Delayed colonisation of Acacia by thrips and the timing of host-conservatism and behavioural specialisation

Abstract

BackgroundRepeated colonisation of novel host-plants is believed to be an essential component of the evolutionary success of phytophagous insects. The relative timing between the origin of an insect lineage and the plant clade they eat or reproduce on is important for understanding how host-range expansion can lead to resource specialisation and speciation. Path and stepping-stone sampling are used in a Bayesian approach to test divergence timing between the origin of Acacia and colonisation by thrips. The evolution of host-plant conservatism and ecological specialisation is discussed.ResultsResults indicated very strong support for a model describing the origin of the common ancestor of Acacia thrips subsequent to that of Acacia. A current estimate puts the origin of Acacia at approximately 6 million years before the common ancestor of Acacia thrips, and 15 million years before the origin of a gall-inducing clade. The evolution of host conservatism and resource specialisation resulted in a phylogenetically under-dispersed pattern of host-use by several thrips lineages.ConclusionsThrips colonised a diversity of Acacia species over a protracted period as Australia experienced aridification. Host conservatism evolved on phenotypically and environmentally suitable host lineages. Ecological specialisation resulted from habitat selection and selection on thrips behavior that promoted primary and secondary host associations. These findings suggest that delayed and repeated colonisation is characterised by cycles of oligo- or poly-phagy. This results in a cumulation of lineages that each evolve host conservatism on different and potentially transient host-related traits, and facilitates both ecological and resource specialisation.

A Global Phylogeny of Leafmining Ectoedemia Moths (Lepidoptera: Nepticulidae): Exploring Host Plant Family Shifts and Allopatry as Drivers of Speciation

“…Multiple phylogenetic studies that incorporated molecular clock analyses have shown that contemporaneous parallel cladogenesis has not been common in the evolution of plants and their herbivorous insects [ 10 – 15 ]. Also little evidence has been found for ‘asynchronous parallel cladogenesis’, where plants diversified first and herbivores later mirrored the speciation events of their hosts through resource tracking [ 16 ].…”

Testing Host-Plant Driven Speciation in Phytophagous Insects: A Phylogenetic Perspective

“…In order to test for successive burst of diversification in plants and insects, many authors have thus simply compared the timing of divergence of plants and associated insects (e. g., Brandle et al 2005;Gómez-Zurita et al 2007;Kergoat et al 2011;Kergoat et al 2015;Leppanen et al 2012;Lopez-Vaamonde et al 2006;McKenna et al 2009;McLeish et al 2013;Pena & Wahlberg 2008;Segar et al 2012;Stone et al 2009;Vea & Grimaldi 2016;Wahlberg et al 2013). Most of these studies suggest delayed colonization of already diversified groups of plants by insects groups at different temporal scales.…”

Testing Host-Plant Driven Speciation in Phytophagous Insects: A Phylogenetic Perspective

“…In order to test for successive burst of diversification in plants and insects, many authors have thus simply compared the timing of divergence of plants and associated insects (e. g., Brandle et al 2005;Gómez-Zurita et al 2007;Kergoat et al 2011;Kergoat et al 2015;Leppanen et al 2012;Lopez-Vaamonde et al 2006;McKenna et al 2009;McLeish et al 2013;Pena & Wahlberg 2008;Segar et al 2012;Stone et al 2009;Vea & Grimaldi 2016;Wahlberg et al 2013;Winter et al 2017). Most of these studies suggest delayed colonization of already diversified groups of plants by insects groups at different temporal scales.…”