Navigation Links
Picky penguins: Does mate choice depend on genes that help resist disease?
Date:9/5/2012

NEWPORT, Ore. Magellanic penguins have a high level of variation in genes associated with the ability to fight infectious disease, but a recent study found that the mechanism the penguins use to ensure that diversity is far from black and white.

Found exclusively south of the equator in South America, Magellanic penguins assemble in large nesting colonies along the coasts of Argentina, Chile, and the Falkland Islands. They typically mate for life, producing clutches of two eggs that are cared for by both parents. While individual colonies can number in the millions of birds, the species as a whole appears to be in decline, and is therefore classified as "Near Vulnerable" by the IUCN Red List.

A recent study published via Advance Access (doi: 10.1093/jhered/ess054) in the Journal of Heredity tested whether the significant diversity in the Major Histocompatibility Complex (MHC) genome region observed in these birds is attributable to mate choice or genetic selection based on disease exposure.

The study first confirmed that MHC diversity is high in these birds compared to other closely-related penguin species. Gabrielle Knafler, a graduate student at Bowling Green University and the first author of the study, explained, "By looking at the MHC genotypes of 50 breeding pairs of Magellanic penguins, we found considerable levels of genetic variation, detecting a significantly greater number of MHC variants or alleles than those reported for Galapagos penguins and Humboldt penguins." Forty-five alleles were found at the gene locus for the Magellanic penguins, sampled from a wild population in southern Patagonia, compared to 3 for Galapagos penguins and 7 for captive Humboldt penguins.

The authors of this study then investigated two possible mechanisms for maintaining the high MHC diversity in the Magellanic penguins: balancing selection, in which heterozygous individuals are better adapted to combat a wide range of diseases and are therefore more likely to survive to pass on their genes, and disassortative mating, or preferentially choosing a mate with a different MHC genotype.

How might a penguin know that a potential mate has different MHC genes? Smell could tell. Dr. Juan L. Bouzat of Bowling Green University, the lead scientist on the study, said, "In some species in which disassortative mating has been detected, individuals discriminate among potential mates by MHC type on the basis of olfactory cues."

To test the mechanism for maintaining MHC diversity, the authors studied the genetic variation of 50 breeding pairs of penguins. They examined whether MHC diversity was greater between breeding pairs as compared to random mating, and determined whether MHC genotype was correlated with measures of reproductive fitness, such as number of eggs hatched and number of chicks fledged.

Surprisingly, they found no direct evidence for disassortative mating based on the genotypes of the breeding pairs. Incidence of shared alleles between males and females in breeding pairs was not significantly different from what would be expected by chance.

But heterozygosity was found to be associated with increased fitness of adults, as heterozygous females hatched significantly more eggs and fledged significantly more chicks than homozygous females (in fact, none of the homozygous females that hatched eggs actually fledged any chicks). This finding suggests that a mechanism for balancing selection is at work in maintaining MHC diversity, even if it is not promoted by disassortative mating.

Other evidence for balancing selection was also found, including a gene phylogeny for MHC alleles from Magellanic, Humboldt, and Galapagos penguins. This analysis, akin to developing a "family tree" for genes, found that MHC alleles did not group together by species, suggesting that balancing selection has maintained different alleles even as species evolved over millions of years.

"There are likely other mechanisms at work as well," said Bouzat. "Spatial and temporal patterns in exposure to different pathogens may shape which alleles are favored at different times," changing selection pressures on the MHC genes. "The direct association of MHC genes with mechanisms of disease resistance suggests that the maintenance of MHC diversity could be driven by periodic selection due to different pathogens, similar to epidemics in humans."


'/>"/>
Contact: Nancy Steinberg
nsteinberg@charter.net
541-574-0908
Journal of Heredity
Source:Eurekalert  

Related biology news :

1. Commonly used pesticide turns honey bees into picky eaters
2. Should high-dose interleukin-2 continue to be the treatment of choice for metastatic melanoma?
3. Spatial knowledge vs. spatial choice: The hippocampus as conflict detector?
4. Kids who cook hungrier for healthy food choices
5. Begin early: Researchers say water with meals may encourage wiser choices
6. In elk hunting, success depends on the animals personality
7. Biodiversity conservation depends on scale: Lessons from the science-policy dialogue
8. Biodiversity conservation depends on scale: Lessons from the sience-policy dialogue
9. Success of engineered tissue depends on where its grown
10. Jekyll and Hyde bacteria aids or kills, depending on chance
11. Nature or nurture? It may depend on where you live
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Picky penguins: Does mate choice depend on genes that help resist disease?
(Date:6/22/2016)... , June 22, 2016   Acuant ... and verification solutions, has partnered with RightCrowd ... solutions for Visitor Management, Self-Service Kiosks and ... products that add functional enhancements to existing ... corporations and venues with an automated ID ...
(Date:6/16/2016)... 16, 2016 The global ... to reach USD 1.83 billion by 2024, according ... Inc. Technological proliferation and increasing demand in commercial ... to drive the market growth.      ... The development of advanced multimodal techniques for biometric ...
(Date:6/7/2016)...  Syngrafii Inc. and San Antonio Credit Union ... integrating Syngrafii,s patented LongPen™ eSignature "Wet" solution into ... result in greater convenience for SACU members and ... existing document workflow and compliance requirements. ... Highlights: ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... June 27, 2016  Sequenom, Inc. (NASDAQ: ... healthier lives through the development of innovative products and ... the United States denied its petition ... claims of Sequenom,s U.S. Patent No. 6,258,540 (",540 Patent") ... established by the Supreme Court,s Mayo Collaborative Services v. ...
(Date:6/27/2016)...  Liquid Biotech USA , ... Sponsored Research Agreement with The University of Pennsylvania ... cancer patients.  The funding will be used to ... clinical outcomes in cancer patients undergoing a variety ... employed to support the design of a therapeutic, ...
(Date:6/24/2016)... ... 24, 2016 , ... Researchers at the Universita Politecnica delle Marche in Ancona ... or pleural mesothelioma. Their findings are the subject of a new article on the ... are signposts in the blood, lung fluid or tissue of mesothelioma patients that can ...
(Date:6/23/2016)... A person commits a crime, and the detective ... the criminal down. An outbreak of foodborne illness ... (FDA) uses DNA evidence to track down the bacteria that ... It,s not. The FDA has increasingly used a complex, cutting-edge ... illnesses. Put as simply as possible, whole genome sequencing is ...
Breaking Biology Technology: