Limited genetic signal from potential cloning and selfing within wild populations of coral-eating crown-of-thorns seasta
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Limited genetic signal from potential cloning and selfing within wild populations of coral-eating crown-of-thorns seastars (Acanthaster cf. solaris) Sven Uthicke1
•
Morgan S. Pratchett2 • Vanessa Messmer2 • Hugo Harrison1,2
Received: 15 April 2020 / Accepted: 21 October 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Population outbreaks of crown-of-thorns seastars (CoTS; Acanthaster spp.) are contributing to extensive coral loss and reef degradation throughout the Indo-Pacific, but the causes and underlying mechanisms of population maintenance and outbreaks are equivocal. Two recent publications suggest that, in addition to outbreeding sexual reproduction, asexual reproduction through larval fission and selfing may contribute to rapid increases in the local abundance of Acanthaster spp. We re-analysed two large microsatellite datasets (collectively representing 3714 individuals) that investigated connectivity in the Great Barrier Reef and wider Pacific region to investigate if potential cloning or selfing can be evidenced in the population genetic structure. Within this dataset, we identified only a small number (18, \ 0.5%) of putative clones (repeated multilocus genotypes). We argue that several of these are due to sampling and processing errors rather than direct evidence of cloning. Analysis of the population genetic structure (i.e. pairwise genetic differences between individuals, deviations from Hardy–Weinberg Equilibrium, and linkage disequilibrium) also yielded no genetic evidence for asexual reproduction. There was a tendency
Topic Editor Simon Davy
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00338-020-02022-5) contains supplementary material, which is available to authorised users. & Sven Uthicke [email protected] 1
Australian Institute of Marine Science, PMB No. 3, Townsville MC, Qld 4810, Australia
2
ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld 4811, Australia
towards slight heterozygote deficits, so we cannot refute that selfing does occur, but observed patterns are most likely attributable to sampling artefacts. Although we cannot exclude that asexual reproduction occurs to some extent in Acanthaster populations, we find no evidence that these processes make a contribution to population structure or directly enhance larval supply. Keywords Crown-of-thorns seastar Asexual reproduction Coral crisis Outbreak
Introduction Crown-of-thorns seastars (CoTS; Acanthaster spp.) periodically undergo major population outbreaks (Uthicke et al. 2009; Pratchett and Cumming 2019), which together with their large size and feeding on reef-building corals, causes extensive coral loss and degradation of coral reef ecosystems (Pratchett et al. 2014). New and renewed population outbreaks of crown-of-thorns seastars (CoTS; Acanthaster spp.) have recently been reported throughout the Indo-Pacific from the Maldives to French Polynesia, causing significant coral loss (Kayal et al.
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