Genomewide investigation of adaptation to harmful algal blooms in common bottlenose dolphins (Tursiops truncatus).
Harmful algal blooms (HABs), which can be lethal in marine species and cause illness in humans, are increasing worldwide. In the Gulf of Mexico, HABs of Karenia brevis produce neurotoxic brevetoxins that cause large-scale marine mortality events. The long history of such blooms, combined with the potentially severe effects of exposure, may have produced a strong selective pressure for evolved resistance. Advances in next-generation sequencing, in particular genotyping-by-sequencing, greatly enable the genomic study of such adaptation in natural populations. We used restriction site-associated DNA (RAD) sequencing to investigate brevetoxicosis resistance in common bottlenose dolphins (Tursiops truncatus). To improve our understanding of the epidemiology and aetiology of brevetoxicosis and the potential for evolved resistance in an upper trophic level predator, we sequenced pools of genomic DNA from dolphins sampled from both coastal and estuarine populations in Florida and during multiple HAB-associated mortality events. We sequenced 129 594 RAD loci and analysed 7431 single nucleotide polymorphisms (SNPs). The allele frequencies of many of these polymorphic loci differed significantly between live and dead dolphins. Some loci associated with survival showed patterns suggesting a common genetic-based mechanism of resistance to brevetoxins in bottlenose dolphins along the Gulf coast of Florida, but others suggested regionally specific mechanisms of resistance or reflected differences among HABs. We identified candidate genes that may be the evolutionary target for brevetoxin resistance by searching the dolphin genome for genes adjacent to survival-associated SNPs.
Nicholas School of the Environment, Duke University, 135 Duke Marine Lab Road, Beaufort, NC, 28516, USA.
Kristina M
KM
Cammen
Nicholas School of the Environment, Duke University, 135 Duke Marine Lab Road, Beaufort, NC, 28516, USA.
Thomas F
TF
Schultz
National Marine Fisheries Service, Southeast Fisheries Science Center, 646 Cajundome Blvd, Lafayette, LA, 70506, USA.
Patricia E
PE
Rosel
Chicago Zoological Society, c/o Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA.
Randall S
RS
Wells
Nicholas School of the Environment, Duke University, 135 Duke Marine Lab Road, Beaufort, NC, 28516, USA.
Andrew J
AJ
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D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000235:genetics*; D005431:Florida; D005787:Gene Frequency; D005838:Genotype; D060851:Gulf of America; D057097:Harmful Algal Bloom; D008387:Marine Toxins / Q000633:toxicity; D008957:Models, Genetic; D035964:Oxocins / Q000633:toxicity; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D000095702:Polyether Toxins
D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins
adaptation; common bottlenose dolphin; harmful algal bloom; restriction site-associated DNA sequencing