Why does female infidelity occur so frequently throughout the animal kingdom? A 10-year study from the University of East Anglia published today shows that female birds may increase their offspring's survival through their infidelity.
Although in many animals females may pair up with a specific 'social' mate who helps raise the pairs' offspring, DNA fingerprinting studies across a wide range of animals reveals that offspring may often be sired by males other than the pair male.
What has perplexed scientists is why females engage in such infidelity – what is the benefit of being fertilised by these other males – males which do not contribute towards raising the offspring.
Despite pairing with the same male for life, female Seychelles warbler birds often prefer to be fertilised by other males, and this appears to increase the genetic quality of their offspring.
The study has shown that these extra-pair fertilisations can result in a higher diversity of specific genes which detect disease and trigger an immune response in offspring. As a consequence, the offspring survive longer probably as a result of having greater resistance to a wider range of diseases.
The research 'MHC-dependent survival in a wild population: evidence for hidden genetic benefits gained through extra-pair fertilisations' has been lead by Dr David Richardson (UEA) and is published today in Molecular Ecology.
Since 1997 more than 97 per cent of warblers on the tiny island of Cousin in the Seychelles were ringed, blood sampled, and their breeding attempts followed. The researchers monitored the fate of 160 birds hatched on the island between 1997 and 1999, over 10 years.
They found that females paired to males with a low diversity of disease-detecting genes (major histocompatibility complex or MHC) elevate the gene diversity of their offspring by gaining extra-pair fertilisations from males with higher diversity. This extra pair fertility was found to be common – accounting for 40 per cent of offspring.
Importantly, the offspring born as a result of this female infidelity have higher genetic diversity at these disease-detecting genes than they would have had if sired by the cuckolded pair male. However they were not found to be higher than the population average.
The researchers then found a positive association between diversity of MHC genes and juvenile survival. A higher than median MHC diversity was found to increase lifespan more than two-fold.
They also found that offspring with a specific rare gene variant (Ase-ua4) had a five times longer life-expectancy than offspring without this allele. However these birds did not necessarily have a greater MHC diversity. It is thought that individuals with this rare variant of MHC genes may survive longer because these rare variants better resist diseases that have already evolved to evade more common variants.
Dr Richardson said: "We first tested whether extra-pair offspring have a survival advantage compared to within-pair offspring. Then we tested whether there are genetic benefits to the patterns of the MHC-dependent extra-pair fertilizations observed in this species."
"We did not find any evidence for genetic benefits of extra-pair fertilisations per se, as on average extra-and within-pair offspring survived equally well.
"However, by not being faithful to a pair male with low MHC diversity, females are ensuring that their offspring do not end up with below average levels of MHC diversity and therefore lower survival.
"We have shown that the association between survival and MHC diversity levelled off with increasing diversity, so choosing males with above average MHC diversity would not have resulted in any additional fitness benefits for the offspring.
"One thing that remains unknown however, is what mechanism drives the patterns of MHC-dependent extra-pair mate choice. Experiments are needed to determine whether females actively choose more diverse MHC males or whether other factors like male-male competition or sperm competition play a role."
The study was lead by the University of East Anglia, with colleagues from the University of Sheffield, the University of Groningen and Nature Seychelles.
Lisa Horton | EurekAlert!
The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung
A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences