Topic
Mitella
About: Mitella is a research topic. Over the lifetime, 33 publications have been published within this topic receiving 940 citations. The topic is also known as: Bishop's cap & Mitrewort.
Papers
TL;DR: This finding indicates that the use of multiple molecular tools has the potential to reveal detailed organismal evolution processes involving interspecific hybridization, as an individual locus varies greatly in its potential to introgress between species.
Abstract: Interspecific hybridization is one of the major factors leading to phylogenetic incongruence among loci, but the knowledge is still limited about the potential of each locus to introgress between species. By directly sequencing three DNA regions: chloroplast DNAs (matK gene and trnL-F noncoding region), the nuclear ribosomal external transcribed spacer (ETS) region, and internal transcribed spacer (ITS) regions, we construct three phylogenetic trees of Asian species of Mitella (Saxifragaceae), a genus of perennials in which natural hybrids are commonly observed. Within this genus, there is a significant topological conflict between chloroplast and nuclear phylogenies and also between the ETS and the ITS, which can be attributed to frequent hybridization within the lineage. Chloroplast DNAs show the most extensive introgression pattern, ITS regions show a moderate pattern, and the ETS region shows no evidence of introgression. Nonuniform concerted evolution best explains the difference in the introgression patterns between the ETS region and ITS regions, as the sequence heterogeneity of the ITS region within an individual genome is estimated to be twice that of an ETS in this lineage. Significant gene conversion patterns between two hybridizing taxa were observed in contiguous arrays of cloned ETS-ITS sequences, further confirming that only ITS regions have introgressed bidirectionally. The relatively slow concerted evolution in the ITS regions probably allows the coexistence of multiple alleles within a genome, whereas the strong concerted evolution in the ETS region rapidly eliminates heterogeneous alleles derived from other species, resulting in species delimitations highly concordant with those based on morphology. This finding indicates that the use of multiple molecular tools has the potential to reveal detailed organismal evolution processes involving interspecific hybridization, as an individual locus varies greatly in its potential to introgress between species.
167 citations
TL;DR: It is suggested that past glaciation may have created discontinuities in the geographic distribution of T. grandiflora following migration of once-isolated populations possessing different chloroplast genomes resulted in the formation of a continuous geographic distribution with a major organellar discontinuity.
Abstract: Tellima grandiflora, a herbaceous, diploid (2n = 14) perennial, is distributed from the peninsula and panhandle of Alaska to central California. Restriction site variation of chloroplast DNA was surveyed in 51 populations representing the geographic range of T. grandiflora using 20 endonucleases. Two well-differentiated clades of populations differing by 19 restriction site mutations and several length mutations are geographically structured. A northern group comprises populations from Alaska to central Oregon; populations from central Oregon to San Francisco, California, form a southern group. The southern lineage of the monotypic Tellima appears to have obtained its chloroplast genome via ancient hybridization with a species of Mitella. Although northern and southern lineages have well-differentiated chloroplast genomes, populations of T. grandiflora show a high degree of genetic similarity of nuclear-encoded allozymes; furthermore, no apparent morphological differences characterize the lineages. Significantly, several populations of T. grandiflora that possess the typical southern chloroplast genome also occur disjunctly on Prince of Wales Island, Alaska, and the Olympic Peninsula, Washington. Because both areas are proposed glacial refugia, we suggest that past glaciation may have created discontinuities in the geographic distribution of T. grandiflora. Following glaciation, migration of once-isolated populations possessing different chloroplast genomes resulted in the formation of a continuous geographic distribution with a major organellar discontinuity. Additional support for this hypothesis is provided by the presence of welldifferentiated northern and southern chloroplast DNA lineages in Tolmiea menziesii, a species having a geographic distribution and life history traits similar to those of Tellima.
87 citations
TL;DR: Investigation of plastome evolution across the Saxifragaceae family, reconstructed the phylogeny of the Heuchera group and examined putative plastid capture between Heucera and Tiarella revealed multiple plastids capture events have occurred through putative ancient hybridization, and developed numerous molecular markers for Tiarella.
