The Mekong-Salween Divide as a Geographical Barrier

1921 ◽  
Vol 58 (1) ◽  
pp. 49 ◽  
Author(s):  
F. Kingdon Ward
Keyword(s):  
Geographical Barrier

scholarly journals New Record of the Leopard Gecko Goniurosaurus araneus (Squamata: Eublepharidae) for China and Habitat Partitioning between Geographically and Phylogenetically Close Leopard Geckos

2014 ◽  
Vol 21 (1) ◽  
pp. 16-27
Author(s):  
Tian-Bo Chen ◽  
Yuan-Jun Meng ◽  
Ke Jiang ◽  
Pi-Peng Li ◽  
Bo-Hao Wen ◽  
...  
Keyword(s):  
New Record ◽  
Small Area ◽  
Nature Reserve ◽  
Phylogenetic Study ◽  
Habitat Partitioning ◽  
Species Pair ◽  
Autonomous Region ◽  
Leopard Gecko ◽  
Geographical Barrier ◽  
First Time

Two specimens of the Leopard Gecko Goniurosaurus araneus (Squamata: Eublepharidae) were collected from Nonggang National Nature Reserve, Chongzuo Prefecture, Guangxi Zhuang Ethnicity Autonomous Region, China, in October 2011. This species is a new record for China and this report is a range extension for the species from northern Vietnam to southern Guangxi. A phylogenetic study demonstrated that Goniurosaurus araneus and G. luii are a species pair. We show for the first time that they coexist broadly but are narrowly allopatric in a small area in southern Guangxi, separated only by a river, similar to what had been reported previously for G. yingdeensis and Goniurosaurus indet. from northwestern Guangdong. A river as a geographical barrier, elevation, and aspect may have contributed to habitat partitioning between G. araneus and G. luii.

scholarly journals A new cryptic species of Pithecopus (Anura, Phyllomedusidae) in north-eastern Brazil

2020 ◽  
Vol 723 ◽  
pp. 108-134
Author(s):  
Felipe Silva De Andrade ◽  
Isabelle Aquemi Haga ◽  
Johnny Sousa Ferreira ◽  
Shirlei Maria Recco-Pimentel ◽  
Luís Felipe Toledo ◽  
...  
Keyword(s):  
Cryptic Species ◽  
Evolutionary History ◽  
Small Body ◽  
Head Width ◽  
The Andes ◽  
Eastern Brazil ◽  
Sister Clade ◽  
North Eastern ◽  
Geographical Barrier ◽  
History Of

The genus of Neotropical frogs Pithecopus includes 11 species occurring east of the Andes from southern Venezuela to northern Argentina. Recent genetic approaches pointed out an unusual genetic diversity among populations from localities in north-eastern Brazil recognized as P. nordestinus. In fact, one of these studies confirmed the hypothesis that the São Francisco River acted as an effective geographical barrier during vicariant events in the evolutionary history of P. nordestinus, resulting in two principal, highly divergent clades. Herein we formally describe this divergent clade as a new cryptic species of Pithecopus from north-eastern Brazil, the sister clade of P. nordestinus. It differs from other species of Pithecopus, except for P. azureus and P. nordestinus, by its small body size, lack of the reticulate pattern on flanks, smaller head width, and advertisement calls generally composed of a three-pulsed core.

scholarly journals Yangtze River, an insignificant genetic boundary in tufted deer (Elaphodus cephalophus): the evidence from a first population genetics study

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2654 ◽  
Author(s):  
Zhonglou Sun ◽  
Tao Pan ◽  
Hui Wang ◽  
Mujia Pang ◽  
Baowei Zhang
Keyword(s):  
Gene Flow ◽  
Yangtze River ◽  
Population Decline ◽  
Molecular Ecology ◽  
Population Increase ◽  
The Yangtze River ◽  
Population Demography ◽  
Vector Autoregressions ◽  
High Genetic Diversity ◽  
Geographical Barrier

