Insects, birds and lizards as pollinators of the largest-flowered Scrophularia of Europe and Macaronesia

Vertebrates can be more important pollinators than invertebrates on islands: the case of Malva (=Lavatera) arborea L

Premise of the study: On islands, flowering plants tend to be more generalist in their pollination needs, as insects (the main pollinators of flowering plants) are underrepresented in these ecosystems compared to the mainland. In addition, some vertebrate species that are typically insectivorous or granivorous on the mainland are forced to broaden their diet and consume other resources such as nectar or pollen on the islands. The shrub Malva arborea, with its large and colourful flowers, attracts different groups of potential pollinators. This study aimed to compare the effectiveness of vertebrates versus insects in an insular population of M. arborea and to investigate its reproductive system. Methods: For three groups of taxa (insects, birds and lizards), we assessed the two components of pollination effectiveness: (i) the quantitative component (i.e. number of visits and number of flowers contacted) through direct observations of flowers; and (ii) the qualitative component (fruit and seed set, number and size of seeds and proportion of seedling emergence) through pollinator exclusion experiments. Key results: Vertebrates (birds and lizards) were quantitatively the most effective pollinators, followed by insects. However, when all three groups visited the flowers, fruit and seed set were higher than when any of them were excluded. We also found that M. arborea has hermaphrodite flowers and is able to reproduce by autogamy, although less efficiently than when pollinated by animals. Conclusions: Both vertebrates and insects play an important role in the reproduction of M. arborea. Although the plant does not need pollinators to produce seeds, its reproductive success increases when all pollinators are allowed to visit the flowers. Besides providing new information on M. arborea, these findings may help to better understand the role of different pollinator groups in the reproduction of other plant species, especially on islands where the co-occurrence of vertebrate and invertebrate pollination in the same plant species is usual.

Phylogenomics sheds new light on the drivers behind a long-lasting systematic riddle: the figwort family Scrophulariaceae

The figwort family, Scrophulariaceae, comprises c. 2000 species whose evolutionary relationships at the tribal level have proven difficult to resolve, hindering our ability to understand their origin and diversification. We designed a specific probe kit for Scrophulariaceae, targeting 849 nuclear loci and obtaining plastid regions as by-products. We sampled c. 87% of the genera described in the family and use the nuclear dataset to estimate evolutionary relationships, timing of diversification, and biogeographic patterns. Ten tribes, including two new tribes, Androyeae and Camptolomeae, are supported, and the phylogenetic positions of Androya, Camptoloma, and Phygelius are unveiled. Our study reveals a major diversification at c. 60 million yr ago in some Gondwanan landmasses, where two different lineages diversified, one of which gave rise to nearly 81% of extant species. A Southern African origin is estimated for most modern-day tribes, with two exceptions, the American Leucophylleae, and the mainly Australian Myoporeae. The rapid mid-Eocene diversification is aligned with geographic expansion within southern Africa in most tribes, followed by range expansion to tropical Africa and multiple dispersals out of Africa. Our robust phylogeny provides a framework for future studies aimed at understanding the role of macroevolutionary patterns and processes that generated Scrophulariaceae diversity.

A generalized bird pollination system in Schotia brachypetala (Fabaceae)

Bird pollination systems are diverse, ranging from narrow-tubed flowers pollinated by specialist nectarivores such as hummingbirds and sunbirds, to relatively open flowers pollinated by opportunistic (i.e. generalist) nectarivores. The role of opportunistic avian nectarivores as pollinators has historically been under-appreciated. A key aspect to understanding the importance of opportunistic birds as pollinators is to investigate how efficiently they transfer pollen among flowers. Here, we document the pollination and breeding systems of Schotia brachypetala, a southern African tree known as the 'weeping boer-bean' on account of its prolific production of dilute hexose-dominated nectar. The cup-shaped flowers of this tree attract a large number of bird species, including both opportunistic and specialist nectarivores. We identified floral visitors using observations and camera traps and quantified the floral traits responsible for animal attraction. We documented the breeding system, used selective pollinator exclusion to test the contribution of birds to fecundity, and performed supplemental pollination to test for pollen limitation. Single-visit pollen deposition trials were undertaken to determine the efficacy of bird pollinators. Controlled hand-pollination experiments showed that S. brachypetala is genetically self-incompatible and therefore dependent on pollinators for seed production. Supplemental hand-pollination experiments showed that natural fecundity is limited by either the amount and/or the quality of pollen on stigmas. Flowers from which birds but not insects were experimentally excluded set fewer seeds than open control flowers. Opportunistic birds deposited more pollen per visit than did specialist sunbirds. We conclude that S. brachypetala has a generalized bird pollination system that mainly involves opportunistic nectarivores.

