Showing papers by "Celeste C. Linde published in 2014"

Congruent species delineation of Tulasnella using multiple loci and methods

Abstract: Understanding evolutionary and ecological processes requires accurate delimitation of species. Species are most commonly defined under the general lineage concept (GLC), where they are considered to be segments of diverging population-level lineages (de Queiroz, 2007). Within the umbrella of the GLC, various species concepts have been developed, including themorphological species concept (MSC), the biological species concept (BSC) and the phylogenetic species concept (PSC). The BSC is characterized by species representing populations that potentially can interbreed. The PSC includes the genealogical concordance phylogenetic species recognition concept, which uses phylogenetic concordance of multiple unlinked genes to identify evolutionary independence of lineages (Taylor et al., 2000). PSC is applied frequently in taxonomic groups where it is difficult to quantify morphological variation or performmating studies. One such group is Tulasnella, a group of fungi where morphological identification of species is problematic. Tulasnella includes putatively saprotrophic species on decayed wood (Roberts, 1999; Cruz et al., 2011). Some species are also encountered as ectomycorrhizas (Tedersoo et al., 2010) or orchid mycorrhizal symbionts (Dearnaley et al., 2012). However, many questions remain about species delimitation in this group. We therefore need a robust multilocus method for species delimitation to establish a framework for studying the evolution, ecology and physiology of orchid–fungus relationships. It is now recognized that the most effective approach to species delineation is the integration of multiple datasets and analytical methods (Sites &Marshall, 2004; Leach e & Fujita, 2010; Yang & Rannala, 2010; Barrett & Freudenstein, 2011). Here we use evidence from six nuclear loci, twomitochondrial loci, orchid-host association and geographical location of samples in a multifaceted approach to delineate species of Tulasnella associated with the Australian orchid genera Chiloglottis, Drakaea, Paracaleana and Arthrochilus. Specifically, we employ gene tree construction methods to resolve fungal species boundaries; use coalescent species tree construction methods (using the programs *BEAST and BPP) to test for host and geographic association; and apply population genetic assignment methods to test for admixture between populations. Finally, germination data are used to explore the correlation between physiological traits and phylogenetic boundaries among Tulasnella. In light of the outcomes we evaluate the implications of multigene approaches for fungal species delimitation in this Tulasnella group.

Himalayan-Tibetan Plateau Uplift Drives Divergence of Polyploid Poppies: Meconopsis Viguier (Papaveraceae)

Abstract: Meconopsis Viguier (Papaveraceae) is an iconic genus of alpine forbs that includes medicinal and ornamental species. This study extends previous phylogenetic analyses of Meconopsis, using ITS sequences representing all the major Meconopsis clades. Phenotypic traits are also analysed for all described species. Our results show that Meconopsis evolved as a >= octaploid clade, with considerable interior structure reflecting further changes in ploidy levels as well as phenotypic differentiation. We support the exclusion of a few species as Cathcartia or Papaver, making Meconopsis a Tibetan region clade. Based on average rates of nucleotide substitution in angiosperm herbs we estimate that the Meconopsis clade diverged from the Meconella clade of Papaver approximately 16.6 Ma. This is soon after the 'hard' collision of the Indian continent with Asia caused uplift of the Himalaya and Hengduan ranges, greatly extended the Tibetan plateau, and initiated monsoonal climates. Eight major clades within Meconopsis are well supported and these correspond closely to previously recognised subgenus groups. However, the relationship among the clades is poorly resolved, probably because they diverged rapidly similar to 15-11 Ma. Two of these clades are, dodecaploid but appear to have originated independently. The eight clades have distinct distributions, variously associated with the Himalaya, the eastern Plateau and Hengduan ranges. Some Meconopsis species were not monophyletic, suggesting that a combination of multilocus molecular and phenotypic traits is required when defining and revising species.

Development of phylogenetic markers for Sebacina (Sebacinaceae) mycorrhizal fungi associated with Australian orchids

Abstract: Premise of the study: To investigate fungal species identity and diversity in mycorrhizal fungi of order Sebacinales, we developed phylogenetic markers. These new markers will enable future studies investigating species delineation and phylogenetic relationships of the fungal symbionts and facilitate investigations into evolutionary interactions among Sebacina species and their orchid hosts. Methods and Results: We generated partial genome sequences for a Sebacina symbiont originating from Caladenia huegelii with 454 genome sequencing and from three symbionts from Eriochilus dilatatus and one from E. pulchellus using Illumina sequencing. Six nuclear and two mitochondrial loci showed high variability (10–31% parsimony informative sites) for Sebacinales mycorrhizal fungi across four genera of Australian orchids (Caladenia, Eriochilus, Elythranthera, and Glossodia). Conclusions: We obtained highly informative DNA markers that will allow investigation of mycorrhizal diversity of Sebacinaceae fungi associated ...