Genome size and climate segregation suggest distinct colonization histories of an orchid species from Neotropical high-elevation rocky complexes

Secondary origin, hybridization and sexual reproduction in a diploid–tetraploid contact zone of the facultatively apomictic orchid Zygopetalum mackayi

“…Zygopetalum mackayi is pollinator‐dependent to form fruit as it does not perform spontaneous self‐pollination (Campacci et al 2017). Still, the larger geographic range of tetraploids (Gomes et al 2018) suggests they are maintaining or expanding over their area of occurrence, even in the presence of triploids. In fact, geographic/ecological parthenogenesis may depend on biological consequences of polyploidy, rather than apomixis, as polyploidy is hypothesized to have transformative effects in plant ecology (Ramsey & Ramsey 2014).…”

“…Genetic structure and clustering analyses reveal relationships of genetic similarity among sampled cytotypes and populations. Our goal was to confirm cytotypes of Z. mackayi are in secondary contact, as hypothesized by Gomes et al (2018). The genetic relatedness among cytotypes was estimated based on Bruvo distances, using the package polysat (Clark & Schreier 2017) for R 3.4.0 (R Core Team 2017).…”

“…However, a basic chromosome number of x = 6 is highly subjective and unreliable, due to unknown chromosome numbers and genome size data of phylogenetically related species (Glick & Mayrose 2014). The geographic structure of Z. mackayi cytotypes, the presence of a well‐defined contact zone between populations of pure cytotypes and restriction of intermediate cytotypes to the contact zone point to a secondary origin of the contact zone, but this hypothesis remains untested (Gomes et al 2018). Cytotype 2N = 96 has a much larger distribution than the others, but cytotype frequency in mixed cytotype populations is extremely unequal, with all three cytotypes being dominant in at least one population (Gomes et al 2018).…”

“…The geographic structure of Z. mackayi cytotypes, the presence of a well‐defined contact zone between populations of pure cytotypes and restriction of intermediate cytotypes to the contact zone point to a secondary origin of the contact zone, but this hypothesis remains untested (Gomes et al 2018). Cytotype 2N = 96 has a much larger distribution than the others, but cytotype frequency in mixed cytotype populations is extremely unequal, with all three cytotypes being dominant in at least one population (Gomes et al 2018). Cytotypes 2N = 72 and 2N = 96 of this species are facultatively apomictic, while 2N = 48 are strictly sexual (Afzelius 1959; Costa 2018).…”

Cytotaxonomy and geographic distribution of cytotypes of species of the South American genus Chrysolaena (Vernonieae, Asteraceae)

“…Environmental heterogeneity, together with polyploidization and hybridization, has been proposed to explain the high species richness and endemism reported in these areas (Echternacht et al, ; Gomes et al, ). The study of the geographical distribution of cytotypes is a key requirement to understand the role of polyploidy in diversification (Sonnleitner et al, ; Gomes et al, ). Cytogeographic patterns may reveal significant amounts of diversity by identifying multiple chromosomal races among related species or within a single taxonomic species and, therefore, contribute to the conservation of rare species and ecological restoration (Soltis et al, ).…”