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

Abstract

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.

Phylogeography of a Widely Distributed Atlantic Species: The Case of the Ghost Crab Ocypode quadrata (Fabricius, 1787) (Decapoda: Brachyura: Ocypodidae)

“…Results among distinct localities within Brazil along with Panama and French Guiana also suggested the absence of genetic separation, evidenced by low genetic distance values, and by the polytomies in the phylogenetic tree and the star-shaped haplotype network, like those observed for other populations of O. quadrata [6,21]. Herein, it is plausible to infer that the absence of a geographic pattern in the composition of the formed subgroups is a good indicator of high panmixia, which is a relevant fact, since the pattern found in most living species tends to be the structuring at some level for distant geographical localities [25,69,70].…”

“…All these characteristics draw attention to O. quadrata being a potential model for several studies, as was the case in other regional genetic population studies [6,21] and in systematics and taxonomy [1]. Despite this well-developed knowledge on biology and ecology of O. quadrata, the information on genetic variability with this taxon is still scanty.…”

The expansion of the Atlantic–Mediterranean ghost crab Ocypode cursor (Linnaeus, 1758): Distribution, environmental niches and future perspectives

“…However, the habitat discontinuity represented by long stretches of rocky coast in northern Sicily could serve as a barrier to the species' dispersion to other areas in Italy, even though ocean currents are expected to play a significant role in overcoming these obstacles and, consequently, in the secondary colonization of other beaches, for example, through transport on floating objects (e.g. detached macroalgae, seagrass and wood) or through larval dispersal (Peña‐Toribio et al, 2017).…”