Sunday, 23 May 2021

Evolution News - Great Tits Evolving to Suit City Living

Great tit, Parus major, adapting to city life
Photo: Caroline Isaksson
A stressful life in the city affects birds' genes | Lund University

Perhaps unsurprisingly, given what we know of the way the environment drives evolution, a group of researchers from Lund University, Sweden, have found that the genome of the common European great tit, Parus major, living in European cities is different to those living in the countryside. What was surprising perhaps, was the very clear evidence of this urban selection in a widespread but genetically very similar European population.

This is probably true for all European cities. Whether Milan, Malmö or Madrid the genetic changes were similar, showing a high degree of convergence on the same solutions to the same environmental factors. At least, this was true for the diverse selection of cities on which the team chose to concentrate their efforts.

They found that the changes involved genes that regulate cognition, aggression and circadian rhythms, all of which are important in a high-stress environment like a city with
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, lights at night, air pollution and constant proximity to people.

We have analysed more than half a million single-nucleotide polymorphisms (snips) spread over the entire genome. There were a handful of genes that had clearly changed in response to the urban environment.

That we see such a clear urban selection across the board, in an otherwise genetically similar European great tit, is surprising.

Caroline Isaksson, Lead author
Senior Lecturer
Department of Biology
Lund University, Lund, Sweden
high levels of pollution, night-time lighting, noise and the proximity to people.

A total of, 192 great tits were examined from populations in Malmö, Gothenburg, Madrid, Munich, Paris, Barcelona, Glasgow, Lisbon and Milan. For each urban population, there was a control group of great tits living on a nearby rural environment. Blood samples have been taken from all of the birds and analysed genetically.

The research is published, open access in the journal, Nature Communications:
Abstract

Urbanisation is increasing worldwide, and there is now ample evidence of phenotypic changes in wild organisms in response to this novel environment. Yet, the genetic changes and genomic architecture underlying these adaptations are poorly understood. Here, we genotype 192 great tits (Parus major) from nine European cities, each paired with an adjacent rural site, to address this major knowledge gap in our understanding of wildlife urban adaptation. We find that a combination of polygenic allele frequency shifts and recurrent selective sweeps are associated with the adaptation of great tits to urban environments. While haplotypes
Click image to enlarge
Study sampling locations and urbanisation intensity.

a Centre: map of Europe, showing the targeted cities where the sampling of great tits (Parus major) was carried out. Red areas indicate the main dense urban areas. The nine inset zooms flanking the central map exemplify the landscape and degree of urbanisation for each of the urban–rural sampling locations. Green shading represents canopy or green areas (i.e., vegetation cover) and roads and buildings are represented in grey. See “Methods”, Supplementary Fig. 1 and Supplementary Table 1 for more details. Map data sources: Stamen Design under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/); data licensed by OpenStreetMap Foundation (OSMF) under ODbL (https://opendatacommons.org/licenses/odbl/).
Shapefiles: Natural Earth.

b Urbanisation scores (principal component, PCurb) for all nine urban–rural pairs. In both figures, the coloured circles represent each city (in b, urban: open circles; rural: closed circles). BCN Barcelona, GLA Glasgow, GOT Gothenburg, LIS Lisbon, MAD Madrid, MAL Malmö, MIL Milan, MUC Munich, PAR Paris.
Great tit illustration: Pablo Salmón.
under selection are rarely shared across urban populations, selective sweeps occur within the same genes, mostly linked to neural function and development. Collectively, we show that urban adaptation in a widespread songbird occurs through unique and shared selective sweeps in a core-set of behaviour-linked genes.

Introduction

Urban development is rapidly expanding across the globe, and although urbanisation is regarded a major threat for wildlife1, its potential role as an evolutionary driver of adaptation has not been explored until recently2,3,4,5. Many species show phenotypic adaptations to the multiple urban challenges, such as higher levels of noise, artificial light at night, air pollution, altered food sources or habitat fragmentation6. These adaptations include changes in behaviour, e.g., refs. 7,8,9, morphology and locomotion, e.g., refs. 10,11,12,13 or toxin tolerance14. Indeed, there is now evidence that the phenotypic divergence between urban and rural populations may have a genetic basis in some species14,15, in line with the finding that micro-evolutionary adaptations in natural populations can occur within short timescales, particularly in response to human activities16,17,18. The study of the genetic signals of adaptation could provide important insights into the magnitude of the evolutionary change induced by urbanisation on wildlife. However, the short evolutionary timescale, the dependence of evolution on local factors, and the polygenic nature of many phenotypic traits, make detecting the genomic signals of adaptation difficult17,19...

Just as with the research into the Mediterranean wall lizards I reported on a few days ago, we find genetic evolution as a species adapts to a new or changing environment, exactly as predicted by the Theory of Evolution. And another piece of research, almost by accident, validates the TOE and shows how it is the foundational theory of biology, and far from being the 'theory in crisis' that Creationist fools have been duped into believing by professional Discovery Institute liars and failed scientists looking for a gullible marketplace for their books, written to pander to an audience of superstitious fools prepared to pay good money to have their biases 'confirmed'.


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