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1.
Algae collected from an oligotrophic crater lake were identified andcompared with similar regional information. A total of 50 genera and105 infrageneric taxa were identified, mostly Chlorophyta (66%),Cyanophyta (20%) and Bacillariophyta (7 genera: one central and sixpennates). Relatively few Chlorococcales were found in thisoligotrophic lake. The families most frequently found wereOedogoniaceae (18 species), Desmidiaceae (17), Zygnemataceae (13),Oscillatoriaceae (11), and Chaetophoraceae (9). Two genera ofCyanophyta, seven of Chlorophyta and 59 species are first records forMexico. 相似文献
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Five new species are described from the state of Oaxaca in southern Mexico:Huperzia beiteliana Mickel,Ophioglossum dudadae Mickel,Selaginella basipilosa Valdespino,Selaginella mickelii Valdespino, andSelaginella nothohybrida Valdespino. 相似文献
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Barbosa-Ledesma IF Gamboa-Contreras JA Aké-Castillo JA 《Revista de biología tropical》2000,48(2-3):353-360
A total of 1,173 specimens of Stomatopoda were captured in 27 localities at different depths (20 to 73 m) during three oceanographic cruises in the Mexican Pacific along the continental shelf of the states of Oaxaca and Chiapas. Seven species were identified of the families Eurysquillidae, Lysiosquillidae and Squillidae. Squilla hancocki and Squilla parva were the most abundant species and the most frequently found together. The relationships between total length and carapace length were obtained for these species, which show that males of S. hancocki have a longer carapace length than females having the same total length, whereas for S. parva the opposite occurs. Larger sizes than previously reported were obtained for Lysiosquilla panamica and Squilla mantoidea. Squilla bigelowi was recorded for the first time in the Gulf of Tehuantepec. All the species were found in the intermediate platform (25-60 m); E. veleronis, S. hancocki and S. parva extended their distributions to the external platform (60-120 m), and S. hancocki and S. parva reached the circalittoral zone (10-25 m). 相似文献
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Assessing onset and length of greening period in six vegetation types in Oaxaca,Mexico, using NDVI-precipitation relationships 总被引:2,自引:0,他引:2
Gómez-Mendoza L Galicia L Cuevas-Fernández ML Magaña V Gómez G Palacio-Prieto JL 《International journal of biometeorology》2008,52(6):511-520
Variations in the normalized vegetation index (NDVI) for the state of Oaxaca, in southern Mexico, were analyzed in terms of precipitation anomalies for the period 1997-2003. Using 10-day averages in NDVI data, obtained from AVHRR satellite information, the response of six types of vegetation to intra-annual and inter-annual fluctuations in precipitation were examined. The onset and temporal evolution of the greening period were studied in terms of precipitation variations through spectral analysis (coherence and phase). The results indicate that extremely dry periods, such as those observed in 1997 and 2001, resulted in low values of NDVI for much of Oaxaca, while good precipitation periods produced a rapid response (20-30 days of delay) from a stressed to a non-stressed condition in most vegetation types. One of these rapid changes occurred during the transition from dry to wet conditions during the summer of 1998. As in many parts of the tropics and subtropics, the NDVI reflects low frequency variations in precipitation on several spatial scales. Even after long dry periods (2001-2002), the various regional vegetation types are capable of recovering when a good rainy season takes place, indicating that vegetation types such as the evergreen forests in the high parts of Oaxaca respond better to rainfall characteristics (timing, amount) than to temperature changes, as is the case in most mid-latitudes. This finding may be relevant to prepare climate change scenarios for forests, where increases in surface temperature and precipitation anomalies are expected. 相似文献
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Begonia (sect.Gireoudia)lyman-smithii is described and illustrated, and its relationships are discussed. 相似文献
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Linda Nicholas Gary Feinman Stephen A. Kowalewski Richard E. Blanton Laura Finsten 《Human ecology: an interdisciplinary journal》1986,14(2):131-162
A decade ago in a seminal monograph, Anne Kirkby proposed a model of colonization for the prehispanic Valley of Oaxaca, Mexico, in which settlement location was determined by the distribution of prime agricultural land. The model was tested against the corpus of known prehispanic settlements and tentative support was found. In the years since this study, a systematic archeological settlement pattern project was completed, making a more adequate test of the model possible. Reexamination of the colonization process suggests that, although agricultural considerations were important, they were less determinant of settlement location than had been implied previously. The adoption of a broader perspective toward regional colonization is suggested. 相似文献
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Gerardo Perez-Ramirez Alvaro Diaz-Badillo Minerva Camacho-Nuez Alejandro Cisneros de Lourdes Maria Munoz 《BMC microbiology》2009,9(1):260
Background
Dengue (DEN) is a serious cause of mortality and morbidity in the world including Mexico, where the infection is endemic. One of the states with the highest rate of dengue cases is Oaxaca. The cause of DEN is a positive-sense RNA virus, the dengue virus (DENV) that evolves rapidly increasing its variability due to the absence of a repair mechanism that leads to approximately one mutational event per genome replication; which results in enhancement of viral adaptation, including the escape from host immune responses. Additionally, recombination may play a role in driving the evolution of DENV, which may potentially affect virulence and cause host tropism changes. Recombination in DENV has not been described in Mexican strains, neither has been described the relevance in virus evolution in an endemic state such as Oaxaca where the four serotypes of DENV are circulating. 相似文献10.
