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Geographical variation in body size of a pelagic seabird, the streaked shearwater Calonectris leucomelas
Author(s) -
Yamamoto Takashi,
Kohno Hiroyoshi,
Mizutani Akira,
Yoda Ken,
Matsumoto Sakiko,
Kawabe Ryo,
Watanabe Shinichi,
Oka Nariko,
Sato Katsufumi,
Yamamoto Maki,
Sugawa Hisashi,
Karino Kiyotaka,
Shiomi Kozue,
Yonehara Yoshinari,
Takahashi Akinori
Publication year - 2016
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.12654
Subject(s) - latitude , shearwater , bergmann's rule , longitude , pelagic zone , range (aeronautics) , taxon , seabird , biology , macroecology , ecology , geography , zoology , biogeography , materials science , geodesy , composite material , predation
Aim In general, within temperate latitudes, races of endotherms tend to show larger body size at higher latitudes, while smaller bodied ones tend to be found at lower latitudes, a pattern known as Bergmann's rule (or James's rule for intra‐specific patterns). The adaptive basis of this geographical variation in body size is explained mostly by the heat conservation hypothesis. Application of Bergmann's rule has been confirmed mostly among terrestrial taxa and studies of marine taxa are rare. Our aim was to examine whether the intra‐specific variation in body size of a pelagic seabird species (streaked shearwater Calonectris leucomelas ) follows Bergmann's/James's rule. Location Eight different breeding colonies of the streaked shearwater , ranging from 24–39° N in latitude (approximately the full latitudinal range of the species) and 123–142° E in longitude. Methods We measured morphological traits of 454 adult streaked shearwaters in total. Principal components analysis was used to create a composite body size index for each sex from each colony using the measured traits, and the value of first principal component was compared. The relationships between body size index and latitude, longitude and the averaged mean air temperature were examined using generalized linear models. Results Body size was positively correlated with latitude and longitude, and negatively correlated with the mean air temperature. Latitude and longitude were highly correlated with air temperature. Nonetheless, between colonies, populations that are considered to forage over large areas appeared to exhibit smaller body size than those of lower latitude populations. Main conclusion The overall trend of the geographical variations in body size of streaked shearwaters followed Bergmann's/James's rule, suggesting that this rule may be applicable to seabirds. However, in addition to thermoregulatory adaptation, intra‐specific differences in foraging characteristic in relation to local marine environment might also affect the body size in highly mobile seabirds.