Great
tits living in cities are genetically different from great tits in the
countryside. Researchers made the discovery after a unique study where they
examined populations of great tits in nine large European cities, including
Glasgow.
The
researchers compared the city bird genes with the genes of their relatives in
the countryside. The findings, which are published today in Nature
Communications, showed that it didn’t matter if the great tits lived in
Barcelona, Malmö or Glasgow: in order to handle an environment created by
humans, the city birds all evolved in a similar way.
The
European research, which was led by Lund University in collaboration with
researchers at the University of Glasgow, included a study of birds from
Kelvingrove Park together with birds from around the forest in the University
of Glasgow’s SCENE (Scottish Centre
for Ecology and the Natural Environment) facility, located near Loch Lomond.
The
researchers found that different genes linked to important biological functions
regulated by serotonin, including aggression and circadian rhythms, were found
to have been selected and passed on from generation to generation in the city
birds. In rural populations, these behaviours are also important, however, the
genes that control them do not confer the same advantage as they do in an urban
environment
Caroline
Isaksson, Senior Lecturer at Lund University, led the study together with Dr
Pablo Salmón, now a research fellow at the University of Glasgow. She said:
“This indicates that these behaviours, and cognition, are very important in
order to live in urban environments with a lot of stress in the form of noise
pollution, light at night, air pollution and constant proximity to people.”
The
study is the largest carried out on how urban environments affect the genome,
and thus the genetic material of the animals that live there. In total, 192
great tits were examined among populations in Malmö, Gothenburg, Madrid,
Munich, Paris, Barcelona, Glasgow, Lisbon and Milan. For each urban population,
the researchers had a control group of great tits living nearby, but in a rural
environment. Blood samples have been taken from the birds and analysed
genetically.
Dr
Pablo Salmón, from the University of Glasgow, said: “It is surprising that cities,
which from an evolutionary perspective are a recent phenomenon, are already
leaving their footprint in the genome of birds.”
The
researchers analysed more than half a million single-nucleotide polymorphisms
(SNPs) spread over the entire genome, and found that a handful of genes that
had clearly changed in response to the urban environment.
Great
tits are common throughout Europe, and it has long been known that they are
quite similar genetically. Despite this, researchers have now identified clear
genetic differences between great tits in the city and great tits in the
countryside.
The
study has been published in Nature Communications: Continent-wide genomic
signatures of adaptation to urbanisation in a songbird across Europe.