Great rivers were generally looked at as the geographical barrier to gene flow for many taxonomic groups. The Yangtze River is the third largest river in the world, and flows across South China and into the East China Sea. Up until now, few studies have been carried out to evaluate its effect as a geographical barrier. In this study, we attempted to determine the barrier effect of the Yangtze River on the tufted deer (Elaphodus cephalophus) using the molecular ecology approach. Using mitochondrial DNA control region (CR) sequences and 13 nuclear microsatellite loci, we explored the genetic structure and gene flow in two adjacent tufted deer populations (Dabashan and Wulingshan populations), which are separated by the Yangtze River. Results indicated that there are high genetic diversity levels in the two populations, but no distinguishable haplotype group or potential genetic cluster was detected which corresponded to specific geographical population. At the same time, high gene flow was observed between Wulingshan and Dabashan populations. The tufted deer populations experienced population decrease from 0.3 to 0.09 Ma BP, then followed by a distinct population increase. A strong signal of recent population decline (T= 4,396 years) was detected in the Wulingshan population by a Markov-Switching Vector Autoregressions(MSVAR) process population demography analysis. The results indicated that the Yangtze River may not act as an effective barrier to gene flow in the tufted deer. Finally, we surmised that the population demography of the tufted deer was likely affected by Pleistocene climate fluctuations and ancient human activities.

scholarly journals Gyraulus marocana sp. nov., a new freshwater snail species (Mollusca, Gastropoda, Planorbidae) from Morocco

2022 ◽  
Vol 7 (1) ◽  
Author(s):  
Youness Mabrouki ◽  
◽  
Peter Glöer ◽  
Abdelkhaleq F. Taybi ◽  
◽  
...  
Keyword(s):  
Protected Area ◽  
Prostate Gland ◽  
Freshwater Snail ◽  
Snail Species ◽  
Gastropod Species ◽  
Biological Interest ◽  
Geographical Barrier ◽  
Middle Atlas ◽  
Deep Suture ◽  
A Site

A new planorbid gastropod species is described: Gyraulus marocana sp. nov. It can be distinguished from other known species by its regularly striated ivory shell, with four whorls separated by a deep suture, prostate gland with 20 diverticula, phallotheca twice as long as the preputium and its orange stylet. The new species was found in the northern part of Morocco, in Lake Zerrouka, a Protected Area, being also a site of ecological and biological interest (known as SIBE). It is located in the Middle Atlas massif, which is a geographical barrier known for its other endemic molluscs.

scholarly journals Evaluation of Road Infrastructure Alternatives Through a Saving Gradient in Travel Times. Case Study: Second Connection Villamaría-Manizales, Colombia

2018 ◽  
Vol 12 (8) ◽  
pp. 103
Author(s):  
Diego Alexander Escobar ◽  
Santiago Cardona ◽  
Carlos Alberto Moncada
Keyword(s):  
Urban Areas ◽  
Social Economic ◽  
Master Plan ◽  
Travel Times ◽  
Investment Projects ◽  
Sustained Development ◽  
Geographical Barrier ◽  
Travel Time Savings ◽  
Time Savings

In the last century, the migration of people from rural to urban areas of cities has generated a set of dynamics in different sectors such as social, economic, educational that have led cities to collaborate among them, generating a constant synergy in order to obtain a sustained development in multiple aspects. In this sense, Manizales as the capital of the department of Caldas in Colombia has generated a conurbation with the nearest neighboring municipality, Villamaría reaching a combined population of 419 943. Although this synergy has taken place for several decades, these municipalities only have a place of connection, because they are separated by a geographical barrier, the Chinchiná River. This connection has had clear connection problems, due to the high flow of vehicles that move between both municipalities, so it is essential to project a second connection, to further boost mobility among its inhabitants. For this reason, in this research four (4) alternatives of connection are proposed, according to the suggestions of the Manizales 2017 Mobility Master Plan, through the calculation of the global average accessibility and the quantification of the gradient of savings generated in the average times of trip, based on the current situation of both cities. The results show which is the alternative that benefits population the most in terms of travel time savings, although three of them generate considerable savings and only one is discarded because it benefits a smaller number of inhabitants in very low percentages of savings compared to the others. The evaluation of infrastructure alternatives through the gradient of savings in travel times is useful to determine the best options in the pre-feasibility phase of investment projects in the transport area.

scholarly journals The contemporary genetic pattern of European moose is shaped by postglacial recolonization, bottlenecks, and the geographical barrier of the Baltic Sea

