Cave In Mexico Research Articles

Complete Genome Sequencing of a NovelGloeobacterSpecies from a Waterfall Cave in Mexico

Only two complete genomes of the cyanobacterial genus Gloeobacter from two very different regions of the world currently exist. Here, we present the complete genome sequence of a third member of the genus isolated from a waterfall cave in Mexico. Analysis of the average nucleotide identities (ANIs) between published Gloeobacter genomes revealed that the complete genome of this new member is only 92.7% similar to Gloeobacter violaceus and therefore we determined it to be a new species. We propose to name this new species Gloeobacter morelensis after the location in Mexico where it was isolated. The complete genome consists of one circular chromosome (4,921,229 bp), one linear plasmid (172,328 bp), and one circular plasmid (8,839 bp). Its genome is the largest of all completely sequenced genomes of Gloeobacter species. Pangenomic comparisons revealed that G. morelensis encodes 759 genes not shared with other Gloeobacter species. Despite being more closely related to G. violaceus, it features an extremely divergent psbA gene encoding an atypical D1 core subunit of Photosystem II previously only found within the genome of Gloeobacter kilaueensis. In addition, we detected evidence of concerted evolution of psbA genes encoding identical D1 in all three Gloeobacter genomes, a characteristic that seems widespread in cyanobacteria and may therefore be traced back to their last common ancestor.

Pleiotropic function of the oca2 gene underlies the evolution of sleep loss and albinism in cavefish

Adaptation to novel environments often involves the evolution of multiple morphological, physiological, and behavioral traits. One striking example of multi-trait evolution is the suite of traits that has evolved repeatedly in cave animals, including regression of eyes, loss of pigmentation, and enhancement of non-visual sensory systems.1,2 The Mexican tetra, Astyanax mexicanus, consists of fish that inhabit at least 30 caves in Mexico and ancestral-like surface fish that inhabit the rivers of Mexico and southern Texas.3 Cave A.mexicanus are interfertile with surface fish and have evolved a number of traits, including reduced pigmentation, eye loss, and alterations to behavior.4-6 To define relationships between different cave-evolved traits, we phenotyped 208 surface-cave F2 hybrid fish for numerous morphological and behavioral traits. We found differences in sleep between pigmented and albino hybrid fish, raising the possibility that these traits share a genetic basis. In cavefish and other species, mutations in oculocutaneous albinism 2 (oca2) cause albinism.7-12 Surface fish with mutations in oca2 displayed both albinism and reduced sleep. Further, this mutation in oca2 fails to complement sleep loss when surface fish harboring this engineered mutation are crossed to independently evolved populations of albino cavefish with naturally occurring mutations in oca2. Analysis of the oca2 locus in wild-caught cave and surface fish suggests that oca2 is under positive selection in 3 cave populations. Taken together, these findings identify oca2 as a novel regulator of sleep and suggest that a pleiotropic function of oca2 underlies the adaptive evolution of albinism and sleep loss.

BEFORE THE MAYA: A REVIEW OF PALEOINDIAN AND ARCHAIC HUMAN SKELETONS FOUND IN THE MAYA REGION

AbstractThis article presents a review of the earliest known skeletal remains in the Maya area, which are found in submerged caves in Mexico and rock shelters in Belize and date to the Paleoindian and Archaic periods. While few in number, several of these individuals have been the focus of intensive analyses, providing an emerging picture of life in the region before the transition to agriculture and settled village communities.

Bat flies (Diptera: Streblidae) associated with phyllostomid bats (Chiroptera: Phyllostomidae) in caves in Mexico

ABSTRACT The Family Streblidae is represented by 246 species distributed worldwide. In order to contribute to the knowledge of streblid richness in Mexico, we recorded the associations between Streblidae and the New World leaf-nosed bats (Phyllostomidae) collected in different caves in Mexico. For each streblid species their geographical and host spectrum is reported, and diagnostic characters are illustrated. Twenty-nine caves from six Mexican states were sampled. A total of 86 bats were collected belonging to eight genera and 11 species and from these a total of 297 streblid specimens of 14 species and five genera were collected. This study updates the knowledge of streblid diversity in Mexican cave habitats providing high resolution images of external anatomy.

