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Boyle, W. Alice; Sandercock, Brett K.; Martin, Kathy

<b>Abstract</b><br/>Elevational gradients provide powerful natural systems for testing hypotheses regarding the role of environmental variation in the evolution of life-history strategies. Case studies have revealed shifts towards slower life histories in organisms living at high elevations yet no synthetic analyses exist of elevational variation in life-history traits for major vertebrate clades. We examined (i) how life-history traits change with elevation in paired populations of bird species worldwide, and (ii) which biotic and abiotic factors drive elevational shifts in life history. Using three analytical methods, we found that fecundity declined at higher elevations due to smaller clutches and fewer reproductive attempts per year. By contrast, elevational differences in traits associated with parental investment or survival varied among studies. High-elevation populations had shorter and later breeding seasons, but longer developmental periods implying that temporal constraints contribute to reduced fecundity. Analyses of clutch size data, the trait for which we had the largest number of population comparisons, indicated no evidence that phylogenetic history constrained species-level plasticity in trait variation associated with elevational gradients. The magnitude of elevational shifts in life-history traits were largely unrelated to geographic (altitude, latitude), intrinsic (body mass, migratory status), or habitat covariates. Meta-population structure, methodological issues associated with estimating survival, or processes shaping range boundaries could potentially explain the nature of elevational shifts in life-history traits evident in this data set. We identify a new risk factor for montane populations in changing climates: low fecundity will result in lower reproductive potential to recover from perturbations, especially as fewer than half of the species experienced higher survival at higher elevations.; <b>Usage notes</b><br /><div class="o-metadata__file-usage-entry"><h4 class="o-heading__level3-file-title">Avian Life History Trait Dataset</h4><div class="o-metadata__file-description">Core dataset upon which the study was based. Details of contents described in the ReadMe file.</div><div class="o-metadata__file-name">ALHTDataset.csv</br></div><div class="o-metadata__file-name"></div></div><div class="o-metadata__file-usage-entry"><h4 class="o-heading__level3-file-title">ALHTTreesFile</h4><div class="o-metadata__file-description">File containing 500 phylogenetic trees for the taxa included in tests of phylogenetic signal in responses of clutch size to elevational differences as described in the README file associated with the main data file.</div><div class="o-metadata__file-name"></div></div>

Dataset

2020-06-30

CC0 1.0

https://doi.org/10.5683/SP2/3JHZMZ

http://creativecommons.org/publicdomain/zero/1.0