Evolution of host plant use and diversification in a species complex of parasitic weevils (Coleoptera: Curculionidae)

Abstract

Weevils (Coleoptera: Curculionoidea) represent one of the most diverse groups of organisms on Earth; interactions with their host plants have been recognized to play a central role in their remarkable diversity, yet the exact mechanisms and factors still remain poorly understood. Using phylogenetic comparative analyses, here we investigate the evolution of host use and its possible role in diversification processes ofRhinusaandGymnetron, two closely related groups of weevils that feed and develop inside plant tissues of hosts within the families Scrophulariaceae and Plantaginaceae. We found strong evidence for phylogenetic conservatism of host use at the plant family level, most likely due to substantial differences in the chemical composition of hosts, reducing the probability of shifts between host families. In contrast, the use of different plant organs represents a more labile ecological trait and ecological niche expansion that allows a finer partitioning of resources.RhinusaandGymnetronweevils initially specialized on plants within Scrophulariaceae and then shifted to the closely related Plantaginaceae; likewise, a gall inducing behavior evolved from non-galler weevils, possibly in response to resource competition, as galls facilitate larval development by providing enhanced nutrition and a favorable microhabitat. Results from trait-dependent diversification analyses suggest that both use of hosts within Plantaginaceae and parasitism on fruits and seed capsules are associated with enhanced diversification ofRhinusaandGymnetronvia low extinction rates. Our study provides quantitative evidence and insights on the ecological factors that can promote diversification in phytophagous insects that feed and develop inside plant tissues.

Plant phylogeny drives arboreal caterpillar assemblages across the Holarctic

“…Many classes of plant secondary metabolites known to have roles in discouraging herbivory are restricted to a monophyletic group of plants (Agrawal, 2007). Likewise, many specialized insect herbivores are adapted to specific secondary metabolites and thus develop only on related plants producing these compounds (Braby & Trueman, 2006; Fordyce, 2010; Hernández‐Vera et al., 2019; Nylin et al., 2014).…”

Why are there not more herbivorous insect species?

“…Niche conservatism, i.e. when species maintain the traits of their fundamental niches through time (Pyron et al 2015), can be a further limiting factor in speciation (Wiens 2004, Hernández-Vera et al 2019. Resource-related traits (e.g.…”

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

“…This assertion stems from mere observations of the reconstructions but numerous studies conduct statistical tests. These include the permutation tail probability test (PTP, Faith & Cranston 1991) or some index of phylogenetic signal such as ʎ's of Pagel (1999) (see Winkler & Mitter 2008 for a review on host plant conservatism patterns and Leppanen et al 2012;Wilson et al 2012, Hernández-Vera et al 2019 for more recent examples).…”