The Neotropical genus Tillandsia (Bromeliaceae) is an excellent model system for macroevolutionary and biogeographic studies owing to its remarkable species diversity (ca. 650 spp.) and varied morphological and ecological adaptations to epiphytic and saxicolous habitats. Recent phylogenetic studies have greatly improved our knowledge about generic limits and infrageneric classification of Tillandsia. These studies have identified two clades of Tillandsia characterized by a distinct geographic distribution: (i) a North and Central American clade that includes species from subgenus Tillandsia; and (ii) a central South American clade containing species from subgenera Aerobia, Anoplophytum, Diaphoranthema, and Phytarrhiza. Our study aimed to determine the size, composition, and potential geographic structure of these two clades within the context of a global phylogeny of Tillandsioideae. With the addition of 100 newly sequenced species to previous studies to cover the now ca. 30% of the known species diversity of Tillandsia, our analyses found both clades to be strongly supported, and revealed that their species richness is much greater than previously known. Ancestral area estimation suggests that most of the diversification of the first of these clades took place in North and Central America, whereas within the second, most of the migratory events occurred from the Andes to the Brazilian shield.

The process of hybridization occurs in approximately 40% of vascular plants, and this exchange of genetic material between non-conspecific individuals occurs unequally among plant lineages, being more frequent in certain groups such as Opuntia (Cactaceae). This genus is known for multiple taxonomic controversies due to widespread polyploidy and probable hybrid origin of several of its species. Southern Mexico species of this genus have been poorly studied despite their great diversity in regions such as the Tehuacán-Cuicatlán Valley which contains around 12% of recognized Mexico’s native Opuntia species. In this work, we focus on testing the hybrid status of two putative hybrids from this region, Opuntia tehuacana and Opuntia pilifera, and estimate if hybridization occurs among sampled southern opuntias using two newly identified nuclear intron markers to construct phylogenetic networks with HyDe and Dsuite and perform invariant analysis under the coalescent model with HyDe and Dsuite. For the test of hybrid origin in O. tehuacana, our results could not recover hybridization as proposed in the literature, but we found introgression into O. tehuacana individuals involving O. decumbens and O. huajuapensis. Regarding O. pilifera, we identified O. decumbens as probable parental species, supported by our analysis, which sustains the previous hybridization hypothesis between Nopalea and Basilares clades. Finally, we suggest new hybridization and introgression cases among southern Mexican species involving O. tehuantepecana and O. depressa as parental species of O. velutina and O. decumbens.

Pilosocereus is one of the Cactaceae family’s most relevant genera in terms of the number of species and its wide geographical range in the Americas. Within Pilosocereus, five informal taxonomic groups have been recognized, one of which is P. leucocephalus group s.s., whose phylogenetic relationships remain unresolved. Therefore, our objectives are to recognize the circumscriptions of the species in P. leucocephalus group s.s. and to corroborate the monophyly and phylogenetic relationships of this group through a set of morphological and molecular characters. This study is based on representative sampling along the broad distribution of this group in Mexico and Central America using multivariate and phylogenetic analyses. The morphological characters identified to contribute to species recognition and group formation are branch diameter, areole length, the areole length-width ratio, the distance between areoles, the length of the longest radial spine, and branch and spines colors. The chloroplast markers rpl16, trnL-trnF, and petL-psbE and the nuclear marker AT1G18270 support the monophyly of the P. leucocephalus group s.s., and two probable synapomorphies are suggested, including one transversion in rpl16 and another in petL-psbE. Together, our results demonstrate that sampled species of P. leucocephalus group s.s. encompass six species distributed in Mexico and Central America: P. alensis and P. purpusii in the western region, P. chrysacanthus and P. collinsii in the central region, and P. gaumeri and P. leucocephalus in the eastern region. A taxonomic key to recognized species is provided.

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Background: Hybridization in nature occurs in numerous botanical families. In particular, the Cactaceae family contains lots of genera in which hybridization is reported. Questions: What are the patterns of reported natural hybridization in Cactaceae and their probable causes? Are there phylogenetic and evolutionary implications related to hybridization, particularly in Opuntioideae? Data description: A total of 62 articles about natural hybridization and classical Cactaceae literature were reviewed. Study site and dates: From 1900 to June 2021 Methods: A search for articles was performed in Web of Science and Google Scholar with the keywords "Cactaceae hybridization", for time span "1900 to 2021" and included information from classic family-specific monographs. Results: Natural hybrids in Cactaceae occur in subfamilies, Cactoideae and Opuntioideae. There is evidence of nonselective mechanisms of reproductive isolation, but only for few taxa. For Cactoideae members the main approach used was morphological description, and the tribe with the highest number of natural hybrids was Trichocereeae. In Opuntioideae, the reviewed articles performed mostly chromosome counts, morphometric and phylogenetic analyses, and showed the highest number of natural hybrids. Conclusions: It has been suggested that hybridization impacts the evolution of Cactoideae and Opuntioideae, but few studies have formally tested this hypothesis. In Cactoideae, we found only descriptive evidences of hybridization; therefore, previous statements suggesting an important role of hybridization in the evolution of Cactoideae should be supported by performing formal analyses. For the postulation that hybridization impacts the evolution of Opuntioideae, we found formal evidence supporting hybridization hypothesis unlike what we found in Cactoideae.