Erythranthe

Abstract: Changes in chromosome number and structure are important contributors to adaptation, speciation and macroevolution. In flowering plants, polyploidy and subsequent reductions in chromosome number by fusion are major sources of chromosomal evolution, but chromosome number increase by fission has been relatively unexplored. Here, we use comparative linkage mapping with gene-based markers to reconstruct chromosomal synteny within the model flowering plant genus Mimulus (monkeyflowers). Two sections of the genus with haploid numbers ⩾14 have been inferred to be relatively recent polyploids because they are phylogenetically nested within numerous taxa with low base numbers (n=8–10). We combined multiple data sets to build integrated genetic maps of the M. guttatus species complex (section Simiolus, n=14) and the M. lewisii group (section Erythranthe; n=8), and then aligned the two integrated maps using >100 shared markers. We observed strong segmental synteny between M. lewisii and M. guttatus maps, with essentially 1-to-1 correspondence across each of 16 chromosomal blocks. Assuming that the M. lewisii (and widespread) base number of 8 is ancestral, reconstruction of 14 M. guttatus chromosomes requires at least eight fission events (likely shared by Simiolus and sister section Paradanthus (n=16)), plus two fusion events. This apparent burst of fission in the yellow monkeyflower lineages raises new questions about mechanisms and consequences of chromosomal fission in plants. Our comparative maps also provide insight into the origins of a chromosome exhibiting centromere-associated female meiotic drive and create a framework for transferring M. guttatus genome resources across the entire genus.

Abstract: Polyploidization plays an important role in species formation as chromosome doubling results in strong reproductive isolation between derivative and parental taxa. In this note I describe a new species, Mimulus peregrinus (Phrymaceae), which represents the first recorded instance of a new British polyploid species of Mimulus (2n = 6x = 92) that has arisen since the introduction of this genus into the United Kingdom in the 1800’s. Mimulus peregrinus presents floral and vegetative characteristics intermediate between Mimulus guttatus and Mimulus luteus, but can be distinguished from all naturalized British Mimulus species and hybrids based on a combination of reproductive and vegetative traits. Mimulus peregrinus displays high pollen and seed fertility as well as traits usually associated with genome doubling such as increased pollen and stomata size. The intermediate characteristics of Mimulus peregrinus between Mimulus guttatus (2n = 2x = 28)and Mimulus luteus (2n = 4x = 60-62), and its close affinity with the highly sterile, triploid (2n = 3x = 44-45) hybrid taxon Mimulus × robertsii (Mimulus guttatus × Mimulus luteus), suggests that Mimulus peregrinus mayconstitute an example of recent allopolyploid speciation.

Abstract: Erythranthe sect. Simiola includes 31 species from North America north of Mexico (s ome of them also occur in Mexico): E. arenicola, E. arvensis , E. brachystylis, E. caespitosa , E. calciphila, Erythranthe charlestonensis Nesom, sp. nov., Erythranthe chinatiensis Nesom, sp. nov., E. corallina, E. cordata, E. decora, E. geyeri , E. glaucescens , E. grandis, E. guttata, E. hallii, E. inamoena, E. laciniata, E. marmorata (including Mimulus whipplei ), E. michiganensis , E. microphylla, E. minor, E. nasuta, E. nudata, E. pardalis (including Mimulus cupriphilus), E. parvula, Erythranthe regni Nesom, sp. nov., E. scouleri , E. thermalis, E. tilingii, E. unimaculata, and E. utahensis . Seven additional species, Erythranthe brevinasuta Nesom, sp. nov., E. dentiloba, Erythranthe lagunensis Nesom, sp. nov., E. madrensis , E. pallens, E. pennellii , and Erythranthe visibilis Nesom, sp. nov., are endemic to Mexico, while E. glabrata sensu stricto occurs only in Mexico, Central America, and South America . Erythranthe geyeri, E. inamoena , and E. utahensis have previously been treated within M. glabratus. The species are divided into 6 informal groups, several including subgroups. Provided here are a key to species , a d cription and distribution map for each species, and details of typification for all names, including synonyms. Lectotypes are designated for Mimulus bakeri Gandoger and ten taxa named by E.L. Greene: M. arvensis, M. implexus, M. lucens, M. scouleri var. caespitosus , M. puberulus, Mimulus guttatus var. grandis, M. guttatus var. insignis, M. marmoratus, M. longulus, and M. subreniformis.

Abstract: Six comparative approaches widely employed in systematics-alpha taxonomy, nu- merical taxonomy, experimental hybridization, chemotaxonomy, allozyme comparisons, and DNA/ DNA hybridization-are critically compared for Mimulus sect. Erythranthe. Each approach is used to indicate the relationships of the same set of nine populations. The set was carefully chosen to represent fairly and fully the morphological and ecological diversity of the section. The results for each method are summarized in a key, crossing polygon, or dendrogram, as appropriate. The chemotaxonomic, allozyme comparisons, and repetitive DNA/DNA hybridization methods reveal significant differences clearly separating out one or more populations, e.g., M. rupestris, but tend, overall, to emphasize the underlying similarities of the whole Erythranthe section. The alpha taxo- nomic, numerical taxonomic, and experimental hybridization methods distinguish subgroups of populations as well as differentiating the populations comprising the subgroups. The six methods are only partially congruent, but they are definitely complementary. Taken together, the numerical taxonomic and experimental hybridization methods produce the clearest distinctions and groupings of the entities of the section and would be the most useful for floristic studies. The other methods add clarity and detail important in monographic studies.