Data from: Seascape genetics along environmental gradients in the Arabian Peninsula: insights from ddRAD sequencing of anemonefishes

Understanding the processes that shape patterns of genetic structure
across space is a central aim of landscape genetics. However, it remains
unclear how geographic features and environmental variables shape gene
flow, particularly for marine species in large complex seascapes. Here, we
evaluated the genomic composition of the two-band anemonefish Amphiprion
bicinctus across its entire geographic range in the Red Sea and Gulf of
Aden, as well as its close relative, Amphiprion omanensis endemic to the
southern coast of Oman. Both the Red Sea and the Arabian Sea are complex
and environmentally heterogeneous marine systems that provide an ideal
scenario to address these questions. Our findings confirm the presence of
two genetic clusters previously reported for A. bicinctus in the Red Sea.
Genetic structure analyses suggest a complex seascape configuration, with
evidence of both Isolation by Distance (IBD) and Isolation by Environment
(IBE). In addition to IBD and IBE, genetic structure among sites was best
explained when two barriers to gene flow were also accounted for. One of
these coincides with a strong oligotrophic-eutrophic gradient at around
16-20˚N in the Red Sea. The other agrees with an historical bathymetric
barrier at the straight of Bab al Mandab. Finally, these data support the
presence of inter-specific hybrids at an intermediate suture zone at
Socotra and indicate complex patterns of genomic admixture in the Gulf of
Aden with evidence of introgression between species. Our findings
highlight the power of recent genomic approaches to resolve subtle
patterns of gene flow in marine seascapes.