Abstract Detail

Species delimitation in polyploid complexes

Rojas Andres, Blanca M. [1], López González, Noemí [2], Bobo Pinilla, Javier [2], Padilla-Garcia, Nelida [2], Martinez-Ortega, M. Montserrat [2].

Morphological resemblance is not enough: Zooming in on the polyploid complex V. austriaca - V. orbiculata within the polyploid complex Veronica subsect. Pentasepalae.

Polyploidization and hybridization are important sources of variation that may lead to species formation, but -at the same time- they frequently blur phylogenetic relationships among lineages, which may also prevent speciation. Polyploid complexes represent therefore challenging research subjects in phylogenetics. Veronica subsect. Pentasepalae comprises ca. 20 diploid and polyploid species. Homoploid hybridization, auto- and allopolyploidization have been detected in the group. Previous studies using DNA sequence data and AFLPs shed some light on the phylogenetic relationships among diploid species of the complex, but failed to resolve relationships among polyploids. We now focus on a small group from the western Balkans, the V. austriaca-V. orbiculata diploid-polyploid complex. Based on previous results, as well as on the morphological similarities observed, two diploids (namely V. dalmatica and V. orbiculata) are the logical candidates a priori expected to be involved in the formation of the tetraploid and hexaploid individuals of the complex. To try to disentangle their phylogenetic relationships and evolutionary history of the group, a combination of nuclear microsatellites, plastid DNA sequences and ploidy level estimations were used. In addition, species distribution models (SDMs) were generated to infer potential climate promoted range shifts since the Last Glacial Maximum (LGM) and assist in the delimitation of taxa. Genetic analyses revealed the existence of four evolutionary significant units. Veronica dalmatica (2x) is the most divergent of them and is restricted to a small area to the south-east of the Neretva river. Veronica orbiculata (2x, 4x) comprises mainly diploid individuals and some tetraploids of auto- and allopolyploid origin. Several tetraploids of uncertain taxonomic identity formed a group with diffuse limits. Finally, the traditionally recognized subspecies V. austriaca subsp. jacquinii corresponds with the hexaploid lineage. Our results show that the tetraploids of uncertain taxonomic identity diverged earlier than V. austriaca subsp. jacquinii, with V. orbiculata involved in the origin of both and representing the most basal lineage of the complex. On the contrary, V. dalmatica is not involved in their formation and a hybrid origin of the polyploids with V. dalmatica and V. orbiculata as parental species is rejected. None of the scenarios tested supported hybridization between the studied taxa. Through this sequential approach and using a combination of techniques, we reconstruct the evolutionary history of a small polyploid complex and get a satisfactory delimitation of evolutionary significant units within it.

1 - Institute of Biology, University of Leipzig, Molecular Evolution and Plant Systematics, Johannisallee 21-23, Leipzig, D-04103, Germany
2 - University of Salamanca, Departamento de Botanica, Licenciado Mendez Nieto s/n, Salamanca, Salamanca, E-37007, Spain

Keywords:
polyploidy
hybridization
species delimitation
SSRs
Veronica subsect. Pentasepalae.

Presentation Type: Colloquium Presentations
Session: CO01, Species delimitation in polyploid complexes
Location: Tucson J/Starr Pass
Date: Monday, July 29th, 2019
Time: 9:15 AM
Number: CO01004
Abstract ID:235
Candidate for Awards:None