Barking up the right tree : the evolutionary and ecological drivers of niche diversification and an adaptive radiation in feather-legged assassin bugs (Hemiptera: Reduviidae: Holoptilinae)

Adaptive radiation is an evolutionary process that has played a fundamental role to shaping much of today’s biodiversity, with it being witnessed among a multitude of study systems from invertebrate and vertebrate animals to plants and occurring even from the remotest islands to the highest mountain ranges. In essence, adaptive radiation occurs when a single common ancestral species experiences ecological opportunity, often through the availability of previously unoccupied niches, and rapidly diversifies as populations adapt to occupy multiple different non-competing niches, driving diversification into multiple distinct lineages. Dependency on these niches leads to speciation with bespoke phenotypic adaptations that enhance the ability to exploit these niches and ultimately increase fitness. Whilst there are some disagreements as to the causes and best methods to identify adaptive radiations, the most widely accepted definition outlines four distinct criteria, (1) common ancestry, (2) correlation between distinct phenotypes and environments, (3) evidence phenotypic traits have utility and (4) rapid speciation. These must be met in order to support the claim that a group has undergone adaptive radiation. Here we use a lesser-known group of Reduviidae, the feather-legged assassin bug (Holoptilinae), as a study system to test these criteria. Ptilocnemus Westwood 1840 is an endemic Australian genus that exhibits a remarkable shift in total body size (4 – 10.5mm), a feature thought to be uncharacteristic within the wider subfamily. In addition, Ptilocnemus is speciose and exhibits a distribution that covers a broad array of contrasting Australian landscapes, far dissimilar to other endemic genera. Such shifts in morphology and habitat are a common indicator of a group having undergone adaptive radiation as shown in other exemplar study systems including Darwin's finches, Caribbean Anolis lizards and the African lake cichlids. Using integrated systematics, including next-generation sequencing, scanning electron microscopy, in-field behavioural assays, and detailed taxonomic comparisons, together with a novel framework for identifying adaptive radiations, we explore the evolutionary drivers and niche adaptations that may have shaped the ancestral diversification of Australian Holoptilinae. We then evaluate Ptilocnemus against the criteria outlined above to determine whether it represents a new study system for investigating the role of adaptive radiation in generating biodiversity.

Name dc:type.qualificationname

Ph.D

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

Oxford Brookes University

Author dc:creator

• Bardey, Daniel Jonathan

Advisors dc:contributor.advisor

• Bulbert, Matthew
• Arif, Saad
• Weirauch, Christiane

DOI dc:identifier.doi

https://doi.org/10.24384/x08y-be81

OAI record oai:identifier

https://radar.brookes.ac.uk/radar/oai?verb=GetRecord&metadataPrefix=uketd_dc&identifier=tle%3Afb8725e5-7c70-4e08-958b-76f3cc480d23%3Ad6bd9758-527a-46cd-bfe2-c433766e8fca%3A1