Long Distance Dispersal and Connectivity in Amphi-Atlantic Corals at Regional and Basin Scales

Abstract

Among Atlantic scleractinian corals, species diversity is highest in the Caribbean, but low diversity and high endemism are observed in various peripheral populations in central and eastern Atlantic islands and along the coasts of Brazil and West Africa. The degree of connectivity between these distantly separated populations is of interest because it provides insight into processes at both evolutionary and ecological time scales, such as speciation, recruitment dynamics and the persistence of coral populations. To assess connectivity in broadly distributed coral species of the Atlantic, DNA sequence data from two nuclear markers were obtained for six coral species spanning their distributional ranges. At basin-wide scales, significant differentiation was generally observed among populations in the Caribbean, Brazil and West Africa. Concordance of patterns in connectivity among co-distributed taxa indicates that extrinsic barriers, such as the Amazon freshwater plume or long stretches of open ocean, restrict dispersal of coral larvae from region to region. Within regions, dispersal ability appears to be influenced by aspects of reproduction and life history. Two broadcasting species, Siderastrea siderea and Montastraea cavernosa, were able to maintain gene flow among populations separated by as much as 1,200 km along the coast of Brazil. In contrast, brooding species, such as Favia gravida and Siderastrea radians, had more restricted gene flow along the Brazilian coast.

Extreme morphological plasticity enables a free mode of life in Favia gravida at Ascension Island (South Atlantic)

“…F. gravida resembles F. fragum (Esper, 1793), another species with an amphi-Atlantic range (Hoeksema et al in press). Molecular evidence supports their status as two genetically distant species (Nunes et al 2008(Nunes et al , 2011. The type specimens of F. gravida are massive corals.…”

Population dynamics of Siderastrea stellata Verrill, 1868 from Rocas Atoll, RN: implications for predicted climate change impacts at the only South Atlantic atoll

“…The taxonomy of this group has been debated and previously S. stellata was considered the only siderastreid in Brazil (Laborel 1974, Maida andFerreira 1997). Recently, the presence of S. radians and S. siderea was confirmed on the Brazilian coast (Neves et al 2008, 2010, Nunes et al 2011 however, neither of those investigations included specimens collected at Rocas Atoll and up to now, only the occurrence of S. stellata is confirmed in this atoll.…”

Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

“…However, there is increasing evidence that the duration of pelagic stages is not directly correlated with dispersal potential (Johannesson 1988;Strathmann et al 2002). This is supported by the fact that many brooding species have wider geographic distributions showing even more genetic connectivity on large scales than congeners with a planktonic larval stage (Highsmith 1985;Ó Foighil et al 2001;Nunes et al 2011;Hoeksema et al 2012;Xavier et al 2012). Passive dispersal through rafting and floating can greatly enhance natural dispersal in the marine environment and is supposed to be the main process leading to long-distance dispersal of these brooding marine invertebrates (Johannesson 1988;Locke and Corey 1989;Thiel and Gutow 2005b;Goodbody-Gringley et al 2010).…”

“…Lester and Ruttenberg 2005;Sherman et al 2008). However, patterns in connectivity are difficult to predict based on reproductive traits alone and are likely strongly influenced by multiple biotic and abiotic environmental factors, especially oceanographic processes such as local water circulation patterns (Bowen et al 2006;Nunes et al 2011). In such situations, genetic analysis of population differentiation can provide a powerful tool for investigating dispersal (Teske et al 2005;Thiel and Haye 2006;Goodbody-Gringley et al 2010).…”