ABSTRACT
Climate change has already altered global biodiversity, causing the migration of species and changes in habitat distribution. To implement a sustainable conservation strategy, it is necessary to understand the impacts of climate change on species. Lessingianthus is a South American genus that includes numerous endangered species, some of which grow in the Brazilian Cerrado, a Neotropical savanna considered a world's biodiversity hotspot. However, the impact of global climate change on these species has still not been estimated. We evaluate the effect of climate change on the habitat of 10 threatened Lessingianthus species and on their potential distribution, and assess the effectiveness of current protected areas (PAs) using ecological niche models. Based on the maximum entropy algorithm (Maxent), we first modeled the potential distribution of these species under current climatic conditions and then projected the distribution for two future scenarios of climate change (RCP 4.5 and RCP 8.5) and two time periods (2050 and 2070). We predicted current habitat suitability and identified suitable bioclimatic variables for these species. Our findings suggest that the area comprising the south and southeast of Cerrado is irreplaceable and the most biotically stable region for these endangered species; therefore, it should be considered a conservation priority area.
Subject(s)
Asteraceae , Climate Change , Animals , Brazil , Conservation of Natural Resources , Ecosystem , Endangered SpeciesABSTRACT
Chromosome counts and karyotypes of two species of Chrysolaena H. Robinson 1988 are presented in this paper. Mitotic analysis revealed that both taxa have x=10, a basic chromosome number considered characteristic of the genus. The chromosome number and the karyotype of Chrysolaena cristobaliana are reported for the first time, as well as a new cytotype and the karyotype of Chrysolaena sceptrum. Chrysolaena cristobaliana showed heptaploid cytotype with 2n=7x=70 and a karyotype composed of 46 m + 24 sm chromosomes. On the other hand, Chrysolaena sceptrum presented tetraploid cytotype with 2n=4x=40 and a karyotype with 30 m + 10 sm chromosomes. Accessory chromosomes were observed in cells of both species. The chromosome analysis showed that these species differ in the chromosome number and the total chromosome length, although they showed similar chromosome morphology and asymmetry indexes. The results support the use of chromosome data in taxonomic treatments of the American members of the tribe Vernonieae.
ABSTRACT
The nuclear DNA content was determined for the first time in 25 species of the South American genus Lessingianthus H.Rob. (Vernonieae, Asteraceae) by flow cytometry. This analysis constitutes the first estimation of the genome size for the Vernonieae tribe. The 2C- and 1Cx-values were calculated in all the species. The 2C-value ranged from 2.04 to 14.34 pg. The 1Cx-value ranged from 0.995 to 1.43 pg. The general tendency indicated a decrease in the 1Cx-value with increasing ploidy level, with some exceptions, in some species the 1Cx-value increased with the ploidy increase. The measuring of DNA content allowed reporting a new cytotype for L. polyphyllus (Sch.Bip.) H.Rob.
