Proximate effects of temperature versus evolved intrinsic constraints for embryonic development times among temperate and tropical songbirds

Abstract

The relative importance of intrinsic constraints imposed by evolved physiological trade-offs versus the proximate effects of temperature for interspecific variation in embryonic development time remains unclear. Understanding this distinction is important because slow development due to evolved trade-offs can yield phenotypic benefits, whereas slow development from low temperature can yield costs. We experimentally increased embryonic temperature in free-living tropical and north temperate songbird species to test these alternatives. Warmer temperatures consistently shortened development time without costs to embryo mass or metabolism. However, proximate effects of temperature played an increasingly stronger role than intrinsic constraints for development time among species with colder natural incubation temperatures. Long development times of tropical birds have been thought to primarily reflect evolved physiological trade-offs that facilitate their greater longevity. In contrast, our results indicate a much stronger role of temperature in embryonic development time than currently thought.

Variation in offspring development is driven more by weather and maternal condition than predation risk

“…Additionally, an interaction between date and maternal condition demonstrated that females in good condition consistently created a nest environment that promoted rapid nestling development compared to poor condition females, regardless of environmental conditions. Contrary to expectations from experimental studies (Nord & Nilsson, 2011;Ospina et al, 2018), we found only minimal support are associated with reduced egg temperatures and prolonged incubation periods (Martin, Auer, Bassar, Niklison, & Lloyd, 2007), particularly in cold-adapted species (Ton & Martin, 2017), while experimentally heating tree swallow Tachycineta bicolor nests during the nestling period promotes rapid development (Dawson et al, 2005). We found colder temperatures prolonged the incubation period, as well as, the nestling period, but only when occurring during the late nestling stage.…”

“…Weather conditions can prolong offspring development and the timing of weather events may be critical. Colder ambient conditions are associated with reduced egg temperatures and prolonged incubation periods (Martin, Auer, Bassar, Niklison, & Lloyd, ), particularly in cold‐adapted species (Ton & Martin, ), while experimentally heating tree swallow Tachycineta bicolor nests during the nestling period promotes rapid development (Dawson et al, ). We found colder temperatures prolonged the incubation period, as well as, the nestling period, but only when occurring during the late nestling stage.…”

Quantification of 27 yolk steroid hormones in seven shrubland bird species: interspecific patterns of hormone deposition and links to life history, development, and predation risk

“…Despite the interest in maternal effects in birds, we still have a limited understanding of how environmental factors such as nest predations risk, and life-history traits such as incubation period, impact patterns of maternal resource allocation (but see e.g. Martin 1995;Conway and Martin 2000;LaManna and Martin 2017;Ton and Martin 2017). This is especially true for maternally-derived yolk hormones such as steroid hormones.…”

Incubation temperature impacts nestling growth and survival in an open‐cup nesting passerine

“…Much of the work on incubation temperature in wild birds has focused on cavity‐nesting species, and/or species with precocial offspring (DuRant et al., ; Hepp, Kennamer, & Johnson, ; Nord & Nilsson, ), primarily because species with these life‐history traits are amenable to temperature manipulation studies. However, the majority of bird species are open‐cup nesting species with altricial young, and to date, little work has been done examining how changes in incubation temperature impact development and survival of open‐cup nesting species with altricial young (but see: Ton & Martin, ). While studies on cavity‐nesting species have provided critical insight into the importance of incubation temperature for proper growth and development (Ardia, Pérez, & Clotfelter, ; Wada et al., ), there are a number of important differences between these species and those that build open‐cup nests and have altricial young.…”