Cryptic lineages and standing genetic variation across independent cane toad introductions

Abstract

Widespread introduced species can be leveraged to investigate the genetic, ecological and adaptive processes underlying rapid evolution and range expansion, particularly the contributions of genetic diversity to adaptation. Rhinella marina, the cane toad, has been a focus of invasion biology for decades in Australia. However, their introduction history in North America is less clear. Here, we investigated the roles of introduction history and genetic diversity in establishment success of cane toads across their introduced range. We used reduced representation sequencing (ddRAD) to obtain 34,000 SNPs from 247 toads in native (

Piecing the barcoding puzzle of Palearctic water frogs (Pelophylax) sheds light on amphibian biogeography and global invasions

“…In fact, their patterns of invasion share many similarities with notorious global invaders, for example, the clawed frog ( X. laevis ), the American bullfrog ( L. catesbeianus ), the cane toad ( R. marina ) and the Asian common toad ( D. melanostictus ). Like Pelophylax , these species can rapidly colonize large areas and feature distinct phylogeographic lineages (and thus geographic origins) among introduced populations (De Busschere et al., 2016; Kamath et al., 2016; Reilly et al., 2017; Vences et al., 2017), sometimes even representing several cryptic species (e.g., Mittan‐Moreau et al., 2022).…”

“…marina) and the Asian common toad (D. melanostictus). Like Pelophylax, these species can rapidly colonize large areas and feature distinct phylogeographic lineages (and thus geographic origins) among introduced populations (DeBusschere et al, 2016;Kamath et al, 2016;Reilly et al, 2017;Vences et al, 2017), sometimes even representing several cryptic species (e.g.,Mittan-Moreau et al, 2022).…”

First in family Rhabdiasidae: the reference-guided genome assembly of an invasive parasite, the cane toad lungworm (Rhabdias pseudosphaerocephala)

“…However, it is worth noting that while it appears one species exists in Australia at this time, we cannot prove with these results that it is not a hybrid of multiple home-range species. Recent research that analysed the path of cane toad translocations show that the Australian toads were likely taken from French Guyana, to Puerto Rico, then to Hawai’i before reaching Australia (14). This means that if multiple nematode species were originally sampled in French Guyana, there were many opportunities for hybridisation before they reached Australia.…”

“…Rhabdias pseudosphaerocephala in the western population have larger eggs, larger free-living adults and infective larvae, reduced age at maturity (6), and are also better at infecting toads than their range-core conspecifics (12, 13). However, the invasion trajectory from South America to Australia was complex, with many intermediate populations of toads (14). This prevents us from concluding that these differences in the invasive population of R. pseudosphaerocephala in Australia are caused by differentiation within a single species.…”

Whole‐mitogenome analysis unveils previously undescribed genetic diversity in cane toads across their invasion trajectory

“…lised ddRAD sequencing has offered a different perspective on the phylogenetic relationship of cane toads. This study revealed toads from the coastal area formed two sister clades, distinct from the clade formed by toads from the rainforest regions(Mittan-Moreau et al, 2022). It becomes crucial to ascertain the precise populations of cane toads from the native range that were used as founding individuals, especially given the limited comprehensive description in prior research(Easteal, 1981).…”