Chromosomal-inversion
Guides
Coelopa
Bristly Kelp Flies, kelp flies, seaweed flies
Coelopa is a genus of kelp flies comprising approximately 13-14 described species. These flies are obligate associates of stranded seaweed (wrackbeds) in coastal environments, where they complete their entire life cycle. The genus is notable for extensive research on sexual selection, chromosomal inversions, and ecological genetics, particularly in the well-studied species Coelopa frigida. Species within this genus exhibit resource competition and dietary niche partitioning where sympatric.
Coelopa frigida
seaweed fly, kelp fly
Coelopa frigida is a seaweed fly and the most widely distributed species in its genus, found on temperate Northern Hemisphere shorelines with stranded algae. Adults are 5–6 mm with dark brown to black bodies, lighter legs, and large translucent wings. The species exhibits a chromosomal inversion polymorphism (αβ system) that generates two distinct size morphs with different developmental rates and life-history strategies. It has become a model organism for studying sexual selection, particularly female choice and sexual conflict, and for investigating the genetic basis of local adaptation through chromosomal inversions.