Isolation and characterization of microsatellites for the neotropical dioecious palm Chamaedorea tepejilote (Arecaceae) and cross‑amplification in other Chamaedorea species

Palms are important components of tropical and subtropical ecosystems and have even been considered keystone plant resources that can support a large array of pollinators and frugivores. Palms are also economically important. Chamaedorea tepejilote Liebm. is a widely distributed palm with important bioeconomic potential for food, traditional medicine and ornamental purposes. Eighteen microsatellite primers were developed for C. tepejilote. Polymorphism and genetic diversity were evaluated in 71 individuals from four populations in Costa Rica. Thirteen loci were polymorphic and the number of alleles in the pooled sample ranged between 5 and 20, the average number of alleles was 10.61. Average observed heterozygosity was Ho = 0.607 ± 0.04 (SD) and the average expected heterozygosity was He = 0.600 ± 0.03. The exclusion probability of the combined 13 loci, was PE = 0.998. We tested transferability of the markers in the congeneric C. costaricana, C. pinnantifrons and C. macrospadix. Dioecious species are common in tropical forests; however, few studies have analyzed gene flow patterns in these species. The markers developed for C. tepejilote are an important tool to quantify gene flow patterns and the distribution of genetic diversity within populations. This information will be useful for the development of conservation and management practices of this dioecious tropical palm species.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Chromosomal diversity in Philodendron (Araceae): taxonomic significance and a critical review

The genus Philodendron is a highly diverse Neotropical group of the monocot family Araceae. Despite chromosome counts being relatively abundant for the family, information on the karyotype evolution within the genus is still scarce and very confusing. Therefore, we report diploid numbers and additional cytological features for 43 species of Philodendron, discussing the importance of our results and reviewing previous data. Species were collected in four different Brazilian biomes (Caatinga, Cerrado, Amazon basin and Atlantic Forest) and chromosome counts were based on Giemsa standard staining procedures. First chromosome counts are given for 35 species, while for another eight species counts are reported for new provenances. The majority of the species (27) presented the diploid number of 2n = 32, while the number 2n = 34, the second most frequent, was observed in eight taxa. Uncommon chromosome numbers were observed for seven species: P. callosum and P. uliginosum with 2n = 28, P. hastatum and P. melinonii with 2n = 30, P. corcovadense and P. saxicola with 2n = 36 and P. brevispathum with 2n = 40. On the other hand, two species showed variation in chromosome numbers among analysed cells: P. insigne with 2n = 30-32 and P. pulchrum with 2n = 26-28. Regarding chromosome morphologies, a prevalence of submetacentric and metacentric pairs could be observed in most species, with some taxa having a tendency to asymmetry and a higher number of acrocentric pairs. A list of all available chromosomal data is presented, considering the actual taxonomic circumscription and synonyms. Considering the present analysis and the literature data, we suggest n = 16 instead of n = 18 as the primary basic number of the genus, from which secondary base numbers n = 17, 18 and (less frequently) 15, 14 and 13 have probably been derived. Dysploidy seems to be the prevalent karyoevolutionary trend within the genus. © 2013 Springer-Verlag Wien