Diversity patterns of lizard assemblages from a protected habitat mosaic in the Brazilian Cerrado savanna

Differences in habitat complexity and structure can directly influence the composition, diversity, and structure of species assemblages. Measurements of functional and phylogenetic diversity complement the commonly used measurements of taxonomic diversity, elucidating the relationships between species, their traits, and their evolutionary history. In this study, we evaluated how the mosaic of open and forested formations in a federal conservation unit in the western portion of the Brazilian Cerrado savanna influences the taxonomic, functional, and phylogenetic structure of lizard assemblages. Lizards were sampled for 15 months using pitfall traps set in open and forested formations. We recorded 292 lizards distributed among 16 species from eight families, with species composition differing among the formations. Richness was greater in the assemblages from open formations, while functional diversity and phylogenetic variability were greater in those of forested formations. Lizard assemblages in open formations were functionally and phylogenetically clustered, probably as a result of environmental filters acting on species, while the assemblages from forested formations were randomly structured. Different environmental and historical mechanisms have apparently shaped the current diversity of lizards in the region. This study shows that Cerrado vegetation mosaics can promote wide variation in different aspects of the taxonomic, functional, and phylogenetic structure from the lizard assemblages.

Chemical Characterization and Anti-HIV-1 Activity Assessment of Iridoids and Flavonols from Scrophularia trifoliata

Plants are the everlasting source of a wide spectrum of specialized metabolites, characterized by wide variability in term of chemical structures and different biological properties such antiviral activity. In the search for novel antiviral agents against Human Immunodeficiency Virus type 1 (HIV-1) from plants, the phytochemical investigation of Scrophularia trifoliata L. led us to isolate and characterize four flavonols glycosides along with nine iridoid glycosides, two of them, 5 and 13, described for the first time. In the present study, we investigated, for the first time, the contents of a methanol extract of S. trifoliata leaves, in order to explore the potential antiviral activity against HIV-1. The antiviral activity was evaluated in biochemical assays for the inhibition of HIV-1Reverse Transcriptase (RT)-associated Ribonuclease H (RNase H) activity and HIV-1 Integrase (IN). Three isolated flavonoids, rutin, kaempferol-7-O-rhamnosyl-3-O-glucopyranoside, and kaempferol-3-O-glucopyranoside, 8-10, inhibited specifically the HIV-1 IN activity at submicromolar concentration, with the latter being the most potent, showing an IC50 value of 24 nM.

Ecosystem services provided by aculeate wasps

The aculeate wasps are one of the most diverse and speciose insect taxa; they are omnipresent across ecosystems and exhibit diverse co-evolutionary and exploitative associations with other organisms. There is widespread conjecture that aculeate wasps are likely to perform essential ecological and economic services of importance to the health, well-being and nutritional needs of our planet. However, the scope and nature of the ecosystem services they provide are not well understood relative to other insect groups (e.g. bees, butterflies, beetles); an appreciation of their value is further tarnished by their public reputation as pointless pests. Here, we conduct the first comprehensive review of how aculeate wasps contribute to the four main areas of ecosystem services: regulatory, provisioning, supporting and cultural services. Uniting data from a large but previously disconnected literature on solitary and social aculeate wasps, we provide a synthesis on how these insects perform important ecosystem services as parasites, predators, biological indicators, pollinators, decomposers and seed dispersers; and their additional services as a sustainable alternative to meat for human consumption, and medicinal potential as sources of research leads for anti-microbials and cancer treatments. We highlight how aculeate wasps offer substantial, but largely overlooked, economic benefits through their roles in natural pest management and biological control programs. Accordingly, we provide data-driven arguments for reasons to consider the ecosystem service value of aculeate wasps on a par with other 'useful' insects (e.g. bees). Finally, we provide a research roadmap identifying the key areas of research required to capitalise better on the services provided by these important insects.

