Ross A. McCauley

Inferring nativity and biogeographic affinities of central and marginal populations of Froelichia floridana (Amaranthaceae) from Inter-Simple Sequence Repeat (ISSR) markers1

and southeastern United States. We analyzed the biogeographic patterns of this species to answer a series of questions regarding its historical dispersal and recent range expansion, and the relationships of a disjunct population in southern Ohio using a combination of genetic analyses based on Inter-Simple Sequence Repeat markers (ISSR) and herbarium studies. Amounts of genetic diversity showed a marked reduction in marginal populations in the far north and northeast of the species range, corresponding to areas where herbarium records show the species has become naturalized during the past 100 years. Our analysis suggests the recognition of three biogeographic lineages within this polymorphic species complex: a Great Plains lineage, an associated Midwestern Mississippian lineage, and an Atlantic Coastal Plain lineage. These lineages have been loosely recognized as taxonomic varieties: the western lineages as F. floridana var. campestris (Small) Fern., and the eastern lineage as F. floridana var. floridana (Nutt.) Moq.; however, our data suggest that the continued recognition of these varieties is not warranted. The disjunct population in Ohio, formerly believed to be a remnant of a once larger distribution and presently state-listed as a rare species, shows patterns of genetic diversity and differentiation comparable to recently established marginal populations in other states, and was most likely derived from the Great Plains or Midwestern lineages.

New Taxa and a New Combination in the North American Species of Froelichia (Amaranthaceae)

Abstract Two new species, one new variety, and a new combination of Froelichia are described from North America. Froelichia xantusii from Baja California Sur is being recognized as a species endemic to southern Baja California and separate from F. interrupta in which it had been previously included. Within F. interrupta two varieties are here recognized, the newly described Froelichia interrupta var. colimensis from southern Nayarit to Oaxaca and the new combination Froelichia interrupta var. alata from the Sonoran Desert. Froelichia latifolia is described from eastern Texas and has been segregated from the widespread F. floridana. A key to the genus in North America is also included.

Population Genetic Structure in Temperate and Tropical Species of Viola (Violaceae) with a Mixed Breeding System

Inter–simple sequence repeat (ISSR) molecular markers were used to characterize inter‐ and intrapopulation genetic diversity in populations of two contrasting species of Viola, Viola striata of the eastern United States and Canada and Viola grahamii of central Mexico. Both species show a mixed breeding system with the production of both chasmogamous and cleistogamous flowers, although the temporal pattern of flowering varies between the two species. In both species the majority of the seeds produced in a given season are the result of cleistogamous flowers; additionally, V. grahamii reproduces asexually by means of runners. Our results indicate similar high levels of genetic diversity, low levels of population subdivision, and weak interpopulation differentiation in both species. In particular V. grahamii showed a slightly higher level of genetic diversity than V. striata, which does not reproduce vegetatively. Modest chasmogamous reproduction is proposed to maintain levels of outcrossing sufficient to ameliorate population subdivision and retard interpopulational divergence that would otherwise result from cleistogamy. These findings reiterate a recurring pattern in Viola in which high population genetic diversity is maintained even with the presence of high levels of cleistogamy and vegetative reproduction.

Phenetic analysis shows conspecificity between Hispaniolan Viola domingensis Urban and North American Viola macloskeyi sensu lato (Violaceae)

Phenetic investigations were undertaken to evaluate differences between the cloud forest endemicViola domingensis of the Dominican Republic and the morphologically similarV. macloskeyi of continental North America. Cluster, principal components (PCA), and canonical variates analyses (CVA) of leaf characters and of ratios derived from them consistently separateV. macloskeyi subsp.macloskeyi of the Pacific states fromV. domingensis and transcontinentalV. macloskeyi subsp.pallens. However, all analyses portray the latter two as extensively intergradient extremes of a continuum, withV. domingensis plants tending to be smaller. Phenetic analyses of capsule and seed features, which are often divergent among other species of subsect.Stolonosae, showV. domingensis to be nested within a broaderV. macloskeyi subsp.pallens. Similarly, floral morphology does not provide observable differences between the pair. Results support the synonymy ofV. domingensis underV. macloskeyi subsp.pallens and reveal that it represents a disjunct outlier of an otherwise continental North American violet.

