Abstract

The lionfish Pterois volitans has become an invader of the greater Caribbean for more than a decade, and since then, the detailed study of its biology and attributes has become of great importance for understanding its impact on the dynamics and structure of ecosystems. Mitochondrial studies have shown that although lionfish have adaptive strategies that make him an excellent invader, its populations have suffered a drastic reduction in their genetic diversity due to the founder effect, and consequently, its evolutionary potential has been reduced. In order to confirm this, a mitochondrial DNA analysis was carried out and 10 novel species-specific nuclear microsatellite were designed. Samples were taken from two locations in the Southwestern Caribbean: San Andrés (SA) and Santa Marta (SM), during the initial period of the invasion (2009-2012). Mitochondrial analysis of the control region included 432 sequences (155 SA and 277 SM) that initially showed the presence of three haplotypes (H1, H2 and H4) in the invasive population of Colombia, and the arrival of a fourth haplotype (H3) represented by a single individual collected in San Andres in 2010. Moreover, a spatio-temporal nuclear analysis of 364 samples (187 of SA and 177 of SM) indicated significant deviation from Hardy–Weinberg equilibrium in all the loci due to an excess of homozygotes. Observed heterozygosity values (Ho) were below the expected heterozygosity (He) and no spatial differences were found between SA and SM. Nevertheless, temporal analysis showed annual differences between years, with a structure in four subpopulations K = 4. These results are evidence of the arrival of genetic material from the source population in the mentioned periods, with differences in reproduction rates of each cluster inside each location. Our findings clearly demonstrate the initial action of the founder effect on the invasive lionfish populations, represented in a high reduction of its genetic variability, deficit of heterozygotes, inbreeding processes and genetic drift, and therefore, in an increase in the expression of deleterious alleles and reduction of their adaptive potential, which constitutes a disadvantage for the success of this invasive fish

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