Underwater caves in Mexico preserve one of the world’s oldest ochre mines

Underwater caves in Mexico preserve one of the world’s oldest ochre mines

A new cave locality for Astyanax cavefish in Sierra de El Abra, Mexico

The characiform fish Astyanaxmexicanus comes in two forms, a surface-dwelling morph which lives in the rivers of North and Central America and a blind, depigmented cave-dwelling morph which inhabits caves in Mexico. In recent years, this species has arguably become among the most influential model system for the study of evolutionary development and genomics in cave biology. While recent articles have analysed in great detail Astyanax genetics, development, physiology, phylogeny and behaviour, there have been comparatively few recent studies concerning its ecology and in particular its biogeography. Mitchell et al. (1977) reported the species inhabiting 29 caves in the Sierra de El Abra region. Despite the elapsing of over 40 years and the latest surge of interest in the model, not a single new cave locality had been described for the species. We describe here a new and 30th cave locality, Chiquitita Cave, inhabited by troglomorphic A.mexicanus. Their morphology, eye histology, 16S rRNA DNA sequence, and smelling capabilities are analysed. This cave represents the southernmost extension for the cave morph’s habitat within the Sierra de El Abra. Its name, Chiquitita Cave (Tiny Cave), was chosen in reference to a potential hydrologic connection to “Chica Cave” (small cave), which is among the most studied populations of Astyanax.

Contrasting feeding habits of post-larval and adult Astyanax cavefish

The subterranean environment is often described as “extreme” and food poor. Laboratory experiments have shown that blind Mexican tetra Astyanax mexicanus (De Filippi, 1853) cavefish are better at finding food in the dark than surface fish. Several morphological and behavioural attributes that could foster this obvious adaptive response to cave environments have been described. Nonetheless, it is currently unknown what young cavefish actually eat in their natural cave environment. Our results from the Pachon cave in Mexico during the dry and rainy season show that fry are efficient predators in their natural cave environment. Their primary food item is aquatic crustaceans. The guts of post-larval, pre-juvenile stage individuals (n=9) contained an average of 17.9 water fleas (Cladocera), copepods, ostracods, and isopods. Thus, the fry in this cave are well-fed. The Pachon cave environment does not appear to be “food poor” for juvenile cavefish. Food regimes change between post-larval and adult stages to become more dependent on partially decomposed material, guano, or detritus from the mud. We discuss the data with regards to our current developmental and genetic understanding of cavefish morphological and behavioural evolution, particularly regarding its enhanced Vibration Attraction Behaviour (VAB).

Anthropology. Comment on "Late Pleistocene human skeleton and mtDNA link Paleoamericans and modern Native Americans".

Chatters et al. (Reports, 16 May 2014, p. 750) reported the retrieval of DNA sequences from a 12,000- to 13,000-year-old human tooth discovered in an underwater cave in Mexico's Yucatan peninsula. They propose that this ancient human individual's mitochondrial DNA (mtDNA) belongs to haplogroup D1. However, our analysis of postmortem damage patterns finds no evidence for an ancient origin of these sequences.

Indoor radon concentration levels in Mexican caves, using nuclear track methodology, and the relationship with living habits of the bats

This work presents the results of a study of the radon levels in four caves in Mexico: Los Riscos Cave and El Judio Cave in the State of Queretaro, and Coyozochico Cave and Karmidas Cave in the State of Puebla. The measurements were made using the passive closed-end cup system, with CR-39 (Lantrack®) as detection material, and following protocols established for the measurement of indoor radon, developed at the Dosimetry Applications Project of the Physics Institute of the Universidad Nacional Autonoma de Mexico. The radon concentration at one location with Karmidas Cave reached more than 60,000 Bq/m3, while concentrations in the other three caves varied from 83.1–1216.0 Bq/m3, was found. During the study was observed an interesting coincidence between the radon concentration distribution inside the caves, and the bat colonies location. In general, the bat colonies are located at the medium or low radon concentration levels zones.

Uranium-series dating of gypsum speleothems: methodology and examples

The analytical problems of dating gypsum speleothems with the U-series technique are reviewed. Gypsum speleothems are, in general, very low in U content, challenging the limits of detection methods. Various approaches to dissolving gypsum and isolation of actinides from the matrix include ion-pairing dissolution with magnesium salts and using nitric acid. The most precise dating technique is Thermal Ionization Mass Spectrometry (TIMS), combined with Fe(OH)3 scavenging and anionic exchange chromatography. Less satisfactory, but much quicker, is direct retention of actinides from HNO3 by means of TRU resin and MC-ICP-MS detection. We have tested these methods on gypsum speleothems from the Sorbas karst in Spain and from the Naica caves in Mexico.

