Rapid evolutionary change in a secondary sexual character linked to climatic change

Abstract

The ability of organisms to respond evolutionarily to rapid climatic change is poorly known. Secondary sexual characters show the potential for rapid evolutionary change, as evidenced by strong divergence among species and high evolvability. Here we show that the length of the outermost tail feathers of males of the socially monogamous barn swallow Hirundo rustica, feathers that provide a mating advantage to males, has increased by more than 1 standard deviation during the period from 1984 to 2003. Barn swallows from the Danish population studied here migrate through the Iberian Peninsula to South Africa in fall, and return along the same route in spring. Environmental conditions on the spring staging grounds in Algeria, as indexed by the Normalized Difference Vegetation Index, predicted tail length and change in tail length across generations. However, conditions in the winter quarters and at the breeding grounds did not predict change in tail length. Environmental conditions in Algeria in spring showed a temporal deterioration during the study period, associated with a reduction in annual survival rate of male barn swallows. Phenotypic plasticity in tail length of males, estimated as the increase in tail length from the age of 1 to 2 years, decreased during the course of the study. Estimates of directional selection differentials for male tail length with respect to mating success, breeding date, fecundity, survival and total selection showed temporal variation, with the intensity of breeding date selection, survival selection and total selection declining during the study. Response to selection as estimated from the product of heritability and total selection was very similar to the observed temporal change in tail length. These findings provide evidence of rapid micro‐evolutionary change in a secondary sexual character during a very short time period, which is associated with a rapid change in environmental conditions.

Survival rates of hirundines in relation to British and African rainfall

“…Swallows are known to be highly site faithful (Turner 2006), martins perhaps less so (Cramp 1988). The estimates of survival are similar to those of previous mark-recapture studies, eg for Sand Martin φ ad = 0.289-0.312 (Cowley & Siriwardena 2005) and for Swallow φ ad = 0.356-0.372 (Møller & Szép 2005). These estimates of return rates are surprisingly close to the are comparable across the country, or whether regional variation can be detected.…”

Effects of climate change on the degree of protandry in migratory songbirds

“…This assumption was supported by a parallel change of a sexually selected characteristic, i.e. tail length, which showed a trend towards larger values (Møller 2004, Møller & Szép 2005. However, at the interspecific level, Spottiswoode et al (2006) found that the relationship between the advancement of spring migration and the strength of sexual selection was stronger for changes in the median migration date of whole populations than for changes in the timing of first-arriving (male) individuals, suggesting that selection has not only acted on protandrous males.…”

Long‐term trends in wind speed, insect abundance and ecology of an insectivorous bird

“…European barn swallows winter in Sub-Saharan Africa with a tendency to winter further north in recent years (Ambrosini et al 2011). Conditions during winter affect timing of spring migration, laying date, reproduction, morphology and many other characteristics of barn swallows (Saino et al 2004a, b, Møller andSzép 2005). Møller et al (2011) showed for barn swallows wintering in South Africa that although arrival in the African winter quarters advanced in recent years as a consequence of earlier breeding, this did not translate into earlier spring migration because the annual molt was delayed.…”