Vine species diversity across environmental gradients in northwestern México

2004 ◽  
Vol 13 (10) ◽  
pp. 1853-1874 ◽  
Author(s):  
Francisco Molina-Freaner ◽  
Reyna Castillo Gámez ◽  
Clara Tinoco-Ojanguren ◽  
Alejandro E. Castellanos V.
Keyword(s):  
Species Diversity ◽  
Environmental Gradients ◽  
Northwestern Mexico

scholarly journals Plant Community Analysis along Environmental Gradients in Moist Afromontane Forest of Gerba Dima, South-western Ethiopia

2020 ◽  
Author(s):  
Abyot Dibaba Hundie ◽  
Teshome Soromessa Urgessa ◽  
Bikila Warkineh Dullo
Keyword(s):  
Cluster Analysis ◽  
Species Diversity ◽  
Plant Species ◽  
Plant Community ◽  
Plant Communities ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Regional Government ◽  
Community Types ◽  
Western Ethiopia

Abstract Background This study was carried out in Gerba Dima Forest, South-Western Ethiopia, to determine the floristic composition, species diversity and community types along environmental gradients. Ninety sample plots having a size of 25 × 25 m (625 m2) were laid by employing stratified random sampling. Nested plots were used to sample plants of different sizes and different environmental variables. All woody plant species with Diameter at breast height (DBH) ≥ 2.5 cm and height ≥ 1.5 m were recorded in 25 m X 25 m plots. Within the major plots, five 3 m x 3 m subplots (9 m2) was used to collect shrubs with dbh < 2.5 cm and > 1.5 m height. Within each 9 m2subplots, two 1 m2 subplots were used to collect data on the species and abundance of herbaceous plants. Hierarchical (agglomerative) cluster analysis was performed using the free statistical software R version 3.6.1 using package cluster to classify the vegetation into plant community types. Redundancy Analysis (RDA) ordination was used in describing the pattern of plant communities along an environmental gradient. Result One hundred and eighty plant species belonging to 145 genera, 69 families and comprising of 15 endemic species were recorded. Cluster analysis resulted in five different plant communities and this result was supported by the ordination result. RDA result showed altitude was the main environmental variable in determining the plant communities. The ANOVA test indicated that the five community types differ significantly from each other with regard to EC and K. Conclusions The studied forest can play a significant role in biodiversity conservation since it harbours high species diversity and richness. Thus, all Stakeholders including Oromia Forest and wildlife enterprise (OFWE) and the regional government should work to designate the forest as a biosphere reserve and being registered under UNESCO.

Pelagic species diversity, biogeography, and evolution

Paleobiology ◽  
2000 ◽  
Vol 26 (S4) ◽  
pp. 236-258 ◽  
Author(s):  
Richard D. Norris
Keyword(s):  
Species Diversity ◽  
Environmental Gradients ◽  
Water Masses ◽  
Morphological Data ◽  
Airborne Spores ◽  
Long Distance ◽  
Population Exchange ◽  
High Dispersal ◽  
Population Sizes ◽  
Parapatric Speciation

Pelagic (open-ocean) species have enormous population sizes and broad, even global, distributions. These characteristics should damp rates of speciation in allopatric and vicariant evolutionary models since dispersal should swamp diverging populations and prevent divergence. Yet the fossil record suggests that rates of evolutionary turnover in pelagic organisms are often quite rapid, comparable to rates observed in much more highly fragmented terrestrial and shallow-marine environments. Furthermore, genetic and ecological studies increasingly suggest that species diversity is considerably higher in the pelagic realm than inferred from many morphological taxonomies.Zoogeographic evidence suggests that ranges of many pelagic groups are much more limited by their ability to maintain viable populations than by any inability to disperse past tectonic and hydrographic barriers to population exchange. Freely dispersing pelagic taxa resemble airborne spores or wind-dispersed seeds that can drift almost anywhere but complete the entire life cycle only in favorable habitats. It seems likely that vicariant and allopatric models for speciation are far less important in pelagic evolution than sympatric or parapatric speciation in which dispersal is not limiting. Nevertheless, speciation can be quite rapid and involve cladogenesis even in cases where morphological data suggest gradual species transitions. Indeed, recent paleoecological and molecular studies increasingly suggest that classic examples of “phyletic gradualism” involve multiple, cryptic speciation events.Paleoceanographic and climatic change seem to influence rates of turnover by modifying surface water masses and environmental gradients between them to create new habitats rather than by preventing dispersal. Changes in the vertical structure and seasonality of water masses may be particularly important since these can lead to changes in the depth and timing of reproduction. Long-distance dispersal may actually promote evolution by regularly carrying variants of a species across major oceanic fronts and exposing them to very different selection pressures than occur in their home range. High dispersal in pelagic taxa also implies that extinction should be difficult to achieve except though global perturbations that prevent populations from reestablishing themselves following local extinction. High rates of extinction in some pelagic groups suggests either that global perturbations are common, or that the species are much more narrowly adapted than we would infer from current taxonomies.

