Abstract

The Cladia aggregata complex is one of the phenotypically most variable groups in lichenized fungi, making species determination difficult and resulting in different classifications accepting between one to eight species. Multi-locus DNA sequence data provide an avenue to test species delimitation scenarios using genealogical and coalescent methods, employing gene and species trees. Here we tested species delimitation in the complex using molecular data of four loci (nuITS and IGS rDNA, protein-coding GAPDH and Mcm-7), including 474 newly generated sequences. Using a combination of ML and Bayesian gene tree topologies, species tree inferences, coalescent-based species delimitation, and examination of phenotypic variation we assessed the circumscription of lineages. We propose that results from our analyses support a 12 species delimitation scenario, suggesting that there is a high level of species diversity in the complex. Morphological and chemical characters often do not characterize lineages but show some degree of plasticity within at least some of the clades. However, clades can often be characterized by a combination of several phenotypical characters. In contrast to the amount of homoplasy in the morphological characters, the data set exhibits some geographical patterns with putative species having distribution patterns, such as austral, Australasian or being endemic to Australia, New Zealand or Tasmania.

Highlights

  • Ever since Darwin’s seminal study on the origin of species was published, the issue of delimiting species as the fundamental taxonomic unit has fascinated evolutionary biologists [1,2,3]

  • We have not been able to get fresh material of C. mutabilis and C. oreophila and have not been able to obtain sequences from herbarium material of these species from HO. The latter species is a rare taxon that is only known from a few localities in remote mountain ranges of south-western Tasmania, whereas C. mutabilis is restricted to high rainfall peatlands in south-western Tasmania

  • In the B/Markov Chain Monte Carlo (MCMC) analysis of the combined data set, the likelihood parameters in the sample had a mean likelihood of LnL = 210,728.85 (60.354), while the maximum likelihood (ML) tree had a likelihood of LnL = 29,763.28

Read more

Summary

Introduction

Ever since Darwin’s seminal study on the origin of species was published, the issue of delimiting species as the fundamental taxonomic unit has fascinated evolutionary biologists [1,2,3]. The main challenge is finding and using appropriate character sets and analytical methods to recognize species. This is especially true for organisms with relatively simple morphologies, such as fungi where it is often difficult to find sufficient defining characters, or the choice of which might be viewed as arbitrary. It has repeatedly been shown that the traditional species delimitation underestimates the diversity of these fungi with numerous cryptic lineages discovered under currently accepted species in various unrelated families [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39]

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call