Pulmonary Histoplasmosis in Three Austrian Travelers After a Journey to Mexico

Three Austrian travelers (a 37-year-old woman, a 47-year-old woman and a 47-year-old man) presented with fever, dyspnea, thoracodynia, cephalea, arthralgia and fatigue 4 weeks after visiting a bat cave in Mexico. Computed tomography of the lungs showed bilateral nodular infiltrates in all three patients and enlarged mediastinal lymph nodes in two patients. In all patients, specific IgM antibodies against Histoplasma capsulatum could be detected. After treatment with itraconazole 200 mg q.d. orally for 2 months, the patients had no further complaints and the pulmonary infiltrates had resolved.

Echinoderms in an anchialine cave in Mexico

Five surveys in an anchialine cave from Cozumel Island, Mexico, were made in order to determine the diversity of invertebrates, especially of the phylum Echinodermata. Aerolito sinkhole (cenote), with an open coastal waters connection, was explored and the organisms were sampled by hand. The abiotic parameters (conductivity, salinity, oxygen, temperature, light and pH) were also measured. We identified three main classes of echinoderms from this cave. The first class is Asteroidea, located below the halocline in marine waters (37 ppt) at 256 m from the entrance and at 45 m from the entrance in marine waters. The second class is Ophiuroidea, located below the halocline in marine waters at 40 and 336 m from the entrance, and the third class, Echinoidea, is located in marine waters 60 m from the entrance. Only the asteroid species shows a depigmentated body; it is the unique species not found outside the cave. To date, only few species of Holothuridae have been reported from caves. We discuss the colonization and adaptations to cave life these animals show.

Ostracoda (Myodocopa) from Anchialine Caves and Ocean Blue Holes

Eleven stygobitic myodocopid ostracodes (two new–Danielopolina palmeri and Spelaeoecia hox) in the Order Halocyprida are reported from anchialine waters in 11 inland blue holes in Bahamas. One stygobitic halocyprid ostracode is reported from two localities in Bermuda, and one from a cave in Mexico. A new subfamily, Spelaeoeciinae, is proposed to contain the genus Spelaeoecia, and the subfamily Deeveyinae is elevated to family status. Two new species of cladocopid ostracode (Pseudopolycope helix and Pontopolycope storthynx), are described from a cave in Mexico and an oceanic blue hole in the Bahamas. Nine species of myodocopid ostracodes (four new—Rutiderma flex, Eusarsiella syrinx, Eusarsiella fax, and Synasterope matrix) in the Suborder Myodocopina and one species in the Suborder Halocypridina are reported from ocean blue holes in the Bahamas. This is the first report of a halocyprid living in both an inland and ocean blue hole in the Bahamas. The sarsiellid genus Dantya Kornicker & Cohen 1978 is reported for the first time in the Bahamas, but the single juvenile specimen is left in open nomenclature as Dantya sp. A. The development of Deeveya bransoni and Eusarsiella syrinx is described in detail. With the exception of one species of Danielopolina from deep waters of the South Atlantic, all other species of Danielopolina, Spelaeoecia and Deeveya have been previously found only in inland, anchialine caves. The discovery of Deeveya inhabiting deeper, hydrologically-isolated waters in ocean blue holes, which are otherwise comparable to classical anchialine environments, has raised questions concerning the geographic limits to the anchialine habitat and its supposed reliance on terrestrial inputs.

Survival in an extreme habitat: the roles of behaviour and energy limitation

Extreme habitats challenge animals with highly adverse conditions, like extreme temperatures or toxic substances. In this paper, we report of a fish (Poecilia mexicana) inhabiting a limestone cave in Mexico. Several springs inside the cave are rich in toxic H(2)S. We demonstrate that a behavioural adaptation, aquatic surface respiration (ASR), allows for the survival of P. mexicana in this extreme, sulphidic habitat. Without the possibility to perform ASR, the survival rate of P. mexicana was low even at comparatively low H(2)S concentrations. Furthermore, we show that food limitation affects the survival of P. mexicana pointing to energetically costly physiological adaptations to detoxify H(2)S.