A review of the cave fauna of Canada, and the composition and ecology of the invertebrate fauna of caves and mines in Ontario

1988 ◽  
Vol 66 (5) ◽  
pp. 1197-1213 ◽  
Author(s):  
Stewart B. Peck
Keyword(s):  
British Columbia ◽  
Species Diversity ◽  
Relative Humidity ◽  
Environmental Gradients ◽  
Forest Litter ◽  
Invertebrate Fauna ◽  
Terrestrial Invertebrates ◽  
Cave Fauna ◽  
Seasonal Basis ◽  
Total Community

Caves and cave-inhabiting faunas of Canada are reviewed. Four species of troglobitic (cave-limited) crustaceans (Amphipoda and Isopoda) are known from Alberta and British Columbia, and one troglobitic mite from Alberta. A study of the subterranean fauna of Ontario involved investigating 35 caves and mines. Collections of 1274 invertebrate specimens contained 301 species in 5 phyla, with spiders and insects being most numerous. Diptera were the most abundant insects with 140 species, mainly in the families Culicidae, Mycetophilidae, and Tipulidae. The fauna is predominantly composed of trogloxenes, in the "parietal association." Few troglophiles and no troglobites were found. The fauna is most abundant in individuals and richest in species diversity within the first 10 m of the entrances, just inside the dark zone, and at 12–14 °C. The total "community" of terrestrial invertebrates does not show significant preferences in either caves or mines for precise locations on environmental gradients of light, temperature, or relative humidity. Faunal movements and changes occur on a daily and a seasonal basis. There is no clear difference between the faunas of "old" caves and those of "young" mines. The cave and mine faunas are generally scavengers or predators recruited from nearby forest litter and soil populations. None of the species were significantly outside their previously known distributional range.

scholarly journals Vegetation Dynamics and Species Diversity in a Saharan Oasis, Egypt

2018 ◽  
Vol 10 (3) ◽  
pp. 363-372 ◽  
Author(s):  
Fawzy Mahmoud SALAMA ◽  
Monier Mohammed ABD EL-GHANI ◽  
Ahmed Abd El Rahman AMRO ◽  
Ali El Saeid GAAFAR ◽  
Ayat Abd El Monem ABD EL-GALIL
Keyword(s):  
Species Diversity ◽  
Date Palm ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Outer Zone ◽  
Western Desert ◽  
Line Transect ◽  
Middle Zone ◽  
Soil Variables ◽  
Kharga Oasis

The present study provides an analysis of the floristic composition, habitat types, vegetation structure and species diversity, elucidating the role of the environmental factors that affect species distribution in Kharga Oasis, Western Desert, Egypt. The vegetation was sampled from 89 permanently visited stands in 12 sites situated along N - S line transect across the oasis, and extending for about 185 km to cover as much as possible the physiognomic variation in habitats. Four main habitats were recognized and forming concentric zones (from inside to outside): farmlands and date-palm orchards represent the inner zone, the waste-salinized lands (not saltmarshes) in the middle zone, and the surrounding (bounding) desert in the outer zone. A total of 122 species from 35 families and 102 genera represented the flora of the study area. Poaceae, Asteraceae and Fabaceae were the major families, which constituted 47% of the total flora. Classification using Bray-Curtis cluster analysis produced 4 vegetation groups (A - D); each can be linked to a certain habitat. The arrangement of habitat zones along the first DCA axis can be noticed: outer zone (bounding desert), middle zone (waste-salinized lands) and inner zone (arable lands). On the other hand, farmlands and date-palm orchard groups were separated from each other along the second DCA axis. The relationship between the vegetation and soil variables was studied using Canonical Correspondence Analysis (CCA); it was indicated the most important environmental gradients those control the vegetation composition and the distribution pattern of species in Kharga Oasis, which were mainly related to gradients in soil moisture content and fine fractions. The present situation of Kharga Oasis urges the conservation of some old historic wells and the naturally growing open dom-palm forests before vanishing due to high human activities in the area.

Species definition of Dioon sonorense (Zamiaceae, Cycadales), and description of D. vovidesii, a new cycad species from northwestern Mexico 

Phytotaxa ◽  
2018 ◽  
Vol 369 (2) ◽  
pp. 107 ◽  
Author(s):  
JOSÉ SAID GUTIÉRREZ-ORTEGA ◽  
KAREN JIMÉNEZ-CEDILLO ◽  
MIGUEL ANGEL PÉREZ-FARRERA ◽  
JOSÉ F. MARTÍNEZ ◽  
FRANCISCO MOLINA-FREANER ◽  
...  
Keyword(s):  
Population Genetics ◽  
Species Diversity ◽  
19Th Century ◽  
Title Page ◽  
New Taxon ◽  
Species Definition ◽  
Important Variation ◽  
Northwestern Mexico ◽  
Definition Of ◽  
The 19Th Century

The cycad genus Dioon (Zamiaceae) was described by J. Lindley in the 19th century, but most species were discovered during the late 1970s through the mid-1980s. Despite recent efforts to clarify the actual species diversity within the genus, the definition of some species is still problematic. The northernmost populations of the cycad genus Dioon in northwestern Mexico are currently recognised as Dioon sonorense, but important variation among populations has been suggested by multiple authors, and the definition of what is D. sonorense remains unclear. Documented evidence on leaf and leaflet morphology, cuticular and epidermal anatomy, and population genetics across the populations of D. sonorense, as currently circumscribed, suggest that the taxon contains two biological units that should be taxonomically distinguished, given their importance for systematics and conservation. Here we highlight that 1) D. sonorense is defined by the variation exhibited only in populations from southern Sonora and northern Sinaloa, Mexico; 2) the northernmost populations of Dioon in northwestern Mexico represent a new taxon that we describe as Dioon vovidesii. We also discuss the implications of this reassessment for cycad systematics and conservation.

Sign in / Sign up

Export Citation Format

Share Document