Adaptive evolution in passerine birds

• Adaptive evolution is the process whereby mutations that provide the carrier with a selective advantage increase in frequency in a population via the process of natural selection. Passerines are widespread, common and long-term targets for field study and they demonstrate a copious diversity in physiological and morphological adaptations to varying habitats, for example, beak size and wing shape, and they are, therefore, an important study system to understand adaptive evolution. Recent technological advancements have made it easier to investigate the mechanistic and evolutionary underpinnings of adaptive evolution by allowing genome sequence data to be generated in almost any species of interest. However, it is important to assess the contribution of neutral forces like demographic events and GC-biased gene conversion before concluding that selection has shaped the patterns observed in genomic data. Initial analyses in passerines have identified candidate genes that might be involved in, for example, song learning, beak morphology, disease resistance, high-altitude adaptation and exploratory behavior, but functional verifications are needed to establish a causative relationship between the identified genes and the traits. Key Concepts:Key Concepts: * Passerines are widespread, generally common and easy targets for field study and they demonstrate a copious diversity in physiological and morphological adaptations to varying habitats and they have, therefore, played an important role in previous studies concerning behaviour, ecology and evolution. * A full understanding of passerine adaptations requires an integrative approach aiming at identifying and characterising both proximate (mechanistic) and ultimate (evolutionary) underpinnings to adaptive traits. * The recent advancements in molecular techniques allows for using both comparative genomics, expression profiling, candidate gene approaches and classical association and QTL mapping strategies to identify the genetic basis of adaptive traits in passerines. * Groundwork studies of ecological genetics and genomics using comparative approaches, expression profiling and candidate genes are now accumulating and in a handful of cases we have an idea about the genetic basis of adaptive traits related to, for example, dietary specialisation, learning, exploratory behaviour, immune response and high-altitude adaptations in passerines. * Demographic history and other neutral processes, for example, GC-biased gene conversion (gcBGC), may mimic signals of selection and it is important to verify findings of adaptive evolution using independent methods.

Subject headings

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Keyword

adaptation

adaptive trait

adaptive evolution

candidate gene

comparative genomics

expression profiling

GC-biased gene conversion

passerines

selection

Publication and Content Type

vet (subject category)

art (subject category)