Luc A. Wauters, Massimiliano Zaninetti, Guido Tosi, Sandro Bertolino
Is coat-colour polymorphism in Eurasian red squirrels (Sciurus vulgaris L.) adaptive?
Coat-colour polymorphism, the relative frequencies of red, brown and black
fur-morphs, was examined in nine populations of the Eurasian red squirrel
(Sciurus vulgaris L.) in northern Italy. The proportions of the three different
coat-colours differed between populations. Red morphs were most common
in mixed woodlands of the Upper Po-plain, but rare in populations from the
Alps. The highest frequencies of black morphs were found in subalpine
conifer forests in the western Alps (Gran Paradiso) and in montane mixed
conifer forests in the central Alps (Valtellina). Coat-colour did not affect juvenile
survival, and there were no significant differences in mean foot length or
body mass among subadults and adults of different colour-morphs. However,
inter-population variation in the frequency of black morphs was positively
correlated with the proportion of spruce (and/or fir) in the forest and with the
density of trees. We suggest that the combination of a denser and more cryptic
fur in black morphs gives them a selective advantage over other coat colour
morphs in wet, dense spruce-fir forests of the Italian Alps, which could
explain the within- and between population variation in the relative frequencies
of coat colour phenotypes observed in this study.
Mammalia, Walter de Gruyter
Print ISSN: 0025-1461
Volume: 68, 07/2004
Pages: 37 - 48
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