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The repeated, rapid and often pronounced patterns of evolutionary divergence observed in insular plants, or the 'plant island syndrome', include changes in leaf phenotypes, growth, as well as the acquisition of a perennial lifestyle. Here, we sequence and describe the genome of the critically endangered, Galápagos-endemic species Scalesia atractyloides Arnot., obtaining a chromosome-resolved, 3.2-Gbp assembly containing 43,093 candidate gene models. Using a combination of fossil transposable elements, k-mer spectra analyses and orthologue assignment, we identify the two ancestral genomes, and date their divergence and the polyploidization event, concluding that the ancestor of all extant Scalesia species was an allotetraploid. There are a comparable number of genes and transposable elements across the two subgenomes, and while their synteny has been mostly conserved, we find multiple inversions that may have facilitated adaptation. We identify clear signatures of selection across genes associated with vascular development, growth, adaptation to salinity and flowering time, thus finding compelling evidence for a genomic basis of the island syndrome in one of Darwin's giant daisies.

Astydamia latifolia is the only species of the genus Astydamia, which forms an early‐diverging lineage of Apiaceae, subfamily Apioideae. This species is subendemic to the Canary Islands and one of the most representative species of the coastal environments of this archipelago. Astydamia displays diplochory, that is, diaspores with two long‐distance dispersal (LDD) syndromes. In particular, A. latifolia has both anemochorous and thalassochorous fruit traits (corky and winged mericarps). Although we expect this species to have a high dispersal capacity, there is no genetic study addressing it. The divergence time of this species from its sister taxon is also unknown. In this study, we aimed (i) to unveil the phylogenetic relationships and divergence times of A. latifolia; (ii) to reconstruct its phylogeographic structure across the Canary Islands; and (iii) to estimate the number of inter‐island colonization events. To these ends, we first sequenced the internal transcribed spacer (ITS) region for A. latifolia, reconstructed the phylogenetic relationships of Astydamia and Apiaceae relatives and estimated divergence times. Then, two plastid DNA regions (psaI‐aacD and psbK‐trnS) were sequenced for 158 individuals (from 36 Canarian population and one NW African population) to reconstruct a haplotype network. The recently developed method Phylogeographic Analysis of Island Colonization Events (PAICE) was used to estimate the number of inter‐island colonization events. Results show that A. latifolia is a phylogenetically isolated lineage that diverged from the most closely related genus (Molopospermum) in the Eocene–Miocene. It displays a low plastid DNA diversity (only four haplotypes detected), which is accompanied by a high degree of haplotype sharing between islands and highly linear rarefaction curves of colonization obtained in PAICE. These findings suggest a high colonization ability for this species, most likely related to the availability of two LDD syndromes. [ABSTRACT FROM AUTHOR]

The current distribution of most species results from ecological niche, past distribution, and migrations during glacial–interglacial periods and in situ evolution. Here, we disentangle the colonization history of Saxifraga longifolia Lapeyr., a limestone plant abundant in the Pyrenees and rare in other Iberian mountains and the African Atlas. Our working hypothesis is that the current distribution results from the shrinkage of a more extensive distribution in previous cold periods. We sampled 160 individuals of 32 populations across the whole distribution range and sequenced four DNA regions (rpl32‐trnL, rps16‐trnQ, trnS‐trnG, and ITS). Ecological conditions were modeled to identify factors promoting high genetic diversity and long‐term persistence areas for S. longifolia. In addition, we inferred phylogenetic relationships, phylogeographic divergence, genetic diversity, and migration routes. Seven plastid haplotypes were found, of which six occur in the Pyrenees and one in the High Atlas (Morocco). Discrete phylogeographic analysis (DPA) estimated migration routes predominantly from the Pyrenees to the other areas. Colonization events to those areas appear to have taken place recently given that the rest of the Iberian mountains do not harbor exclusive haplotypes. Iberian–Northern African distribution was inferred to be the result of long‐distance dispersal because the split between Iberian and High Atlas haplotypes is estimated to have taken place in the last 4 million years ago when the Strait of Gibraltar was already open. Migrations from the Pyrenees to the south may have been favored by a corridor of predominant limestone rocks along Eastern Iberia, followed by successful overcoming the Strait of Gibraltar to reach northern Africa. [ABSTRACT FROM AUTHOR]

Sedges (Cyperaceae) are commonly pollinated by wind, but some transitions from wind to insect pollination have been reported in tropical sedges. Despite being a temperate sedge, the pollination strategy of Rhynchospora alba may partly depend on insects, as suggested by its white-colored inflorescences. Here we quantify the contribution of insects to the reproductive fitness of R. alba as an exploration of the success of entomophily in temperate sedges. Honeybees and hoverflies seem to be the primary visitors of R. alba in the study site, and pollen of R. alba was recovered from the mouthparts and legs of the insects. Treatments excluding insects led to a lower reproductive fitness (regarding fruit weight and fruit viability) than those not excluding them. Therefore, insects seem to contribute significantly to the pollination of R. alba despite moderate morphological adaptation. We highlight the role of entomophily as an overlooked reproductive mechanism in cold-temperate sedges. [ABSTRACT FROM AUTHOR]

