TY - JOUR
T1 - Números cromosómicos para tres especies de Cosmos sección Discopoda (Asteraceae, Coreopsideae), con notas citogeográficas
AU - Castro-Castro, Arturo
AU - Vargas-Amado, Georgina
AU - Castañeda-Nava, José Juvencio
AU - Harker, Mollie
AU - Munguía-Lino, Guadalupe
AU - Santacruz-Ruvalcaba, Fernando
AU - Rodríguez, Aarón
PY - 2017
Y1 - 2017
N2 - Background and Aims: Cosmos section Discopoda (Asteraceae, Coreopsideae) is a model for studying polyploidy and aneuploidy. This section is monophyletic, including 24 herbaceous perennials with some polyploid species and others aneuploids. However, the chromosome numbers of some species are still unknown and their cytogeography has not been studied. Here the chromosome counts for three species are revealed and the ancestral levels of ploidy as well as geographical distributions of the different ploidy levels are compared. Methods: Previously known chromosome counts were retrieved and chromosome counts were made from vegetative parts of three species. After designating a ploidy level to each of 810 registers, including all species and through the use of a geographic information system, their distributions were analyzed based on those ploidy levels. In addition, using a maximum likelihood model, a reconstruction of ancestral ploidy was made. Key results: Cosmos nitidus and C. ramirezianus are diploids (2n=2x=24) while C. pseudoperfoliatus is tetraploid (2n=4x=48). To date, chromosome counts for the 20 species of Cosmos section Discopoda are known, of which 12 are diploids (2n=2x), six are exclusively polyploids (2n=4x, 6x, 8x), four are diploids and polyploids and there are two independent events of aneuploidy. The reconstruction of ancestral ploidy levels revealed that x=12 is the basic number of chromosomes in this section of Cosmos. Conclusions: A correlation between the ploidy levels and geographical ranges of the species of Cosmos section Discopoda does not seem apparent. In contrast, there does seem to be an increase in ploidy levels from south to north, with a concentration of polyploids in the northern area of the Sierra Madre Occidental.
AB - Background and Aims: Cosmos section Discopoda (Asteraceae, Coreopsideae) is a model for studying polyploidy and aneuploidy. This section is monophyletic, including 24 herbaceous perennials with some polyploid species and others aneuploids. However, the chromosome numbers of some species are still unknown and their cytogeography has not been studied. Here the chromosome counts for three species are revealed and the ancestral levels of ploidy as well as geographical distributions of the different ploidy levels are compared. Methods: Previously known chromosome counts were retrieved and chromosome counts were made from vegetative parts of three species. After designating a ploidy level to each of 810 registers, including all species and through the use of a geographic information system, their distributions were analyzed based on those ploidy levels. In addition, using a maximum likelihood model, a reconstruction of ancestral ploidy was made. Key results: Cosmos nitidus and C. ramirezianus are diploids (2n=2x=24) while C. pseudoperfoliatus is tetraploid (2n=4x=48). To date, chromosome counts for the 20 species of Cosmos section Discopoda are known, of which 12 are diploids (2n=2x), six are exclusively polyploids (2n=4x, 6x, 8x), four are diploids and polyploids and there are two independent events of aneuploidy. The reconstruction of ancestral ploidy levels revealed that x=12 is the basic number of chromosomes in this section of Cosmos. Conclusions: A correlation between the ploidy levels and geographical ranges of the species of Cosmos section Discopoda does not seem apparent. In contrast, there does seem to be an increase in ploidy levels from south to north, with a concentration of polyploids in the northern area of the Sierra Madre Occidental.
KW - Cytogeography
KW - Heliantheae
KW - Mexican transition zone
KW - Polyploidy
KW - Sierra madre occidental
UR - http://www.scopus.com/inward/record.url?scp=85031038569&partnerID=8YFLogxK
U2 - 10.21829/abm118.2017.1199
DO - 10.21829/abm118.2017.1199
M3 - Artículo
SN - 0187-7151
VL - 2017
SP - 41
EP - 52
JO - Acta Botanica Mexicana
JF - Acta Botanica Mexicana
IS - 118
ER -