PT  - JOURNAL ARTICLE
AU  - Christopher R. Cooney
AU  - Catherine Sheard
AU  - Andrew D. Clark
AU  - Susan D. Healy
AU  - András Liker
AU  - Sally E. Street
AU  - Camille A. Troisi
AU  - Gavin H. Thomas
AU  - Tamás Székely
AU  - Nicola Hemmings
AU  - Alison E. Wright
TI  - Ecology, phylogeny, and the evolution of developmental duration in birds
AID  - 10.1101/797498
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 797498
4099  - http://biorxiv.org/content/early/2019/10/08/797498.short
4100  - http://biorxiv.org/content/early/2019/10/08/797498.full
AB  - The duration of the developmental period represents a fundamental axis of life history variation in animals, yet broad insights regarding the drivers of this diversity are currently lacking. Here using embryological data combined with information on incubation and fledging periods for 3096 species, we test key mechanistic and adaptive explanations for the evolutionary diversification of developmental durations in birds. First, using data on embryonic development for 20 model species, we show that developmental phases associated primarily with growth are longer and more variable than earlier phases, consistent with a role for allometric constraint in determining the duration of development. Second, using phylogenetic comparative methods, we find that avian developmental durations retain a strong imprint of deep evolutionary history, and that after accounting for these effects, body size differences among species explain less variation (5-22%) in developmental period lengths than previously thought. Finally, by collecting data for a suite of potential explanatory variables, our analyses reveal broad-scale ecological correlates of developmental durations, including variables associated with the relative safety of the developmental environment (e.g. nest height, insularity) and pressures of breeding phenology (e.g. migration). Overall, our results reveal that the combined effects of species’ body size, ecology, and phylogenetic history can account for 62-93% of the variation in developmental durations across birds, providing broad-scale quantitative insight into the relative importance of mechanistic constraints, adaptive evolution and evolutionary constraints in shaping the diversification of this key life-history trait.