2015 ◽  
Vol 117 (4) ◽  
pp. 879-894 ◽  
Author(s):  
Magdalena Niedziałkowska ◽  
Kris J. Hundertmark ◽  
Bogumiła Jędrzejewska ◽  
Vadim E. Sidorovich ◽  
Hanna Zalewska ◽  
...  
Keyword(s):  
Baltic Sea ◽  
The Baltic Sea ◽  
Postglacial Recolonization ◽  
Genetic Pattern ◽  
Geographical Barrier ◽  
The Baltic

scholarly journals Speciation with gene flow via cycles of isolation and migration: Insights from multiple mangrove taxa

2018 ◽  
Author(s):  
Ziwen He ◽  
Xinnian Li ◽  
Ming Yang ◽  
Xinfeng Wang ◽  
Cairong Zhong ◽  
...  
Keyword(s):  
Gene Flow ◽  
Indian Ocean ◽  
Large Scale ◽  
Marine Species ◽  
Allopatric Speciation ◽  
Unified Framework ◽  
Geographical Isolation ◽  
Mangrove Species ◽  
Geographical Barrier ◽  
Time Required

AbstractAllopatric speciation requiring an unbroken period of geographical isolation has been the standard model of neo-Darwinism. While doubts have been repeatedly raised, strict allopatry without any gene flow remains a plausible mechanism in most cases. To rigorously reject strict allopatry, genomic sequences superimposed on the geological records of a well-delineated geographical barrier will be necessary. The Strait of Malacca, narrowly connecting the Pacific and Indian Ocean coasts, serves at different times either as a geographical barrier or a conduit of gene flow for coastal/marine species. We surveyed 1,700 plants from 29 populations of five common mangrove species by large scale DNA sequencing and added several whole-genome assemblies. Speciation between the two oceans is driven by cycles of isolation and gene flow due to the fluctuations in sea level leading to the opening/closing of the Strait to ocean currents. Because the time required for speciation in mangroves is longer than the isolation phases, speciation in these mangroves has proceeded through many cycles of mixing-isolation-mixing, or MIM cycles. The MIM mechanism, by relaxing the condition of no gene flow, can promote speciation in many more geographical features than strict allopatry can. Finally, the MIM mechanism of speciation is also efficient, potentially yielding mn (m>1) species after n cycles.Significance statementMechanisms of species formation have always been a conundrum. Speciation between populations that are fully geographically isolated, or allopatric speciation, has been the standard solution in the last 50 years. Complete geographical isolation with no possibility of gene flow, however, is often untenable and is inefficient in generating the enormous biodiversity. By studying mangroves on the Indo-Malayan coasts, a global hotspot of coastal biodiversity, we were able to combine genomic data with geographical records on the Indo-Pacific barrier that separates Pacific and Indian Ocean coasts. We discovered a novel mechanism of speciation, that we call mixing-isolation-mixing (MIM) cycles. By permitting intermittent gene flow during speciation, MIM can potentially generate species at an exponential rate, thus combining speciation and biodiversity in a unified framework.

scholarly journals Crossing and Transgressing Borders in The Heart of Midlothian

2011 ◽  
pp. 0
Author(s):  
Céline Sabiron
Keyword(s):  
Great Britain ◽  
The Novel ◽  
Natural Boundary ◽  
Geographical Barrier ◽  
Political Border ◽  
The Mind ◽  
Physical Boundary

If the 1707 Act of Union removed the immaterial legal and political border between England and Scotland by merging them into the single kingdom of Great Britain, it could not erase the almost impassable natural boundary dividing the twin sisters. This tangible geographical barrier remained as a magnificent reminder of a former separation, thus questioning the disappearance of the national frontier. The confrontation between abstract and concrete boundaries, which is at stake in historical Scotland, is staged in Walter Scott’s The Heart of Midlothian set a few decades after the Union. The heroine’s physical journey across the Anglo-Scottish border gradually takes on a more symbolic significance as she trudges through the marches to redeem her sinful sister. In studying the novel, I will analyse the series of embedded tangible boundaries present on the British territories and show how they are constantly crossed by the protagonists. This physical crossing of concrete borders often goes with the mental crossing of abstract barriers. Overstepping a physical boundary can lead to transgressing moral and societal limits as it is exemplified with the Scottish Borders, a den of iniquity and unlawful transactions. External borders can thus embody more internal boundaries and serve to map territories of the mind.

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