Phylogenomics, introgression, and demographic history of South American true toads (Rhinella)

Abstract

How introgression affects reproductive isolation and speciation is an enduring question in evolutionary biology. Reproductive isolation has long been viewed as the primary factor behind lineage divergence and stable boundaries between closely related species

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

“…Establishing the identity and origin of non-native amphibians is instrumental to inform wildlife managers and conservation scientists (Dubey, Lavanchy, et al, 2019;Koster et al, 2023;Kuijt et al, 2023), but it first requires a priori knowledge of their native diversity, which is rarely trivial (Robbemont et al, 2023). For example, infamous global invaders such as the cane toad (Rhinella marina), the clawed frog (Xenopus laevis) or the Asian common toad (Duttaphrynus melanostictus) all belong to species complexes composed of multiple lineages in their home range (Furman et al, 2015;Rivera et al, 2022;Wogan et al, 2016). Hence, invasion genetics and historical phylogeography must go hand in hand to understand the onset of biological invasions.…”

Cryptic lineages and standing genetic variation across independent cane toad introductions

“…Both Rhinella marina and R. horribilis are described from our sampling range, with Panamanian and Texan toads formally assigned to R. horribilis (Acevedo et al, 2016; Figures 1 and 8). However, reciprocal monophyly between the clades and high F ST values suggest than they may be part of a larger species complex, as has been postulated elsewhere (Acevedo et al, 2016;Bessa-Silva, 2020;Rivera et al, 2021;Vallinoto et al, 2010). Although beyond the scope of our current sampling and study, further investigation into the native range of the R. marina complex may uncover additional species, or at least highly divergent lineages.…”

“…We find that Ecuador diverges earlier than other populations in South America. Recent work in the native range of Rhinella suggests cryptic diversity in this area (Rivera et al, 2021 ), nonetheless, the Ecuadorian specimens are morphologically consistent with Rhinella marina . High differentiation between Guiana Shield populations, Ecuador, Panama, and Texas are suggestive of distinct lineages.…”

“…Further, our analyses showed that Hawaiʻi, Puerto Rico and Bermuda derive approximately 10% of their ancestry from French Guiana. This may be due to incomplete lineage sorting between inland French Guiana and Guyana populations, a common pattern in amphibians, and within the R. marina and R. horribilis species complex in particular (Firneno et al, 2020 ; Rivera et al, 2021 ). This pattern could also result from admixture between French Guiana and Guyana at some point in the introduction history.…”

“…However, until recently, research largely centered on introduced populations in Australia, Hawaiʻi, and Puerto Rico. Recent morphological work in the native range identified two species within R. marina, with R. horribilis occurring in northwestern South America, Central America and the southern United States and R. marina occurring exclusively in South America (Acevedo et al, 2016;Bessa-Silva, 2020), and this has been largely confirmed by genetic data (Rivera et al, 2021). Given this finding, gaps remain in our understanding of the broader context of invasion in Rhinella.…”