The role of climate factors in geographic variation in body mass and wing length in a passerine bird

Abstract

Background: Geographic variation in body size is assumed to reflect adaptation to local environmental conditions. Although Bergmann's rule is usually sufficient to explain such variation in homeotherms, some exceptions have been documented. The relationship between altitude, latitude and body size, has been well documented for some vertebrate taxa during the past decades. However, relatively little information is available on the effects of climate variables on body size in birds. Methods:We collected the data of 267 adult Eurasian Tree Sparrow (Passer montanus) specimens sampled at 48 localities in China's mainland, and further investigated the relationships between two response variables, body mass and wing length, as well as a suit of explanatory variables, i.e. altitude, latitude, mean annual temperature (MAT), annual precipitation (PRC), annual sunshine hours (SUN), average annual wind speed (WS), air pressure (AP) and relative humidity (RH). Results:Our study showed that (1) although the sexes did not differ significantly in body mass, males had longer wings than females; (2) body mass and wing length were positively correlated with altitude but not with latitude; (3) body mass and wing length were negatively correlated with AP and RH, but not significantly correlated with WS. Body mass was positively correlated with SUN and inversely correlated with MAT. Wing length was not correlated with MAT in either sex, but was positively correlated with SUN and negatively correlated with PRC in male sparrows; (4) variation in body mass could be best explained by AP and SUN, whereas variation in wing length could be explained by RH and AP in both sexes. In addition, variation in male sparrows can be explained by SUN, WS and PRC but not in females. Conclusions:Two different proxies of body size, body mass and wing length, correlated with same geographic factors and different climate factors. These differences may reflect selection for heat conservation in the case of body mass, and for efficient flight in the case of wing length.

Life-history dependent relationships between plasma alkaline phosphatase activity and body condition in male Eurasian Tree Sparrows

“…Previous studies have demonstrated that the body mass or body condition of Eurasian Tree Sparrows vary with life-history stage (Li et al 2008(Li et al , 2011(Li et al , 2012Zheng et al 2014) and living environment (Zhang et al 2011;Sun et al 2016Sun et al , 2017. Furthermore, male sparrows during the early breeding stage had significantly greater Hct values compared to those from the early wintering stage, whereas there were no significant differences in SCM between the two life-history stages (Zhao et al 2017).…”

Bergmann’s rule and Allen’s rule in two passerine birds in China

“…There is no agreement about whether Bergmann's pattern is general or valid (Blackburn et al 1999;Meiri and Dayan 2003;Watt et al 2010;Teplitsky and Millien 2014). Empirical studies have found the predicted pattern at both the intraspecific and interspecific levels (Meiri 2011;Salewski and Watt 2017) in numerous mammals (Ashton et al 2000;Rodriguez et al 2008) and birds (Olson et al 2009;Sun et al 2017). At the same time, animals that do not conform to Bergmann's rule have also been reported (Yom-Tov et al 2002;Freeman 2017;Sargis et al 2018).…”

Comparative transcriptomic and metabolomic analysis reveals pectoralis highland adaptation across altitudinal songbirds

“…Great body mass and muscle weight in highland are concordance with Bergmann's rule [15,16]. Avian pectoralis is used to support the high metabolic costs through aerobic metabolism for flight or thermogenesis [4].…”