Abstract Detail

Species delimitation in composite organisms: the value of recognizing species boundaries in lichen symbionts

Athukorala, Sarangi, N. P. [1], Doering, Jennifer [1], Stenroos, Soili [2], Ahti, Teuvo [2], Heubner, Erwin [1], Piercey-Normore, Michele [1].

Species delimitations in Cladonia.

The genus Cladonia is a large genus of ground-dwelling lichen-forming fungi and many species are globally distributed. Taxa formerly included in the genus Cladina (reindeer lichens) are distinguished by branching patterns and chemistry, but little is known about their reproductive biology and symbiont interactions that allow them to dominate large expanses in northern geographic regions. Previous studies showed evolutionary relationships within the groups referred to as Impexae, Crustaceae, and Tenues, but few specimens of each species were used in the analysis. The goal of this presentation is to examine species boundaries using a larger number of specimens within selected species and to explore reproductive isolation and symbiont plasticity within two pairs of non-monophyletic species. The internal transcribed spacer region of the nuclear ribosomal DNA (ITS rDNA) and mitochondrial small subunit gene of the mitochondrial ribosomal DNA (mtSSU) were sequenced and subjected to phylogenetic analyses. The phylogenetic tree showed separate clades for Impexae, and one clade representing species that belong to Crustaceae and Tenues. Five of 18 species, viz. C. pycnoclada, C. stellaris, C. evansii, C. ciliata and C. subtenuis showed monophyly. Species boundaries were further examined in two pairs of non-monophyletic species (C. arbuscula-C. mitis and C. rangiferina-C. stygia) using haplotype networks and AMOVA analysis, which provided support for species differentiation within the pairs of species. Colony morphology and Randomly Amplified Polymorphic DNA (RAPD) analyses showed evidence for levels of genetic variation within and among apothecia that were consistent with heterothallism and recombination. The Cladonia rangiferina morphotype showed higher rates of growth than the C. arbuscula morphotype. However, more variability in inter-apothecial growth was observed in the C. arbuscula than the C. rangiferina morphotype. When the C. rangiferina morphotype was paired with two algae in resynthesis experiments, the evidence suggested a strong interaction with Asterochloris and a weak interaction with Chlorella. Implications of these results are discussed with respect to fungal reproductive isolation and symbiont plasticity in species delimitations.

1 - University of Manitoba, Biological Sciences, Winnipeg, MB, R3T 2N2, Canada
2 - University of Helsinki, Botanical Museum, Finnish Museum of Natural History, P.O. Box 7, Helsinki, FI-00014, Finland

Keywords:
Cladonia
reindeer lichens
Phylogeny
reproductive isolation
algal plasticity.

Presentation Type: Symposium or Colloquium Presentation
Session: C3
Location: Cottonwoods North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 10:45 AM
Number: C3003
Abstract ID:461
Candidate for Awards:None