How clasper morphology relates to genetic and behavioural isolation in the New Zealand Stick Insect genus Clitarchus

Shelley Myers *1, Greg Holwell 2, Thomas Buckley 3

1 Landcare Research,The University of Auckland
2 The Univeristy of Auckland
3 Landcare Research

A hybrid zone is the geographic area where two species meet and form offspring.  It is common for the offspring of hybridising species to have reduced fitness. The theory of reinforcement predicts that prezygotic barriers will evolve between hybridising groups and there will be selection against hybridisation.  In the Far North of New Zealand, the widely-distributed stick insect species C. hookeri is replaced by an ecologically similar and undescribed species of Clitarchus. These species are differentiated on the basis of male terminalia (specifically the claspers), egg morphology and mitochondrial DNA. Populations sampled between the two species show intermediate morphology. The aim of this research project is to describe the level of isolation between species of Clitarchus using interdisplinary techniques including behavioural studies, genetics and morphology. Genetic divergence and gene flow is being measured using SNP data obtained from 454 genomic reduction sequencing. Three dimensional morphometrics accurately describes differences in intra and inter-specific clasper shape. These quantitative approaches are being combined with mating experiments to provide a basis for addressing the following questions: does variation in morphology correspond to differences in mating behaviour and does morphological variation correlate with reproductive isolation?

Download (PDF)