Pontificia Universidad Católica de Chile: The rayadito’s strategy to ensure their offspring

A recent work revealed the existence of “extra pair” young in clutches of two populations of rayadito, a socially monogamous bird in Chile. This study, published in the journal Ecology and Evolution, is the first in a series of papers that expand the knowledge of polyandria in rayadito and its ecological importance.

Rayadito, winged inhabitant of the forests of Chile and Argentina. Photo Yanina Poblete.
photo_cameraA study carried out by researchers from Chile, Argentina and Germany evaluated the occurrence of offspring born outside the couple in two populations of rayadito (Aphrastura spinicauda), a winged inhabitant of the forests of Chile and Argentina that, in our country, nests along the throughout an extensive area that ranges from the Coquimbo region to Tierra del Fuego. Photo: Yanina Poblete

A study carried out by researchers from Chile, Argentina and Germany evaluated the occurrence of offspring born outside the couple in two populations of rayadito (Aphrastura spinicauda) , a winged inhabitant of the forests of Chile and Argentina that, in our country, nests along the throughout an extensive area that ranges from the Coquimbo region to Tierra del Fuego.

The “extra pair paternity” (EPP, for its acronym in English) is a common event in socially monogamous birds, that is, they live with a single pair during the breeding period, and it occurs when, inside the brood, there are chicks of parents other than the social parent. However, information about the presence of this behavior in species native to tropical or subtropical zones, such as rayadito, is still scarce.

Using a long-term study started in 2007, the researchers collected data from more than 266 clutches and 895 chicks of this species over six breeding seasons (from 2010 to 2017) in two locations in the country: Fray National Park. Jorge, in the north-central area, and the southern forests of Isla Navarino , in the south. The objective? Estimate the frequency of appearance of offspring born in “extra pair parenting” (EPP) and “extra pair offspring” (EPO).

“It is thought that polyandry is a behavior that allows females to obtain benefits, increasing the genetic quality of the offspring. This hypothesis is known as genetic compatibility or “good genes.” Another hypothesis is that unfaithful females reduce the risk of failing in their reproductive attempt if their social partner is infertile ”, comments CAPES researcher and academic from the University of Las Américas, Yanina Poblete , one of the authors of the study.

“It is thought that polyandry is a behavior that allows females to obtain benefits, increasing the genetic quality of the offspring. Another hypothesis is that unfaithful females reduce the risk of failing in their reproductive attempt if their social partner is infertile ”- Yanina Poblete, CAPES researcher, one of the study authors.

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