Understanding Variation in Extra-Pair Paternity in Birds: A Focus on Neotropical Birds

VALENTINA FERRETTI

Behavioral Ecology of Neotropical Birds

Springer Nature

Año: 2019; p. 21 - 40

Variation in life-history traits has long captivated ecologists and evolutionarybiologists. Classical studies of life-history theory identify latitudinal clinesin life-history traits and, as a result, there are now several ecological andevolutionary hypotheses that attempt to explain this variation. Extra-pairpaternity is considered a life-history trait, and much research has been doneto try to disentangle the causes of variation in this trait. One ecologicalhypothesis proposed to explain geographic variation in extra-pair paternity isthe breeding synchrony hypothesis. The prediction of this hypothesis is thatsynchrony increases towards the poles because of shorter breeding seasons;rates of extra-pair paternity are therefore expected to increase towards higherlatitudes. However, the scarcity of studies of extra-pairpaternity rates amongNeotropical birds to date makes it difficult to predict any direction of change. Inthis chapter I argue that it is still premature to look at why species differ in extrapairpaternity rates, as the sampling of species that inhabit the Neotropics, themost biodiverse realm on Earth, is still very poor and insufficient. In addition,I agree with other researchers that our scientific views are biased by studies inthe less diverse Palearctic and Holarctic realms, which may have slowed ourunderstanding of the patterns and processes in the Neotropics. I explore herethese two perspectives by examining interspecific variation in genetic matingsystem in the swallow genus Tachycineta, and look at geographic variation insynchrony and extra-pair paternity. I found that differences in rates of extrapairpaternity among species of this genus are not explained by differences intheir breeding synchrony, and that the large variation in breeding synchronyexperienced by the different species/populations is not related to latitude. Infact, neither synchrony nor extra-pair paternity followed the predicted patternof latitudinal variation. Work on Tachycineta helps redress the paucity ofinformation on tropical and south temperate species and the underrepresentationof closely related taxa that characterized previous studies. It also reminds us ofthe complexity of relationships among life-history traits and their environmentalinfluences, forcing us to consider more than one hypothesis and causal path inexplaining hemisphere-wide patterns in life-histories.