Floral nectar spurs are widely considered a key innovation promoting diversification in angiosperms by means of pollinator shifts. We investigated the macroevolutionary dynamics of nectar spurs in the tribe Antirrhineae (Plantaginaceae), which contains 29 genera and 300–400 species (70–80% spurred). The effect of nectar spurs on diversification was tested, with special focus on Linaria, the genus with the highest number of species. We generated the most comprehensive phylogeny of Antirrhineae to date and reconstructed the evolution of nectar spurs. Diversification rate heterogeneity was investigated using trait-dependent and trait-independent methods, and accounting for taxonomic uncertainty. The association between changes in spur length and speciation was examined within Linaria using model testing and ancestral state reconstructions. We inferred four independent acquisitions of nectar spurs. Diversification analyses revealed that nectar spurs are loosely associated with increased diversification rates. Detected rate shifts were delayed by 5–15 Myr with respect to the acquisition of the trait. Active evolution of spur length, fitting a speciational model, was inferred in Linaria, which is consistent with a scenario of pollinator shifts driving diversification. Nectar spurs played a role in diversification of the Antirrhineae, but diversification dynamics can only be fully explained by the complex interaction of multiple biotic and abiotic factors., This work was supported by the Marie Curie Intra‐European Fellowship LINARIA‐SPECIATION (FP7‐PEOPLE‐2013‐IEF, reference 624396), an Isaac Newton Trust Research Grant (Trinity College, Cambridge), a Juan de la Cierva fellowship to MF‐M (Spanish Ministry of Economy and Competitivity, reference IJCI‐2015‐23459) and a Generalitat Valenciana postdoctoral grant to AJ (Ministry of Education, Culture and Sport, reference BEST/2014/264)., Peer reviewed

Disentangling species boundaries and phylogenetic relationships within recent evolutionary radiations is a challenge due to the poor morphological differentiation and low genetic divergence between species, frequently accompanied by phenotypic convergence, interspecific gene flow and incomplete lineage sorting. Here we employed a genotyping-by-sequencing (GBS) approach, in combination with morphometric analyses, to investigate a small western Mediterranean clade in the flowering plant genus Linaria that radiated in theQuaternary.After confirming the morphological and genetic distinctness of eight species, we evaluated the relative performances of concatenation and coalescent methods to resolve phylogenetic relationships. Specifically, we focused on assessing the robustness of both approaches to variations in the parameter used to estimate sequence homology (clustering threshold). Concatenation analyses suffered from strong systematic bias, as revealed by the high statistical support for multiple alternative topologies depending on clustering threshold values. By contrast, topologies produced by two coalescent-based methods (NJst, SVDquartets) were robust to variations in the clustering threshold. Reticulate evolution may partly explain incongruences between NJst, SVDquartets and concatenated trees. Integration of morphometric and coalescent-based phylogenetic results revealed (i) extensive morphological divergence associated with recent splits between geographically close or sympatric sister species and (ii) morphological convergence in geographically disjunct species. These patterns are particularly true for floral traits related to pollinator specialization, including nectar spur length, tube width and corolla color, suggesting pollinatordriven diversification. Given its relatively simple and inexpensive implementation, GBS is a promising technique for the phylogenetic and systematic study of recent radiations, but care must be taken to evaluate the robustness of results to variation of data assembly parameters., This work was supported by the Marie Curie Intra-European Fellowship LINARIA-SPECIATION (FP7-PEOPLE-2013-IEF, project reference 624396) and an Isaac Newton Trust Research Grant (Trinity College, Cambridge), Peer reviewed

[Background and Aims] Ecological speciation is frequently invoked as a driver of plant radiation, but the
behaviour of environmental niches during radiation is contentious, with patterns ranging from niche conservatism to niche divergence. Here, we investigated climatic and edaphic niche shifts during radiation in a western
Mediterranean lineage of the genus Linaria (Plantaginaceae)., [Methods] Detailed distributional, phylogenomic and environmental data were integrated to analyse changes
in climatic and edaphic niches in a spatiotemporal context, including calculation of niche overlap, niche equivalency and similarity tests, maximum entropy modelling, phylogenetic comparative methods and biogeographical
analyses., [Key Results] Active divergence of climatic and edaphic niches within a limited subset of available conditions
was detected among the eight study species and particularly between sister species. Speciation and niche divergence are estimated to have happened in the southern Iberian Peninsula in Mediterranean conditions, followed by waxing and waning of distribution ranges resulting from the Quaternary climatic cycles., [Conclusions] The results support the idea that the prevalence of niche conservatism or niche divergence patterns is a matter of phylogenetic scale. Habitat isolation pertaining to both climatic and soil conditions appears to have played a role in plant speciation in the western Mediterranean biodiversity hotspot, most probably in combination with pollinator isolation and some degree of geographical isolation. These fndings are in agreement with an adaptive radiation scenario incorporating certain non-adaptive features., This work was supported by the European Commission through Marie Curie Intra-European Fellowship LINARIASPECIATION (FP7-PEOPLE-2013-IEF, reference 624396), the Isaac Newton Trust (Trinity College, Cambridge, UK) through an Isaac Newton Trust Research Grant, the Spanish Ministry of
Economy and Competitiveness through a Juan de la Cierva fellowship (reference IJCI-2015-23459) and the Spanish Ministry of Science, Innovation and Universities through a Ramón y Cajal fellowship (reference RYC2022-036418-I) to MF-M., Peer reviewed