Systematics of North American Froelichia (Amaranthaceae subfam. Gomphrenoideae) I: Identification of consistent morphological variation and segregation of species complexes

Phenetic analyses of morphological variation were used to elucidate distinctiveness and circumscription of taxa within, the genus Froelichia in North America. Preserved specimens representing all recognized taxa and one suspected hybrid taxon were measured for 39 continuous and discrete characters and subjected to univariate and multivariate analyses. Principal coordinate analysis indicated the presence of three distinct groups of species with intergradation of morphological intermediates. Two of the groups corresponded to two large complexes of species, the F. floridana complex of the south-central and southeastern United States and the F. interrupta complex, principally of Mexico, while the third consisted of F. gracilis native to the southern United States and adjoining Mexico. Discriminant analysis on each of the two complexes indicated morphologically distinct forms within each morphologically variable complex. The use of novel characters for the discrimination of taxa resulted in the identification of less plastic traits among the recognized species. Use of these newly discovered traits provides more reliable means for the identification of taxa. An instance of potential, hybridization among three taxa in southern Texas was additionally explored with the putative hybrid taxa exhibiting an intermediate combination of morphological traits between each of the putative parents.ResumenUn análisis fenético de la variación morfológica presente en los taxa del género Froelichia en Norte América fue realizado para determinar la circunscripción y diferencias entre ellos. Treinta y nueve caracteres tanto discretos como continuos fueron medidos en ejemplares de herbario de todos los taxa reconocidos así como en un híbrido potencial, y éstos fueron sometidos a análisis uni y multivariados. El análisis de coordinadas principales indicó la presencia de tres grupos distintos de especies con un gradiente de intermedios morfológicos Dos de los grupos corresponden a dos grandes complejos de especies, el complejo de F. floridana de la parte Surcentro y del Sureste de los Estados Unidos y el complejo de F. interrupta de distribución principalmente en México. El tercer grupo corresponde, a F. gracilis especie nativa al sureste de Estados Unidos y a la parte adyacente de México. El análisis discriminante hecho en cada uno de los dos complejos indicó formas morfológicamente distintas dentro de cada complejo. El uso de caracteres nunca antes usados para la discriminación, de los taxa resultó en la identificación de caracteres que son menos, plásticos entre las especies reconocidas y que facilita su identificación de una manera más eficaz y confiable. Se exploró adicionalmente el potencial de hibridización entre tres taxa del sur de Texas, con los híbridos mostrando una mezcla de caracteres intermedios entre los padres putativos.

Systematics of North American Froelichia (Amaranthaceae subfam. Gomphrenoideae) II: Phylogeny and biogeographic speciation patterns inferred from nrITS sequence data

Molecular phylogenetic analyses of the nuclear ribosomal DNA internal transcribed spacer (ITS 1 and ITS 2) and the 5.8S gene were used to infer a phylogeny among the ten recognized taxa of Froelichia in North America. Analyses using both maximum parsimony (MP) and maximum-likelihood (ML) depicted a low level of sequence divergence though it was sufficient in most cases to differentiate taxa. Froelichia xantusii, a species restricted to southern Baja California was shown to be the basalmost member of the group subtending three clades. Two of the clades received good bootstrap support in the MP analysis and corresponded to a genetically homogeneous F. interrupta, and a clade comprising the two species F. latifolia and F. texana. A third clade receiving low bootstrap support contained F. floridana, F. gracilis, F. arizonica, and F. drummondii. Species diversity within the genus was centered within the Tamaulipan Brushland region of north-east Mexico and the southern portion of the US state of Texas where taxa from two of the three principal clades occurred, indicating a region of high speciation and diversification within the genus.ResumenSe realizó un análisis filogenético usando secuencias del ADN ribosomal ITS1 e ITS2 (espaciador trascrito interno 1 y 2) y el gen 5.8S para determinar las relaciones entre los diez taxa reconocidos del género Froelichia en Norte América. Se realizaron análisis de máxima parsimonia (MP) y máxima similitud (ML) los cuales mostraron bajos niveles de divergencia genética entre los taxa, pero suficientes para separarlos. Froelichia xantusii, una especie restringida al Sur de Baja California, es la más basal del grupo y de la cual se separan tres clados. Dos de los clados recibieron un muy buen soporte en el análisis de máxima parsimonia, el primero esta formado por individuos genéticamente homogéneos, de F. interrupta y el otro incluye a F. latifolia y F. texana. El tercer clado, que recibió un soporte bajo, incluye a F. floridana, F. gracilis, F. arizonica y F. drummondii. La mayor diversidad de especies dentro del género se centra dentro de la región del Matorral Tamaulipeco del noreste de México y la parte sur del estado Estadounidense de Texas, donde se encuentran representantes de dos de los tres clados en Froelichia, indicando que ésta es una región con alta especiación y diversificación dentro del género.