Abstract Detail

Population Genetics/Genomics

Arnelas Seco, Itziar [1], Perez-Collazos, Ernesto [2], Devesa, Juan [3], Manzaneda, Antonio J. [4], Catalan, Pilar [5].

Morphological differentiation and genetic isolation of intraspecific floral morphotypes of Iberian knapweeds (Centaurea sects. Jacea and Lepteranthus, Asteraceae).

Evolutionary processes, especially high rates of hybridization, in Centaurea make difficult to establish its specific and infraspecific taxonomic limits. Centaurea presents two major floral morphs, Radiant (R) and non-radiant (NR) capitula. We studied the taxonomic differentiation of 12 taxa (510 individuals from 58 populations) and the potential effect of genetic isolation in R and NR populations of Iberian Centaurea sects. Jacea and Lepteranthus, using 165 AFLP markers. We performed phylogenetic and genetic diversity and structure analyses for different sets of taxa. We tested whether there was correlation between population pairwise Fst distances and the inbreeding coefficient (Fis), taken as a surrogate of reproductive isolation between the R and NR morphotypes of each group, and also taking into account geographic distances, using distance-based redundancy analysis (dbRDA). We also performed Isolation by distance (IBD) tests between different floral morphotypes, aiming to infer the impact of genetic isolation in the evolutionary and taxonomic divergence of the individuals. Genetic diversity was highest in C. debeauxii subspp. debeauxii and grandiflora and in C. jacea subsp. angustifolia (R) and lowest in C. nevadensis (NR) within the C. sect. Jacea clade, whereas it was highest in C. linifolia within the C. sect. Lepteranthus clade. Population level dbRDA tests did not detect a significant correlation of R vs NR genetic distances and Fis values in any of the studied cases, by contrast they found significant correlation with longitude (C. jacea subsp. angustifolia, C. debeauxii, C. linifoliaC. stuessyi) or latitude (C. nigra). IBD analysis at the individual level showed that, in addition to geography, other morphotype-related factors may affect the genetic differentiation of R vs NR morphs in C. gr. nigra, C. gr. debeauxii and C. linifoliaC. stuessyi. These results suggest that the fixation of the different morphs within the same taxon or group may be explained by geographic isolation though we could not discard other potential unknown factors that could have contributed to microspeciation in these recently divergent populations. Our results showed that C. sects. Jacea and Lepteranthus taxa constitute independent evolutionary lineages, and that the majority of the detected genetic clusters agrees with the taxonomic circumscriptions proposed in our most recent treatments.    
Keywords: AFLP, floral morphs, gene flow barriers, population genetics, taxonomy.

1 - Universidad Técnica Particular de Loja, Ciencias Biológicas, San Cayetanl Alto s/n, Loja, Loja, 11-01-608, Ecuador
2 - Zaragoza University, Ciencias Agrarias y del Medio Natural, Escuela Politecnica Superior de Huesca, Carretera de Cuarte s/n, Huesca, Spain
3 - Universidad de Córdoba, Botánica, Ecología y Fisiología Vegetal, Campus Universitario de Rabanales Ctra. N-IVa, Km. 396., Celestino Mutis (C-4), 3, Oeste, Córdoba, Córdoba, Andalucía, 14071, España
4 - Universidad de Jaén, Biología Animal, Biología Vegetal y Ecología, Campus Las Lagunillas Edificio Ciencias Experimentales y de la Salud (B3), Jaén, Jaén, Andalucía, 23009, España
5 - Escuela Politecnica Ctra. Cuarte Km 1, Huesca, HU, 22071, Spain

floral morphs
gene flow barriers
population genetics

Presentation Type: Oral Paper
Session: POPGEN1, Population Genetics/Genomics I
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 3:30 PM
Number: POPGEN1003
Abstract ID:498
Candidate for Awards:Margaret Menzel Award

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