Speciation genes in native New Zealand leafroller moths

Abstract

This thesis tests predicted characteristics of speciation genes made by the 'genic view' of speciation. The genic view states that the genome of a species is mosaic, and is divided into regions that contribute to a speciation event (speciation genes) and regions that do not (neutral genes). These speciation loci are characterized by the absence of ancestral polymorphism and diminished or no gene ow. This work investigates whether Pheromone Binding Protein 1 (PBP1) fulls the criteria of a speciation gene in a complex of native New Zealand Leafroller moths. Ctenopseustis and Planotortrix comprise ve and seven species, respectively. Intraspecic sampling resolved many allelic variants in four neutral genes (COI [barcoding region],COI-COII, EF-1 and TPI ). These loci show evidence of purifying selection and typically are not reciprocally monophyletic for P. octo + P. excessana and C. obliquana + C. herana. PBP1 is no better at recovering monophyly of species groups than any of the neutral genes. The phylogenetic patterns are dierent among loci conrming a mosaic genome for recently speciated groups. PBP1 is under purifying selection or functional constraint, however there are indications of excess non-synonymous substitutions within PBP1 in P. octo, P. excessana and P. avicenniae. Some of these amino acid changes are in positions predicted to be involved in pheromone binding and receptor interactions. In addition the lineage leading to the species C. fraterna and C. licis show evidence of positive selection in the PBP1 gene tree. In conclusion, PBP1 may be a speciation gene for some of the speciation events that gave rise to this species complex