Evidence for a double mutualistic interaction between a lizard and a Mediterranean gymnosperm, Ephedra fragilis

An increasing number of double mutualisms (i.e. two interacting species benefiting each other in two different functions, e.g. pollination and seed dispersal) have been reported, mainly from island ecosystems, although we still lack much information on how effective such species are in both processes. Here, we assessed the pollination effectiveness of a double mutualism between an ancient Mediterranean gymnosperm, Ephedra fragilis, and a lizard, Podarcis lilfordi. On the one hand, we assessed the lizard contribution to different fitness measures (seed set and germination success), relative to that of insects and the wind effect; on the other, we determined the lizards' seed removal rate (i.e. the quantity component of seed dispersal effectiveness). In both processes, we further tested for differences in their contributions among male, female and juvenile lizards. Ephedra fragilis showed to be mostly anemophilous, lizards and insects playing only a minor role on seed set. However, lizards qualitatively contributed to pollination success, as seeds coming from lizard-pollinated cones germinated at higher rates than those pollinated by wind or insects, although this was detected only for small seeds (<8 mg). The plant produced a low seed set (c. 23 %), which was compensated by a high seed germinability (c. 70 %). Adult male lizards were those most implicated in pollination, quantitatively more important than insects, and in seed dispersal. This work, thus, reports the importance of a lizard species in one of the few double mutualisms found in the World involving a gymnosperm, and it represents the first documentation of a double mutualism in the Mediterranean region. Our findings further contribute to highlight the role of both inter- and intraspecific differences in the effectiveness of mutualistic interactions.

Plant reproductive ecology and evolution in the Mediterranean islands: state of the art

The ca. 12,000 islands and islets that encompass the Mediterranean Basin represent a biodiversity hotspot. They have been disconnected from each other and from the continent for hundreds of thousands to millions of years and encompass a high incidence of endemic plant species, with values that can exceed 20% of the local flora. Despite this, relatively few studies have been carried out to unravel ecological and evolutionary aspects of plant reproduction. We synthesise here the available information on the breeding systems, pollination and seed dispersal mode of the Mediterranean island flora. The main objective is to identify general patterns as well as to detect the main gaps in information on reproductive ecology in these particular and vulnerable systems in the face of global change. We also briefly review the information on impacts of invasive species on plant reproduction and dispersal, as these are some of the main threats to island biodiversity in general and Mediterranean island plant diversity in particular. The review has revealed that most available information is very geographically biased towards the western Mediterranean islands, especially the Balearic Islands, although a good fraction of studies have also been carried out on the eastern islands in the Aegean archipelago. Moreover, the majority of data come from species-focused studies, mainly endemic species of restricted range, whereas only a small fraction of studies have been performed at a community level. Relatively little work has involved genetic analyses, mainly focused on assessing the genetic differentiation and variability on narrow endemics. Contrary to our expectations, most island species do not rely on autonomous selfing, which might be related to the relatively high diversity of pollinators. The small, uninhabited, islands might be the last refuges of peculiar interactions that evolved in them in ancient times; they thus should be considered as sanctuaries of extraordinary biodiversity. Finally, we point out the main gaps of information and formulate a set of hypotheses that we believe are worth testing in future studies if we are to advance knowledge on the reproductive biology of Mediterranean island plants.

Confirmed mixed bird-insect pollination system of Scrophularia trifoliata L., a Tyrrhenian species with corolla spots

Both bird and mixed vertebrate-insect (MVI) pollination systems are very rare in Europe and the Mediterranean region. Because MVI can ensure reproduction over a wider range of environmental conditions than when insects are the sole pollinators, under certain circumstances such systems are highly advantageous to plants. Here, we investigated the pollination and some reproductive traits of the Tyrrhenian Scrophularia trifoliata, the only species of the genus possessing two showy dark spots inside the corolla, for which MVI pollination system had been inferred on the basis of limited censuses. We conducted field experiments to study MVI pollination and some reproductive traits and elucidate the role of corolla spots, analysing their ultraviolet pattern, histology and pigments versus the rest of the corolla. The primary pollinators were wasps and passerine birds. Corolla spots absorb UV light, present abundant anthocyanins and are histologically identical to the rest of the corolla. Control flowers had higher visitation frequency than flowers without spots. S. trifoliata is self-compatible, with efficient intrafloral protogyny and herkogamy that prevent self-pollination but not geitonogamy. We confirmed the existence of a mixed bird-insect pollination system in S. trifoliata. This system is found in three other Scrophularia species with large, showy flowers - two Mediterranean (S. grandiflora and S. sambucifolia) and one Macaronesian (S. calliantha). Unlike those species, S. trifoliata has two large spots inside the corolla. These likely operate as nectar guides and their dark colouration is related to abundant anthocyanin content.