Methods used for collection/generation of data: A GIS layer (at 30 arc-second resolution) mapping nine major lithological classes potentially influencing plant distributions across the Iberian Peninsula. It was built using information from lithological maps of continental Spain (IGME, 2006), continental Portugal, Andorra and southern France (http://portal.onegeology.org/; Laxton et al., 2010), and it is provided in ASCII raster format, FP7-PEOPLE-2013-IEF, reference 624396, Peer reviewed, in

1 p.-5 fig. IBC 2024 XX International Botanical Congress July 21st-27th, P.0485, p.259 (2024), The Mediterranean Basin is a biodiversity hotspot harbouring numerous plant lineages that have undergone rapid in situ diversification. The Baetic Mountains, in the western Mediterranean, are a particularly rich centre of plant diversification associated with high topographic, climatic and edaphic heterogeneity. A plant lineage that has radiated in this region is the tribe Antirrhineae (Plantaginaceae), and particularly the genus Linaria.
Interestingly, this genus displays a floral key innovation potentially driving diversification, the nectar spur. The pair of recently-diverged sister species formed by L. becerrae and L. clementei,endemic to neighbouring areas of the Baetic Mountains (Málaga, Spain), is an ideal system to investigate the interplay of factors driving plant
speciation. These species occur on calcareous substrates and display a striking difference in spur length. They interbreed under nursery conditions,but this does not seem to happen in nature,most likely because of ecological isolating factors, potentially including biotic interactions and small-scale differences in climate and soil.To disentangle the factors driving speciation and population differentiation in this species pair,we generated genotyping-by-sequencing (GBS)data and investigated climatic and edaphic variables, accompanying plant communities and pollinator interactions. The GBS analyses revealed strong genetic isolation between species
despite their geographical proximity (<5 km for the closest population pair). According to pollinator censuses and discriminant analyses of ecological variables, pollination interactions or climatic differences alone do not seem to explain this genetic pattern. Remarkably, both species inhabit edaphic islands on distinct calcareous lithologies:calcarenite for L. becerrae and marble for L. clementei. We propose that these edaphic differences have been a primary driver of speciation in these species, possibly in combination with climatic and biotic factors. These results are congruent with a major role of the edaphic factor as driver of plant diversification in the western Mediterranean biodiversity hotspot., This work has been supported by Fellowship PRE2022-102456, funded by MCIN/AEI/10.13039/501100011033 and ESF+HISPAPHYLO project PID2021-124234NA-I00, fundedMCIN/AEI /10.13039/501100011033/ERDF, EU Fellowship IJCI-2015-23459, funded by Ministerio de Economía y Competitividad, Spain LINARIA-SPECIATION project FP7-PEOPLE-2013-IEF, reference 624396, funded by European Commission, EU., Peer reviewed

Floral nectar spurs are widely considered a key innovation promoting diversification in angiosperms by means of pollinator shifts. We investigated the macroevolutionary dynamics of nectar spurs in the tribe Antirrhineae (Plantaginaceae), which contains 29 genera and 300-400 species (70-80% spurred). The effect of nectar spurs on diversification was tested, with special focus on Linaria, the genus with the highest number of species. We generated the most comprehensive phylogeny of Antirrhineae to date and reconstructed the evolution of nectar spurs. Diversification rate heterogeneity was investigated using trait-dependent and trait-independent methods, and accounting for taxonomic uncertainty. The association between changes in spur length and speciation was examined within Linaria using model testing and ancestral state reconstructions. We inferred four independent acquisitions of nectar spurs. Diversification analyses revealed that nectar spurs are loosely associated with increased diversification rates. Detected rate shifts were delayed by 5-15 Myr with respect to the acquisition of the trait. Active evolution of spur length, fitting a speciational model, was inferred in Linaria, which is consistent with a scenario of pollinator shifts driving diversification. Nectar spurs played a role in diversification of the Antirrhineae, but diversification dynamics can only be fully explained by the complex interaction of multiple biotic and abiotic factors.

Floral nectar spurs are widely considered a key innovation promoting diversification in angiosperms by means of pollinator shifts. We investigated the macroevolutionary dynamics of nectar spurs in the tribe Antirrhineae (Plantaginaceae), which contains 29 genera and 300–400 species (70–80% spurred). The effect of nectar spurs on diversification was tested, with special focus on Linaria, the genus with the highest number of species. We generated the most comprehensive phylogeny of Antirrhineae to date and reconstructed the evolution of nectar spurs. Diversification rate heterogeneity was investigated using trait‐dependent and trait‐independent methods, and accounting for taxonomic uncertainty. The association between changes in spur length and speciation was examined within Linaria using model testing and ancestral state reconstructions. We inferred four independent acquisitions of nectar spurs. Diversification analyses revealed that nectar spurs are loosely associated with increased diversification rates. Detected rate shifts were delayed by 5–15 Myr with respect to the acquisition of the trait. Active evolution of spur length, fitting a speciational model, was inferred in Linaria, which is consistent with a scenario of pollinator shifts driving diversification. Nectar spurs played a role in diversification of the Antirrhineae, but diversification dynamics can only be fully explained by the complex interaction of multiple biotic and abiotic factors.