DNA Restriction Site Variation Research Articles

Mitochondrial discrimination of stingless beesTetragonisca angustula(Apidae: Meliponini) from Santa Catarina state, Brazil

The stingless bee Tetragonisca angustula is a meliponini bee naturally distributed from Argentina to Mexico. Morphologically, based on the mesepisternum color, it is separated into T. angustula angustula and T. angustula fiebrigi subspecies. The objective of this study was to characterize the restriction site variation in the mitochondrial DNA of each subspecies. Samples of worker bees were collected from two regions of Santa Catarina state, known as having a natural distribution of each subspecies. Each of the 138 colonies collected in the distribution region of T. a. angustula and of 72 colonies from the region of T. a. fiebrigi was individually analyzed. The ATPases 8, 6 and COIII mitochondrial genes were amplified and digested with seven restriction enzymes (PCR + RFLP). Large genetic differences were observed among bees collected in both geographical areas of natural distribution for the T. angustula subspecies. Four enzymes showed different restriction patterns that allowed separation of the subspecies.

Detection of mitochondrial DNA restriction site differences between the subspecies of Melipona quadrifasciata Lepeletier (Hymenoptera: Apidae: Meliponini)

The endemic range of the stingless bee Melipona quadrifasciata Lepeletier extends from the southern most state in Brazil, Rio Grande do Sul, up to the state of Paraíba, where it originally inhabited the Atlantic Rain Forest. Two subspecies have been morphologically recognized based on the tergal band pattern (yellow stripes across the abdomen), M. q. quadrifasciata and M. q. anthidioides. The objective of the present study was to characterize restriction site variation in the mitochondrial DNA of each subspecies. Four colonies of each subspecies were sampled. One individual per colony was used for DNA extraction and further analysis through amplification of nine fragments of the mitochondrial genome and digestion with 13 restriction enzymes (PCR+RFLP). Three enzymes showed restriction pattern differences between the subspecies. Those differences will be useful to determine the maternal origin of hybrids colonies, which may occur naturally or due to colony transportation among breeders.

Relationships in Ananas and other related genera using chloroplast DNA restriction site variation.

Chloroplast DNA (cpDNA) diversity was examined using PCR-RFLP to study phylogenetic relationships in Ananas and related genera. One hundred fifteen accessions representing the seven Ananas species and seven other Bromelioideae including the neighboring monospecific genus Pseudananas, two Pitcairnioideae, and one Tillandsioideae were included in the study. Eight primers designed from cpDNA were used for generating fragments. Restriction by 18 endonucleases generated 255 variable fragments. Dissimilarities were calculated from the resulting matrix using the Sokal and Michener index and the neighbor-joining method was used to reconstruct the diversity tree. Phylogenetic reconstruction was attempted using Wagner parsimony. Phenetic and cladistic analyses gave consistent results. They confirm the basal position of Bromelia in the Bromelioideae. Ananas and Pseudananas form a monophyletic group, with three strongly supported sub-groups, two of which are geographically consistent. The majority of Ananas parguazensis accessions constitute a northern group restricted to the Rio Negro and Orinoco basins in Brazil. The tetraploid Pseudananas sagenarius joins the diploid Ananas fritzmuelleri to constitute a southern group. The third and largest group, which includes all remaining species plus some accessions of A. parguazensis and intermediate phenotypes, is the most widespread and its distribution overlaps those of the northern and southern groups. Ananas ananassoides is dominant in this sub-group and highly variable. Its close relationship to all cultivated species supports the hypothesis that this species is the wild ancestor of the domesticated pineapple. The data indicate that gene flow is common within this group and scarcer with both the first and second groups. Comparison of cpDNA data with published genomic DNA data point to the hybrid origin of Ananas bracteatus and support the autopolyploidy of Pseudananas. The Ananas-Pseudananas group structure and distribution are consistent and we propose a scenario based on the refugia hypothesis to explain our data. These results and hypotheses bring some interesting points to consider in the current discussion on Ananas taxonomy.