New Species of the Genus Typhlatya (Decapoda: Atyidae) from Anchialine Caves in Mexico, the Bahamas, and Honduras

Abstract Three new species of the genus Typhlatya from anchialine caves in Mexico (T. dzilamensis), the Bahamas (T. kakuki), and Honduras (T. utilaensis) are described. Typhlatya dzilamensis is the fourth species to be described from the Yucatan Peninsula, Mexico, and is morphologically similar to T. mitchelli. Typhlatya kakuki is the first species of the genus to be described from the Bahamas archipelago. Its morphology departs from the patterns showed by the Cuban species, which are the closest geographically. Typhlatya utilaensis is the first species described from Central America, and is found in Utila, one of the Honduras Bay Islands. Morphologically, T. utilaensis is related to T. monae from Mona Island, Puerto Rico, and Barbuda. A revised diagnosis of the genus and a key for the 17 known species are provided.

Initial mutational steps toward loss of opsin gene function in cavefish.

The river-dwelling fishes of Astyanax fasciatus and their derivatives from Pachon and Micos caves in Mexico were collected. By comparing red (r007) and green (g103) opsin gene sequences from the three populations, we found a high frequency of C-->T changes in r007 and g103 of the eyed Micos fishes presumably due to spontaneous cytosine methylation or enzymatic deamination of the CG dinucleotide, and a deletion of 12 consecutive nucleotides in g101 of the blind Pachon fishes. Thus, high rates of nucleotide substitution and C-->T transitions, usually found for pseudogenes, may occur even before they become nonfunctional.

The "African" Shrimp Genus Potamalpheops in Australia, With the Description of P. Hanleyi, New Species (Decapoda: Alpheidae)

Small shrimps collected from a mangrove creek in Darwin Harbor, Northern Territory, Australia, belong to a new species of alpheid shrimp, Potamalpheops hanleyi, which is described and illustrated. The genus Potamalpheops, not previously recorded from the Australian continent, is known from four species in West Africa, in brackish and fresh water, and a single species occurring in a cave in Mexico. The disjunct distribution on three continents suggests an ancient origin for the genus and an original Tethyan distribution. The genus Potamalpheops was first designated by Powell (1979) to include P. pylorus Powell from Nigeria, as well as two other species, originally described as species of Alpheopsis by Coutiere (1906) and Sollaud (1932), P. haugi from Gabon and P. monodi from the Cameroons and Senegal, respectively. The genus is also represented in Central America by a single troglobitic species, P. stygicola (Hobbs, 1973), from Oaxaca, Mexico, originally also placed in the genus Alpheopsis by Hobbs (1973) and subsequently transferred to the genus Potamalpheops by Hobbs (1983). The discovery of a further species on another continent, Australia, therefore represents a very considerable increase in the known distribution of the genus. The present lack of records between the known occurrences of species of Potamalpheops suggests that they represent relict populations derived from a former wider distribution, and an ancient origin in Tethyan seas.

Nothoaspis reddelli, New Genus and New Species (Ixodoidea: Argasidae), from a Bat Cave in Mexico

Described is Nothoaspis reddelli , new genus and new species from 3 males taken on bat guano, Grutas de Xtacumbilxunam, Campeche, Mexico. N. reddelli appears to be most closely related to species of the genus Antricola , but differs significantly because of a nothoand aspis (false shield) over the anterior half of the dorsum by virtue of its having a hypostome in the adult stage. The presence of a shield-like structure is unique among argasid ticks; thus, a new genus is proposed to accommodate this distinctive tick.

Mexicerberus Troglodytes N. Gen., N. Sp. From a Cave in Mexico, With Notes On Isopod Crustaceans of the Microcerberidea From the New World

Die Arten des Genus Microcerberus Karaman von Sandstranden der Neuen Welt werden angefuhrt. Eine neue Art einer neuen Gattung wird beschrieben. Sie stammt von einem Susswassertumpel in einer Hohle (1.526 m hoch) in der Sierra de Guatemala in der Nahe der Municipio de Gomes Farias, Tamaulipas, Mexiko. Die neue Art ist langer als irgendeine vorher beschriebene Art von Microcerberus und besitzt andere, einmalige Charakteristika wie zum Beispiel ein Rostrum auf dem frontalen Rand des Cephalons.