Estudos citotaxônomicos em Sapindales

Abstract

The citogenetics is the study of chromosomes and uses the chromosome number and the basic number as the main parameters of evaluation. The citotaxonomy as a tool has proved to be valuable means to elucidating biosystematic questions. The Sapindales order has nine families, where six of them are large families (Anacardiaceae, Burseraceae, Meliaceae, Sapindaceae e Simaroubaceae) and another three are small families (Biebersteiniaceae, Kirkiaceae and Nitrariaceae). Despite the order has already been corroborated as monofiletic many times, the relationships between families and their evolution still remain without a satisfactory model. Therefore, the study of state of art and of Sapindales chromosome number's evolution may serve as a database to solve these challenges. In chapter 1, we search in literature the chromosome numbers already published, as well as the extranumeric information such as: karyotype; images; discussions associated with phylogeny, basic number and ploidy level; logintudinal characterization; DNA content and microsporogenesis. We trace a cytogenetic knowledge order's, besides discuting chromosome number's evolution for the order and their families with suggestion of basic number. In chapter 2, we use the database of chromosome number with two phylogenetic trees for reconstruction of chromosome number's evolution for Sapindales orders and their families. The cytogenetic knowledge is low, with less than 50% of genders and 14% of species with a known number. The situation is similar for Brazilian genders. The extranumerical information is scarce, with the illustrations of the chromosomes being the most commonly presented. The ploidy level is the topic more discussed in publications. The records are mostly asiatics. There has been a decline in cytogenetic research since the 1980s. Regarding chromosome number evolution, in formation of large families of Sapindales, events of duplication and increase of chromosome number occurred from a common ancestor with x = 7, where x = 14 is the basic number in the root of the large families. The families had different evolutions of the chromosome number, but the internal tendency is the decrease of the chromosomic numbers through disploidia. Events of disploidia, mainly descending, are well recurrent throughout the evolutionary history of Sapindales. Polyploidy is an event that is not so present in the group, however, in the families in which it occurs, it was extremely important in diversification, as in Meliaceae and Rutaceae. The basic number suggestions were: