An international team of scientists analyzed the difference in immune gene expression among male and female shorebirds residing on various coasts and lakes across the globe. A recent study suggests that male shorebirds have a stronger immune system than the latter.
Male Vs. Female Immune System in Kentish Plovers
Researchers analyzed populations of the common shorebird, the Kentish Plovers, that lived on China's coasts and high-altitude areas. While the team found no significant differences in the immune strength between birds from both habitats, they were able to find evidence suggesting a difference in immune systems between male and female birds.
In human genetics, males have both the X and Y chromosomes, while females have two copies of the X sex chromosome. However, only one of the X chromosomes is activated for the female sexes; hence, for males and females, each has one active chromosome.
In comparison, male birds have two copies of the Z sex chromosome, while females have Z and W sex chromosomes. On the other hand, male birds have both copies of their Z sex chromosome active.
Many of the genes associated with immunity can be found on Z chromosomes. The researchers believed that having two copies of the genes may have increased the immune system of the male birds. They have a much lower mortality rate compared to female birds, according to the study.
Gene Expression Influences Species Mortality Rates
Dr. Jose Valdebenito, a research associate of the Milner Center for Evolution at the University of Bath, explains that in humans, women are likely to longer than men. However, the opposite has been observed in birds, which is one of the motivations for the study.
He adds that for the first time, the team found evidence of a difference in the immune gene systems among male and female plovers. It could be the reason male birds live longer than their female counterparts, PhysOrg.
Valdebenito added that in plovers, the higher mortality in female cause imbalances in the populations' sex ratio. It has a knock-on effect on both mating and parenting behaviors of the bird species. Currently, the team is investigating a deeper link between sex differences in the species immunity and variations on mating systems by analyzing the immune genes of several shorebird species. The team is hopeful that the research will help them expand our knowledge on the drivers behind the sex differences of mortality in bird species.
Sion Lecturer at the Milner Center for Evolution and senior author of the study Dr. Araxi Urrutia says in the paper that it was an exciting project, and was glad to coordinate data analyses, fieldwork, and writing up the joint project between the Chinese, Hungarian scientists and the Milner Center, reports
Dr. Araxi Urrutia, Senior Lecturer from the Milner Centre for Evolution and senior author on the paper, said their next step is to expand the study to other shorebirds. They aim to understand the genomic causes of the sex different mortalities for biodiversity conservation.
The study is published in Immunogenetics.
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