Phylogenetic and population genetic analyses of diploid Leucaena (Leguminosae; Mimosoideae) reveal cryptic species diversity and patterns of divergent allopatric speciation

Abstract

Findings from this study highlight the importance and utility of multilocus data in the recovery of complex evolutionary histories. The results are consistent with allopatric divergence representing the predominant mode of speciation among diploid Leucaena. These findings contrast with the potential hybrid origin of several tetraploid species and highlight the importance of human translocation of seed to the origin of these tetraploids. The recognition of one previously unrecognized species (L. cruziana) and the elevation of another taxon (L. collinsii subsp. zacapana) to specific status (L. zacapana) is consistent with a growing number of newly diagnosed species from neotropical seasonally dry forests, suggesting these communities harbor greater species diversity than previously recognized.

Neotropical Plant Evolution: Assembling the Big Picture

“…Olmstead, ), predominance of allopatry and allopatric speciation (e.g. Govindarajulu et al ., ), pre‐Pleistocene divergence time estimates for species and clade ages and well‐supported monophyly of individual species in densely sampled gene trees. Taken together, this evidence points to a scenario of dispersal limitation across the highly fragmented, disjunct distribution of SDTFs, in‐situ diversification of pairs or small clades of species in specific SDTF nuclei and long persistence and relative stasis of stable populations of SDTF species and lineages over the past two to ten or more million years (Lavin et al ., ; Lavin ; Pennington et al., , b, , ).…”

“…Despite a history of neglect compared to the more charismatic and widely publicized lowland tropical rain forests, research on seasonally dry tropical forests has blossomed in the last decade, revealing not only the biological importance of these forests in terms of their highly endemic floras, but also important insights into the biogeography of this biome and the processes and factors that have apparently shaped the historical assembly of SDTF species diversity (Linares‐Palomino et al ., ; Prado, ; Lavin et al ., ; Pennington et al ., , , b, , ; Lavin, ; Särkinen et al ., , ). A growing number of detailed and well‐sampled phylogenetic analyses of SDTF lineages show high levels of dry forest niche conservatism (Pennington et al ., ; Govindarajulu et al ., ), high geographical phylogenetic structure (e.g. Olmstead, ), predominance of allopatry and allopatric speciation (e.g.…”

“…possibly a minimum of 80% taxon sampling to estimate diversification rates confidently; Cusimano & Renner, ) and, ideally, should sample multiple individuals per species to encompass intra‐ as well as interspecific diversity and assist in uncovering potential cryptic species (e.g. Govindarajulu et al ., ; Särkinen et al ., ). More difficulties arise because a potentially significant proportion of the actual species diversity is yet to be discovered or, even worse, because many species may have already gone extinct by human activity (disrupting the background extinction rate).…”

Incipient speciation in the Chihuahuan Desert shrub Berberis trifoliolata under divergent climate scenarios

“…A number of phylogeographical studies carried out in recent years have revealed that widespread species are often subdivided into genetically distinct forms that lack morphological differences (e.g., Forsdyke 2013;Johnson et al 2013;Govindarajulu et al 2011;Pillon et al 2009;Carstens and Satler 2013;Paupério et al 2012). The discovery and characterization of these forms contribute to the understanding of speciation (Sites and Marshall 2003).…”

Generic identity of Camptorrhiza indica (Colchicaceae) based on cytogenetics and molecular phylogenetics

“…The morphological characters might be overlapping between these species and it might not be possible to distinguish them. Within the genus Leucaena (Leguminosae; Mimosoideae) cryptic diversity was found among allopatric populations (Govindarajulu et al, ). Cryptic speciation is observed frequently in mosses and liverworts which occur in a wide geographical area (McDaniel & Shaw, 2003; Yu et al, ).…”