Evolution of Hedera (the Ivy Genus, Araliaceae): Insights from Chloroplast DNA Data

Hedera L., the ivy genus, comprises approximately 16 taxa distributed throughout Europe, North Africa, Macaronesia, and Asia. Phylogenetic relationships within Hedera were examined using chloroplast DNA restriction site variation and noncoding sequence data. The cpDNA data were compared with the published nuclear ribosomal internal transcribed spacer (ITS) data. Phylogenetic incongruence between the two data sets is evident, with no identical clades shared between the topologies. Three centers of diversification for Hedera are hypothesized: Europe, Western Asia, and the Macaronesian region, with allopolyploidization playing a major part in the evolution of Hedera. The maternal parents of the polyploid species H. hibernica, H. iberica, and H. pastuchovii are identified on the basis of the comparison of the chloroplast DNA phylogeny and the ITS topology. The diploid H. helix is supported as the maternal parent of the tetraploid H. hibernica. The comparison of the cpDNA and the ITS phylogenies also indicates that H. canariensis was the diploid maternal ancestor that hybridized with H. hibernica, resulting in the formation of H. iberica. The maternal parent of the hexaploid H. pastuchovii is perhaps H. nepalensis var. sinensis. Diversification of taxa in each region is relatively recent, as indicated by relatively low levels of sequence divergence.

Chloroplast DNA evidence for the roles of island colonization and extinction in Tolpis (Asteraceae: Lactuceae)

Tolpis consists of ∼13 species native to Africa, Europe, and Macaronesia, with at least one species endemic to each of the four major archipelagos of the Azores, Madeira Islands, Canary Islands, and Cape Verde Islands. All but two of these species develop woody stems by maturity. Chloroplast DNA restriction site variation was analyzed for all species of Tolpis and four outgroups in order to understand the patterns of island colonization and evolution of woodiness in this genus. Parsimony analyses revealed a strongly supported monophyletic Tolpis. Within the genus, the following three well-supported groups were detected: all species from the Canary Islands and Cape Verde Islands, both Azorean species, and both continental species. The Canary Island/Cape Verde clade was sister to the two continental species, and the Azorean clade was sister to this group. The two Madeiran species of Tolpis occupied the basalmost positions within the genus. When biogeography was mapped onto this phylogeny, nine equally parsimonious reconstructions (five steps each) of dispersal history were detected, which fell into two groups: eight reconstructions implied that Tolpis colonized Madeira from the continent, followed by continental extinction and subsequent continental recolonization, while one reconstruction implied that Tolpis colonized Macaronesia four times. Two of the reconstructions involving continental extinction required the least amount of overall dispersal distance. The cpDNA phylogeny also suggests that woodiness arose in the common ancestor of all extant Tolpis, followed by two independent reversals to an herbaceous habit. Assuming that one of the eight reconstructions favoring continental extinction and recolonization is true, our results suggest that Tolpis may represent the first documented example of a woody plant group in Macaronesia that has recolonized the mainland in herbaceous form.

Population Genetics of Southeastern Wood Ducks

Numerous studies document nest-site philopatry in wood ducks (Aix sponsa). Such behavior should promote unique genetic structure among breeding populations. This hypothesis was tested by analyzing restriction site variation in mitochondrial DNA (mtDNA) of 218 nesting wood duck hens. We tested the utility of mtDNA variation in identifying migrants from a sample of 92 wood ducks harvested by duck hunters. Genetic variation was found only in the cytochrome b gene. Statistically significant genetic structure existed among 8 breeding populations, but was a function of haplotype frequencies in 1 population that differed from the other 7. Restriction enzyme digestion revealed 2 haplotypes common to all populations and 3 rare haplotypes. Haplotype diversity within populations was low with respect to other avian studies. Direct sequence analysis of 41 wood ducks produced 2 common and 16 rare mtDNA haplotypes with no geographic structure. Hunter-harvested birds had similar haplotypes as breeding birds. For many years, wood duck managers in the southeastern United States have been interested in delineating subpopulations of wood ducks. Our data may reinforce and broaden existing efforts to manage southern wood ducks using management units determined by band returns.

