D. montana seems to be an excellent species to address the issue of speciation. This species seems to be made of several populations with varying degrees of differentiation among them. There is preliminary data suggesting that there is inversion polymorphism, morphological, courtship male song traits and cuticular hydrocarbons differences among populations (Lakovaara and Hackman 1973; Notulae Entomologicae LIII:167-169; Suvanto et al. 2000; J. Evol. Biol. 13: 583-592; A. Hoikkala, personal communication). There is also some data supporting the view that males from different strains may affect the number of eggs laid by females differently (Suvanto et al. 2000; J. Evol. Biol. 13: 583-592) but it is unclear whether this contributes to post-mating pre-zygotic isolation. There is significant differentiation at the DNA sequence level between Scandinavian and North American populations and very likely between Finnish, American and Alaskan-Canadian populations (Vieira and Hoikkala 2001; Heredity 86: 506-511; Päällysaho et al. submitted). The observed differentiation between D. montana populations may thus offer the unique possibility of studying the molecular and phenotypic changes occurring in the very first steps of reproductive isolation and thus speciation. Together with our international collaborators, we are planning to collect D. montana from the whole range of distribution of the species (from the Atlantic coast of North America, across Canada, Japan and Northern Asia to Scandinavia) and characterise the different D. montana populations at the molecular, cytological, morphological and behavioural levels. The degree of population differentiation and migration levels between populations will then be estimated from molecular data. Finally, the role of local adaptation in speciation will also be addressed.
Researchers involved in this project:
Collaborators:
Anneli Hoikkala
Roger Butlin
Christian Schlötterer
Michael Ritchie