Abstract: Saxifragaceae, a family of over 600 species and approximately 30 genera of herbaceous perennials, is well-known for intergeneric hybridization. Of the main lineages in this family, the Heuchera group represents a valuable model for the analysis of plastid capture and its impact on phylogeny reconstruction. In this study, we investigated plastome evolution across the family, reconstructed the phylogeny of the Heuchera group and examined putative plastid capture between Heuchera and Tiarella. Seven species (11 individuals) representing Tiarella, as well as Mitella and Heuchera, were selected for genome skimming. We assembled the plastomes, and then compared these to six others published for Saxifragaceae; the plastomes were found to be highly similar in overall size, structure, gene order and content. Moreover, ycf15 was lost due to pseudogenization and rpl2 lost its only intron for all the analyzed plastomes. Comparative plastome analysis revealed that size variations of the plastomes are purely ascribed to the length differences of LSC, SSC, and IRs regions. Using nuclear ITS + ETS and the complete plastome, we fully resolved the species relationships of Tiarella, finding that the genus is monophyletic and the Asian species is most closely related to the western North American species. However, the position of the Heuchera species was highly incongruent between nuclear and plastid data. Comparisons of nuclear and plastid phylogenies revealed that multiple plastid capture events have occurred between Heuchera and Tiarella, through putative ancient hybridization. Moreover, we developed numerous molecular markers for Tiarella (e.g., plastid hotspot and polymorphic nuclear SSRs), which will be useful for future studies on the population genetics and phylogeography of this disjunct genus.
52 citations
TL;DR: Generic relationships suggest generic relationships that agree with those based on morphology, flavonoid chemistry, and crossability of Saxifraginae genera.
Abstract: A base chromosome number of x = 7 characterizes many genera of the Saxifraginae. A high degree of karyotypic constancy was found among species representing six of these genera (Boykinia, Heuchera, Mitella, Sullivantia, Tiarella, and Tolmiea). Boykinia aconitifolia and six species of Sullivantia are characterized by the same karyotype. Four species of Heuchera, Mitella diphylla, Tiarella cordifolia, and Tolmiea menziesii (the last at the tetraploid level) possess a second karyotype that differs from the first in the position of the centromere of only one chromosome pair. These karyological observations suggest generic relationships that agree with those based on morphology, flavonoid chemistry, and crossability.
52 citations
TL;DR: Since these genera are vegetatively very homogeneous and differ largely in floral morphology, the occurrence of intergeneric hybrids sug- gests that they may not be highly differentiated genetically may suggest that barriers to crossability often are not well-developed among genera of this tribe.
Abstract: Based on morphology, intergeneric hybridization appeared evident between Conimi- tella williamsii and Mitella stauropetala in a mixed population of these species from western Wyoming. Evidence from starch gel electrophoresis confirmed the occurrence of natural intergeneric hybrid- ization between these taxa. Conimitella williamsii and M. stauropetala each possess unique allozymes at four of 18 loci examined. Using these allozymes as markers, plants of intermediate morphology were determined to be of hybrid origin. Electrophoretic data also suggest that several additional plants were the result of backcrossing of F1 hybrid plants to M. stauropetala, or that they are F2 or later generation plants. Although this is the first report of intergeneric hybridization between Conimitella and Mitella, naturally occurring hybrids have been reported between other related gen- era of tribe Saxifrageae, including Mitella and Tiarella, and Tellima and Tolmiea. The occurrence of hybrids between so many genera of Saxifrageae suggests that barriers to crossability often are not well-developed among genera of this tribe. Furthermore, since these genera are vegetatively very homogeneous and differ largely in floral morphology, the occurrence of intergeneric hybrids sug- gests that they may not be highly differentiated genetically.
40 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2020 | 2 |
| 2018 | 1 |
| 2017 | 1 |
| 2016 | 2 |
| 2014 | 1 |