RediscoveringRana onca: Evidence for Phylogenetically Distinct Leopard Frogs from the Border Region of Nevada, Utah, and Arizona

Remnant populations of leopard frogs within the Virgin River drainage and adjacent portions of the Colorado River (Black Canyon) in northwestern Arizona and southern Nevada either represent the reportedly extinct taxon Rana onca or northern, disjunct Rana yavapaiensis. To determine the evolutionary distinctiveness of these leopard frogs, we evaluated mitochondrial DNA (mtDNA) restriction site variation (RFLP), mtDNA control region sequences, randomly amplified polymorphic DNA (RAPD) markers, and morphological characters. Individuals from the Virgin River drainage and Black Canyon represented a single RFLP haplotype and were identical for nucleotides along a portion of control region sequence. Evaluations of RAPD data demonstrated high levels of similarity among individuals and populations from this region. Leopard frogs from the Virgin River drainage and Black Canyon differed from R. yavapaiensis from west-central Arizona and northern Mexico in maximum parsimony and distance analyses of RFLP and control region sequence data and in maximum-likelihood analysis of the sequence data. Multidimensional scaling of RAPD data provided a similar and congruent indication of this separation. Analysis of principal component scores demonstrated significant morphological differentiation between leopard frog specimens from the Virgin River drainage and R. yavapaiensis. Parallel patterns of divergence observed in the mtDNA, RAPD, and morphological analyses indicate that leopard frogs from the Virgin River drainage and adjacent portions of the Colorado River are phylogenetically distinct. These leopard frogs should be recognized as a lineage separate from southern populations of R. yavapaiensis and classified as the species R. onca.

Phylogenetic relationships in tribe Lepidieae (Brassicaceae) based on chloroplast DNA restriction site variation

Tribal and subtribal boundaries within the Brassicaceae are often artificially drawn. Most of the currently recognized tribes and subtribes are separated by only a few morphological characters. Furthermore, these characters are variable even within genera, or they conflict with one another in their distribution patterns, resulting in controversial classification systems. Therefore, tribes and subtribes as traditionally delimited may not reflect natural groups. Up to now no cladistic analysis has been performed in tribe Lepidieae. In the current study, we have analyzed restriction site variation of chloroplast DNA among 41 species representing 19 genera to get insights into phylogenetic relationships within the Lepidieae. Phylogenetic lineages derived from our chloroplast data were critically compared with the traditional concepts. Our chloroplast DNA phylogeny most easily supports the classification of genera in the system of Hayek with some modifications.

Restriction Site Variation in Ribosomal DNA in 24 Species of the Order Galliformes

Examination of restriction site length polymorphism (RFLP) in the nuclear ribosomal RNA (rDNA) gene in four species of jungle fowl showed that a Sac I site in the external spacer region exists in the three jungle fowl, Gallus sonnerati, G. lafayettei and G. varius but is entirely absent in the domestic fowl, G. gallus. In order to understand the phylogenetic meaning, an interspecific survey on restriction site variation in 4 species of Gallus and 20 related genera that belong to 12 species of the same family Phasianidae and 8 species of the families Meleagrididae, Tetoraonidae, Odontophoridae, Numididae, Megapodidae and Cracidae that belong to the order Galliformes was performed. A Sac I fragment of 2.7kb in length was observed consistently in the members of Phasianidae, except for G. gallus, Phasianus versicolor and Lophophorus impeyanus using the Southern blot survey with the 18S mouse rDNA probe. On the other hand, the length of Sac I fragments in the other species of outgroups differed from that of the common type of Phasianidae. Our data thus indicated that the presence of the Sac I site in the spacer region was a common feature of the ancestral branch of the family Phasianidae and that the site had differentiated until it was lost in G. gallus during the course of speciation. It is suggested, therefore, that the absence of the Sac I site may be a convenient diagnostic marker of G. gallus in surveys of genetic backgrounds in stocks of domestic fowl as well as populations of jungle fowl.

