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[Aim] Plants on islands are often subjected to lower levels of herbivory relative to those found at mainland sites. As a consequence, island plants are predicted to exhibit lower levels of physical or chemical defences, which renders them more susceptible to introduced herbivores. Yet, instances of high pressure by superabundant herbivores native to islands have been reported in many insular systems, which presumably would result in heightened plant defences. To date, no quantitative review has been conducted to determine how common these contrasting patterns are and their implications for the evolution of plant-herbivore interactions., [Location] Islands worldwide., [Taxon] Plants, insects, molluscs, mammals., [Methods] We conducted a meta-analysis of insularity effects on herbivory and plant defences by including studies that involved island-mainland comparisons of the same plant species in both environments (90% of cases), or insular endemics versus mainland congeners (10% of cases). We tested for differences between mammalian and invertebrate (mollusc or insect) herbivory as well as between plant chemical and physical defences by specifying comparisons based on the type of herbivore (vertebrate or invertebrate) or plant trait included in the study., [Results] Mammalian herbivory was significantly higher on islands than on mainlands. In contrast, no significant effect was observed on invertebrate herbivory. In addition, we found no significant difference in either plant physical or chemical defences between insular and mainland plants, though physical defences tended to be higher for plants on islands., [Main conclusions] All analysed mammal studies focused on species introduced to islands, suggesting greater susceptibility of insular plants to exotic mammals, whereas the lack of effects in the case of invertebrate herbivory suggests no difference in susceptibility to molluscs or insects between insular and mainland plants. Interestingly, plant trait patterns suggest a trend for increased physical defences by insular plants, possibly due to heightened pressure by exotic mammalian herbivores on islands, whereas chemical defences appear uncorrelated to differences in herbivory. These findings call for further experimental and observational studies measuring defences and herbivory for multiple sympatric plant species occurring at both mainland and island sites within a system, or comparing insular endemics to congeneric mainland species., This research was financially supported by a grant from the Regional Government of Galicia (IN607D 2016/001), a grant from the Spanish Ministry of Science, Innovation and Universities (RTI2018-099322-B-100) and the Ramón y Cajal Research Programme (RYC-2013-13230) to XM. CG-V is supported by a postdoctoral Vicenç Mut fellowship (Govern de les Illes Balears, Conselleria d'Innovació, Recerca i Turisme and the European Social Fund).

The genus Dracaena in Macaronesia comprises two threatened species of arborescent monocots that are often associated with one of the most intriguing biogeographic disjunctions: the Rand Flora pattern. Molecular information is, however, largely missing for the Macaronesian Dracaena taxa (“MDT”, hereafter), and the biogeographic or population genetic patterns of this lineage have not yet been thoroughly assessed. To fill this gap, we generated plastid DNA sequence data of 14 Dracaena populations representing the entire natural distribution of MDT (including mainland Morocco and all recognized subspecies), 9 additional populations of subspontaneous origin, and a set of related species of the genus. We performed phylogenetic, biogeographic, and population genetic analyses at different spatial scales and conducted a comparative review on plant haplotype diversity in Macaronesian plants. The results of our phylogenetic analyses indicated the monophyly of the MDT and an origin separate from a clade of geographically distant species that so far were postulated as their closest living relatives (D. cinnabari, D. ombet, D. schizantha, D. serrulata). The results of our phylogeographic analyses indicated that diversification within D. draco occurred throughout the Pleistocene and that wild peripheral populations (Madeira, mainland Morocco) may have a recent origin from Canarian source populations. Recent dispersals, coupled with remarkably low levels of haplotype diversity, probably account for the weak phylogeographic signal observed across wild populations. However, our results suggested that human‐assisted expansion of Dracaena inflates the extant phylogeographic signal by non‐random translocation of a specific subset of haplotypes. Our study demonstrates that many of the previous biogeographic scenarios on MDT are not supported by molecular data. Instead, our results highlight (i) the impact that human activity may have on the phylogeographic pattern of island plants, and (ii) the need of a deeper taxonomic sampling in future investigations on MDT and close relatives., This research was funded by the European Regional Development Fund (Intereg projects CAVEGEN and ENCLAVES). JP was funded by the Marie Sklodowska‐Curie COFUND, Researchers’ Night and Individual Fellowships Global (MSCA grant agreement No 747238, “UNISLAND”’), and the Ramón y Cajal program (RYC‐2016‐20506). CG‐V was financially supported by a “Vicenç Mut” postdoctoral fellowship (Conselleria d'Innovació, Recerca i Turisme, Govern de les Illes Balears and the European Social Fund).

[Premise] The endangered shrub Daphne rodriguezii (Thymelaeaceae) is endemic to the Balearic island of Menorca, where fragmentation and severe population decline are ongoing threats to this taxon. We developed a set of microsatellite markers to analyze the fine-scale genetics of its few extant populations., [Methods and Results] Fifteen microsatellite markers were obtained through Illumina high-throughput sequencing and tested in two populations. Twelve of these loci showed no evidence of null alleles and were highly polymorphic, with a mean number of 8.3 alleles per locus. Levels of observed and expected heterozygosity ranged from 0.100 to 0.952 and from 0.095 to 0.854, respectively. Seven to nine of these loci were successfully amplified in five other Daphne species., [Conclusions] This set of markers provides a useful tool for investigating the factors driving fine-scale population structure in this threatened species, and it represents a novel genetic resource for other European Daphne species., J.C.I. was funded by a GRUPIN research grant from the Regional Government of Asturias (Ref.: IDI/2018/000151), and C.G.‐V. was supported by a Vicenç Mut postdoctoral fellowship awarded by the Govern de les Illes Balears–Conselleria d'Innovació, Recerca i Turisme. The study was funded by the Ministerio de Economía, Industria y Competitividad (project Islet‐Foodwebs CGL2017‐88122‐P).

