Citogenética de Croton L. (Euphorbiaceae Juss.) do Parque Estadual do Pico do Jabre, Matureia, Paraíba, Brasil.

Abstract

It is through Natural Selection, which the Evolution presents itself as the basic principle of the occurrence of life, and understand the evolutionary mechanisms that enabled the emergence of diverse species existing today is one of the biggest challenges of Genetics. Being one of the greatest representatives of the family Euphorbiaceae Juss., the genus Croton L. is widely distributed in the Brazilian Northeast represented by several species, many of them endemic. There is still a wide divergence as to the taxonomic classification of this genus, due to the lack of detailed studies related to the evolutionary processes occurring in this group. As a strong ally in understanding these processes the Cytotaxonomy that through a detailed analysis of morphology and chromosome number variation helps to elucidate barriers in taxonomic classification. In this study, young or adult plants were collected of five species of the Croton genus occurring in the State Park of Pico do Jabre, aiming to determine the chromosome number of them. For chromosome counting, were prepared slides of all the species collected from the young root tips being registered the number counting of the chromosomes from three of them, identified as Croton grewioides Baill. (2n = 20) was the first data for Section Decarininum MOll.Arg., C. cf. laceratogladulosus Caruzo & Lamb (2n = 20), as also an unpublished data for this species that was recently identified, and C. urticifolius Lam (2n = 20). After checking up the lack of information regarding many species studied in this work, it can be concluded that the results obtained here can substantially contribute to Cytotaxonomy studies in addition to providing important data for understanding the evolutionary phenomena that occurring in the genus Croton, having also great ecological importance to the researches conducted in the study area, being the Pico do Jabre an important conservation area in the state of Parafba.