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  • 1
    Electronic Resource
    Electronic Resource
    Foliole movement and canopy architecture of Larrea tridentata (DC.) Cov. in Mexican deserts (1992)
    Springer
    Oecologia 92 (1992), S. 83-89 
    Details
    ISSN: 1432-1939
    Keywords: Larrea tridentata ; Mexico ; Deserts ; Canopy architecture ; Foliole movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The creosote bush (Larrea tridentata) is a common desert perennial with bifoliate, amphistomatic, divaricate leaves. The leaves can vertically close their folioles and vary their profile with respect to direct solar radiation. Field data from different Mexican deserts showed a significant correlation between foliole aperture and mean foliole inclination: in plants in which folioles were more open, the foliole surfaces were less vertical. In a series of field experiments in the Chihuahuan Desert, foliole aperture varied significantly with the water-status of the plant and the hour of the day. In moist plants, folioles opened in the early morning and closed in the afternoon. Water-stressed plants showed significantly lower foliole apertures. A simulation of the light interception patterns of the plants showed that foliole closure in water-stressed individuals reduces direct radiation interception by around 24%. Most (64%) of the reduction in interception was due to the vertical inclination of the photosynthetic surfaces induced by foliole closure in the water-stressed plants. The rest (36%) of the reduction in interception was due to differential self-shading between foliole pairs, which was higher in the closed folioles of the water-stressed plants, but operated more towards the early hours of the day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317266
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  • 2
    Electronic Resource
    Electronic Resource
    Germination response to temperature, salinity, light and depth of sowing of ten tropical dune species (1992)
    Springer
    Oecologia 92 (1992), S. 343-353 
    Details
    ISSN: 1432-1939
    Keywords: Dunes ; Germination ; Mexico ; Ecophysiology ; Neotropic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study describes the germination responses of ten tropical dune species to several factors to which their seeds are exposed in the field. Species studied were: three sand dune endemics (Amaranthus greggii, Palafoxia lindenii, and Trachypogon gouini), three pantropical coastal species (Sesuvium portulacastrum, Sporobolus virginicus and Ipomoea stolonifera) and four cosmopolitan grasses also found inland (Panicum repens, Panicum maximum, Pappophorum vaginatum and Andropogon glomeratus). Six species germinated when exposed to different constant temperatures. Four required temperature fluctuation (S. portulacastrum, P. lindenii, S. virginicus, P. repens). Light promoted germination of three species (S. Portulacastrum, P. vaginatum, P. lindenii). Species varied in their degree of sensitivity to salinity. Seeds of T. gouini, I. stolonifera, S. portulacastrum, P. repens, P. Maximum and P. vaginatum were able to germinate under some of the salinity concentrations. Not all species were able to recover after being transferred to distilled water. Seedling emergence was inhibited when seeds were buried. This response was related to depth and to seed size. S. portulacastrum and S. virginicus were the most affected. Nitrates only affected germination response of two species. Seed age promoted germination under a wider range of conditions. P. lindenii showed very heterogeneous responses depending on seed cohort. No dormancy mechanisms were found, other than a thermoperiod and/or light requirement for some of the species. Cosmopolitan grasses tolerated both sand burial and salinity, although the endemics were the most successful in emerging from sand burial; coastal pantropicals were very tolerant to high saline concentrations and recovered completely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317460
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  • 3
    Electronic Resource
    Electronic Resource
    Transformation of dairy activity in Mexico in the context of current globalization and regionalization (2000)
    Springer
    Agriculture and human values 17 (2000), S. 157-167 
    Details
    ISSN: 1572-8366
    Keywords: Coahuila state ; Dairy production ; Globalization ; Jalisco state ; Mexico ; Regionalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To explain globalization of the Mexicandairy production more precisely, globalization indairy systems worldwide and within Mexico ispresented, using an intensive dairy operation in theregion of La Laguna (North Mexico), and a traditionaldairy operation in Los Altos de Jalisco (West Mexico)as examples. The focus is on the economic aspects ofregionalization, and how it relates to theglobalization process. In this context, the process ofregionalization of the North American dairy systemsand their relationships with the local systems in LaLaguna and Los Altos de Jalisco are presented. Themain thesis in this paper is whether globalization hasacted as a factor to help homogenize the dairy systemsin terms of economic, political, and culturalprocesses affected by world tendencies as well aslocal trends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007691125382
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  • 4
    Electronic Resource
    Electronic Resource
    Distribution of species of Anostraca, Notostraca, Spinicaudata, and Laevicaudata in Mexico (1991)
    Springer
    Hydrobiologia 212 (1991), S. 209-219 
    Details
    ISSN: 1573-5117
    Keywords: Anostraca ; Notostraca ; Spinicaudata ; Laevicaudata ; Branchiopoda ; Mexico ; distribution ; conchostracan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We inventorize the known distribution of the species of Anostraca, Notostraca, Spinicaudata, and Laevicaudata present in Mexico. Determinations of the species and their distribution involved: 1) Examination of Mexican collections of phyllopods, 2) Extensive sampling in 17 states, and 3) Study of laboratory cultures. The number of phyllopod species known to occur in Mexico is 27: 14 of Anostraca, including three undescribed species, 1 of Notostraca, 10 of Spinicaudata, and 2 of Laevicaudata. These results also include 44 new state records. The records of Branchinecta packardi are the first for Mexico. Some species have extensive distributions, not limited to Mexico: Streptocephalus mackini, S. texanus, Thamnocephalus platyurus, Triops longicaudatus and Leptestheria compleximanus. The species known only from Mexico are Streptocephalus kargesi, S. moorei, Paralimnetis mapimi, two undescribed species of Branchinecta, and an undescribed species of Streptocephalus. The largest number of species found to occur in the same pond at one time was eight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026003