8 páginas, 2 figuras, 1 tabla, Aim: Research on plant–herbivore interactions has shown that islands typically have low abundances and diversity of herbivores because of barriers to dispersal, isolation and reduced land area. Islands commonly have lower levels of herbivory relative to mainland regions, and, as a consequence, insular plants should exhibit lower levels of defences than their mainland counterparts. Despite these predictions, there are significant gaps in our understanding of insularity effects on plant–herbivore interactions. For instance, most work addressing the effects of insularity on plant–herbivore interactions have compared one or a few islands with a single mainland site. In addition, studies have measured herbivory or plant defences but not both, and the influence of abiotic factors has been neglected. Location: Mediterranean Basin (from Spain to Greece). Taxon: Quercus ilex L. Methods: We conducted a large-scale study to investigate whether insect leaf herbivory and plant chemical defences in holm oak (Quercus ilex L.) differ between insular versus mainland populations. We further investigated mechanisms by which insularity effects on herbivory may take place by assessing the influence of defences and climatic variables on herbivory. Results: We found that insular populations exhibited lower herbivory and higher defences (condensed tannins) than their mainland counterparts. Our analyses, however, suggest that these concomitant patterns of insect herbivory and plant defences were seemingly unrelated as island versus mainland differences in defences did not account for the observed pattern in herbivory. Furthermore, climatic factors did not explain insularity effects on either herbivory or plant defences. Main conclusions: Overall, this study provides one of the most robust assessments to date on insularity effects on herbivory and builds towards a better understanding of the ecology and evolution of plant–insect interactions in insular ecosystems., This research was financially supported by a Spanish National Research Grant (AGL2015‐70748‐R), a Regional Government of Galicia Grant (IN607D 2016/001) and the Ramón y Cajal Research Programme (RYC‐2013‐13230) to XM.

Los días 1 y 3 de febrero se celebró en Mallorca la XV Reunión anual de ECOFLOR (http://webecoflor.webs.uvigo.es) (Fig. 1), red temática y grupo de trabajo sobre ecología y evolución floral de la Asociación Española de Ecología Terrestre (AEET). Fue organizada por el grupo de Ecología Terrestre del Instituto Mediterráneo de Estudios Avanzados (IMEDEA-CSIC, http://imedea.uib-csic.es/icg/ecol_ terr/cast/group.html).

Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long-standing idea that island populations have lower GD than their mainland counterparts. Plastid data showed that colonization of the Canary Islands promoted strong lineage divergence within P. laevigata, which was accompanied by selective sweeps at several nuclear microsatellite loci. Inclusion of loci affected by strong divergent selection produced a significant downward bias in the GD estimates of the mainland lineage, but such underestimates were substantial (>14%) only when more than one loci under selection were included in the computations. When loci affected by selection were removed, we did not find evidence that insular Periploca populations have less GD than their mainland counterparts. The analysis of data obtained from a comprehensive literature survey reinforced this result, as overall comparisons of GD estimates between island and mainland populations were not significant across plant taxa (N = 66), with the only exception of island endemics with narrow distributions. This study suggests that identification and removal of markers potentially affected by selection should be routinely implemented in estimates of GD, particularly if different lineages are compared. Furthermore, it provides compelling evidence that the expectation of low GD cannot be generalized to island plant popula- tions.

Background: Phylogenetic and phylogeographic investigations have been previously performed to study the evolution of the olive tree complex (Olea europaea). A particularly high genomic diversity has been found in north-west Africa. However, to date no exhaustive study has been addressed to infer putative polyploidization events and their evolutionary significance in the diversification of the olive tree and its relatives. Methods: Representatives of the six olive subspecies were investigated using (a) flow cytometry to estimate genome content, and (b) six highly variable nuclear microsatellites to assess the presence of multiple alleles at co-dominant loci. In addition, nine individuals from a controlled cross between two individuals of O. europaea subsp. maroccana were characterized with microsatellites to check for chromosome inheritance. Key Results: Based on flow cytometry and genetic analyses, strong evidence for polyploidy was obtained in subspp. cerasiformis (tetraploid) and maroccana (hexaploid), whereas the other subspecies appeared to be diploids. Agreement between flow cytometry and genetic analyses gives an alternative approach to chromosome counting to determine ploidy level of trees. Lastly, abnormalities in chromosomes inheritance leading to aneuploid formation were revealed using microsatellite analyses in the offspring from the controlled cross in subsp. maroccana. Conclusions: This study constitutes the first report for multiple polyploidy in olive tree relatives. Formation of tetraploids and hexaploids may have played a major role in the diversification of the olive complex in north-west Africa. The fact that polyploidy is found in narrow endemic subspecies from Madeira (subsp. cerasiformis) and the Agadir Mountains (subsp. maroccana) suggests that polyploidization has been favoured to overcome inbreeding depression. Lastly, based on previous phylogenetic analyses, we hypothesize that subsp. cerasiformis resulted from hybridization between ancestors of subspp. guanchica and europaea.