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Abstract Detail



Biogeography

Saghatelyan, Anna [1].

Regions of Endemism and Chorotypes in SC USA Based on Species of Texas Flora.

East to West floristic boundary passes through Texas and its western floras belong to the Western Floristic Region, wile eastern ones to the Eastern Region of the Nearctic chorion. One can check if this classical view, based on the flora composition and species ranges, is supported by analyses with different biogeographic tools. To find areas of endemism and chorotypes in South Central US, I performed endemicity analysis of 116 selected species of Texas flora, using NDM/VNDM software. I also generated ENMs for these species and compared them to each other. The choice of species comes from the classification of chorotypes, based on the species distribution outlines, I developed and used to analyze three Texas floras: Big Bend Region (1587species), Edwards Plateau (1618 specie), and South TX Plains (1250 species). The digitazed specimen records for the species selected from these floras were downloaded from GBIF. The species with very wide geographic ranges and fewer than 40 herbarium records were dropped, while those with ample points and good herbarium data were cleaned and included in the data set. The region was framed by -125 to -75 longitude and 20 to 45 latitude, where almost all the chosen species ranges fit. Suitable areas for the species were then modeled using MAXENT and 11 uncorrelated bioclimatic variables. The thresholded models were evaluated with AUC and an omission rate. Then I searched for clusters of correlative ENMs and compared the overlapping models with the areas of endemism produced by NDM analyses under different cell sizes. The NDM analysis at smaller cell sizes generated consensus areas, which characterize the following phytochoria/chorotypes: Sonoran desert, S Rocky Mountains (Apachian), Sonoran-Chihuahuan, and Chihuahuan of the Western Region; as well as Southcentral North American and Chihuahuan-Tamaulipan of West-East transition zone. Larger cell sizes revealed SE North American, SE Prairie (Comanchian), and S Prairie areas of endemism/chorotypes of the Eastern Region. Smaller cell sizes showed many overlapping areas of endemism in SC US and were better for fine tuning, such as showing S TX Plains (Tamaulipan), or Edwards Plateau endemism, while the ENMs and large cell NDM analyses revealed also the chorotypes of broader scale. Crosschecking the results of all three methods was useful and supportive of some parts of classical chorionomic systems and/or some recent works.


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1 - McMurry University, Biology, McMurry Station Box 368, Abilene, TX, 79697, United States

Keywords:
endemism
chorotypes
chorionomy
SC US
Texas.

Presentation Type: Oral Paper
Session: BIOG1, Biogeography I
Location: Tucson E/Starr Pass
Date: Monday, July 29th, 2019
Time: 11:15 AM
Number: BIOG1012
Abstract ID:616
Candidate for Awards:None


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