Male birds have stronger immune system than females, research suggests


Date:
February 22, 2022
Source:
University of Bath
Summary:
Scientists studied the differences in activity of immune genes
between male and female Kentish Plovers and found that the immune
genes of males were more active. This is evidence that males live
longer than females due to differences in their immune systems.



FULL STORY ========================================================================== Whilst human males tend to suffer more than females from infectious
diseases like Covid19 or flu, for birds it's the males that appear to
have stronger immune systems, suggests a new study led by the University
of Bath.


==========================================================================
A team of international scientists led by the University of Bath looked at differences between the sexes in the expression, or activity, of immune
genes in Kentish Plovers, a common species of shorebird that live on
coasts and lakes all over the world.

The researchers studied populations living in coastal and high-altitude
inland areas in China.

Whilst they found no significant differences in immunity between the
birds from the two habitats, they found evidence of a difference between
the immune systems of male and female birds.

In humans, males have an X and a Y chromosome whereas females have two
copies of the X chromosome, however only one of these two X chromosomes
is activated, meaning both males and females have just one active
X chromosome.

In contrast, in birds it's the males that have two copies of the sex
chromosome Z, with females having two different chromosomes, Z and
W. However in males, both copies of the Z chromosome are active.



==========================================================================
Many of the genes linked with immunity are on the Z chromosome, so the researchers suggest that by having two active copies of these genes,
males might have increased activity in their immune systems, resulting
in lower mortality compared with females.

Dr Jose' Valdebenito, Research Associate from the Milner Centre for
Evolution at the University of Bath, said: "Whilst in humans women tend
to live longer than men, the opposite is true of birds, so we wanted to
find out why.

"For the first time, we've found evidence that there is a difference in
the activity of the immune genes in male and female plovers, suggesting
that males have stronger immune systems which could explain why they
tend to survive longer than females.

"In plovers, the higher mortality in females causes an imbalance in
the sex ratio, which has a knock-on effect on the mating and parenting behaviours of this species.

"Currently we are working on a project that investigates the relationship between sex differences in immunity and mating system variation, by
looking at the immune genes across several shorebird species.

"Hopefully this will help us expand our understanding on the drivers
behind sex differences in mortality in birds." Dr Araxi Urrutia, Senior Lecturer from the Milner Centre for Evolution and senior author on the
paper, said: "This was an exciting project, and I was glad to coordinate fieldwork, data analyses and writing up of this joint project between
the Milner Centre, Chinese and Hungarian scientists.

"The next step is to expand this approach to other shorebirds. From
demographic data we know that in some shorebirds the males live longer
than the females whereas in other shorebirds the male lives longer than
the females.

"My group is striving to understand the genomic causes of the
sex different mortalities -- this work is important not only for
fundamental science but also biodiversity conservation since these
data will help protecting these species in their natural habitats." ========================================================================== Story Source: Materials provided by University_of_Bath. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Jose' O. Valdebenito, Kathryn H. Maher, Gergely Zacha'r, Qin Huang,
Zhengwang Zhang, Larry J. Young, Tama's Sze'kely, Pinjia Que, Yang
Liu, Araxi O. Urrutia. Sex differences in immune gene expression
in the brain of a small shorebird. Immunogenetics, 2022; DOI:
10.1007/s00251-022- 01253-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220222135203.htm

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