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Excluding spatial sampling bias does not eliminate over-splitting in DNA-based species delimitation analyses
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  • Daniel Lukic,
  • Jonas Eberle,
  • Jana Thormann,
  • Carolus Holzschuh,
  • Dirk Ahrens
Daniel Lukic
Zoological Research Museum Alexander Koenig
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Jonas Eberle
University of Salzburg
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Jana Thormann
Zoological Research Museum Alexander Koenig
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Carolus Holzschuh
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Dirk Ahrens
Zoological Research Museum Alexander Koenig
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Abstract

DNA-barcoding and DNA-based species delimitation are major tools in DNA taxonomy. Sampling has been a central debate in this context, because the geographical composition of samples affect the accuracy and performance of DNA-barcoding. Performance of complex DNA-based species delimitation is to be tested under simpler conditions in absence of geographic sampling bias. Here, we present an empirical data set sampled from a single locality in a Southeast-Asian biodiversity hotspot (Laos: Phou Pan mountain). We investigate the performance of various species delimitation approaches on a megadiverse assemblage of herbivore chafer beetles (Coleoptera: Scarabaeidae) to infer whether species delimitation suffers in the same way from exaggerate infraspecific variation despite the lack of geographic genetic variation that led to inconsistencies between entities from DNA-based and morphology-based species inference in previous studies. For this purpose, a 658 bp fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) was analysed for a total of 186 individuals of 56 morphospecies. Tree based and distance based species delimitation methods were used. All approaches showed a rather limited match ratio (max. 77%) with morphospecies. PTP and TCS prevailingly over-splitted morphospecies, while 3% clustering and ABGD also lumped several species into one entity. ABGD revealed the highest congruence between molecular operational taxonomic units (MOTUs) and morphospecies. Disagreements between morphospecies and MOTUs were discussed in the context of historically acquired geographic genetic differentiation, incomplete lineage sorting, and hybridization. The study once again highlights how important morphology still is in order to correctly interpret the results of molecular species delimitation.

Peer review status:UNDER REVIEW

27 Jan 2021Submitted to Molecular Ecology Resources
15 Feb 2021Assigned to Editor
15 Feb 2021Submission Checks Completed
16 Feb 2021Reviewer(s) Assigned
26 Mar 2021Review(s) Completed, Editorial Evaluation Pending