Latitude, elevation and body mass variation in Andean passerine birds |
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| Authors: | Tim M. Blackburn, Adriana Ruggiero, |
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| Affiliation: | NERC Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire, SL5 7PY, U.K. Lab. Ecotono, Depto de Ecología, Centro Regional Universitario Bariloche, Universidad Nacional del Comahue, Quintral 1250 (8400) Bariloche, Rio Negro, Argentina |
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| Abstract: | - 1 Relationships between body mass and latitude, and body mass and elevation are examined in the assemblage of Andean passerine birds.
- 2 Across species, body mass is positively correlated with the mid‐point of the species elevational distribution, but there is no significant relationship between body mass and latitudinal range mid‐point.
- 3 When the assemblage is separated into Andean endemic and non‐endemic species, the former group shows a significant positive relationship between body mass and elevation, and the latter a significant positive relationship between body mass and latitude (‘Bergmann’s rule’). Andean endemic species exhibit Bergmann’s rule once elevation is controlled for using multiple regression.
- 4 These relationships are not a consequence of the phylogenetic non‐independence of species. All the effects shown are very weak, with latitude and elevation explaining only a few per cent of the variation in body mass. Relationships are strongest when phylogenetically controlled analyses are performed just within genera.
- 5 The implications of these results for the mechanistic understanding of Bergmann’s rule are discussed.
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| Keywords: | Andean birds Bergmann's rule body size ecogeographic rule elevation latitude |
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