this project was provided by the DBWarnell School of Forestry and Natural Resources and a grant from the Morris Animal FoundationSupport for the field word of this project came form an NSF grant (NSF-DEB DEB0542974)
文摘Throughout the animal kingdom there are species that have two or more phenotypic forms or ‘morphs＇, and many of these are amphibians. In North America, the red-backed salamander Plethodon cinereus can have either a red dorsal stripe or no dorsal stripe （lead-phase form）, and evidence to date indicates the lead-phase form incurs a greater number of attacks from predators. In a recent collection of 51 P cinereus, blood smears of both color morphs （35 red-stripe, 16 lead-phase） were examined to obtain numbers of circulating leukocytes （via light microscopy）, which can be used to indirectly estimate levels of stress hormones in vertebrates via a ‘hematological stress index＇, which is the ratio between the number of two leukocyte types （neutrophils and lymphocytes）. Our results showed that lead-phase salamanders tended to have greater numbers of circulating neutrophils and lower numbers of circulating lymphocytes than red-stripe morphs, leading to higher average neutrophil-lymphocyte ratios in lead-phase individuals. Since the salamanders were held （refrigerated） for 7 days before sampling, we cannot be certain if this effect is a stress reaction to the captivity or the normal level for this morph. However comparison with two sets of related salamanders that were captured and sampled immediately indicates the red-stripe salamanders were either not stressed from the captivity at all, or their white blood cell distributions had returned to normal after 7 days of captivity. Taken together, our results indicate that lead-phase forms of P. cinereus have higher stress levels than the red-stripe forms, which may be a consequence of their higher exposure to, and/or attacks from, predators. They may also indicate that the lead-phase form is less-suited to captivity than the red-stripe form of this species.
