Phylogeography of Supralittoral Rocky Intertidal Ligia Isopods in the Pacific Region from Central California to Central Mexico

Ligia isopods are widely distributed in the Pacific rocky intertidal shores from central California to central Mexico, including the Gulf of California. Yet, their biological characteristics restrict them to complete their life cycles in a very narrow range of the rocky intertidal supralittoral. Herein, we examine phylogeographic patterns of Ligia isopods from 122 localities between central California and central Mexico. We expect to find high levels of allopatric diversity. In addition, we expect the phylogeographic patterns to show signatures of past vicariant events that occurred in this geologically dynamic region.We sequenced two mitochondrial genes (Cytochrome Oxidase I and 16S ribosomal DNA). We conducted Maximum Likelihood and Bayesian phylogenetic analyses. We found many divergent clades that, in general, group according to geography. Some of the most striking features of the Ligia phylogeographic pattern include: (1) deep mid-peninsular phylogeographic breaks on the Pacific and Gulf sides of Baja peninsula; (2) within the Gulf lineages, the northern peninsula is most closely related to the northern mainland, while the southern peninsula is most closely related to the central-southern mainland; and, (3) the southernmost portion of the peninsula (Cape Region) is most closely related to the southernmost portion of mainland.Our results shed light on the phylogenetic relationships of Ligia populations in the study area. This study probably represents the finest-scale phylogeographic examination for any organism to date in this region. Presence of highly divergent lineages suggests multiple Ligia species exist in this region. The phylogeographic patterns of Ligia in the Gulf of California and Baja peninsula are incongruent with a widely accepted vicariant scenario among phylogeographers, but consistent with aspects of alternative geological hypotheses and phylo- and biogeographic patterns of several other taxa. Our findings contribute to the ongoing debate regarding the geological origin of this important biogeographic region

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

re-habitar El Carmen : Un proyecto sobre patrimonio contemporáneo

El proyecto _re-HABITAR suponía para el propio proceder de la institución un avance más allá del reconocimiento, registro, inventario o protección patrimonial de la arquitectura del siglo XX y del Movimiento Moderno para posicionarse en la acción preventiva y conservativa de ese legado contemporáneo. Para ello, la praxis patrimonial se aferraba a un modelo: el de la vivienda social en España en la segunda mitad del siglo XX; a un caso concreto: el de la barriada de Nuestra Señora del Carmen (Recasens Méndez-Queipo de Llano, 1958); y a un requisito fundamental: analizar un objeto vivo y en uso, aún con la presencia de quienes lo vivieron y usaron desde su origen

A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales

The Caryophyllales constitute a major lineage of flowering plants with approximately 12500 species in 39 families. A taxonomic backbone at the genus level is provided that reflects the current state of knowledge and accepts 749 genera for the order. A detailed review of the literature of the past two decades shows that enormous progress has been made in understanding overall phylogenetic relationships in Caryophyllales. The process of re-circumscribing families in order to be monophyletic appears to be largely complete and has led to the recognition of eight new families (Anacampserotaceae, Kewaceae, Limeaceae, Lophiocarpaceae, Macarthuriaceae, Microteaceae, Montiaceae and Talinaceae), while the phylogenetic evaluation of generic concepts is still well underway. As a result of this, the number of genera has increased by more than ten percent in comparison to the last complete treatments in the Families and genera of vascular plants” series. A checklist with all currently accepted genus names in Caryophyllales, as well as nomenclatural references, type names and synonymy is presented. Notes indicate how extensively the respective genera have been studied in a phylogenetic context. The most diverse families at the generic level are Cactaceae and Aizoaceae, but 28 families comprise only one to six genera. This synopsis represents a first step towards the aim of creating a global synthesis of the species diversity in the angiosperm order Caryophyllales integrating the work of numerous specialists around the world

Late pliocene abrasion platform from the cantil costero formation of Baja California

An unusually extensive and well preserved marine abrasion platform of Late Pliocene age is present 84 m above sea leve1 north of El Rosario, in Baja California. The surface extends for 6 km along the coast and is up to 3 km wide. The abrasion platform is a major disconformity that separates siltstones of the Upper Cretaceous Rosario Formation from the basal conglomerates of the Upper Pliocene Cantil Costero Formation. During its creation under transgressive conditions, the platform was kept clear of nearshore sediments and colonies of the pholadid bivalve Penitella penita (Conrad, 1837) with densities of up to 200/m2, bored into the underlying platform rocks. Tectonic uplift of the peninsula and the Sierra San Pedro Martir, starting about 2 m.y. ago, stimulated a massive progradation of land-derived clastics, which inundated the platform and locally exterminated the pholadid bivalves. This example clearly illustrates a model of transition from subtidal to intertidal conditions, in contrast to unconformities of strictly submarine origin

