Areas of endemism of the North American species of Tigridieae (Iridaceae)

2016 ◽  
Vol 29 (2) ◽  
pp. 142 ◽  
Author(s):  
Guadalupe Munguía-Lino ◽  
Tania Escalante ◽  
Juan J. Morrone ◽  
Aarón Rodríguez
Keyword(s):  
North American ◽  
Grid Cell ◽  
Volcanic Belt ◽  
Data Matrix ◽  
Central Mexico ◽  
Southern Mexico ◽  
Western Mexico ◽  
The North ◽  
Areas Of Endemism ◽  
Andean South America

The tribe Tigridieae (Iridoideae: Iridaceae) is a New World group with centres of diversity in Mexico and Andean South America. North America harbours 67 of the 172 species recognised within the tribe, 54 being endemic. Our aims were to identify areas of endemism of the North American Tigridieae using endemicity analysis (EA) and to infer their relationships using parsimony analysis of endemicity (PAE). A data matrix with 2769 geographical records of Tigridieae was analysed. The EA allowed to identify six consensus areas of endemism in Mexico. The PAE resulted in one cladogram with four clades and the following five biotic components: northern Mexico, western Mexico, central Mexico, southern Mexico and central–southern Mexico. The richness analysis of these areas of endemism indicated that the greatest concentration of species is located in central Mexico, with 14 species in one grid-cell. Grid-cells with 12 species each were identified in low western Mexico, high western Mexico, southern Mexico and central–southern Mexico. This last area is characterised by the greatest endemism, including nine species. The formation of the Transmexican Volcanic Belt seems to have been a key element to explain the diversification of North American Tigridieae.

Overview of Naturally Occurring Asbestos in California and Southwestern Nevada

2020 ◽  
Vol 26 (1) ◽  
pp. 9-14
Author(s):  
R. Mark Bailey
Keyword(s):  
Sierra Nevada ◽  
North American ◽  
Volcanic Belt ◽  
Island Arc ◽  
North American Plate ◽  
Mountain Range ◽  
The North ◽  
Rock Types ◽  
Naturally Occurring ◽  
Naturally Occurring Asbestos

ABSTRACT Naturally occurring asbestos (NOA) is being discovered in a widening array of geologic environments. The complex geology of the state of California is an excellent example of the variety of geologic environments and rock types that contain NOA. Notably, the majority of California rocks were emplaced during a continental collision of eastward-subducting oceanic and island arc terranes (Pacific and Farallon plates) with the westward continental margin of the North American plate between 65 and 150 MY BP. This collision and accompanying accretion of oceanic and island arc material from the Pacific plate onto the North American plate, as well as the thermal events caused by emplacement of the large volcanic belt that became today's Sierra Nevada mountain range, are the principal processes that produced the rocks where the majority of NOA-bearing units have been identified.

The southern Mexico block: main boundaries and new estimation for its Quaternary motion

2008 ◽  
Vol 179 (2) ◽  
pp. 209-223 ◽  
Author(s):  
Louis Andreani ◽  
Xavier Le Pichon ◽  
Claude Rangin ◽  
Juventino Martínez-Reyes
Keyword(s):  
North American ◽  
Triple Junction ◽  
Strike Slip ◽  
North American Plate ◽  
Southern Mexico ◽  
Active Deformation ◽  
Lateral Strike Slip ◽  
Counterclockwise Rotation ◽  
The North ◽  
Slip Partitioning

Abstract Numerous studies, mainly based on structural and paleomagnetic data, consider southern Mexico as a crustal block (southern Mexico block, SMB) uncoupled from the North American plate with a southeast motion with respect to North America, accommodated by extension through the central Trans-Mexican volcanic belt (TMVB). On the other hand, the accommodation of this motion on the southeastward boundary, especially at the Cocos–Caribbean–North American triple junction, is still debated. The boundary between the SMB and the North American plate is constituted by three connected zones of deformation: (1) left-lateral transtension across the central TMVB, (2) left-lateral strike-slip faulting along the eastern TMVB and Veracruz area and (3) reverse and left-lateral strike-slip faulting in the Chiapas area. We show that these three active deformation zones accommodate a counterclockwise rotation of the SMB with respect to the North American plate. We specially discuss the Quaternary motion of the SMB with respect to the surrounding plates near the Cocos–Caribbean–North American triple junction. The model we propose predicts a Quaternary counterclockwise rotation of 0.45°/Ma with a pole located at 24.2°N and 91.8°W. Finally we discuss the geodynamic implications of this counterclockwise rotation. The southern Mexico block motion is generally assumed to be the result of slip partitioning at the trench. However the obliquity of the subduction is too small to explain slip partitioning. The motion could be facilitated by the high thermal gradient and gravitational collapse that affects central Mexico and/or by partial coupling with the eastward motion of the Caribbean plate.

Ecogeography and the Great American Interchange

Paleobiology ◽  
1991 ◽  
Vol 17 (3) ◽  
pp. 266-280 ◽  
Author(s):  
S. David Webb
Keyword(s):  
North America ◽  
South America ◽  
North American ◽  
Mammalian Fauna ◽  
The South ◽  
Land Bridge ◽  
Southern Mexico ◽  
The North ◽  
Land Mammal ◽  
The Impact