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  • 5
    Electronic Resource
    Electronic Resource
    Branchinecta belki n. sp. (Branchiopoda: Anostraca), a new fairy shrimp from Mexico, hybridizing withB. packardi Pearse under laboratory conditions (1992)
    Springer
    Hydrobiologia 239 (1992), S. 151-162 
    Details
    ISSN: 1573-5117
    Keywords: Branchinecta ; Branchiopoda ; Anostraca ; Mexico ; hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new fairy shrimp,Branchinecta belki n.sp., endemic to the south of Coahuila state is described and figured. A total of nine species of phyllopods, including the new species, occur in ponds in the type area. The laboratory hybridization ofB. belki andB. packardi through ‘no-choice’ mating tests in reciprocal crosses is discussed. A mixture of characteristics of parental species is present in male F1 and F2 hybrids. This may provide a biological tool, or ‘search image’ (sensu Wiman, 1979a), for detecting male hybrids, should such exist, between theBranchinecta species of this study in nature. In addition to the reported interspecific hybridizations inStreptocephalus (Wiman, 1979a & 1979b) and inArtemia (Bowenet al., 1985) under laboratory conditions, the new evidence inBranchinecta suggests that absence of efficient premating mechanisms may be common in Anostraca.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007672
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  • 6
    Electronic Resource
    Electronic Resource
    Contribution to the knowledge of the rotifera of Mexico (1993)
    Springer
    Hydrobiologia 255-256 (1993), S. 467-474 
    Details
    ISSN: 1573-5117
    Keywords: Rotifera ; zoogeography ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This faunistic survey of Mexican Rotifera, covering 32 localities, mostly in Central Mexico, has yielded 96 taxa of which 41 are new to Mexican fauna. The zoogeographic status of the rotifer fauna of Mexico was reevaluated on the basis of the present data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025875
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  • 7
    Electronic Resource
    Electronic Resource
    Boa constrictor, an introduced predator threatening the endemic fauna on Cozumel Island, Mexico (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 957-963 
    Details
    ISSN: 1572-9710
    Keywords: boa ; Boa constrictor ; Cozumel Island ; conservation ; insular fauna ; introduced predator ; introduction ; invasion ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We present evidence indicating that the boa (Boa constrictor) was introduced onto Cozumel Island, Quintana Roo, Mexico, in 1971. This snake is now firmly established and has a wide distribution on Cozumel. We recorded an encounter rate of 1.8 boas per 100 km of forest surveyed. The introduction of the boa onto Cozumel, where it has few predators, is a threat to the existence of endemic and other native terrestrial vertebrates of the island. We recommend the following immediate actions: (1) undertake research to confirm the origin of the boa on Cozumel; (2) assess the effect of the boa on the biota of Cozumel; and, (3) if an anthropogenic origin is confirmed, an eradication programme for the boa on Cozumel should be undertaken, obtaining information on the biology and ecology of the species. Options for the destiny of the eradicated boas are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008815004072
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  • 8
    Electronic Resource
    Electronic Resource
    Temporal and spatial variation of litter production in Sonoran Desert communities (1999)
    Springer
    Plant ecology 145 (1999), S. 37-48 
    Details
    ISSN: 1573-5052
    Keywords: Desertscrub ; Ecosystem ; Litterfall ; Mexico ; Phenology ; Spatial heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal pattern of litter production was analyzed in three contiguous desert communities near the southern boundaries of the Sonoran Desert. There was a large spatial variation in annual litter production mainly caused by differences in the composition and structure of vegetation. In the most productive site (Arroyos) annual litterfall was 357 g m-2yr-1, a figure higher than some tropical deciduous forests. Litter production was only 60g m-2yr-1in the open desert in the plains (Plains) and 157 g m-2yr-1 in the thornscrub on the slopes (Hillsides). Topographic and hydrologic features influence the composition, structure and function of the vegetation, modifying the general relationship between rainfall and productivity described for desert ecosystems. The temporal pattern of litter production showed marked seasonality with two main periods of heavy litterfall: one after the summer rains from September to November (autumn litter production) and another after the winter rains from March to May (spring litter production). In the open desert areas, spring litter production was significantly higher than the autumn pulse, while in the slopes, the autumn production was the most important. The Arroyos site produced similar litterfall amounts during the two dry seasons. The species composition defined the season of maximum leaf-fall. In the Plains, the vigorous winter growth of ephemeral and perennial plants made up most of the litter production, while in the Hillsides, most perennials remained dormant throughout the winter-spring period and a significant peak of litterfall occurred only after the summer growth. This difference in growth between seasons was less pronounced in the Arroyos. The timing of maximum production of reproductive and woody litter also differed from site to site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009896201047
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