Eric J Tepe

Publications (10)21.73 Total impact

• Article: A new species of Solanum named for Jeanne Baret, an overlooked contributor to the history of botany.

  Eric J Tepe, Glynis Ridley, Lynn Bohs
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  ABSTRACT: We describe Solanum baretiaesp. nov., a new species of Solanum section Anarrhichomenum, named in honor of Jeanne Baret, who sailed as the assistant to botanist Philibert Commerson on Louis Antoine de Bougainville's global circumnavigation (1766-1769). The species is similar to Solanum chimborazense, but differs in having larger flowers, more flowers per inflorescence, and different patterns of pubescence on the filaments (pubescent adaxially and glabrous abaxially) and style (papillose to sparsely pubescent). A description, illustration, photos, and comparisons to similar species are included. Also included is a preliminary conservation assessment, along with a brief account of the important role played by Baret during the expedition. The new species appears to be restricted to the Amotape-Huancabamba zone, an area of southern Ecuador and northern Peru known for its exceptional biodiversity.
  PhytoKeys. 01/2012;
• Article: A Revision of Solanum Section Herpystichum

  Eric J. Tepe, Lynn Bohs
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  ABSTRACT: Abstract—Solanum section Herpystichum includes 10 species of ground-trailing and climbing vines that root adventitiously at the nodes. Molecular data support section Herpystichum as a member of the Potato clade of Solanum. All of the species inhabit primary and secondary rainforests and occur from southern Mexico to northern Peru. The group is defined by its vining, node-rooting habit, and by its fruit structure; several species have strongly flattened fruits that are unique in Solanum. Most species of sect. Herpystichum have narrow distributions, and four species are endemic to Ecuador and one is endemic to Colombia. Moreover, they tend to be rare in the habitats where they occur and, as a result, are poorly collected and poorly known. Also, because of their restricted distributions, small numbers of populations, and habitat destruction, seven of the 10 species are considered rare and threatened. Descriptions, distribution maps, a phylogeny, photos or illustrations, and a key to the species are presented.
  Systematic Botany 09/2011; 36(4):1068-1087. · 1.52 Impact Factor
• Source

  Available from: Richard Olmstead

  Article: Multiple recent horizontal transfers of the cox1 intron in Solanaceae and extended co-conversion of flanking exons.

  Maria V Sanchez-Puerta, Cinthia C Abbona, Shi Zhuo, Eric J Tepe, Lynn Bohs, Richard G Olmstead, Jeffrey D Palmer
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  ABSTRACT: The most frequent case of horizontal transfer in plants involves a group I intron in the mitochondrial gene cox1, which has been acquired via some 80 separate plant-to-plant transfer events among 833 diverse angiosperms examined. This homing intron encodes an endonuclease thought to promote the intron's promiscuous behavior. A promising experimental approach to study endonuclease activity and intron transmission involves somatic cell hybridization, which in plants leads to mitochondrial fusion and genome recombination. However, the cox1 intron has not yet been found in the ideal group for plant somatic genetics - the Solanaceae. We therefore undertook an extensive survey of this family to find members with the intron and to learn more about the evolutionary history of this exceptionally mobile genetic element. Although 409 of the 426 species of Solanaceae examined lack the cox1 intron, it is uniformly present in three phylogenetically disjunct clades. Despite strong overall incongruence of cox1 intron phylogeny with angiosperm phylogeny, two of these clades possess nearly identical intron sequences and are monophyletic in intron phylogeny. These two clades, and possibly the third also, contain a co-conversion tract (CCT) downstream of the intron that is extended relative to all previously recognized CCTs in angiosperm cox1. Re-examination of all published cox1 genes uncovered additional cases of extended co-conversion and identified a rare case of putative intron loss, accompanied by full retention of the CCT. We infer that the cox1 intron was separately and recently acquired by at least three different lineages of Solanaceae. The striking identity of the intron and CCT from two of these lineages suggests that one of these three intron captures may have occurred by a within-family transfer event. This is consistent with previous evidence that horizontal transfer in plants is biased towards phylogenetically local events. The discovery of extended co-conversion suggests that other cox1 conversions may be longer than realized but obscured by the exceptional conservation of plant mitochondrial sequences. Our findings provide further support for the rampant-transfer model of cox1 intron evolution and recommend the Solanaceae as a model system for the experimental analysis of cox1 intron transfer in plants.
  BMC Evolutionary Biology 09/2011; 11:277. · 3.52 Impact Factor
• Article: A 10-gene phylogeny of Solanum section Herpystichum (Solanaceae) and a comparison of phylogenetic methods.

