Abstract
Pseudolaelia is a genus endemic to the eastern Brazilian Atlantic Forest, consisting of 12 accepted species. Some Pseudolaelia species, such as P. vellozicola, P. aguadocensis, P. oliveirana, and P. regentii, referred to here as the PV complex, present extensive intra‐ and interpopulation morphological polymorphism, raising uncertainty regarding their circumscriptions. Although previous morphological analyses were used to solve the generic boundaries in the PV complex, persuasive genetic evidence is lacking. In order to test the hypothesis that the group under investigation contains only one taxon, amplification profiles of five intersimple sequence repeat (ISSR) markers were used to evaluate genetic diversity, genetic structure, and the relationships among the PV complex species. A total of 134 reproductive individuals were sampled in eight insular populations. Intrapopulation genetic analysis indicated low levels of genetic diversity. Analysis of genetic structure revealed that each of the eight sample locations can be considered unique biological populations as they are highly differentiated from each other. The Mantel test showed a high and positive correlation between genetic and geographic distance (r = .841, p < .002), indicating isolation by distance. The results are consistent with that expected for plants with insular geographical distribution. When testing for the null hypothesis, the low levels of genetic variation among species (F CT = 0.155) suggest that the populations constitute only one highly polymorphic species with a wide distribution.
Highlights
The orchid family (Orchidaceae) is one of the largest families of flowering plants, with roughly 26,000 species distributed worldwide, the majority of which occur in tropical regions
Besides small population sizes and habitat specificity, all Pseudolaelia species are threatened to some degree due to habitat degradation caused by mining and uncontrolled tourism (Menini Neto, 2011)
We found no significant differences for the studied genetic diversity indexes: P. aguadocensis (HE—95% CI 0.034, 0.152; I—95% CI 0.056, 0.228); P. oliveirana (HE— 95% CI 0.106, 0.212; I—95% CI 0.169, 0.325); P. regentii (HE—95% CI −0.004, 0.100; I—95% CI −0.005, 0.143); P. vellozicola (HE—95% CI 0.141, 0.319; I—95% CI 0.223, 0.481)
Summary
The orchid family (Orchidaceae) is one of the largest families of flowering plants, with roughly 26,000 species distributed worldwide, the majority of which occur in tropical regions. The majority of species morphologies for Pseudolaelia are quite homogeneous, a taxonomic revision based on analyses of herbarium specimens and field studies for the genus revealed remarkable floral polymorphism for Pseudolaelia vellozicola (Hoehne) Porto & Brade populations (Menini Neto et al, 2013). These results, along with recent descriptions of some very similar taxa, viz. Pseudolaelia aguadocensis Campacci (Campacci, 2016), Pseudolaelia regentii V.P.Castro & Marçal (Castro Neto & Marçal, 2007), and Pseudolaelia oliveirana V.P.Castro & Chiron (Castro Neto & Chiron, 2009), have made the taxonomical definition of P. vellozicola species more complex. Amplification profiles of five intersimple sequence repeat (ISSR) markers were used to evaluate genetic diversity, genetic structure, and the relationships among the studied populations and species of the PV complex
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