Phylogenetic Relationships Within Lithophragma (Saxifragaceae): Hybridization, Allopolyploidy, and Ovary Diversification

We explore phylogenetic relationships in Lithophragma through parsimony and maximum like- lihood estimation analyses of internal transcribed spacer sequences of 18S-26S ribosomal DNA. Results based on internal transcribed spacer sequences are compared with those from previous studies based on chloroplast DNA restriction site, morphological, and flavonoid variation. Phylogenetic analysis of internal transcribed spacer sequences produces a highly resolved topology with six main clades. These results suggest that three previously described species of Lithophragma are not monophyletic. Based on this topology and previous findings, two species not recognized in the most recent monograph, L. thompsonii and tetraploid L. bolanderi, are hypothesized to have arisen through hybridization and allopolyploidy, respectively. Flowers of Lithophrag- ma exhibit a diverse array of ovary positions ranging from what has been described as superior to deeply inferior. Analysis of ovary position in light of our phylogenetic results reveals a complex pattern of diversi- fication in Lithophragma. This pattern is explored through character mapping and correlation analyses and is found to be inconsistent with either an active or a passive trend toward greater inferiority. A weak relation- ship between variation in ovary position and the topological position of each taxon suggests homoplastic

Evolutionary history of an adaptive radiation in species pairs of threespine sticklebacks (Gasterosteus): insights from mitochondrial DNA

Species pairs of threespine stickleback, Gasterosteus aculeatus, co-exist in several lakes in the Strait of Georgia, southwestern British Columbia. One species, ‘benthics’ is robust-bodied and is morphologically and behaviourally specialized for benthivory. The other species, ‘limnetics’ is specialized for planktivory in open-water habitats of the lakes. We examined mitochondrial DNA restriction site variation in benthic and limnetic sticklebacks as well as in solitary freshwater, anadromous (sea-run), and marine populations to test: (i) if benthic and limnetic pairs have evolved only once or multiple times (parallel evolution) and (ii) if the species have evolved sympatrically, or allopatrically from ‘double invasions’ of lakes by ancestral anadromous/marine sticklebacks. Stickleback mtDNA comprised a single clade with a low (mean = 0.40%) degree of sequence divergence among the 77 haplotypes resolved. Most nucleotide diversity (97%) was found within (rather than among) populations of anadromous/marine sticklebacks whereas most diversity (77%) was found among populations in freshwater sticklebacks. Significant differences in haplotype frequencies were found between benthics and limnetics in three of the four species pair lakes examined, but in all cases the pairs within lakes were characterized by unique assemblages of closely related haplotypes. Hierarchical clustering of divergence estimates suggested that comparable species from different lakes have originated independently in all lakes because in no case did comparable species from different lakes cluster together. Divergent species within lakes tended to be more closely related to one another than to species in other lakes and there were two cases were benthics and limnetics within a particular lake were monophyletic. In two of the four two-species lakes, limnetics were less divergent from putative ancestral anadromous/marine stickleback as predicted by the double invasion hypothesis, but in the two other lakes benthics were less divergent. Our data argue strongly that the species pairs have evolved independently in each lake were they now co-exist. Further, in two lakes our data are consistent with the species having evolved by sympatric divergence, but allopatric divergence followed by introgression of mtDNA that has obscured ancestral relationships cannot be discounted completely. Finally, despite remaining uncertainty about the geography of speciation, the species appear to have evolved in the face of gene flow arguing that natural selection acting on trophic ecology has been a major component of ecological speciation in sticklebacks.

Evolutionary history of an adaptive radiation in species pairs of threespine sticklebacks (Gasterosteus): insights from mitochondrial DNA

Species pairs of threespine stickleback,Gasterosteus aculeatus, co-exist in several lakes in the Strait of Georgia, southwestern British Columbia. One species, «benthics» is robust-bodied and is morphologically and behaviourally specialized for benthivory. The other species, «limnetics» is specialized for planktivory in open-water habitats of the lakes. We examined mitochondrial DNA restriction site variation in benthic and limnetic sticklebacks as well as in solitary freshwater, anadromous (sea-run), and marine populations to test: (i) if benthic and limnetic pairs have evolved only once or multiple times (parallel evolution) and (ii) if the species have evolved sympatrically, or allopatrically from «double invasions» of lakes by ancestral anadromous/marine sticklebacks. Stickleback mtDNA comprised a single clade with a low (mean=0.40%) degree of sequence divergence among the 77 haplotypes resolved. Most nucleotide diversity (97%) was found within (rather than among) populations of anadromous/marine sticklebacks whereas most diversity (77%) was found among populations in freshwater sticklebacks. Significant differences in haplotype frequencies were found between benthics and limnetics in three of the four species pair lakes examined, but in all cases the pairs within lakes were characterized by unique assemblages of closely related haplotypes. Hierarchical clustering of divergence estimates suggested that comparable species from different lakes have originated independently in all lakes because in no case did comparable species from different lakes cluster together. Divergent species within lakes tended to be more closely related to one another than to species in other lakes and there were two cases were benthics and limnetics within a particular lake were monophyletic. In two of the four two-species lakes, limnetics were less divergent from putative ancestral anadromous/marine stickleback as predicted by the double invasion hypothesis, but in the two other lakes benthics were less divergent. Our data argue strongly that the species pairs have evolved independently in each lake were they now co-exist. Further, in two lakes our data are consistent with the species having evolved by sympatric divergence, but allopatric divergence followed by introgression of mtDNA that has obscured ancestral relationships cannot be discounted completely. Finally, despite remaining uncertainty about the geography of speciation, the species appear to have evolved in the face of gene flow arguing that natural selection acting on trophic ecology has been a major component of ecological speciation in sticklebacks.

