Hybridization: a ‘double-edged sword’ for Neotropical plant diversity

Abstract

Hybridization can facilitate both evolutionary diversification and extinction and has had a critical role in plant evolution, with c. 25% of species known to hybridize in some temperate floras. However, in the species-rich Neotropical flora, the role of hybridization in the evolution of diversity remains unclear. Our review examines studies of hybridization in seed plants from across the Neotropics and explores its outcomes on Neotropical plant evolution. We review studies on a per-biome basis and a spectrum of evolutionary outcomes from hybridization are evident across Neotropical biomes and taxa. These range from short-term impacts, such as the broadening of ecological amplitude in hybrid progeny with transgressive phenotypes and genetic swamping, through to long term impacts, such as the generation of new lineages. Among these studies certain themes emerge, such as the pervasive hybridization among species-rich plant radiations from the Andean páramos, suggesting a role for hybridization in rapid diversification events. Finally, we highlight that hybridization is relatively understudied in the Neotropical flora, despite its remarkable species richness. The advent of genomic techniques can facilitate the study of hybridization and its effects in understudied biomes and plant groups. The increasing availability of genomic resources will eventually allow comparisons between tropical and temperate floras and therefore shed light on the evolutionary impacts of hybridization across the latitudinal biodiversity gradient.

Genetic markers in Andean Puya species (Bromeliaceae) with implications on plastome evolution and phylogeny

“…Hybridization is common in plants and has a principal role in the origin of new species (Mallet, 2007 ; Xu et al, 2021 ). In the high‐elevation Andes, hybridization is also a relatively common occurrence, rendered by “flickering connectivity” and the diversity of habitats, resulting from Pleistocene climate changes and the steep ecological clines along mountain slopes, respectively (Schley et al, 2021 ). The hybridization hypothesis stands out as the most probable explanation for the biogeographic patterns and the extremely short branch length observed between P. macrura and P. macropoda (Figure 6a ).…”

The genetic mechanisms underlying the convergent evolution of pollination syndromes in the Neotropical radiation of Costus L.

“…Additionally exploring the signals in the UV spectrum (overlooked by our character coding) could also provide valuable information to understand the pollination biology of Costus ( Bergamo et al, 2016 ). Studying the morphology of hybrids presenting trait combinations that do not match the pollination syndromes, coupled with observations of floral visitors and quantification of reproductive success, could reveal reinforcement of reproductive isolation with unfit individuals resulting from gene flow between lineages attracting different pollinators ( Schley et al, 2022 ).…”

Evolutionary Genetics of Cacti: Research Biases, Advances and Prospects

“…Natural hybridization plays an important role in plant evolution [ 129 , 130 , 131 ]. Introgressive hybridization, reinforcement, local extinction, or hybrid speciation are the most relevant outcomes of hybridization, but interspecific gene flow may lead to a variety of results depending on the level of divergence between species, geographical context, and the balance with selective forces [ 132 ]. The role of hybridization in cactus evolution has long been highlighted [ 10 , 13 , 15 , 27 , 28 , 133 , 134 ].…”

“…Molecular markers are valuable allies to study the frequency and extension of hybridization [ 25 ]. Moreover, many statistical methods are available to investigate gene flow, depending on the depth of hybridization that one aims to detect [ 132 ]. For instance, these methods may involve the detection of genetic admixtures and F1 hybrids (e.g., STRUCTURE [ 135 ]; NEWHYBRIDS [ 136 ]), symmetric and asymmetric gene flow (e.g., MIGRATE [ 137 ]; G-PhoCS [ 138 ]), introgressive hybridization (e.g., INTROGRESS [ 139 ]), and gene tree inconsistencies (e.g., SNaQ [ 140 ]).…”

“…Undoubtedly, the study of hybridization in many Cactaceae taxa will be more accessible by the use of new sequencing technologies. The possibility of generating genomic datasets will allow the investigation of genetic variation across the entire genome, providing deep insights into the hybridization process in Cactaceae [ 132 , 149 ]. Specifically, for the cactus family, we seek to understand many open questions, such as: How permeable to gene flow are species?…”