Phylogeography of the banded butterflyfish, Chaetodon striatus, indicates high connectivity between biogeographic provinces and ecosystems in the western Atlantic

Abstract

Among the four butterflyfishes of the genus Chaetodon present in the western Atlantic, the banded butterflyfish Chaetodon striatus has the largest distribution range, spanning 44 degrees of latitude (from Massachusetts, USA to Santa Catarina, Brazil). Although the ecology of the banded butterflyfish has been well studied over its entire range, nothing is known about its phylogeography and how biogeographic barriers structure its populations. To assess the level of genetic connectivity among populations from distinct biogeographic provinces and environmental conditions, we collected samples from seven localities: Puerto Rico, in the Caribbean, and Tamandaré, Salvador, Abrolhos, Trindade Island, Arraial do Cabo and Florianópolis, in Brazil. One nuclear (rag 2) and two mitochondrial (control region and cyt b) molecular markers were sequenced. Our findings are consistent with a recent population expansion, around 30-120 thousand years ago, which was found for all populations. Haplotype network analyses point to the Caribbean as a refugium before the population expansion. Results show no geographic pattern of genetic diversity. Indeed, a lack of population structure was found and no isolation was observed across oceanographic barriers, as well as between coral and rocky reef ecosystems. Furthermore, no directionality in the migration pattern was found among populations. Since ecological and environmental characteristics are very diverse across such a vast geographic range, the lack of genetic differentiation suggests that C. striatus evolved ecological plasticity rather than local adaptation in the western Atlantic.

Brazilian marine phylogeography: A literature synthesis and analysis of barriers

“…In particular, the northernmost reaches, along the Amazonian Rainforest coastline, towards longitude 48°29′25″W, is where very little is known about the phylogeographical structure of most coastal marine species. The Amazon river plume is considered a strong barrier to gene flow for many coastal and shallow benthic species (Rocha, 2003; Rocha et al, 2007), but studies in which the Amazon river explains genetic discontinuities usually compare northern vs. southern hemisphere populations (i.e., Caribbean vs. northeastern Brazil populations) sampled thousands of kilometres apart across the western Atlantic Ocean (Cóndor‐Luján et al, 2021; de Souza et al, 2015; Liedke et al, 2020; Volk et al, 2021). Still, for some species including deep‐water reef species, the Amazon river plume is considered either a porous barrier to gene flow or a porous barrier to species dispersal (Floeter et al, 2008; Rocha, 2003; Rocha et al, 2005).…”

Comparative phylogeography of reef fishes indicates seamounts as stepping stones for dispersal and diversification

“…During lowstand sea levels in glacial periods, continental shelves and seamounts emerge and often have their shelf area considerably contracted (Ludt and Rocha 2015), consequently affecting the population size of shallow water species (Ludt et al 2012;Liedke et al 2020). Therefore, the wider bathymetric range of the Coney may have favored its stronger connectivity along the VTC.…”

Phylogeography of Agathistoma (Turbinidae, Tegulinae) snails in tropical and southwestern Atlantic

“…Several factors influence the effectiveness of the Orinoco/Amazon as a barrier or filter: changing sea levels, sedimentation, current speeds, salinity and the availability of marine habitats beneath the freshwater river plume (Figueiredo et al, 2009;Floeter et al, 2008;Rocha, 2003). Because different species experience these factors differently, the Orinoco/Amazon is a selective barrier, affecting different species to varying degrees (Liedke et al, 2020;Trovant et al, 2016). The Orinoco/Amazon barrier seems to drive speciation for several coastal taxa, including reef fishes, lobsters and mussels (Floeter et al, 2008;Rocha, 2003;Tourinho et al, 2012;Trovant et al, 2016).…”

“…The Orinoco/Amazon barrier seems to drive speciation for several coastal taxa, including reef fishes, lobsters and mussels (Floeter et al, 2008;Rocha, 2003;Tourinho et al, 2012;Trovant et al, 2016). On the other hand, many reef fishes show high genetic connectivity between populations to either side of the Orinoco/Amazon (Floeter et al, 2008;Liedke et al, 2020;Rocha et al, 2005), as do some invertebrates, including the marine gastropods Stramonita and Neritina (Barroso et al, 2020;Claremont et al, 2011). The existence of truly marine ecosystems located off the Amazon's mouth at depths below the influence of the river plume may act as a corridor for many species adapted to subtidal conditions (Cordeiro et al, 2015;Moura et al, 1999Moura et al, , 2016.…”