Taxonomy and Biogeography of <I>Gaillardia</I> (Asteraceae): A Phylogenetic Analysis

Biogeographical diversification of Mentzelia section Bartonia in western North America

“…This hypothesis is supported by the parsimony (see Fig. The possible transitions between the NAPP and the Chihuahuan Desert, which were not recovered in parsimony reconstructions, are consistent with the conclusions of Axelrod (1985) and Takhtajan et al (1986), who pointed out similarities between floristic elements of the two regions, a pattern identified in the comparable western North American genus, Gaillardia (Asteraceae; Marlowe & Hufford, 2007). S2 in Appendix S2), which associated the NAPP and the Rocky Mountains with the highest transition rate (Table 1) and in which the only other NAPP transition rate above one was between the NAPP and the Chihuahuan Desert (Table 1).…”

“…Given the phylogenetic relationships among the edaphic endemics, establishment on these soils has probably occurred more than once (Figs 1 & 2). Marlowe & Hufford (2007) and Moore & Jansen (2007) have demonstrated the importance of these soils in the diversification of other plant groups, and these soils seem to play an equally important role in isolating and diversifying section Bartonia in the Chihuahuan Desert and probably other regions as well.…”

“…Much of what we know about plant migrations among the floristic regions of western North America comes from studies based on fossil data (Axelrod, 1948(Axelrod, , 1949(Axelrod, , 1958(Axelrod, , 1983(Axelrod, , 1985, pack rat middens (Devender & Spaulding, 1979;Axelrod, 1985;Lyford et al, 2004;Coats et al, 2008), extant taxa associations (Harper et al, 1978;Krings, 2000), and molecular historical biogeographical studies (Moore & Jansen, 2006Marlowe & Hufford, 2007. Molecular studies have corroborated and expanded previous studies based on other lines of evidence, such as fossil data, but additional studies are nevertheless needed before a consensus can be established on the complex evolutionary history of western North America.…”

Morphological Variation within and Between taxa of the Santolina rosmarinifolia L. (Asteraceae: Anthemideae) Aggregate

“…As opposed to the situation found in Gaillardia by Marlowe and Hufford (2007) , hybridization and polyploidization play an important role in speciation in Santolina . The intriguing taxonomic complexity of the S .…”

“…They show a less diverse ecological preference and are located on soils derived from limestone, marl, gypsiferous marl, and clay. The disjunctive distribution of the polyploids arose from fragmentation or contraction of the species range, preventing gene flow between them ( Richardson et al 2003 ) and allowing fixation of chromosomal, ontogenetic, and morphological changes, which favored differentiation and allopatric speciation ( Marlowe and Hufford 2007 ;Rivero-Guerra 2008c ). In addition, the results suggest that the variation between taxa is not associated with ploidy level because all taxa are significantly different from each other.…”