Ramón Andrés López-Pérez

Testing the genetic predictions of a biogeographical model in a dominant endemic Eastern Pacific coral (Porites panamensis) using a genetic seascape approach

The coral fauna of the Eastern Tropical Pacific (ETP) is depauperate and peripheral; hence, it has drawn attention to the factors allowing its survival. Here, we use a genetic seascape approach and ecological niche modeling to unravel the environmental factors correlating with the genetic variation of Porites panamensis, a hermatypic coral endemic to the ETP. Specifically, we test if levels of diversity and connectivity are higher among abundant than among depauperate populations, as expected by a geographically relaxed version of the Abundant Center Hypothesis (rel-ACH). Unlike the original ACH, referring to a geographical center of distribution of maximal abundance, the rel-ACH refers only to a center of maximum abundance, irrespective of its geographic position. The patterns of relative abundance of P. panamensis in the Mexican Pacific revealed that northern populations from Baja California represent its center of abundance; and southern depauperate populations along the continental margin are peripheral relative to it. Genetic patterns of diversity and structure of nuclear DNA sequences (ribosomal DNA and a single copy open reading frame) and five alloenzymatic loci partially agreed with rel-ACH predictions. We found higher diversity levels in peninsular populations and significant differentiation between peninsular and continental colonies. In addition, continental populations showed higher levels of differentiation and lower connectivity than peninsular populations in the absence of isolation by distance in each region. Some discrepancies with model expectations may relate to the influence of significant habitat discontinuities in the face of limited dispersal potential. Environmental data analyses and niche modeling allowed us to identify temperature, water clarity, and substrate availability as the main factors correlating with patterns of abundance, genetic diversity, and structure, which may hold the key to the survival of P. panamensis in the face of widespread environmental degradation.

Marine and coastal biodiversity of Oaxaca, Mexico [with erratum]

The state of Oaxaca in southern Mexico harbors the highest faunistic and floristic biodiversity of the region; however, to date, research effort has focused on terrestrial flora and fauna. Despite this bias, there is a large amount of dispersed information regarding the coastal and marine biodiversity of Oaxaca. The present study aimed to: 1) update and synthesize existing information to improve understanding of coastal and marine biodiversity; and 2) provide a baseline for future biodiversity studies in Oaxaca. The review of 198 references about Oaxacas flora and fauna produced 2, 157 species records, from 15 taxonomic groups (Division, Phyla or Class). Nevertheless, knowledge about the fauna and flora of Oaxaca remains scarce compared to other regions, such as the Gulf of California. Additionally, floristic and faunistic knowledge is heterogeneous among the taxonomic groups; for instance, 242 (11 .2 °/o) species represent macroalgae, three invertebrate groups (annelids, crustaceans and mollusks) represent about 44.0% (949 species) of all species recorded, while the vertebrates are represented by 762 species (35.3°/o). Similarly, many invertebrate groups recorded in adjacent regions have not yet been recorded on the Oaxaca coast, including some platyhelminthes, rotifers, nematodes, oligochaetes, sipunculids, echiurans, tardigrades, pycnogonids, some crustaceans, brachiopods, chaetognaths, ascidians and cephalochordates. The study of the marine flora and fauna is far from finished; additional effort is required to complete the marine biodiversity inventory of Oaxaca.