Multispecies colour polymorphisms associated with contrasting microhabitats in two Mediterranean wrasse radiations.

Intraspecific colour polymorphisms (CPs) present unique opportunities to study fundamental evolutionary questions, such as the link between ecology and phenotype, mechanisms maintaining genetic diversity and their putative role in speciation. Wrasses are highly diverse in ecology and morphology and harbour a variety of colour-polymorphic species. In the Mediterranean Sea, wrasses of the tribe Labrini evolved two species radiations each harbouring several species with a brown and a green morph. The colour morphs occur in complete sympatry in mosaic habitats with rocky outcrops and Neptune grass patches. Morph-specific differences had not been characterized yet and the evolutionary forces maintaining them remained unknown. With genome-wide data for almost all Labrini species, we show that species with CPs are distributed across the phylogeny, but show evidence of hybridization. This suggests that the colour morphs are either ancient and have been lost repeatedly, that they have evolved repeatedly or have been shared via hybridization. Focusing on two polymorphic species, we find that each colour morph is more common in the microhabitat providing the best colour match and that the morphs exhibit additional behavioural and morphological differences further improving crypsis in their respective microhabitats. We find little evidence for genetic differentiation between the morphs in either species. Therefore, we propose that these colour morphs represent a multi-niche polymorphism as an adaptation to the highly heterogeneous habitat. Our study highlights how colour polymorphism (CP) can be advantageous in mosaic habitats and that Mediterranean wrasses are an ideal system to study trans-species polymorphisms, i.e. polymorphisms maintained across several species, in adaptive radiations.

Maritime ports and beach management as sources of coastal macro-, meso-, and microplastic pollution.

Plastic pollution is a major environmental issue that affects coasts all around the world. Many studies point out the importance of a better management of this type of pollution. In this pioneering study, we have analyzed the distribution of macro-, meso-, and microplastics along the coast of Asturias (southwest Bay of Biscay, Spain). Significant correlation analysis suggests that mesoplastics are produced in situ by fragmentation of macroplastics. Differences between groups of beaches revealed the importance of maritime ports and fishing activities as sources of macroplastics and likely of microplastics as well. Another source of microplastics could be atmospheric deposition, especially for fibers. Multiple regression model allowed to confirm the utility of beach services like cleaning and trash bins to control macroplastics. These results emphasize the need of an integral treatment of marine plastic pollution involving fishers and maritime ports, as well as the importance of providing beach services.