Hawaiian lobeliads exhibit extensive adaptive radiations and are considered the largest plant clade (143 species) endemic to any oceanic archipelago. Rapid insular radiations are prone to reticulate evolution, yet detecting hybridization has been limited by species sampling or inadequate nuclear data in previous Hawaiian studies. We analyzed 633 nuclear loci (including tetraploid duplications) and whole plastomes for 89% of extant species to derive phylogenies for the Hawai­ian lobeliads. Nuclear data provide strong support for nine major clades in both likelihood and ASTRAL analyses. All genera/sections are monophyletic except Clermontia and Cyanea. Nuclear and plastome phylogenies conflict on short, deep branches; the nuclear tree resolves a fleshy-fruited clade of Hawaiian Clermontia/Cyanea-Brighamia/Delissea, sister to Polynesian Sclerotheca, with both sister to a capsular-fruited Hawaiian clade. Incomplete lineage sorting in a rapid radiation starting 8.5-11.3 million years ago is sufficient to explain uncertainty and cytonuclear discordance along the backbone; sequence data strongly supports reticulation within Clermontia and especially Cyanea. Nuclear data identify 42 inter-island dispersal events, of which 89% accord with the progression rule, involving movement to the next younger, formerly unoccupied islands in the hotspot chain, consistent with ecological theory; plastid data overestimate such dispersals by 17%. Clermontia and Cyanea have undergone parallel adaptive radiations in elevational distribution and flower length on all major islands, but with some inter-island divergence. Within-island adaptive radiation and ecological speciation in these traits within Clemontia/Cyanea, combined with widespread single-island endemism, frequent inter-island dispersal, and occasional hybridization drove Hawaiian lobeliad diversification, together with early intergeneric divergence in habitat.

The California Floristic Province (CA-FP) is the most species-rich region of North American north of Mexico. Several hypotheses have been proposed to explain why this region is exceptionally diverse, including that it harbors many recently diverged clades with weak or no barriers to reproduction. Salvia subgenus Audibertia is a conspicuous element of the CA-FP, with multiple species often occurring in sympatry. Using 305 nuclear loci and both organellar genomes, we reconstruct species trees, examine genomic discordance, conduct divergence-time estimation, and analyze contemporaneous patterns of geneflow and mechanical reproductive isolation. Despite strong genomic discordance, an underlying bifurcating tree is supported. Organellar genomes capture additional introgression events not detected in the nuclear genome. Most interfertility is found within clades and species are generally not mechanically isolated. Rapid, recent speciation with some horizontal geneflow during the rise of Mediterranean climate is the underlying cause of extant diversity in subgenus Audibertia. Geneflow has largely not facilitated speciation. Its signal in the nuclear genome seems to mostly be erased by backcrossing, but organellar genomes each capture different events of historical geneflow, perhaps characteristic of many lineages in the CA-FP. Mechanical reproductive isolation is likely only part of a mosaic of factors limiting geneflow.

Ecological communities are structured by a diverse set of processes acting at different spatial scales. In plant communities, assembly processes like ecological sorting, limiting similarity, and stochastic events are all expected to influence plant distributions and co-occurrence patterns. We assembled a data set describing the distribution of 139 herbaceous plant species within and among 257 forest stands in Wisconsin (USA) to elucidate the spatial scales at which these assembly processes operate. Analyses of these data in conjunction with detailed information about environmental conditions, plant functional traits, and phylogenetic relationships provided new insights into the scale-dependent drivers of plant community assembly in temperate forest understories. Traits like leaf height, specific leaf area, and seed mass all influenced individualistic plant distributions along landscape-scale gradients in soil texture, soil fertility, light availability, and climate while phylogenetic relationships did not predict species-environment relationships. These findings point to the importance of trait-mediated ecological sorting in shaping individualistic plant distributions at broad spatial scales. Contrary to our expectations about the importance of limiting similarity at local scales, neither functionally similar nor phylogenetically related herbs segregated among microsites within forest stands. We hypothesize strong ecological sorting among forest stands coupled with stochastic fine-scale interactions among species appear deterministic, niche-based assembly processes at local scales.

The mint family (Lamiaceae) is one of the largest and most economically important families of flowering plants. Despite focused study on relationships within subclades, higher-level relationships have been understudied. Moreover, the herbaceous habit of much of the family has resulted in a poor fossil record and has hampered estimates of divergence times. Using a new dataset of five plastid loci from 178 Lamiaceae representing all subfamilies and nearly all tribes, we clarify major infrafamilial relationships and present a robust set of divergence times. We use this phylogenetic hypothesis as a platform to test prior hypotheses regarding the historical biogeography and evolution of major traits within the family. We confirm the placement of subfamily Nepetoideae, show continued uncertainty in the placement of subfamilies Ajugoideae and Premnoideae, and highlight extreme discordance with recent results from nuclear data. Lamiaceae originated during the Late Cretaceous as a woody plant with a nutlet fruit and four stamens, probably in Southeast Asia. Most subfamilies diverged during the Eocene, perhaps facilitated by climatic cooling. Our results provide a valuable set of secondary dates for Lamiaceae and highlight the need for focused study of subfamilies Callicarpoideae and Viticoideae. Our results also provide several hypotheses regarding trait or range-dependent diversification.

