Origins of North American arid land Verbenaceae: more than one way to skin a cat.

FROST, L.; MCADAMS, S.; LU-IRVING, PATRICIA; O'LEARY, NATALY; OLMSTEAD, RICHARD

AMERICAN JOURNAL OF BOTANY

BOTANICAL SOC AMER INC

Lugar: St. Louis; Año: 2017 vol. 104 p. 1708 - 1716

0002-9122

Premise of the study: Verbenaceae are a family that originated and initially diversified in South America in wet forest habitats.  They have diversified extensively in arid habitats in both South and North America.  This study aims to understand the origin of the North American arid-land members of Verbenaceae. Methods: A phylogenetic approach is used to examine four genera (Aloysia, Citharexylum, Glandularia, Verbena) in three distinct clades with representatives in North American deserts and that have disjunct South and North American distributions.   Phylogenetic analyses were conducted using maximum likelihood and Bayesian approaches. Analyses included both plastid and nuclear DNA regions and include the first study of Citharexylum and an expanded sampling of tribe Verbeneae (Glandularia and Verbena). ·        Key results: North Americandesert species of Aloysia and Glandularia were likely derived from ancestors in arid temperateSouth America, perhaps by long distance dispersal.  The pattern for Verbena was less clear, with evidence from plastid DNA implicatingAndean species as sister to the North American clade, suggesting an Andeanmigration corridor, while nuclear DNA trees suggest that the Andean speciesbelong to a clade with the southern South America species and that clade issister to the North American clade.  Apreviously unrecognized clade of Andean Verbeneae was discovered, which raisesthe possibility of an Andean origin of Verbenaor Verbena and Glandularia.  Citharexylum does not occur in the aridregions of temperate South America; its North American desert species representmultiple, independent origins from mesic habitat ancestors in Mesoamerica.·        Conclusions: North American arid-zone Verbenaceae are derived from South andCentral American ancestors via multiple avenues, possibly including longdistance, amphitropical dispersal, Andean migration corridors, and in situ evolution of desert-adaptedspecies.