Inbred lark explains the immune system of songbirds
The number of Raso larks on the island is occasionally as few as 50 individuals.
Currently, there are approximately one thousand Raso larks on the island and in a recent study, researchers from Lund University in Sweden, together with colleagues in Cambridge, UK, have studied the immune system genes of 122 individuals.
The results show that there is extremely low variation in these so-called MHC genes in the population as a whole compared to other small birds. On an individual level, on the contrary, every Raso lark has high genetic variation. According to the researchers, this can be explained by the many genetic copies that all look different in each individual.
“The total variation in the population is not much greater than that found in each individual”, says Helena Westerdahl, Lund University.
She gives an example:
“Imagine that every MHC gene is a different car make, then the Raso lark has only one model of each make, while other bird species have many different models. That is, the Raso lark has few models but relatively many makes”.
“With this simple structure of the Raso lark’s immune system, we now have an idea of how the MHC genes have evolutionarily changed over time, and an explanation for why songbirds have such a range of MHC genes compared to humans.”
The results are published in an article in the journal Molecular Ecology.