When the isthmian land bridge triggered the Great American Interchange, a large majority of land-mammal families crossed reciprocally between North and South America at about 2.5 Ma (i.e., Late Pliocene). Initially land-mammal dynamics proceeded as predicted by equilibrium theory, with roughly equal reciprocal mingling on both continents. Also as predicted, the impact of the interchange faded in North America after about 1 m.y. In South America, contrary to such predictions, the interchange became decidedly unbalanced: during the Pleistocene, groups of North American origin continued to diversify at exponential rates. Whereas only about 10% of North American genera are derived from southern immigrants, more than half of the modern mammalian fauna of South America, measured at the generic level, stems from northern immigrants. In addition, extinctions more severely decimated interchange taxa in North America, where six families were lost, than in South America, where only two immigrant families became extinct.This paper presents a two-phase ecogeographic model to explain the asymmetrical results of the land-mammal interchange. During the humid interglacial phase, the tropics were dominated by rain forests, and the principal biotic movement was from Amazonia to Central America and southern Mexico. During the more arid glacial phase, savanna habitats extended broadly right through tropical latitudes. Because the source area in the temperate north was six times as large as that in the south, immigrants from the north outnumbered those from the south. One prediction of this hypothesis is that immigrants from the north generally should reach higher latitudes in South America than the opposing contingent of land-mammal taxa in North America. Another prediction is that successful interchange families from the north should experience much of their phylogenetic diversification in low latitudes of North America before the interchange. Insofar as these predictions can be tested, they appear to be upheld.

scholarly journals First Report of Heterobasidion annosum on the Endemic Abies hickeli of Southern Mexico

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 1047-1047 ◽  
Author(s):  
M. Garbelotto ◽  
I. Chapela
Keyword(s):  
Dna Sequences ◽  
North American ◽  
Heterobasidion Annosum ◽  
Internal Transcribed Spacer Region ◽  
Southern Mexico ◽  
Geographic Ranges ◽  
The North ◽  
Mexican State ◽  
Standing Trees ◽  
Pinus Spp

The basidiomycete Heterobasidion annosum (Fr.:Fr.) Bref. is a pathogen of conifers in the Northern Hemisphere. This fungus has been previously reported from Pinus spp. (1) and from Abies religiosa (H.B.K.) Schl. et Cham. (2) in Central Mexico. In 1998, H. annosum was collected for the first time from stumps of Abies hickeli Flous et Gaussen in the Southern Mexican State of Oaxaca, at an altitude of 2,900 m (Lat 17° 28′ N, Long 96° 31′ W). Although standing trees at the sampled site were asymptomatic, the sapwood and heartwood of several fir stumps were extensively decayed. The white laminated rot was similar to that caused by H. annosum on other Abies spp. Decay pockets extended to the upper surface of the stumps, indicating the fungus had infected and colonized the tree butts prior to tree felling. H. annosum basidiocarps were found both outside the roots in the duff layer and inside the decay pockets. The anamorph of H. annosum (Spiniger meineckellum (A. Olson) Stalpers) was isolated from the context of three basidiocarps. Based on comparative analysis of DNA sequences of the nuclear ribosomal internal transcribed spacer region, all three isolates belonged to the North American S intersterility group (ISG). This report expands the host and the geographic ranges of the North American S ISG, and represents the world's southernmost finding of an Abies species infected by this pathogen. References: (1) R. Martinez Barrera and R. Sanchez Ramirez. Ciencia Forestal 5(26):3, 1980. (2) M. Ruiz-Rodriguez and L. M. Pinzon-Picaseno. Bol. Soc. Bot. Mexico 54:225, 1994.

scholarly journals Characteristics of North American Summertime Rainfall with Emphasis on the Monsoon

2008 ◽  
Vol 21 (6) ◽  
pp. 1277-1294 ◽  
Author(s):  
Brant Liebmann ◽  
Ileana Bladé ◽  
Nicholas A. Bond ◽  
David Gochis ◽  
Dave Allured ◽  
...  
Keyword(s):  
North American ◽  
Rain Rate ◽  
Daily Rainfall ◽  
Summer Rainfall ◽  
Wet Season ◽  
Southern Mexico ◽  
The North ◽  
Sierra Madre ◽  
Grid Points ◽  
Northwestern Mexico

Abstract The core region of the North American summer monsoon is examined using spatially averaged daily rainfall observations obtained from gauges, with the objective of improving understanding of its climatology and variability. At most grid points, composite and interannual variations of the onset and end of the wet season are well defined, although, among individual stations that make up a grid average, variability is large. The trigger for monsoon onset in southern and eastern Mexico appears to be related to a change in vertical velocity, while for northwestern Mexico, Arizona, and New Mexico it is related to a reduction in stability, as indicated by a decrease in the lifted index. The wet-season rain rate is a combination of the wet-day rain rate, which decreases with distance from the coast, and the wet-day frequency, which is largest over the Sierra Madre Occidental. Thus the maximum total rate lies slightly to the west of the highest orography. As has been previously noted, onset is not always well correlated with total seasonal precipitation, so in these areas, variations of wet-day frequency and wet-day rain rate must be important. Correlations are small between the wet-day frequency and the wet-day rate, and the former is better correlated than the latter with the seasonal rain rate. Summer rainfall in central to southern Mexico exhibits moderate negative correlations with the leading pattern of sea surface temperature (SST) anomalies in the equatorial Pacific, which projects strongly onto El Niño. The influence of equatorial SSTs on southern Mexico rainfall seems to operate mainly through variability of the wet-day frequency, rather than through variations of the wet-day rain rate.

scholarly journals Transition zones and biogeographic characterization of endemism in three biogeographic provinces of central Mexico

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Enrique Ortiz-Bermúdez ◽  
José Luis Villaseñor
Keyword(s):  
Species Distribution ◽  
Volcanic Belt ◽  
Central Mexico ◽  
Transition Zones ◽  
Biogeographic Provinces ◽  
Sierra Madre ◽  
Areas Of Endemism ◽  
Sierra Madre Del Sur ◽  
Study Species

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.

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