A fundamental question in evolutionary biology is how clades of organisms exert influence on one another. The evolution of the flower and subsequent plant/pollinator coevolution are major innovations that have operated in flowering plants to promote species radiations at a variety of taxonomic levels in the Neotropics. Here we test the hypothesis that pollination by Neotropical endemic hummingbirds drove the evolution of two unique stigma traits in correlation with other floral traits in New World Salvia (Lamiaceae). We examined morphometric shapes of stigma lobing across 400 Salvia spp., scored presence and absence of a stigma brush across Salvia, and used a suite of phylogenetic comparative methods to detect shape regime shifts, correlation of trait shifts with BayesTraits and phylogenetic generalized least square regressions, and the influence of scored pollinators on trait evolution using OUwie. We found that a major Neotropical clade of Salvia evolved a correlated set of stigma features, with  a longer upper stigma lobe and stigmatic brush, following an early shift to hummingbird pollination. Evolutionary constraint is evident as subsequent shifts to bee pollination largely retained these two features. Our results support the hypothesis that hummingbirds guided the correlative shifts in corolla, anther connective, style and stigma shape in Neotropical Salvia, despite repeated shifts back to bee pollination.

PREMISE OF THE STUDY: We tested 25 classic and novel hypotheses regarding trait-origin, trait-trait, and trait-environment relationships to account for flora-wide variation in life history, habit, and especially reproductive traits using a plastid DNA phylogeny of most native (96.6%, or 1494/1547 species) and introduced (87.5%, or 690/789 species) angiosperms in Wisconsin, USA. METHODS: We assembled data on life history, habit, flowering, dispersal, mating system, and occurrence across open/closed/mixed habitats across species in the state phylogeny. We used phylogenetically structured analyses to assess the strength and statistical significance of associations predicted by our models. KEY RESULTS: Introduced species are more likely to be annual herbs, occupy open habitats, have large, visually conspicuous hermaphroditic flowers, and bear passively dispersed seeds.  Among native species, hermaphroditism is associated with larger, more conspicuous flowers; monoecy, with small inconspicuous flowers and passive seed dispersal; and dioecy, with small inconspicuous flowers and fleshy fruits. Larger flowers with more conspicuous colors are more common in open habitats, and in understory species flowering under open (spring) canopies; fleshy fruits are more common in closed habitats. Wind pollination may help favor dioecy in open habitats. CONCLUSIONS: These findings support predictions regarding how breeding systems depend on flower size, flower color, and fruit type, and how those traits depend on habitat. This study is the first to combine flora-wide phylogenies with complete trait databases and phylo­genetically structured analyses to provide powerful tests of evolutionary hypotheses about reproductive traits and their variation with geographic source, each other, and environmental conditions.

Natural selection by pollinators is an important factor in the morphological diversity and adaptive radiation of flowering plants. Selection by similar pollinators in unrelated plants leads to convergence in floral morphology, or “floral syndromes.” Previous investigations into floral syndromes have mostly studied relatively small and/or simple systems; emphasizing vertebrate-pollination. Despite the importance of multiple floral traits in plant-pollinator interactions, these studies have examined few quantitative traits, so their co-variation and phenotypic integration have been underexplored. To gain better insights into pollinator-trait dynamics, we investigate the model system of the phlox family (Polemoniaceae), a clade of ~ 400 species pollinated by a diversity of vectors. Using a comprehensive phylogeny and large dataset of traits and observations of pollinators, we reconstruct ancestral pollination system; accounting for the temporal history of pollinators. We conduct phylogenetically controlled analyses of trait co-variation and association with pollinators, integrating many analyses over phylogenetic uncertainty. Pollinator shifts are more heterogeneous than previously hypothesized. The evolution of floral traits is partially constrained by phylogenetic history and trait co-variation, but traits are convergent and differences are associated with different pollinators. Trait shifts are usually gradual, rather than rapid, suggesting complex genetic and ecological interactions of flowers at macroevolutionary scales.

Phylogenomic data from a rapidly increasing number of studies provide new evidence for resolving relationships in recently radiated clades, but they also pose new challenges for inferring evolutionary histories. Most existing methods for reconstructing phylogenetic hypotheses rely solely on algorithms that only consider incomplete lineage sorting as a cause of intra- or inter-genomic discordance. Here, we utilize a variety of methods, including those to infer phylogenetic networks, to account for both incomplete lineage sorting and introgression as a case for nuclear and cytoplasmic-nuclear discordance using phylogenomic data from the recently radiated flowering plant genus Polemonium (Polemoniaceae), an ecologically diverse genus in Western North America with known and suspected gene flow between species. We find evidence for widespread discordance among nuclear loci that can be explained by both incomplete lineage sorting and reticulate evolution in the evolutionary history of Polemonium. Furthermore, the histories of organellar genomes show strong discordance with the inferred species tree from the nuclear genome. Discordance between the nuclear and plastid genome is not completely explained by incomplete lineage sorting, and only one case of discordance is explained by detected introgression events. Our results suggest that multiple processes have been involved in the evolutionary history of Polemonium and that results from the plastid genome do not accurately reflect species relationships. We discuss several potential causes for this cytoplasmic-nuclear discordance, which emerging evidence suggests is more widespread across the Tree of Life than previously thought.

Switches in pollinators have been argued to be key drivers of floral evolution in angiosperms. However, few studies have tested the relationship between floral shape evolution and switches in pollination in large clades. In concert with a dated phylogeny, we present a morphometric analysis of corolla, anther connective, and style shape across 44% of nearly 1,000 species of Salvia (Lamiaceae) and test four hypotheses of floral evolution. We demonstrate that floral morphospace of New World (NW) Salvia is largely distinct from that of Old World (OW) Salvia and that these differences are pollinator driven; that shifts in floral morphology sometimes mirror shifts in pollinators; that anther connectives (key constituents of the Salvia staminal lever) and styles co-evolved from curved to linear shapes following shifts from bee to bird pollination; and that morphological differences between NW and OW bee flowers are partly the legacy of constraints imposed by an earlier shift to bird pollination in the NW. The distinctive staminal lever in Salvia is a morphologically diverse structure that has evolved in concert with both the corolla and style, under different pollinator pressures, and in contingent fashion.