Mitochondrial DNA sequence variation among populations and host races of Lambdina fiscellaria (Gn.) (Lepidoptera: Geometridae).

The hemlock looper, Lambdina fiscellaria (Gn.), is a recurring major forest pest that is widely distributed in North America. Three subspecies (L. f. fiscellaria, L. f. lugubrosa (Hulst) and L. f. somniaria (Hulst)) have been recognized based on larval host or adult pheromone differences, but no consistent morphological differences have been reported. To clarify their taxonomic status, we surveyed mitochondrial DNA (mtDNA) sequence and restriction site variation in two protein coding genes, cytochrome oxidase I and II (COI and COII), in populations across the range of L. fiscellaria. In addition to variation in COI and COII, we found an intergenic spacer region of 20-23 bp located between the tRNA tyrosine gene and the start of COI. Of the 141 specimens of L. fiscellaria assayed, 137 were grouped into two distinct mtDNA lineages, one of which was disproportionately associated with eastern populations and one with western populations. However, single specimens and two populations in eastern Canada had mtDNA resembling that of western populations. Three divergent and rare haplotypes had basal affinities to the two common lineages. The two major lineages of L. fiscellaria were diverged by approximately 2% from each other, as well as from the mtDNA of two outgroup species, L. athasaria (Walker) and L. pellucidaria(G. & R.). The two outgroup species had essentially the same mtDNA and may be conspecific. We interpret the pattern of mtDNA variation within L. fiscellaria as indicating genetic polymorphism within a single species without clear subspecific divisions, rather than evidence of multiple cryptic species.

Phylogenetic relationships in tribe Lepidieae (Brassicaceae) based on chloroplast DNA restriction site variation

Phylogenetic relationships in tribe Lepidieae (Brassicaceae) based on chloroplast DNA restriction site variation

Molecular Phylogeny of Artemisia Section Tridentatae (Asteraceae) Based on Chloroplast DNA Restriction Site Variation

Chloroplast DNA restriction site variation was used to examine phylogenetic relationships in Artemisia sect. Tridentatae, a complex of eleven species of woody shrubs, which are dominant components of sagebrush communities of western North America. Twenty-seven endonucleases were utilized to identify 82 variable site mutations, 27 of which were phylogenetically informative. The resulting cpDNA phylogeny indicates that sect. Tridentatae is monophyletic, with the exception of A. palmeri and A. bigelovii, two historically anomolous species. A sister-group relationship between A. palmeri and species of subg. Artemisia supports the exclusion of A. palmeri from sect. Tridentatae (subg. Seriphidium), and its inclusion within subg. Artemisia. Artemisia bigelovii, a species with heterogamous capitula, is nested within the Tridentata clade, supporting its inclusion within the section. Introgression and subsequent chloroplast capture of the Tridentatae genome by two unrelated species, A. californica and A. fihlifolia, may explain the unexpected placement of these two species in the Tridentata clade. Low cpDNA sequence divergence provides only limited resolution of phylogenetic relationships within sect. Tridentatae, indicative of a recently differentiated and/or hybridizing polymorphic species complex. In addition, the cpDNA data provide only equivocal evidence for either of two competing hypotheses regarding the origin and phylogenetic relationship of sect. Tridentatae within Artemisia s.l.

