Beryl B. Simpson

Paraphyly of Tarasa (Malvaceae) and Diverse Origins of the Polyploid Species

Abstract A molecular phylogenetic analysis of the Andean genus Tarasa (Malvaceae) and related genera yielded unexpected results regarding generic boundaries, the origins of polyploidy, and the morphological attributes of the polyploid taxa. The polyploid species of Tarasa are particularly unusual because they have life histories and floral morphologies that contradict two traditional polyploid dogmas: they are annuals and have smaller floral features (including pollen) than the diploid species. Typically, polyploids are perennial and larger than their parents. Nuclear (ITS1, 5.8S, and ITS2) and chloroplast (psbA-trnH and trnT-trnL spacers, matK-3′ trnK intron) sequence data were used to reconstruct independent phylogenies to test the monophyly of the genus, determine its sister group(s), and investigate the origin of the polyploid species. Neither the nuclear nor the chloroplast phylogeny supports monophyly of Tarasa as currently circumscribed. The high Andean genus Nototriche, the North/South American disjunct genus Sphaeralcea, and Malacothamnus chilensis are placed within the Tarasa clade. The polyploid species of Tarasa are not monophyletic and thus have been generated multiple times. These findings suggest that the unusual morphological features of the tetraploids are the result of convergent evolution and not shared ancestry.

Phylogenetic Relationships and Chromosome Number Evolution in Passiflora

Abstract The phylogenetic relationships and chromosomal evolution of the diverse tropical genus Passiflora (Passifloraceae) are explored using data from two chloroplast markers: the rpoC1 intron and the trnL/trnT spacer region. A survey of the presence or absence of the rpoC1 intron in 136 species representing 17 of Killips (1938) 22 subgenera of Passiflora and four other genera in the Passifloraceae revealed intron losses in 46 taxa. A minimum of two losses were confirmed by a parametric bootstrap approach on sequence data from the trnL/trnT chloroplast non-coding region for 61 taxa. The results of phylogenetic analyses of the trnL/trnT sequence data support the reduction of Killips 22 subgenera to four as proposed in a new classification system by Feuillet and MacDougal (2004). The monophyly of the ‘n=6’ and ‘n=9’ chromosomal and morphological groups is strongly supported. In addition, these data indicate that Passiflora biflora, or closely related species, is the likely continental sister to the red-flowered Caribbean taxa, while P. auriculata is weakly supported as the New World sister to the Old World Passifloras. Finally, character optimization of chromosome numbers on the phylogenetic tree supports x=12 as the base chromosome number for Passiflora.

Biogeography and Breeding System Evolution of the Woody Bencomia Alliance (Rosaceae) in Macaronesia Based on ITS Sequence Data

Abstract The origin of the flora of the Macaronesian archipelagos has been a subject of controversy for over a century with the traditional opinion asserting that it is a relictual fragment of a widespread Tertiary subtropical European flora. A phylogenetic investigation of the three Macaronesian genera of the Bencomia alliance (Bencomia, Dendriopoterium, and Marcetella) using sequence data from the nuclear rDNA Transcribed Spacer region (ITS) has provided evidence relevant to the origin of the Macaronesian flora and the evolution of morphological characters of interest to students of island biology. In the ITS phylogeny, the Bencomia alliance, Sarcopoterium, a monotypic genus of the eastern Mediterranean, and Sanguisorba ancistroides, also a Mediterranean species, form a clade that is sister to the Eurasian Sanguisorba minor. These relationships contradict the relictual hypotheses and show that the endemic Macaronesian Rosaceae are sister to Mediterranean Sanguisorbeae. The data also contradict a recent placement of Dendriopoterium and Marcetella together in a subgenus of Sanguisorba. The ITS tree demonstrates that dioecy evolved in the islands from a continental monoecious or gynomonecious ancestor and that there has been an increase in plant size and woodiness compared to continental relatives rather than the decrease suggested by previous workers. Communicating Editor: Matt Lavin

High-resolution phylogeny for Helianthus (Asteraceae) using the 18S-26S ribosomal DNA external transcribed spacer

The sunflower genus, Helianthus, is recognized widely for the cultivated sunflower H. annuus and scientifically as a model organism for studying diploid and polyploid hybrid speciation, introgression, and genetic architecture. A resolved phylogeny for the genus is essential for the advancement of these scientific areas. In the past, phylogenetic relationships of the perennial species and polyploid hybrids have been particularly difficult to resolve. Using the external transcribed spacer region of the nuclear 18S-26S rDNA region, we reveal for the first time a highly resolved gene tree for Helianthus. Phylogenetic analysis allowed the determination of a monophyletic annual H. sect. Helianthus, a two-lineage polyphyletic H. sect. Ciliares, and the monotypic H. sect. Agrestis, all of which were nested within a large perennial and polyphyletic H. sect. Divaricati. The distribution of perennial polyploids and known annual diploid hybrids on this phylogeny suggested multiple independent hybrid speciation events that gave rise to at least four polyploids and three diploid hybrids. Also provided by this phylogeny was evidence for homoploid hybrid speciation outside H. sect. Helianthus. Finally, previous hypotheses about the secondary chemistry in the genus were tested in a phylogenetic framework to obtain a better understanding of the evolution of these compounds in Helianthus.