Adolfo Molina-Cruz Marcela Martinez-Lpez 《Palaeogeography, Palaeoclimatology, Palaeoecology》1994,110(3-4):179-195
The morphology of the Gulf of Tehuantepec, Mexico, is redefined through a bathymetric analysis and this redifinition is considered to explain the distribution patterns of non-carbonate sediments, particularly the radiolarian remains. Although the distribution patterns of pelagic sediments are influenced by the Gulf of Tehuantepec bathymetrical morphology and the terrigenous input, these “reflect” clearly the regional oceanography. Northern strong winds, called the “Tehuanos”, blowing across the sea surface of this Gulf when the Intertropical Convergence is at its southernmost position, define the main sedimentologic dynamics of this region. This wind field gives rise to an oceanic front at the southwestern part of the Gulf, as well as upwelling processes at its central-eastern part. In the mixing at the front there is some contribution of California Current waters, while in the upwelling area there is a large contribution of the tropical-subtropical water which is carried by the Costa Rica Coastal Current. This oceanographic framework controlls the makeup of radiolarian assemblages. Consequently, at the seabottom, under the oceanic front, the presence of the radiolarian species Lithomelissa thoracites and Cycladophora davisiana is observed, while under the upwelling region, Acrosphaera murrayana is conspicuous. 相似文献
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Tapirira chimalapana is a new species of tree common in the rain forests and lower montane forests of the Isthmus of Tehuantepec in the Mexican states of Veracruz and Oaxaca. It is most similar to the AndeanT. guianensis Aubl. subsp.subandina Barfod &; Holm-Niels. but differs from this and all other congeners by having larger petals on pistillate flowers than on staminate flowers and by pubescence features. Details of field characteristics, distribution, ecology, phenology, germination, and local names and uses are included. 相似文献
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Sicyos mcvaughii, a new species from Oaxaca, is described and illustrated. It is similar to Sicyos sertuliferus Cogn., and grows in secondary tropical deciduous forest, between 20 and 630 meters. 相似文献
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Tigridia amatlanensis is described and illustrated as a new species from Mexico. It is recognized by its nodding flowers and its inner and outer tepals cirrhous and markedly dimorphic in length. It is most closely related toT. hallbergii subsp.hallbergii andT. meleagris. Other morphologically similar species areT. catarinensis andT. molseediana. 相似文献
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Quinto-Cortés CD Arriola LA García-Hughes G García-López R Molina DP Flores M Palacios R Piñero D 《Human biology; an international record of research》2010,82(4):409-432
We used 15 short tandem repeat (STR) loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, and FGA) to genetically characterize 361 individuals from 11 indigenous populations (Amuzgo, Chinanteco, Chontal, Huave, Mazateco, Mixe, Mixteco, Triqui, Zapoteco del Istmo, Zapoteco del Valle, and Zoque) from Oaxaca, Mexico. We also used previously published data from other Mexican peoples (Maya, Chol, Tepehua, Otomí, and Mestizos from northern and central Mexico) to delineate genetic relations, for a total of 541 individuals. Average heterozygosity (H) was lower in most populations from Oaxaca (range 0.687 in Zoque to 0.756 in Chontal) than values observed in Mestizo populations from Mexico (0.758 and 0.793 in central and northern Mestizo, respectively) but higher than values observed in other Amerindian populations from South America; the same relation was true for the number of alleles (n(a) ). We tested (using the software Structure) whether major geographic or linguistic barriers to gene flow existed among the populations of Oaxaca and found that the populations appeared to constitute one or two genetic groups, suggesting that neither geographic location nor linguistics had an effect on the genetic structure of these culturally and linguistically highly diverse indigenous peoples. Moreover, we found a low but statistically significant between-population differentiation. In addition, the genetic structure of Oaxacan populations did not fit an isolation-by-distance model. Finally, using AMOVA and a Bayesian clustering approach, we did not detect significant geographic or linguistic barriers to gene flow within Oaxaca. These results suggest that the indigenous communities of Oaxaca, although culturally isolated, can be genetically defined as a large, nearly panmictic population in which migration could be a more important population mechanism than genetic drift. Finally, compared with outgroups in Mexico (both indigenous peoples and Mestizos), three groups were apparent. Among them, only the Otomí population from Hidalgo has a different culture and language. 相似文献
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Phylogenetic and biogeographical relationships among some holarctic frog lung flukes (Digenea: Haematoloechidae). 总被引:3,自引:0,他引:3
