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Abstract Detail



Biogeography

Gomes, Shaiany Sabrina Lopes  [1], Vidal, João [2], Koehler, Samantha [3], Viccini, Lyderson [4].

Genome size, polyploid origin and geographical distribution of Zygopetalum cytotypes from Neotropical high altitude rochy complexes.

Knowledge on the geographic distribution of cytotypes is crucial to understand the role of polyploidy in diversification. However, most of cytogeographical studies are concentrated in temperate regions. High altitude rocky complexes (HARCs) are heterogeneous formations found mainly in elevated areas of eastern Brazil. They harbour one of the most endemic floras within the Neotropical region and little is known about the occurrence and distribution of plant cytotypes in this region. Here, we investigate the distribution of Zygopetalum mackayi orchid cytotypes and propose a hypothesis for the polyploid origin in this species. We also investigate the association of environmental variables and the cytotypes. We describe chromosome counts, genomes size estimates, karyotypic traits and meiotic behaviour of representative individuals from 21 localities. The average of DNA content revealed three 2C values, 7.36 pg, 10.52 pg and 14.09 pg of DNA, which were associated to 2n = 48; 2n = 72 and 2n = 96 chromosomes, respectively. The variation of genome size was observed within and among populations. Karyotypic data (morphometry, 5S and 45S rDNA) is similar among all ploidy levels. Meiosis behavior is irregular as we observed chromosome delay and loss, bridges, micronuclei, chromosomal stickiness and asynchrony. We described three cytotypes for Z. mackayi. Cytotypes 2n = 48 and 2n = 96 are geographically structured and meet in a contact zone where an intermediate cytotype (2n = 72) is also found. The proportionality of DNA content and the chromosome number as well as the number of RNA sites, in addition to the similarity of the karyotypes and meiotic abnormalities suggest a possible autopolyploidy origin for the cytotypes. We provide a hypothesis for the independent expansion of cytotypes through distinct ecological habitats and discuss the implications of our results for chromosome evolution in Zygopetalum. Financial support: Fapemig, Fapesp, Capes.


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1 - UFJF, Biology, UFJF Campus, Juiz de Fora, MG, 36036-900, Brazil
2 - UNESP, Instituto de Biociências de Botacatu, UNESP Campus, Botucatu, SP, 18618-689
3 - UNICAMP, IB/Biologia Vegetal, Rua Monteiro Lobato, 255, Campinas, SP, 13083970, Brazil
4 - Biologia, Instituto De Ciências Biológicas, Campus Da UFJF, Bairro Martelos, Juiz De Fora, 36036-900, Brazil

Keywords:
Polyploidy
hybrid zone
Neotropics
Orchidaceae.

Presentation Type: Poster
Session: P, Biogeography
Location: Grand Ballroom - Exhibit Hall/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PBG009
Abstract ID:851
Candidate for Awards:None


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