TESTING MODELS OF MIGRATION AND ISOLATION AMONG POPULATIONS OF CHINOOK SALMON (ONCORHYNCHUS TSCHAWYTSCHA)

The chinook salmon (Oncorhynchus tschawytscha) is a behaviorally, morphologically, and ecologically variable species distributed over a large geographic range. Although previous genetic surveys have revealed considerable genetic differences among populations with different life history types and from different major river drainages, it is not clear to what degree these genetically distinct populations are connected by low levels of gene flow. The work described in this paper addresses this question by surveying DNA restriction site variation at six nuclear genes from nine populations encompassing most of the species's North American range, and then attempting to fit the patterns of variation observed at these genes to five different evolutionary models using computer simulations of the coalescent process. Two commonly used constant population size models, one hypothesizing no migration among populations and one hypothesizing equal rates of migration among populations, were found to be statistically inconsistent with the observed patterns of variation. The other three models, which involved either recent divergence among populations coupled with large changes in populations size, unequal migration rates among populations, or selection, were all found to be consistent with the observed patterns of variation. Assuming selective neutrality, these results suggest that either the populations have all descended from a common ancestral population within the last ~50,000 years and have all suffered large declines in effective population size since that time, or that they have a more ancient divergence time but are connected by low levels of gene flow. These conclusions rest on the assumption of selective neutrality. With the methods employed, it was not possible to simultaneously test hypotheses of both selective neutrality and population structure.

PARALLEL EVOLUTION OF LAKE-STREAM PAIRS OF THREESPINE STICKLEBACKS (GASTEROSTEUS) INFERRED FROM MITOCHONDRIAL DNA VARIATION.

Three drainage systems in British Columbia, Canada, contain divergent parapatric lake-stream pairs of threespine sticklebacks (Gasterosteus aculeatus): Drizzle and Mayer Lakes on Graham Island, Queen Charlotte Islands, and Misty Lake on northeastern Vancouver Island. Ecological and morphological differences between members of all three lake-stream pairs are strikingly similar; lake fish are melanistic and slim bodied with smaller mouths and more gill rakers than the mottled-brown and robust-bodied stream sticklebacks. We estimated the level of genetic divergence between lake and stream fish in Misty Lake and tested hypotheses of single versus multiple origins of the pairs by assaying mitochondrial DNA (mtDNA) restriction site variation in samples from the three lake systems. MtDNA analysis revealed the existence of two highly divergent lineages differing by 2.7% in sequence. One lineage predominated in Misty stream fish (73%), whereas the other lineage predominated in Misty Lake samples (96%). Comparable forms (lake or stream) in the different lakes did not cluster together in terms of mtDNA nucleotide divergence, suggesting that the pairs have had independent origins. We concluded that: (1) divergent mtDNA lineages in North Pacific sticklebacks stem from historical isolation in the two major glacial refugia proposed for the North Pacific (Beringia and Cascadia); (2) the stream and lake pair in Misty Lake are distinct gene pools; (3) the divergence between parapatric lake and stream Gasterosteus represents parallel evolution having occurred at least twice in the North Pacific; and (4) different scales of evolutionary divergence exist in North Pacific Gasterosteus, that is, a relatively ancient divergence of mtDNA clades as well as recent (i.e., postglacial) divergence of ecotypes within major clades.

Chloroplast DNA Evidence for Divergence in Ferocactus and its Relationships to North American Columnar Cacti (Cactaceae: Cactoideae)

An analysis of chloroplast DNA restriction site variation was undertaken to investigate the evolutionary divergence of Ferocactus and its possible relationship with North American columnar cacti of tribe Pachycereeae. Our chloroplast DNA study using parsimony-based phylogenetic reconstruction methods provides molecular synapomorphies to define major lineages within Ferocactus and columnar cacti of the tribe Pachycereeae. The issue of monophyly in Ferocactus remains problematic: it appears to be a paraphyletic assemblage derived from an Echinocactus-like ancestor from which three major lineages have evolved. Also, there is a lack of support for the hypothesized basal position of F flavovirens and F robustus, and no evidence was found to favor the phylogenetic relationship of Ferocactus with North American columnar cacti, in particular with Escontria chiotilla. For the columnar cacti, the study supports the monophyly of the tribe Pachycereeae as well as its two subtribes: Stenocereinae and Pachycereinae. In the Stenocereinae, Stenocerelus dumortieri was found to be in a basal position, and forms a phylogenetically distinct lineage from Stenocereus s. str. and other columnar cacti such as Escontria, Polaskia, and Myrtillocactuis. This supports the segregation of S. dumortieri from Stenocereus, and the resurrection of Isolatocereus dumortieri as a distinct genus.