The Phylogeny of Linum and Linaceae Subfamily Linoideae, with Implications for Their Systematics, Biogeography, and Evolution of Heterostyly

Abstract The genus Linum consists of over 180 species, the most famous being L. usitatissimum, the source of linen and linseed oil. The eight genera of Linaceae subf. Linoideae, of which Linum is the largest, exhibit a complex biogeographic distribution, inhabiting all continents except Antarctica. Numerous species in Linoideae are heterostylous, but the ancestral breeding system of the group has not been determined. We present phylogenetic analyses of 44 species representing all eight genera of subf. Linoideae and 37 species of Linum, with data from the chloroplast (ndhF, trnL-F, trnK 3′ intron) and the nuclear ITS, with Hugonia (Linaceae subf. Hugonioideae) as outgroup. Sequences of rbcL from 48 species of Linaceae, including five species from Hugonioideae and seven species from other families of Malpighiales, were analyzed independently. Our results suggest that Linaceae and subf. Linoideae are monophyletic, but Linum is not. Anisadenia, Reinwardtia, and Tirpitzia are found to be the basal members of Linoideae. The rest of the subfamily forms two major lineages: a blue-flowered clade (Linum sections Linum and Dasylinum) and a yellow-flowered clade (Linum sects. Linopsis, Syllinum, and Cathartolinum, and the genera Cliococca, Hesperolinon, Radiola, and Sclerolinon). Diversification of Linoideae may have begun 46–51 mya, probably in Southeast Asia. Linum appears to have arisen in Eurasia, from which it spread to Africa, North America, South America, and Australasia. Our analyses indicate that neither heterostyly nor homostyly can yet be confirmed as the ancestral state in Linoideae or Linaceae, but provide strong evidence that breeding system is evolutionarily labile in this group.

THE ROLES OF PHENOLOGY AND REWARD STRUCTURE IN THE POLLINATION BIOLOGY OF WILD SUNFLOWER ( HELIANTHUS ANNUUS L., ASTERACEAE)

ABSTRACT A seven-year study of Helianthus annuus L., the common sunflower, in its native range in Texas has shown that the phenology and reward production schedules of individual florets within a head are of paramount importance in determining the foraging behavior of both specialist and generalist bees that serve as pollinators. Both pollen and nectar are produced only during the male phase of the protandrous disk florets, but pollen is produced bimodally whereas sugar accumulation is constant. Acceptance of heads by native bees was positively correlated with the number of male-phase florets per head, although the number of approaches was not. Native bees responded to increases in nectar amounts, as determined by experiments using bagged heads in which nectar accumulated, by increasing time per head and time spent foraging per floret. Comparisons across an array of visitors showed that large bees were more effective pollinators than small bees, but within the large bee category, there were no differences...

Hybrid Origin and Parentage of Dendrochilum acuiferum (Orchidaceae) Inferred in a Phylogenetic Context Using Nuclear and Plastid DNA Sequence Data

Abstract In this paper, molecular phylogenetic analyses were used to investigate a putative hybrid origin for Dendrochilum acuiferum, a species endemic to Mount Kinabalu, Sabah, Malaysia. Phylogenetic analyses of the plastid (pt) accD-psaI intergenic spacer region and a unique shared 117 bp indel indicate that D. grandiflorum and D. acuiferum are closely related. Direct sequencing of PCR products from the ITS 1 and 2 of the nuclear ribosomal repeat region revealed single site nucleotide polymorphisms in D. acuiferum that were additive between two hypothesized parents in addition to other sampled species. Dendrochilum acuiferum within-individual cloned ITS allelic sequence variants were analyzed in a phylogenetic context to determine the relative support for a hybrid (biphyletic) origin versus a nonhybrid (monophyletic) origin of the alleles. Because there was a significantly higher level of support for a hybrid origin of the alleles (P < 0.05), we subsequently compared likelihood scores for multiple parent pairs that could have hybridized. Although ptDNA evidence suggests Dendrochilum grandiflorum was the most likely maternal parent of D. acuiferum, ITS results are ambiguous about paternity because the phylogenetic results support D. grandiflorum + D. stachyodes and D. grandiflorum + D. kamborangense as equally likely parents of D. acuiferum. In addition, two other parent pairs could not be rejected (P > 0.05). Communicating Editor: Jeff H. Rettig

Phylogenetic relationships within the tribe Malveae (Malvaceae, subfamily Malvoideae) as inferred from ITS sequence data

