Insect Speciation Rules: Unifying Concepts in Speciation Research

Abstract

The study of speciation is concerned with understanding the connection between causes of divergent evolution and the origin and maintenance of barriers to gene exchange between incipient species. Although the field has historically focused either on examples of recent divergence and its causes or on the genetic basis of reproductive isolation between already divergent species, current efforts seek to unify these two approaches. Here we integrate these perspectives through a discussion of recent progress in several insect speciation model systems. We focus on the evolution of speciation phenotypes in each system (i.e., those phenotypes causally involved in reducing gene flow between incipient species), drawing an explicit connection between cause and effect (process and pattern). We emphasize emerging insights into the genomic architecture of speciation as well as timely areas for future research.

Promises and challenges in insect–plant interactions

“…This specialization pattern not only involves host plant as a feeding source but also as a multi-dimensional ecological niche of the insect, providing resources and conditions for its development, reproduction, nutrition, and protection (Kergoat et al, 2017). This arms race is also a major driver of diversification, as plants and herbivorous insects contribute to more than half of current estimated biodiversity (Mullen & Shaw, 2014;Wiens et al, 2015). This arms race is also a major driver of diversification, as plants and herbivorous insects contribute to more than half of current estimated biodiversity (Mullen & Shaw, 2014;Wiens et al, 2015).…”

Identifying genomic hotspots of differentiation and candidate genes involved in the adaptive divergence of pea aphid host races

“…Reduced gene flow should increase density of pairwise nucleotide differences (absolute divergence) between populations in islands of differentiation (Cruickshank & Hahn, ), while linked selection should not (Begun et al., ; Burri et al., ). Phytophagous insects represent good models to characterize the genomic bases of adaptation, as their intricate relationships with host plants may favour host‐associated ecological divergence (Drès & Mallet, ; Mullen & Shaw, ; Soria‐Carrasco et al., ), eventually leading to speciation (Mullen & Shaw, ). Furthermore, several species are well characterized in terms of functional genomics (reviewed in Simon et al., ).…”

Multiple strong postmating and intrinsic postzygotic reproductive barriers isolate florally diverse species of Jaltomata (Solanaceae)

“…Species differences in elaborated mating traits have frequently been associated with premating reproductive barriers (Coyne and Orr 2004; Lowry et al 2008; Baack et al 2015), including behavioral isolation in diverse animal groups such as birds (Seddon et al 2013), fish (Mendelson 2003; Selz et al 2016), and especially insects (Mullen and Shaw 2014; Merrill et al 2015), as well as pollinator isolation in plants (specifically angiosperms). Divergent floral traits can produce strong pollinator isolation via differential attraction or efficiency, and available data support a key direct role for pollinators in reducing gene flow between lineages via premating effects (e.g.…”