Divergence times of the Rhoadsia clade (Characiformes: Characidae)

Abstract

The family Characidae is the most diverse group of fishes in the Neotropics with challenging systematics. The three genera Carlana, Parastremma, and Rhoadsia, formerly considered the subfamily Rhoadsiinae, are now included in the subfamily Stethaprioninae. Previous phylogenetic analyses did not include all genera of Rhoadsiinae, specifically Parastremma. Here, we estimated the phylogenetic relationships and divergence times of the genera of Rhoadsiinae (the Rhoadsia clade) relative to the most representative genera of the Characidae. We used six molecular markers from the mitochondrial and nuclear genome to estimate the phylogeny and divergence times. We confirmed the monophyly of the Rhoadsia clade. Furthermore, we estimated that the Central American genus Carlana and the western Colombian genus Parastremma diverged approximately 13 Mya (95% HPD 8.36–18.11), consistent with the early-closure estimates of the Isthmus of Panama (~15 Mya). The genus Rhoadsia, endemic to Western Ecuador and Northern Peru, was estimated to originate at around 20 Mya (95% HPD 14.35–25.43), consistent with the Andean uplift (~20 Mya).

Conservation threats and future prospects for the freshwater fishes of Ecuador: A hotspot of Neotropical fish diversity

“…Rising seawater levels or increasing storm intensity can also threaten freshwater fishes in low‐lying coastal areas, including the small drainages west of the coastal mountain ranges that may be inhabited by locally adapted populations or endemic species (Aguirre et al ., 2019a; Cucalón Tamayo, 2019; Jiménez‐Prado & Aguirre, 2021). We are not aware of studies on this topic in Ecuador.…”

“…Methods for DNA sequencing are now extremely robust, and new low‐cost genomic sequencing technologies are emerging that allow the creation of mobile genomics laboratories (Krehenwinkel et al ., 2019). Studies employing molecular markers with Ecuadorian freshwater fishes are still relatively sparse and constitute a major direction for future growth (Cucalón Tamayo, 2019; Cucalón Tamayo & Bajaña Zambrano, 2015; Escobar‐Camacho et al ., 2015; Loh et al ., 2014; Lujan et al ., 2015b; Malato et al ., 2017; Vu et al ., 2013). Other biodiversity research tools like geographic information systems (Menéndez‐Guerrero & Graham, 2013) and geometric morphometrics (Aguirre & Jiménez Prado, 2018; Zelditch et al ., 2012) require minimal laboratory resources and can provide great insights into the ecology and evolution of freshwater fishes.…”

“…However, Barriga (2012) recognized a distinct biogeographic zone for freshwater fishes in the southern portion of this region, the Catamayo zone, spanning from the Jubones River just north of the city of Machala southward to northern Peru. This region is recognized as an important hotspot of endemism for other groups, suggesting that there has been significant historical isolation (Aguirre et al ., 2016; Cucalón Tamayo, 2019; Tapia‐Armijos et al ., 2015). Major rivers in this system include the Taura, Cañar, Bulubulu, Balao, Jubones and Santa Rosa.…”