Accurate inference in phylogeography requires appropriate sampling strategies. Complex questions demand a large sample size at both the population and genetic levels to obtain precise reconstructions. This is the case of the phylogeographic history of Cistus monspeliensis, a plant that displays low plastid (cpDNA) diversity in the Mediterranean Basin but high diversity in the Canary Islands. Here, we aimed to identify Mediterranean refugial areas and to accurately quantify inter‐island colonization events in the Canaries. Using a previous study as starting point, we increased sample size in two ways: (i) additional sampling of plastid genetic markers (from 1041 to 1899 bp); and (ii) additional sampling of populations (from 47 to 69) in long‐term persistence areas suggested by species distribution modeling (SDM). The synergy between SDM and extended population sampling helped find higher genetic diversity. Our deeper phylogeographic sampling of C. monspeliensis revealed the following: (i) potential refugia in long‐term persistence areas with high cpDNA diversity in western Europe and the Canary Islands; and (ii) a significant increase (from 7 to 12) in the number of inferred inter‐island colonization events across the archipelago. Our results stress the usefulness of SDM to identify the genetic signature associated with potential refugial areas. We herein propose a field sampling approach based on SDM that, in combination with a larger cpDNA sampling, can help answer a wide array of phylogeographic questions, such as the location of Quaternary refugia and number of colonizations across archipelagos. [ABSTRACT FROM AUTHOR]

The high diversification rates of plant lineages in the Mediterranean Basin hotspot have been linked to a complex interaction of climatic stressors, geographic isolation and soil type, but the question remains as to which of these factors has been the most significant environmental driver of recent speciation.Here, we draw on distributional data for the entire endemic flora of the Iberian Peninsula, together with DNA‐based phylogenies and spatial phylogenetic methods, to explore the patterns of relative phylogenetic endemism at different spatial resolutions and phylogenetic scales (superclades) and assess how environmental factors contribute to explain these patterns.We found that recent diversification of angiosperms as a whole, and particularly of eudicots, has been boosted by environmental stressors including high values of soil pH and dry‐seasonal climatic conditions, while diversification of monocots has not been associated with soil conditions but with high elevation and less seasonal climate.Synthesis. These results provide robust insights into the environmental factors driving recent plant diversification in the Mediterranean Basin, including a role of soil properties that had not been quantified before. The contrasting environmental drivers of diversification in eudicots and monocots highlight the importance of analysing spatial phylogenetic patterns at multiple phylogenetic scales to get a better understanding of the processes that shape biodiversity. [ABSTRACT FROM AUTHOR]

Drosophyllaceae is the only plant family endemic to the Mediterranean Floristic Region. It includes a single species, the carnivorous Drosophyllum lusitanicum, which is hypothesised to be a relict plant. Our aim here is to reconstruct the evolutionary history of Drosophyllum to evaluate whether the African-European disjunction across the Strait of Gibraltar is the result of vicariance or long-distance dispersal, and to assess the role of the Strait of Gibraltar area in the long-term persistence of this species. A time-calibrated phylogeny based on nuclear ITS sequences estimated a mid-Eocene to mid-Miocene age (19–44 Mya) for the common ancestor of Drosophyllaceae and its sister clade (Ancistrocladaceae-Dioncophyllaceae). In contrast, differentiation of ITS lineages of Drosophyllum occurred in the Pleistocene, after the opening of the Strait of Gibraltar (ca. 5 Mya). A haplotype network built using two plastid DNA regions revealed six haplotypes in Drosophyllum, five of which occur in the Strait of Gibraltar area. Four of the six haplotypes were present in both European and African populations. Therefore, although Drosophyllaceae diverged from the closest relatives in ancient times, the current distribution of Drosophyllum is relatively recent (Pleistocene). Given that the Strait of Gibraltar was already open in the Pliocene, the disjunct distribution of this species between Europe and Africa appears to be the result of multiple events of long-distance dispersal. Species distribution modelling (SDM) was used to reconstruct the potential distribution of Drosophyllum throughout the late Quaternary (last interglacial, Last Glacial Maximum, mid-Holocene and present), which revealed long-term persistence around the Strait of Gibraltar and in the south-western Iberian Peninsula. The Strait of Gibraltar area and the south-western Iberian Peninsula may have shared similar climatic conditions, and thus acted as refugia for Drosophyllum throughout the late Quaternary. [ABSTRACT FROM AUTHOR]