Abstract Detail

Hybrids and Hybridization

Pezzi, Pedro Henrique [1], Guzmán-Rodriguez, Sebastián [1], Giudicelli, Giovanna [1], Turchetto, Caroline [2], Bombarely, Aureliano [3], Freitas, Loreta [1].

A convoluted tale of hybridization between two Petunia species.

Recently diverged species may hybridize in their contact zone if effective reproductive barriers have not yet emerged. Petunia inflata and P. interior are closely related endemic species, share morphological features, genetic markers, and pollinators, and occupy a transitional area between the Pampa grasslands and the Atlantic Forest. Here, we used genomic data to verify the species boundaries, identify putative hybrids and shed light on their speciation process. We characterized 59 individuals from their allopatric and contact zones using genotyping-by-sequencing technology, resulting in a final dataset of 21,759 high-quality single nucleotide polymorphisms (SNP). Our results show that these species belong to distinct evolutionary lineages that hybridized after secondary contact. A combination of geographic distance, elevation, and climate explains the genetic divergence between species. Ecological niche modeling and niche overlap analysis revealed that even though these species have overlapped distributions and similar habitat preferences (Schoener’s D = 0.49), they are more distinct than expected by chance, rejecting the niche conservatism hypothesis. Demographic analysis suggests that the species diverged ~40,000 but came into secondary contact ~7,500 years ago. The secondary contact led to limited gene flow between species and bidirectional introgression. We identified 1,360 potentially under selection SNPs, associated with 1,731 unique gene ontology terms, of which 20 were statistically enriched terms involved in metabolic processes and signaling routes. A distribution expansion of P. inflata and P. interior ancestral into a transitional zone of biomes with elevational ranges followed by habitat fragmentations led to their speciation and niche differentiation. However, these species still exchanged genes after secondary contact since they are not yet reproductively isolated. This study is the first record of hybridization between species that belong to the short corolla tube Petunia clade. These species show a complex evolutionary history with conservation implications of these two endemic species.

1 - Universidade Federal Do Rio Grande Do Sul, Genetics, Po Box 15053, Porto Alegre, 91501-970, Brazil
2 - Universidade Federal do Rio Grande do Sul, Department of Botany, Porto Alegre, RS, Brazil
3 - University Of Milan, Bioscience, Via Celoria 26, Milan, MI, 20133, Italy

Keywords:
hybridization
species delimitation
populationg genetics
Speciation.

Presentation Type: Oral Paper
Session: HH2, Hybrids and Hybridization II
Location: /
Date: Wednesday, July 21st, 2021
Time: 1:30 PM(EDT)
Number: HH2005
Abstract ID:126
Candidate for Awards:Margaret Menzel Award