Evolution of the staminode in a representative sample of Scrophularia and its role as nectar safeguard in three widespread species

Approximately 30% of the genera of Scrophulariaceae s.str. have a staminode, which is the remnant of a sterile stamen. However, there are no studies of the functionality or evolutionary pattern of staminodes in that family. This paper investigates three Scrophularia species with different staminode sizes to determine if the staminode safeguards nectar from dilution by rainwater and if it influences pollinator behavior. We also study staminode evolution and ancestral state reconstruction onto a phylogeny containing 71 species and subspecies with four different staminode developmental stages: tiny, large, enormous, and absent. The results showed that large staminodes did not hinder nectar collection or modify pollinator-visiting time but acted as a barrier to reduce rainwater entry. The latter reduced the dilution of nectar, which did not occur with tiny staminodes. The phylogenetic study revealed that the ancestral state in the genus corresponds with the presence of a large staminode vs. the tiny and enormous staminodes that are considered as derived. The complete disappearance of the staminode has occurred independently at least twice. Events occurred that increased or reduced the staminode size in one of the clades (Clade II), which includes species of sect. Caninae; most of these events occurred during the Pleistocene (0.6-2.7 Ma).

The floral morphospace--a modern comparative approach to study angiosperm evolution

Morphospaces are mathematical representations used for studying the evolution of morphological diversity and for the evaluation of evolved shapes among theoretically possible ones. Although widely used in zoology, they--with few exceptions--have been disregarded in plant science and in particular in the study of broad-scale patterns of floral structure and evolution. Here we provide basic information on the morphospace approach; we review earlier morphospace applications in plant science; and as a practical example, we construct and analyze a floral morphospace. Morphospaces are usually visualized with the help of ordination methods such as principal component analysis (PCA) or nonmetric multidimensional scaling (NMDS). The results of these analyses are then coupled with disparity indices that describe the spread of taxa in the space. We discuss these methods and apply modern statistical tools to the first and only angiosperm-wide floral morphospace published by Stebbins in 1951. Despite the incompleteness of Stebbins’ original dataset, our analyses highlight major, angiosperm-wide trends in the diversity of flower morphology and thereby demonstrate the power of this previously neglected approach in plant science.

Main sugar composition of floral nectar in three species groups of Scrophularia (Scrophulariaceae) with different principal pollinators

In some angiosperm groups, a parallelism between nectar traits and pollination syndromes has been demonstrated, whereas in others there is not such relationship and it has been explained as due to phylogenetic constraints. However, nectar trait information remains scarce for many plant groups. This paper focuses on three groups of Scrophularia species, with different flower sizes and principal pollinators, to find out whether nectar sugar composition is determined by pollinator type or reflects taxonomic affinities. Since the species we examined have protogynous flowers, and gender bias in nectar sugar composition has been noted in few plant groups, we also investigated whether sexual phase influenced Scrophularia nectar composition. The sugar composition was found to be similar in all species, having high-sucrose nectar, except for the Macaronesian Scrophularia calliantha, which was the only species with balanced nectar; this last kind of nectar could be associated with the high interaction rates observed between S. calliantha and passerine birds. The nectar sugar composition (high in sucrose) was unrelated to the principal pollinator group, and could instead be considered a conservative taxonomic trait. No gender bias was observed between functionally female and male flowers for nectar volume or concentration. However, sexual phase significantly affected sucrose percentage in the largest-flowered species, where the female phase flowers had higher sucrose percentages than the male phase flowers.

Diversification of Scrophularia (Scrophulariaceae) in the Western Mediterranean and Macaronesia--phylogenetic relationships, reticulate evolution and biogeographic patterns

The flora of the Mediterranean region and Macaronesia is characterized by high levels of species diversity and endemism. We examined phylogenetic relationships of Scrophularia within one of its secondary centers of diversity located in the Iberian Peninsula and adjacent Macaronesia. In total, 65 ingroup accessions from 45 species, representing an almost complete sampling of the region, were analyzed using sequences from the internal transcribed spacer region (ITS) and the plastid trnQ-rps16 intergenic spacer. Phylogenetic relationships were inferred using Bayesian inference, maximum likelihood and statistical parsimony networking. Incongruence between datasets was assessed with statistical tests and displayed by split networks. Biogeographic inferences incorporating information from both markers (despite low resolution in some parts of the trees) and all incongruent taxa were accomplished with a novel combination of methods, using trees generated with the taxon duplication approach as input for Bayesian binary MCMC (BBM) analysis as implemented in RASP. Nuclear and chloroplast markers support a clade which comprises the majority of Iberian and Macaronesian species and consists of three subclades. Analyses of the substantial incongruence observed among markers indicate reticulate evolution and suggest that Scrophularia species diversity in this region is largely attributable to hybridization; a combination of both polyploidy and dysploidy in the karyotypic evolution of Western Mediterranean Scrophularia taxa is proposed. Our results provide support for an ancient hybridization event between two widespread lineages, which resulted in an allopolyploid ancestor of the Iberian - Macaronesian group with 2n=58 chromosomes. The ancestor then diverged into the three main lineages present in the Iberian Peninsula, Northern Africa and Macaronesia today. Subsequent interspecific hybridizations at different ploidy levels additionally generated new species. Presumably, hybridization and diversification within the genus in the Western Mediterranean have not been restricted to one particular event, but occurred repeatedly. It can be assumed that the topographical complexity found in the Iberian Peninsula has promoted diversification and hybrid speciation processes in Scrophularia, and that isolation in glacial refugia has preserved recent and ancient lineages. For the Macaronesian taxa, biogeographic analyses support several origins, by colonizations from at least four distinct lineages.

