Genetic Diversity of the Atlantic Ghost Crab Ocypode quadrata (Decapoda: Ocypodidae) in Two Beaches With Different Anthropogenic Disturbance in the North Coast of Veracruz, Mexico

The constant demographic expansion of human population is now recognized as a stressing factor for ecological communities on beaches, and their effects have been barely explored in developing countries such as Mexico, where heavy coastline industrialization is currently undergoing. In this work, we study how anthropogenic factors have affected the Atlantic Ghost Crab (Ocypode quadrata) in two beaches with different anthropogenic disturbance in northern Veracruz (near Tuxpan and Tamiahua), Mexico. To this end, we evaluated the species genetic diversity using a fragment of the Cytochrome Oxidase I gene, along with several measurements (number of haplotypes, haplotype diversity, and nucleotide diversity, etc.), estimations of genetic relationship (haplotype network, phylogenetic analysis, gene flow), and statistical tests on average genetic distances (Student's t test). We found 32 haplotypes, 22 from Tuxpan and 15 from Tamiahua. Despite the occurrence of almost 50% more haplotypes in Tuxpan than in Tamiahua, the correction for differences in sample size indicated that such a difference is statistically nonsignificant. A similar pattern was found with other genetic measurements. Similarly, the haplotype network and the phylogenetic reconstruction failed to recover haplotype clusters or haplogroups associated exclusively to one or another beach, whereas gene flow between localities was of the same order of magnitude in both directions. The Student's t test showed that differences in genetic distances between localities (estimated using p-distances and Jukes-Cantor 69) were not statistically significant. Finally, although the anthropogenic effects between beaches in Tuxpan and Tamiahua are remarkable different, this has not been reflected in the genetic diversity of O. quadrata.