Clone wars: asexual reproduction dominates in the invasive range of Tubastraea spp. (Anthozoa: Scleractinia) in the South-Atlantic Ocean.

Katia Cristina Cruz Capel,Zac Forsman,Caio T.C.C Rachid,Joel C Creed,Robert J Toonen,Marcelo V Kitahara,Carla Zilberberg

doi:10.7717/peerj.3873

Abstract

Although the invasive azooxanthellate corals Tubastraea coccinea and T. tagusensis are spreading quickly and outcompeting native species in the Atlantic Ocean, there is little information regarding the genetic structure and path of introduction for these species. Here we present the first data on genetic diversity and clonal structure from these two species using a new set of microsatellite markers. High proportions of clones were observed, indicating that asexual reproduction has a major role in the local population dynamics and, therefore, represents one of the main reasons for the invasion success. Although no significant population structure was found, results suggest the occurrence of multiple invasions for T. coccinea and also that both species are being transported along the coast by vectors such as oil platforms and monobouys, spreading these invasive species. In addition to the description of novel microsatellite markers, this study sheds new light into the invasive process of Tubastraea.

Highlights

The marine environment is continuously subjected to multiple stressors, many of which are associated with human activities (Halpern et al, 2014; Gallardo et al, 2016)
While two loci failed to amplify for T. tagusensis (Tco36 and Tco38), this species exhibited two loci at a single locus with no evidence of linkage disequilibrium between them (Tco32a and Tco32b), so both were included in these analyses
Evidence for null alleles for T. coccinea Todos-os-Santos Bay (TSB) population was observed in the same two loci (Tco36 and Tco38) that failed to amplify for T. tagusensis

Summary

Introduction

The marine environment is continuously subjected to multiple stressors, many of which are associated with human activities (e.g., over-exploitation of resources, pollution, climate change and invasive species) (Halpern et al, 2014; Gallardo et al, 2016). Among these stressors, invasive species are considered to be a major threat to biodiversity (Molnar et al, 2008) with the potential to quickly trigger changes in native communities and the ecosystem services and functions, which can have wide-ranging negative impacts. Three scleractinian species from the genus Tubastraea were introduced and are spreading rapidly throughout the Western Atlantic Ocean (De Paula & Creed, 2004; Fenner, 2001; Fenner & Banks, 2004; Sammarco, Atchison & Boland, 2004; Sammarco, Porter & Cairns, 2010; Capel, 2012; Sampaio et al, 2012; Costa et al, 2014; Silva et al, 2014), threatening native and endemic species (Mantellato et al, 2011; Santos, Ribeiro & Creed, 2013; Creed, 2006) and fouling man-made structures and vessels

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Discussion

Conclusion