Interspecific behavioural interference and range dynamics: genomic analysis of rubyspot damselflies

Abstract

The ongoing reshuffle of Earth’s biota, particularly from climate change, has increased the necessity to understand and predict how the spatial distribution of species can shift. In this thesis, I further our knowledge of the processes that influences the ranges of species by conducting novel research into the how interspecific behavioural interference affects range dynamics. Interspecific behavioural interference is any aggressive or mating behaviour by one species that is directed towards and has a negative impact on the fitness of another. I primarily using next-generation sequence data to conduct phylogenetic, phylogeographic, and population genetic analysis on rubyspot damselflies (Hetaerina). The research focuses on smoky rubyspot damselflies (Hetaerina titia) which exhibit a striking seasonal polyphenism in wing colouration which influences the degree of interspecific behavioural interference seen between individuals and populations. Chapter 2 provides a synthesis of past research into how interspecific behavioural interference affects range dynamics across taxa and then outlines potential future avenues of research. Chapter 3 presents a de-novo chromosome level draft genome of H. titia which is the first chromosome level draft genome for a broad winged damselfly (Calopterygidae). Chapter 4 determines the spatiotemporal dynamics of the speciation cycle across several species of Hetaerina supporting the hypothesis that time since divergence predicts the stage of the non-ecological speciation cycle. Genetic sequencing identifies a region of secondary contact between two lineages of H. titia separated by an estimated 3.6 million years. One individual is identified as an F1 hybrid, suggesting that reproductive isolation exists between Pacific and Atlantic lineages of smoky rubyspot. Chapter 5 uses multivariate models of trait evolution to test for co-evolution between the peak and off-peak seasonal phenotype of H. titia. Models do not support co-evolution but do support different selective regimes in different geographic regions. Finally, Chapter 6, uses population genetics and species distribution models to show that populations of H. titia that reside in higher latitudes likely originate from a range expansion from Florida since the last glacial maximum (LGM). Consequently, the loss of polyphenism in high latitude populations may be an adaptation to novel species assemblies that arose since the LGM. Collectively, this thesis provides novel research into the ecological and evolutionary consequences of interspecific behavioural interference, particularly into spatial and temporal dynamics of species distributions.