Intercontinental karyotype - environment parallelism supports a role for a chromosomal inversion in local adaptation in a seaweed fly

• Large chromosomal rearrangements are thought to facilitate adaptation to heterogeneous environments by limiting genomic recombination. Indeed, inversions have been implicated in adaptation along environmental clines and in ecotype specialization. Here, we combine classical ecological studies and population genetics to investigate an inversion polymorphism previously documented in Europe among natural populations of the seaweed fly Coelopa frigida along a latitudinal cline in North America. We test if the inversion is present in North America and polymorphic, assess which environmental conditions modulate the inversion karyotype frequencies, and document the relationship between inversion karyotype and adult size. We sampled nearly 2000 flies from 20 populations along several environmental gradients to quantify associations of inversion frequencies to heterogeneous environmental variables. Genotyping and phenotyping showed a widespread and conserved inversion polymorphism between Europe and America. Variation in inversion frequency was significantly associated with environmental factors, with parallel patterns between continents, indicating that the inversion may play a role in local adaptation. The three karyotypes of the inversion are differently favoured across micro-habitats and represent life-history strategies likely to be maintained by the collective action of several mechanisms of balancing selection. Our study adds to the mounting evidence that inversions are facilitators of adaptation and enhance within-species diversity.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

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

Keyword

chromosomal inversions

environmental gradient

local adaptation

balancing selection

parrallelism

Diptera

alcohol-dehydrogenase locus

coelopa-frigida

natural-populations

sexual selection

trade-offs

drosophila-melanogaster

genetic-variation

adult size

polymorphism

evolution

Life Sciences & Biomedicine - Other Topics

Ecology

Evolutionary Biology

arlesworth b

1976

genetics

v83

p181

Publication and Content Type

ref (subject category)

art (subject category)