Herbarium of vascular plants collection of the university of extremadura (Spain)

The herbarium of University of Extremadura (UNEX Herbarium) is formed by 36451 specimens of vascular plants whose main origin is the autonomous region of Extremadura (Spain) and Portugal, although it also contains a smaller number of specimens from different places, including the rest of peninsular Spain, the Baleares Islands, the Macaronesian region (Canary Islands, Madeira and Azores), northwest of Africa (Morocco) and Brazil. 98% of the total records are georeferenced. It is an active collection in continuous growth. Its data can be accessed through the GBIF data portal at http://data.gbif.org/datasets/resource/255 and http://www.eweb.unex.es/eweb/botanica/herbario/. This paper describes the specimen associated data set of the UNEX Herbarium, with an objective to disseminate the data contained in a data set with potential users, and promote the multiple uses of the data.

The role of birds and insects in pollination shifts of Scrophularia (Scrophulariaceae)

The mixed vertebrate-insect pollination system is rare in Holarctic plants. Phylogenetic relationships of 116 Scrophularia taxa were investigated based on two plastid (ndhF and trnL-trnF) and one nuclear (ITS) DNA regions. A wider time-calibrated analysis of ndhF sequences of the Lamiales revealed that Scrophularia diverged as early as in the Miocene (<22 Ma). Results of maximum-likelihood optimizations supported wasp pollination as the ancestral pollination system from which other systems derived (hoverfly, mixed vertebrate-insect and bird systems). Four origins for a mixed vertebrate-insect (MVI) pollination system were inferred, in which two western Mediterranean species (S. sambucifolia and S. grandiflora) and two island species (the Tirrenian S. trifoliata and the Canarian S. calliantha) were involved. S. calliantha is the only species in which a more complex MVI system, including pollination by the lizard Gallotia stehlini, has evolved. In addition, bird (hummingbird) floral traits found in the New Mexican S. macrantha appear to have been independently acquired. In contrast, we failed to find evidence for an ancient role of hummingbirds in the evolution of European Scrophularia. Indeed, paleontological data revealed that extinction of European hummingbirds (30-32 Ma) occurred earlier than the divergence of European MVI lineages of Scrophularia. In conclusion, our results showed that a role of birds in pollination of Scrophularia may not have been effective in the Miocene-Pliocene, but bird pollination that shows its origin in the Pliocene-Pleistocene is still operating independently in different islands and continents.

Behaviour of pollinator insects within inflorescences of Scrophularia species from Iberian Peninsula

Several hypotheses have been proposed to explain the pattern of pollinator visits to vertical inflorescences. These range from a response to a pattern of resources to merely instinctive behaviour. In dichogamous plants, such behaviour has been associated with promoting outcrossing and avoiding geitonogamy. We here analyse behaviour of the principal pollinator groups in five protogynous species of Scrophularia with different flower sizes (S. sambucifolia, S. grandiflora, S. lyrata, S. scorodonia and S. canina), and the distribution of sexual phases along the inflorescences. The results in all cases show that pollinators follow a pattern of ascending visits accompanied by movements between flowers of the same whorl (horizontal movements). The relative frequency of these horizontal movements depends on the flower size, with a higher frequency in species with large flowers. In vertical movements of the three more common pollinator groups to several plant species (bumblebees, wasps and small bees), the behaviour was essentially independent of flower size, with bumblebees having the highest ratio of ascents to descents. Behaviour of the pollinators, together with the absence of a definite pattern of distribution of the sexual phases along the inflorescence, implies that geitonogamy is not avoided in any of the Scrophularia species studied.