Evaluation of paleo-wave conditions from oscillatory structures preserved in cretaceous sediments of Baja California

Measurements were obtained of spacing (E), dip and height of oscillatory ripples (hum- mochyylswaley cross-stratification) preserved within the sections of Punta Banda and Peñasco La Lobera in the Late Cretaceous Rosario Formation, in Baja California. From these data we estimated the hydrodynamic characteristics of paleo-waves that produced the oscillation ripples: near-bottom orbital diameter of the wave motion (do), near-bottom orbital velocity (Um), wave period (T) and wave height (H). A clear dependence is shown through the use of ripple spacing and five equations to obtain these paleo-wave parameters. The localities studied represent the higher limit (Peñasco La Lobera) and lower limit (Punta Banda) of the shoreface

Lower Cretaceous Alisitos Formation at Punta San Isidro: Coastal sedimentation and volcanism

The Lower Cretaceous (Aptian-Albian) Alisitos Formation is well exposed at Punta San Isidro and adjacent sea cliffs on the Pacific shores of Baja California near Eréndira, Mexico. Continuous coastal outcrops define a local stratigraphic succession less than 100 m in total thickness, including repetitious tuff, sandstone and conglomerate units interbedded with discontinuous limestone beds rarely more than 2.5 m thick. The limestone beds are biostromal units that include scattered oysters and/or corals, as well as units dominated by the rudistid bivalve, Caprinuloidea perfecta. Two distinctive conglomerate units are composed of andesite cobbles colonized by encrusting oysters in a quasi rocky-shore setting. One sandstone unit includes abundant fossil wood with tree limbs up to 55 cm long and 5 cm in diameter. Proximal volcanic activity is indicated by a series of dikes that cut through pyroclastic beds and lead to a 10-m thick andesitic flow that caps the succession at Punta San Isidro. Compared with thicker intervals of the Alisitos Formation elsewhere in Baja California that are dominated by andesitic flows and offshore limestone, the Punta San Isidro sequence offers a window on a back-reef environment adjacent to a paleoshore that received pyroclastic lahars from a terrestrial origin or mass flows from shallow submarine explosions. Recovery of marine life and the renewal of a carbonate substrate followed successive episodes of volcanism and massive erosion along an active coastline. This scenario is very different from depositional processes of the Upper Cretaceous (Campanian-Maastrichtian) Rosario Formation that cannibalized and subsequently formed a regional unconformity against tilted Alisitos strata with substantial topographic relief in the Eréndira region

Rhodolith detritus impounded by a coastal dune on Isla Coronados, Gulf of California

Sand from a small dune on the southwest side of Isla Coronados with an estimated volume of 30,000 m3 is enriched as much as 86.5% by calcium-carbonate detritus from beached rhodoliths. Elsewhere in the Gulf of California, coastal sand dunes often occur on the north sides of islands or north-facing peninsular shores, and calcium-carbonate input is more commonly linked to bivalve mollusks from adjacent sand flats. The local calcium-carbonate budget for the west-facing shore of Isla Coronados must take into account how many rhodoliths of a given size are required to build a sand dune with a known composition and volume. To this end, 135 whole rhodoliths were collected from above the tide line at Punta El Bajo, across from Isla Coronados, on the peninsular mainland. One cubic meter is calculated to accommodate 8640 whole rhodoliths with an average diameter of 5 cm and an average sphericity of 0.86. The age of a rhodolith this size could be several decades. Through stages, the sample rhodoliths were crushed to a maximum grain size ≤ 2.38 mm in diameter (–1.25ø equivalent), and the product was used to estimate the proportion required to generate 1 m3 of pure carbonate sand. Accounting for 2% loss throughout the reduction process, about 16,265 crushed rhodoliths are needed to produce 1 m3 of carbonate sand. Thus, a 30,000-m3 dune requires approximately 488,000,000 rhodoliths to generate 86% of the dune´ s volume. Dunes of this kind may be rare, but the computation is applicable to other rhodolith-derived dunes in the Gulf of California