Phylogenetic relationships among genera of tribe Malveae (Malvaceae, subfamily Malvoideae) were reconstructed using sequences of the internal transcribed spacer (ITS) region of the 18S-26S nuclear ribosomal repeat. Newly generated sequences were combined with those available from previous generic level studies to assess the current circumscription of the tribe, monophyly of some of the larger genera, and character evolution within the tribe. The ITS data do not support monophyly of most generic alliances as presently defined, nor do the data support monophyly of several Malveae genera. Two main well-supported clades were recovered, which correspond primarily to taxa that either possess or lack involucral bracts, respectively. Chromosomal evolution has been dynamic in the tribe with haploid numbers varying from n = 5 to 36. Aneuploid reduction, hybridization, and/or polyploidization have been important evolutionary processes in this group.

A chloroplast DNA study of the Agavaceae

A chloroplast DNA restriction site analysis of 40 taxa in the Agavaceae s.l. was undertaken to test the accuracy of several current systems of classification. In Cronquists system, the Agavaceae contain 18 genera of fibrous-leaved, more or less woody plants such as Yucca, Hes- peraloe, Agave, Manfreda, Polianthes, Dracaena, Sansevieria, Nolina, Beaucarnea, Dasylirion, and Cordyline. In Dahlgrens system, the Agavaceae are restricted to Yucca, Hesperaloe Agave, Manfreda, Polianthes, Beschorneria, and Furcraea, while the other genera are placed in different families. These contrasting phylogenetic schemes were investigated by a chloroplast DNA restriction site analysis of these genera plus Xanthorrhoea, Hosta, Hypoxis, Hemerocallis, Asparagus, Liriope, Aspidistra, Maianthemum, and Convallaria. Phylogenetic analysis of 110 restriction site mutations, 90 of which were phylo- genetically informative, strongly supports the conclusion that there are two major lineages in this group of taxa. One well supported clade contains, sensu Dahlgren, the Nolinaceae, Dracaenaceae, and Convallariaceae. It appears that Nolina and Dasylirion are more closely related to genera such as Liriope, Maianthemum, and Dracaena than to Yucca and Agave. The other major lineage contains Yucca, Hesperaloe, Agave, Manfreda, Polianthes, Beschorneria, and Furcraea, with Hosta and perhaps Xanthorrhoea at the base. Asparagus appears to be intermediate between the two lineages. The cpDNA suggests that Cordyline, Hypoxis, and Hemerocallis are not closely related to the Agavaceae. A major problem in monocot taxonomy con- cerns the classification and phylogeny of the genera in the Liliaceae s.l. and smaller families that have been split off from it, such as the Agavaceae. Two distinct systems of classifica- tion have been proposed and both are in use at the present time (Cronquist 1981; Dahlgren et al. 1985). The apparent frequency of convergent and parallel evolution of characters in these taxa makes it difficult to recover the phylogeny us- ing morphological characters alone. In this pa- per these problems are examined using evi- dence from chloroplast DNA restriction site analysis. In the traditional taxonomic systems of Ben- tham and Hooker (1883) and Engler and Prantl (1888), most liliaceous plants with a superior ovary, including Yucca L. and Dasylirion Zucc., were placed in a broadly conceived Liliaceae with many tribes, while those with an inferior ovary, such as Agave L., were placed in the Amaryllidaceae. Hutchinson (1934) is generally

Consequences of frugivore-mediated seed dispersal for the spatial and genetic structures of a neotropical palm

The idiosyncratic behaviours of seed dispersers are important contributors to plant spatial associations and genetic structures. In this study, we used a combination of field, molecular and spatial studies to examine the connections between seed dispersal and the spatial and genetic structures of a dominant neotropical palm Attalea phalerata. Field observation and genetic parentage analysis both indicated that the majority of A. phalerata seeds were dispersed locally over short distances (<30 m from the maternal tree). Spatial and genetic structures between adults and seedlings were consistent with localized and short‐distance seed dispersal. Dispersal contributed to spatial associations among maternal sibling seedlings and strong spatial and genetic structures in both seedlings dispersed near (<10 m) and away (>10 m) from maternal palms. Seedlings were also spatially aggregated with juveniles. These patterns are probably associated with the dispersal of seeds by rodents and the survival of recruits at specific microsites or neighbourhoods over successive fruiting periods. Our cross‐cohort analyses found palms in older cohorts and cohort pairs were associated with a lower proportion of offspring and sibling neighbours and exhibited weaker spatial and genetic structures. Such patterns are consistent with increased distance‐ and density‐dependent mortality over time among palms dispersed near maternal palms or siblings. The integrative approaches used for this study allowed us to infer the importance of seed dispersal activities in maintaining the aggregated distribution and significant genetic structures among A. phalerata palms. We further conclude that distance‐ and density‐dependent mortality is a key postdispersal process regulating this palm population.