Format: ORAL

Roseane R.dos Santos1; José J. Amorim-Silva1; Juliano S. Cabral2; Ana P. Moraes3

1.Universidade Federal do ABC - UFABC, São Bernardo do Campo, Brazil. 2.University of Birmingham, Birmingham, United Kingdom. 3.Universidade Estadual Paulista - UNESP, IBB, Botucatu, Brazil

The relationship between cytogenetic and ecological data is a classical hypothesis. Recently, this subject was poorly analyzed within an evolutionary framework using phylogenetic comparative methods (PCM). To address this gap, we investigated the association between cytogenetic data and habitat using the subfamily Epidendroideae (Orchidaceae) as a model through PCM. The chromosome number (CN) and genome size (GS) data were organized into an online database (http://orchidcountsdb.epizy.com/) and a new phylogenetic tree was constructed based on four markers encompassing 1,754 species.Habit information was surveyed for all species with cytogenetic data. The CN varied 24x and presented a low phylogenetic signal (=0.53), while GS varied 119x and presented a high phylogenetic signal (=0.95). The mode and tempo of evolution suggest that both CN and GS show punctual evolution (=0.34), with long branches contributing more to the evolution of both characters (=3.00). When analyzing each tribe individually, Cymbidieae stands out as an interesting exception. This tribe shows adaptive radiation for CN and GS ( = 0 and 0 / = 0.46 and 0.31, respectively), and CN presents a high phylogenetic signal (=0.89). The OU evolutionary model, suggesting a response to stabilizing selection, was considered the best model for CN in the subfamily and in individual tribes as well, while BM was the best for GS. Once again, the exception is Cymbidieae, which had EB as the best model for both characters, reinforcing the suggestion of adaptive radiation.Based on these results, GS is more suitable for performing macroecological analysis, while PCM using CN will function as an ordinary test. Considering GS, small GS is associated with an epiphytic habitat (p=0.00067). In conclusion, GS is associated with habit at higher taxonomical levels, such as subfamily, while CN, is associated with ecological traits, it should be true at lower taxonomic level.