Plant Species Complexes as Models to Understand Speciation and Evolution: A Review of South American Studies

Abstract

Identifying discontinuous entities within species complexes is a major topic in systematic and evolutionary biology. Comprehensive inventories describing and identifying species rapidly and correctly before they or their habitats disappear is especially important in megadiverse regions, such as South America continent, where a large part of the biodiversity is still unknown and remains to be discovered. Species complexes may account for a substantial number of plant groups in the South American flora, and studies investigating species boundaries in such challenging groups are needed. In this context, multidisciplinary approaches are crucial to understanding the species integrity and boundaries within species complexes. Morphometrics, cytogenetics, anatomy, crossing experiments, and molecular markers have been combined in different ways to investigate species complexes and have helped depict the mechanisms underlying the origin of South American species. Here, we review the current knowledge about plant species complexes on the hyperdiverse South American continent based on a detailed examination of the relevant literature. We discuss the main findings in light of the potential evolutionary mechanisms involved in speciation and suggest future directions in terms of integrating multispecies coalescence methods with several complementary types of morphological, ecological, and geographical data in this research field.

Ecological niche modeling and a lack of phylogeographic structure in Vriesea incurvata suggest historically stable areas in the southern Atlantic Forest

“…However, the design of efficient strategies requires knowledge of current biodiversity patterns and, more importantly, a better understanding of its evolutionary history (Álvarez‐Presas et al., ). Much effort has been put into understanding the complex and high levels of biodiversity in the AF through phylogeographic, biogeographic, and paleomodeling studies, which may provide valuable insights into the historical processes underlying diversification in this region (Martins, ; Turchetto‐Zolet et al., ; Leal et al., ; Antonelli et al., ; Pinheiro et al., ). Nevertheless, neotropical biodiversity data present numerous uncertainties, which hamper the generalization of patterns (Antonelli et al., ).…”

Targeted Capture of Hundreds of Nuclear Genes Unravels Phylogenetic Relationships of the Diverse Neotropical Palm Tribe Geonomateae

“…Various hypotheses have been proposed to explain this kind of chaotic intraspecific phenotypic variation, such as population contraction and expansion during Pleistocene climatic oscillations (Cronk, 1998), rapid dispersal followed by selection (Cronk, 1998), or niche divergence induced by forest heterogeneity (Henderson, 2011). From a genetic perspective, incomplete lineage sorting or hybridization are commonly invoked to explain the widespread occurrence of plant species complexes similar to those found in Geonoma (Bacon et al, 2012b; Pinheiro et al, 2018). Although our results pointed to high level of gene tree incongruence in the species complexes of Geonoma (Figure 3), likely due to incomplete lineage sorting, it is beyond the scope of our study to test for any of these underlying mechanisms.…”

Systematics of Vriesea (Bromeliaceae): phylogenetic relationships based on nuclear gene and partial plastome sequences

“…Alternatively, the non-monophyly of many species of Vriesea could reflect true biological processes. Indeed, species complexes and non-monophyletic species are common in plants (Naciri & Linder, 2015;Pinheiro, Dantas-Queiroz & Palma-Silva, 2018) and are thought to be the result of hybridization or incomplete lineage sorting. Assuming that post-zygotic barriers for reproduction of bromeliads are potentially weak (Palma-Silva et al, 2011;Wagner et al, 2015) and that the individuals often grow in mixed aggregates of species sharing the same pollinator, interspecific gene flow may occur and lead to the formation of natural hybrids (Palma-Silva et al, 2011;Lexer et al, 2016;Zanella et al, 2016;Neri, Wendt & Palma-Silva, 2017;Mota et al, 2019).…”