scholarly journals Towards a knowledge of marine boundaries using ascidians as indicators: characterising transition zones for species distribution along Atlantic-Mediterranean shores

1998 ◽  
Vol 64 (2) ◽  
pp. 151-177 ◽  
Author(s):  
Santiago Naranjo ◽  
José Luis Carballo ◽  
José Carlos García-Gómez
2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Enrique Ortiz-Bermúdez ◽  
José Luis Villaseñor

Background: Sites of overlap in the species distribution among regions are known as transition zones. Their floristic and biogeographic complexity is rarely discussed. Questions: Is it possible to identify transition zones amid the biogeographic provinces of Mexico? Can transition zones also be considered areas of endemism? Study species: 315 Asteraceae taxa endemic to Mexico.Study site: Volcanic Belt, Balsas Depression and Sierra Madre del Sur biogeographic provinces. Methods: For species of Asteraceae endemic to three biogeographic provinces of central Mexico, we characterized the province to which each species belonged and estimated the distance it could penetrate the neighboring province. We defined transition zones between biogeographic provinces as the average penetration distances of the species. We also evaluated the presence of species with restricted distribution to transition zones. Results: Two transition zones were identified in the Balsas Depression, first, at the junction with the Volcanic Belt with a width of 13 km, and second, with the Sierra Madre del Sur, with a width of 12.3 km. There were 45 species whose distribution was restricted to those transition zones.Conclusions: Understanding how richness and endemism are exchanged from one region to another is essential to explain how their floras have been assembling and evolving. This analysis has allowed us to better understand the relationships among regions as complex as those studied here.


2019 ◽  
Author(s):  
Renan Maestri ◽  
Leandro Duarte

ABSTRACTBiogeographic regionalization offers context to the geographical evolution of clades. The positions of bioregions inform both the spatial location of clusters in species distribution and where their most important boundaries are. Nevertheless, defining bioregions based on species distribution alone only incidentally recovers regions that are important during the evolution of the focal group. The extent to which bioregions correspond to centers of independent diversification depends on how clusters of species composition naturally reflect the radiation of single clades, which is not the case when mixed colonization occurred. Here, we showed that using phylogenetic turnover based on fuzzy sets, instead of species composition, led to more adequate detection of evolutionary important bioregions, that is, regions that truly account for the independent diversification of lineages. Mapping those evoregions in the phylogenetic tree quickly reveals the timing and location of major shifts of biogeographic regions. Moreover, evolutionary transition zones are easily mapped, and permits the recognition of regions with high phylogenetic overlap. Our results using the global radiation of rats and mice (Muroidea) recovered four evoregions—three major evolutionary arenas corresponding to the Neotropics, a Nearctic-Siberian, and a Paleotropical-Australian evoregion, and a fourth and fuzzy Afro-Palearctic evoregion. In comparison, an analysis with a method considering species distribution alone found 52 bioregions. Evoregions is a useful framework whenever the question is related to the identification of the most important centers of a group’s diversification history and its evolutionary transitions zones.


Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
B Liu ◽  
F Li ◽  
Z Guo ◽  
L Hong ◽  
W Huang ◽  
...  

2020 ◽  
Vol 54 (2) ◽  
pp. 497-513 ◽  
Author(s):  
L. N. Beldiman ◽  
I. N. Urbanavichene ◽  
V. E. Fedosov ◽  
E. Yu. Kuzmina

We studied in detail a moss-lichen component of Shokalsky Island vegetation for the first time and identified 79 species of mosses and 54 species and 2 subspecies of lichens and lichenicolous fungi. All species of mosses and 23 species and 2 subspecies of lichens and lichenicolous fungi are recorded for the first time for the island. The study is based on collections made in South West part of the island, in arctic tundra. We also explored the participation of the mosses and lichens in the main types of plant communities and the species distribution in 10 ecotopes. The paper describes the noteworthy findings (Abrothallus parmeliarum, Aongstroemia longipes, Arthonia peltigerea, Caloplaca caesiorufella, Catillaria stereocaulorum, Ceratodon heterophyllus, Lecanora leptacinella, Sphagnum concinnum, S. olafii) and features of bryo- and lichenoflora of Shokalsky Island.


2014 ◽  
Vol 48 ◽  
pp. 81-88
Author(s):  
A. F. Luknitskaya

76 species, 3 varieties and 1 form from 21 genera of Streptophyta, Conjugatophyceae (Actinotaenium, Bambusina, Closterium, Cosmarium, Cylindrocystis, Euastrum, Gonatozygon, Haplotaenium, Micrasterias, Mougeotia, Netrium, Penium, Planotaenium, Pleurotaenium, Raphidiastrum, Spirogyra, Spirotaenia, Staurastrum, Staurodesmus, Tetmemorus, Xanthidium) were found in the basins of the Valdai District area of the National Park «Valdaiskiy» (Novgorod Region, Russia). The list of species is annotated with data on the species distribution in 55 collecting sites of 29 water bodies of the national park, and species abundance in collected samples according to Luknitskaya (2009). Among above mentioned genera, the genus Cosmarium is represented by the greatest number of species (20). Staurastrum chaetoceros has been found for the first time for the Novgorod Region.


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