  Eric J Tepe, Frank T Farruggia, Lynn Bohs
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  ABSTRACT: Solanum section Herpystichum is a lineage that comprises both widespread and very narrowly distributed species. This study investigates the phylogenetic relationships of sect. Herpystichum and evaluates several phylogenetic methods for analysis of multiple sequences. Sequence data from seven nuclear (ITS, GBSSI, and five COSII) and three plastid (psbA-trnH, trnT-trnF, and trnS-trnG) regions were concatenated and analyzed under maximum parsimony and Bayesian criteria. In addition, we used two analytical methods that take into account differences in topologies resulting from the analyses of the individual markers: Bayesian Estimation of Species Trees (BEST) and supertree analysis. The monophyletic Solanum sect. Herpystichum was resolved with moderate support in the concatenated maximum parsimony and Bayesian analyses and the supertree analysis, and relationships within the section were well-resolved and strongly supported. The BEST topology, however, was poorly resolved. Also, because of how BEST deals with missing sequences, >25% of our accessions, including two species, had to be excluded from the analyses. Our results indicate a progenitor-descendent relationship with two species nested within the widespread S. evolvulifolium. Analytical methods that consider individual topologies are important for studies based on multiple molecular markers. On the basis of analyses in this study, BEST had the serious shortcoming that taxa with missing sequences must be removed from the analysis or they can produce spurious topologies. Supertree analysis provided a good alternative for our data by allowing the inclusion of all 10 species of sect. Herpystichum.
  American Journal of Botany 08/2011; 98(8):1356-65. · 2.66 Impact Factor
• Article: Weighing Defensive and Nutritive Roles of Ant Mutualists Across a Tropical Altitudinal Gradient

  Genoveva Rodríguez-Castañeda, Rebecca E. Forkner, Eric J. Tepe, Grant L. Gentry, Lee A. Dyer
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  ABSTRACT: The diversity of mutualistic interactions influences many ecological components of community structure, including biodiversity and ecosystem stability. However, mutualistic interactions are not well resolved because of a historical bias toward examining antagonistic interactions. Here we examine both antagonistic and facilitative interactions between tropical plants and arthropods by characterizing the biotic interactions between a common myrmecophytic shrub, Piper immutatum Trel. (Piperaceae), the ants hosted by this plant, Pheidole sp. (Formicidae: Myrmicinae), and their associated communities of herbivorous and predatory arthropods. To determine if ant mutualists affect the altitudinal distribution of Neotropical myrmecophytes, P. immutatum interactions with arthropods were quantified across a tropical elevational gradient. Piper immutatum was most abundant in lower montane forests (1000–1600 m asl) and disappeared above 1600 m asl, and colonies of Pheidole sp. inhabited 90 percent of the sampled plants. The myrmecophyte was then transplanted within and beyond its altitudinal range, excluding ants from half of the transplanted plants. Plant survival was affected primarily by elevation, with only 20 percent surviving above 1600 m asl. Ant exclusion did not significantly affect plant mortality. Nevertheless, ant colony size did affect both herbivory and nutrient availability for surviving P. immutatum, with nutrient availability having a stronger effect than antiherbivore defense on growth and biomass. This approach of studying the contributions of ant mutualisms across the myrmecohpyte's habitat range yields an improved picture of the role of mutualistic interactions in determining community structure.Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.
  Biotropica 09/2010; 43(3):343 - 350. · 2.23 Impact Factor
• Article: A molecular phylogeny of Solanum sect. Pteroidea (Solanaceae) and the utility of COSII markers in resolving relationships among closely related species

  Eric J. Tepe, Lynn Bohs
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  ABSTRACT: Solanum sect. Pteroidea is a lineage of ten species of neotropical herbs and vines with a center of distribution in the eastern Andean slopes. It is a member of the Potato clade of Solanum, a group that includes the potato (S. tuberosum) and tomato (S. lycopersicum). Members of S. sect. Pteroidea are characterized by inflorescences that emerge from the leaf axils and rugose, sharply pointed fruits in most species. The aim of this study is to infer phylogenetic relationships among sixteen species of Solanum, including all ten species of S. sect. Pteroidea, using DNA sequence data from the chloroplast trnT-trnF and five nuclear regions: ITS, the granule bound starch synthase gene (GBSSI or waxy), and three Conserved Orthologous Set II (COSII) markers. Results provide strong support for the monophyly of S. sect. Pteroidea and for its sister group relationship to S. sect. Herpystichum. Solanum mite, one of the most widespread and morphologically variable species in the section, is not monophyletic. Bayesian analyses using a total evidence concatenated approach and a coalescent approach implemented in BEST produced largely congruent topologies. The total evidence trees, however, were much more highly supported than the BEST trees. Although not useful individually in S. sect. Pteroidea, the three COSII markers were easy to amplify, provided clean sequences, and were tremendously useful in increasing resolution and support among the closely related species of S. sect. Pteroidea in combined analyses.
  Taxon 05/2010; 59(3):733-743. · 2.70 Impact Factor
• Article: Patterns and causes of incongruence between plastid and nuclear Senecioneae (Asteraceae) phylogenies.