A phylogenetic study of 8 North American and European species of frog lung flukes belonging to Haematoloechus was conducted using approximately 850 to 1,000 bases of the intemal transcribed spacer region (ITS 1 + 5.8S + ITS 2) and 1,250 bases of the large subunit (LSU) of the nuclear ribosomal DNA. Adequate phylogenetic resolution could not be obtained from 5.8S or ITS 2 data. Analysis of ITS 1 data produced 2 equally parsimonious trees that differed only in the position of Haematoloechus breviplexus relative to H. medioplexus and H. varioplexus. Single, identical trees were produced by analysis of both LSU sequence data and a data set comprised of all ITS and LSU data. All trees demonstrated 3 distinct evolutionary lineages within the Holarctic Haematoloechus examined. The results confirmed the taxonomic validity of H. abbreviatus and demonstrated that the presence or absence of extracecal uterine loops is not a character meaningful to the recognition of evolutionary lineages or differentiation of genera. Examination of ITS sequence data revealed almost no intraspecific variation within 5 species of Haematoloechus and demonstrated an approximately 150-base indel common to the North American H. longiplexus and the European H. asper. Two of 3 clades revealed by the phylogenetic analyses are comprised of both European and North American species, indicating that lineages of Haematoloechus arose before the breakup of Laurasia and radiated after Eurasia and North America split. Within each of 3 evolutionary lineages, members share similar patterns of arthropod host specificity distinct from patterns found in the other lineages. This suggests that second intermediate host specificity may be a trait that has been conserved through evolutionary time. 相似文献
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D C Hodges 《American journal of physical anthropology》1987,73(3):323-332
The effects of agricultural intensification on health are examined in prehistoric populations of the Valley of Oaxaca, Mexico. Agriculture was practiced in the Valley of Oaxaca by the beginning of the Early Formative period (ca. 1400 B.C.), and had intensified by the Late Formative (ca. 500 B.C.). Skeletal remains from 14 archaeological sites in the Valley are pooled by temporal affiliation into a nonintensive agriculture group (1400-500 B.C.) and an intensive agriculture group (500 B.C.-1400 A.D.). The health effects of agricultural intensification are assessed by comparing the frequency of periosteal reactions, cribra orbitalia, and enamel hypoplasia between the intensive and nonintensive agricultural groups. Overall, no significant differences (alpha = 0.05) are found between the nonintensive and intensive groups. Power analyses of the chi-square tests indicate that the tests have a high probability of rejecting a false null hypothesis. The intensification of agriculture does not appear to have had a deleterious effect on the health of the prehistoric population of the Valley. The differences between this study and previous studies of health and agricultural development may be explained by differences between the processes of intensification and development or by differences between primary and secondary centers of agricultural development. 相似文献
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R. J. Haroun W. F. Prud'homme van Reine D. G. Müller E. Serrao R. Herrera 《Helgoland Marine Research》1993,47(2):125-143
Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different
distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae
recently collected around the Canarian archipelago are discussed. These areBryopsidella neglecta (Berthold) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck,Hincksia onslowensis (Amsler et Kapraun) P. C. Silva,Syringoderma floridana Henry,Peyssonnelia harveyana J. Agardh,Cryptonemia seminervis (C. Agardh) J. Agardh,Botryocladia wynnei Ballantine,Gloiocladia blomquistii (Searles) R. E. Norris,Halichrysis peltata (W. R. Taylor) P. Huvé et H. Huvé,Leptofauchea brasiliensis Joly, andSarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae, support the strong affinity of the Canary Islands
seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the
east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western
Atlantic regions. 相似文献
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A study of williamsonian cones from Middle Jurassic rocks of Oaxaca, Mexico, indicates that Weltrichia mexicana (Wieland) Harris (formerly Williamsonia mexicana) is probably not a fructification. Ovulate cones recognized from localities near Tezoatlán are Williamsonia netzahualcoyotlii Wieland, W. oaxacensis sp. nov., W. huitzilopochtlii Wieland, and W. diquyui sp. nov. Notable is the similarity among williamsonian cones in Jurassic rocks of such widely separated places as Oaxaca, Mexico, Yorkshire, England, and Rajmahal Hills, India. The mode of preservation of williamsonian cones suggest a growth habit involving slender, branched stems with exposed cones that abscised from the plants on which they were borne. Conceivably, further development, including fertilization, could have occurred after the cones were dropped. 相似文献
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