Phylogenetic implications of chloroplast DNA restriction site variation in subtribes Raphaninae and Cakilinae (Brassicaceae, tribe Brassiceae)

Chloroplast DNA restriction site data was used to assess relationships among 41 taxa of the subtribes Raphaninae and Cakilinae (tribe Brassiceae, Brassicaceae). A total of 456 restriction site mutations was observed, with 237 (52%) being phylogenetically informative. Cladistic analysis, based on Wagner parsimony analysis, indicated four major clades: (i) CAKILE, (ii) CRAMBE, (iii) NIGRA lineage, and (iv) RAPA-OLERACEA lineage. The CAKILE clade was divided into two lineages: (i) Cakile, Erucaria (including Reboudia), and Didesmus (previously assigned by Schulz to the Raphaninae) and (ii) Crambella (previously assigned by Schulz to the Raphaninae). The Raphaninae as currently circumscribed is polyphyletic in origin. The cpDNA data supported separate subtribal status for Crambe (Raphaninae) and indicated two major lineages corresponding to sect. Dendrocrambe and the combined sections Crambe and Leptocrambe. Enarthrocarpus arcuatus, Enarthrocarpus lyratus, Morisia monanthos, Raphanus raphanistrum, Raphanus sativus, and Rapistrum perenne were included in the RAPA-OLERACEA lineage of subtribe Brassicinae. Ceratocnemum rapistroides, Cordylocarpus muricatus, Guiraoa arvensis, Hemicrambe fruticulosa, Kremeriella cordylocarpus, Muricaria prostrata, Otocarpus virgatus, Raffenaldia primuloides, and Rapistrum rugosum were included in the NIGRA lineage of subtribe Brassicinae. Key words: Brassicinae, Raphaninae, Cakilinae, chloroplast DNA restriction site variation, molecular systematics.

Reexamination of series relationships of South American wild potatoes (Solanaceae: Solanum sect. Petota): evidence from chloroplast DNA restriction site variation

Chloroplast DNA (cpDNA) restriction enzyme site analysis was used to test hypotheses of series and superseries affiliations of 76 taxa, representing 11 of the 13 South American series (material unavailable for two series) of wild potatoes (Solanum sect. Petota) recognized in the latest classification by Hawkes. The cladistic results, combined with those from earlier cpDNA studies of 30 taxa of the Mexican and Central American species (representing eight series; ser. Conicibaccata and ser. Tuberosa have representatives in Mexico and in South America), support four main clades for 17 of the 19 series examined in sect. Petota: (1) the Mexican and Central American diploid species, exclusive of S. bulbocastanum, S. cardiophyllum, and S. verrucosum, (2) S. bulbocastanum and S. cardiophyllum (ser. Bulbocastana, ser. Pinnatisecta), (3) South American diploid species constituting all of ser. Piurana, but also members of ser. Conicibaccata, ser. Megistacroloba, ser. Tuberosa, and ser. Yungasensia, (4) all Mexican and Central American polyploid species (ser. Longipedicellata, ser. Demissa), S. verrucosum (diploid Mexican species in ser. Tuberosa), and South American diploid and polyploid members of ser. Acaulia, ser. Circaeifolia, ser. Commersoniana, ser. Conicibaccata, ser. Cuneoalata, ser. Lignicaulia, ser. Maglia, ser. Megistacroloba, ser. Tuberosa, and ser. Yungasensia. Each of these clades contains morphologically and reproductively very diverse species, and there are no evident morphological features that unite members within a clade to therefore distinguish them. These results strongly suggest a need for a reevaluation of the series and superseries classifications of sect. Petota.