  Pieter B Pelser, Aaron H Kennedy, Eric J Tepe, Jacob B Shidler, Bertil Nordenstam, Joachim W Kadereit, Linda E Watson
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  ABSTRACT: One of the longstanding questions in phylogenetic systematics is how to address incongruence among phylogenies obtained from multiple markers and how to determine the causes. This study presents a detailed analysis of incongruent patterns between plastid and ITS/ETS phylogenies of Tribe Senecioneae (Asteraceae). This approach revealed widespread and strongly supported incongruence, which complicates conclusions about evolutionary relationships at all taxonomic levels. The patterns of incongruence that were resolved suggest that incomplete lineage sorting (ILS) and/or ancient hybridization are the most likely explanations. These phenomena are, however, extremely difficult to distinguish because they may result in similar phylogenetic patterns. We present a novel approach to evaluate whether ILS can be excluded as an explanation for incongruent patterns. This coalescence-based method uses molecular dating estimates of the duration of the putative ILS events to determine if invoking ILS as an explanation for incongruence would require unrealistically high effective population sizes. For four of the incongruent patterns identified within the Senecioneae, this approach indicates that ILS cannot be invoked to explain the observed incongruence. Alternatively, these patterns are more realistically explained by ancient hybridization events.
  American Journal of Botany 05/2010; 97(5):856-73. · 2.66 Impact Factor
• Source

  Available from: Genoveva Rodriguez-Castaneda

  Article: Characterizing the cauline domatia of two newly discovered ecuadorian ant plants in piper: an example of convergent evolution.

  Eric J Tepe, Walter A Kelley, Genoveva Rodriguez-Castañeda, Lee A Dyer
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  ABSTRACT: The stems of some myrmecophytes in Piper are used as domatia by resident ant colonies. Hollow, ant-occupied stems were previously known only in four species of southern Central American Piper, all members of Section Macrostachys. Here we present two additional, unrelated, hollow-stemmed myrmecophytes from Ecuador: P. immutatum and P. pterocladum (members of sections Radula and Peltobryon, respectively). Although similar superficially, stem cavities of the Ecuadorian Piper species differ morphologically and developmentally from those of Central American taxa. The stem cavities of P. immutatum, and possibly P. pterocladum, are formed during stem development, and begin forming only a few millimeters behind the apical meristem. This mode of cavity formation differs markedly from myrmecophytes in section Macrostachys, where the stems remain solid unless excavated by the specialized ant partner Pheidole bicornis. The stems of P. immutatum and P. pterocladum do not produce wound-response tissue around the cavity, unlike the stems in section Macrostachys. The entrance holes in stems of P. immutatum are formed through apoptotic processes and are located at each node below the petiole, whereas those in section Macrostachys are excavated by the ants in the leaf axil. This study documents convergent evolution of ant-plant associations in Piper, and emphasizes the need for careful comparison of apparently homologous, ant-associated structures in specialized myrmecophytes.
  Journal of Insect Science 02/2009; 9:27. · 0.95 Impact Factor
• Article: The importance of petiole structure on inhabitability by ants in Piper sect. Macrostachys (Piperaceae)

  ERIC. J. TEPE, MICHAEL A. VINCENT, LINDA E. WATSON
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  ABSTRACT: Several Central American species of Piper sect. Macrostachys have obligate associations with ants, in which the ant partner derives food and shelter from modified plant structures and, in turn, protects the plant against fungal infection and herbivory. In addition to these obligate ant-plants (i.e. myrmecophytes), several other species in Piper have resident ants only sometimes (facultative), and still other plant species never have resident ants. Sheathing petioles of sect. Macrostachys form the domatia in which ants nest. Myrmecophytes in sect. Macrostachys have tightly closed petiole sheaths with bases that clasp the stem. These sheathing petioles appear to be the single most important plant character in the association between ants and species of sect. Macrostachys. We examined the structure and variation of petioles in these species, and our results indicate that minor modifications in a small number of petiolar characters make the difference between petioles that are suitable for habitation by ants and those that are not. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153, 181–191.
  Botanical Journal of the Linnean Society 01/2007; 153(2):181 - 191. · 2.82 Impact Factor
• Article: Stem diversity, cauline domatia, and the evolution of ant-plant associations in Piper sect. Macrostachys (Piperaceae).

  Eric J Tepe, Michael A Vincent, Linda E Watson
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  ABSTRACT: Plants possess a variety of structures that harbor ant nests, and the morphology of these domatia determines the nature of ant-plant mutualisms in a given plant species. In this study, we report on the differences in anatomy between myrmecophytes of Piper, which are regularly excavated by an obligate ant mutualist (Pheidole bicornis) and nonmyrmecophytes of Piper, which consistently have solid stems. Stems of excavated plant species lacked outward evidence of modification; however, striking anatomical differences were apparent between hollow-stemmed species before excavation and the remainder of the solid-stemmed species studied. Prior to excavation by ants, stems of myrmecophytes were characterized by strongly heterogeneous piths in which a large, central area had relatively large cells lacking intracellular crystals with a periphery of smaller cells containing numerous crystals. The domatium excavated by the ants was restricted to the large-celled region. This is the first report of the absence of crystals in ant-excavated portions of stems of myrmecophytes. Cauline domatia became lined with 3-8 cell layers of suberized wound tissue, which may have an impact on nutrient absorption by Piper myrmecophytes.
  American Journal of Botany 01/2007; 94(1):1-11. · 2.66 Impact Factor