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Contrasting latitudinal patterns of life-history divergence in two genera of new world thrushes (Turdinae)

April 1, 2017

Several long-standing hypotheses have been proposed to explain latitudinal patterns of life-history strategies. Here, we test predictions of four such hypotheses (seasonality, food limitation, nest predation and adult survival probability) by examining life-history traits and age-specific mortality rates of several species of thrushes (Turdinae) based on field studies at temperate and tropical sites and data gathered from the literature. Thrushes in the genus Catharus showed the typical pattern of slower life-history strategies in the tropics while co-occuring Turdus thrushes differed much less across latitudes. Seasonality is a broadly accepted hypothesis for latitudinal patterns, but the lack of concordance in latitudinal patterns between co-existing genera that experience the same seasonal patterns suggests seasonality cannot fully explain latitudinal trait variation in thrushes. Nest-predation also could not explain patterns based on our field data and literature data for these two genera. Total feeding rates were similar, and per-nestling feeding rates were higher at tropical latitudes in both genera, suggesting food limitation does not explain trait differences in thrushes. Latitudinal patterns of life histories in these two genera were closely associated with adult survival probability. Thus, our data suggest that environmental influences on adult survival probability may play a particularly strong role in shaping latitudinal patterns of life-history traits.

Citation Information

Publication Year 2017
Title Contrasting latitudinal patterns of life-history divergence in two genera of new world thrushes (Turdinae)
DOI 10.1111/jav.01113
Authors Andy J. Boyce, Thomas E. Martin
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Avian Biology
Series Number
Index ID 70192691
Record Source USGS Publications Warehouse
USGS Organization Coop Res Unit Seattle

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