Clutch size declines with elevation in tropical birds

The Auk
By: , and 

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Abstract

Clutch size commonly decreases with increasing elevation among temperate-zone and subtropical songbird species. Tropical songbirds typically lay small clutches, thus the ability to evolve even smaller clutch sizes at higher elevations is unclear and untested. We conducted a comparative phylogenetic analysis using data gathered from the literature to test whether clutch size varied with elevation among forest passerines from three tropical biogeographic regions—the Venezuelan Andes and adjacent lowlands, Malaysian Borneo, and New Guinea. We found a significant negative effect of elevation on variation in clutch size among species. We found the same pattern using field data sampled across elevational gradients in Venezuela and Malaysian Borneo. Field data were not available for New Guinea. Both sets of results demonstrate that tropical montane species across disparate biogeographic realms lay smaller clutches than closely related low-elevation species. The environmental sources of selection underlying this pattern remain uncertain and merit further investigation.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Clutch size declines with elevation in tropical birds
Series title The Auk
DOI 10.1642/AUK-14-150.1
Volume 132
Issue 2
Year Published 2015
Language English
Publisher American Ornithological Society
Contributing office(s) Coop Res Unit Seattle
Description 9 p.
First page 424
Last page 432
Country Malaysian Borneo, New Guinea, Venezuela
Online Only (Y/N) N
Additional Online Files (Y/N) N