Josefa López

Pollination mechanisms and pollen-ovule ratios in some Genisteae (Fabaceae) from Southwestern Europe

We studied the biology and floral rewards of 34 taxa ofGenisteae from the SW of Europe. Most of the floral attributes show a statistically significant direct relationship. Anther biomass of the lower whorl (lW) is significantly lower than that of the upper whorl (uW), and the ratio of the two (Rv) differs among the taxa. All taxa are polliniferous, andRetama sphaerocarpa also secretes nectar. They can be considered xenogamous or facultative xenogams on the basis of their high pollen/ovule (P/O) ratios. Three principal mechanisms of pollen releasing are identified in this tribe: valvular, pump and explosive; the latter comprises specialized and nonspecialized subtypes. Pollination is sternotribic except in the specialized explosive mechanism, in which it is noto-sternotribic. Thus some pollen serves as food (pollen from the uW, which adheres to the ventral surface of the insect) and part of the pollen fulfils a polliniferous function (pollen from the lW, which adheres to the dorsal surface). Species that use a pump mechanism have very low Rv values (Rv=0.08−0.26); species with valvular or nonspecialized explosive mechanisms have Rv values between 0.24 and 0.58; those with a specialized mechanism of pollen presentation have high Rv values (0.6−0.76). In contrast to expectations, the highest P/O ratios appear in the specialized explosive system, which allows a single visit from the insect.

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

BACKGROUND AND AIMS It has traditionally been considered that the flowers of Scrophularia are mainly pollinated by wasps. We studied the pollination system of four species which stand out for their large and showy flowers: S. sambucifolia and S. grandiflora (endemics of the western Mediterranean region), S. trifoliata (an endemic of the Tyrrhenian islands) and S. calliantha (an endemic of the Canary Islands). Our principal aim was to test whether these species were pollinated by birds or showed a mixed pollination system between insects and birds. METHODS Censuses and captures of insects and birds were performed to obtain pollen load transported and deposited on the stigmas. Also, a qualitative and quantitative analysis of the flowers and inflorescences was carried out. KEY RESULTS Flowers were visited by Hymenoptera and by passerine birds. The Canarian species was the most visited by birds, especially by Phylloscopus canariensis, and its flowers were also accessed by juveniles of the lizard Gallotia stehlini. The most important birds in the other three species were Sylvia melanocephala and S. atricapilla. The most important insect-functional groups in the mixed pollination system were: honey-bees and wasps in S. sambucifolia; bumble-bees and wasps in S. grandiflora; wasps in S. trifoliata; and a small bee in S. calliantha. CONCLUSIONS The species studied show a mixed pollination system between insects and passerine birds. In S. calliantha there is, in addition, a third agent (juveniles of Gallotia stehlini). The participation of birds in this mixed pollination system presents varying degrees of importance because, while in S. calliantha they are the main pollinators, in the other species they interact to complement the insects which are the main pollinators. A review of different florae showed that the large showy floral morphotypes of Scrophularia are concentrated in the western and central Mediterranean region, Macaronesia and USA (New Mexico).

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.

Scrophularia arguta, a widespread annual plant in the Canary Islands: a single recent colonization event or a more complex phylogeographic pattern?

Abstract Many studies have addressed evolution and phylogeography of plant taxa in oceanic islands, but have primarily focused on endemics because of the assumption that in widespread taxa the absence of morphological differentiation between island and mainland populations is due to recent colonization. In this paper, we studied the phylogeography of Scrophularia arguta, a widespread annual species, in an attempt to determine the number and spatiotemporal origins of dispersal events to Canary Islands. Four different regions, ITS and ETS from nDNA and psbA‐trnH and psbJ‐petA from cpDNA, were used to date divergence events within S. arguta lineages and determine the phylogenetic relationships among populations. A haplotype network was obtained to elucidate the phylogenetic relationships among haplotypes. Our results support an ancient origin of S. arguta (Miocene) with expansion and genetic differentiation in the Pliocene coinciding with the aridification of northern Africa and the formation of the Mediterranean climate. Indeed, results indicate for Canary Islands three different events of colonization, including two ancient events that probably happened in the Pliocene and have originated the genetically most divergent populations into this species and, interestingly, a recent third event of colonization of Gran Canaria from mainland instead from the closest islands (Tenerife or Fuerteventura). In spite of the great genetic divergence among populations, it has not implied any morphological variation. Our work highlights the importance of nonendemic species to the genetic richness and conservation of island flora and the significance of the island populations of widespread taxa in the global biodiversity.

Causes of Low Fruit and Seed Set in Bird-Pollinated Anagyris foetida (Leguminosae): Pollen Limitation and Other Extrinsic Factors

We studied the extrinsic factors behind the low number of offspring in two populations of Anagyris foetida, a bird-pollinated leguminous shrub of the Mediterranean region. Fruit initiation was pollen limited, but fruit maturation was not. This limiting effect varied between flowering seasons and between populations, and also within a given phenological stage. In the first season, the early flowers had the lowest fruit set, while in the second season fruit set was highest in these early flowers. This was possibly related to the pollination environment. Seed initiation (fertilized ovules) increased following pollen supplementation, but this was not translated into a significant increase in either the number of seeds per fruit, or seed mass. This indicates that seed initiation is pollen limited but that other factors (e.g., resource availability) are involved in seed maturation. Abiotic factors such as excess humidity during flowering were responsible for the loss of inflorescences, especially in one of the two populations. In this population, the prevailing wind in autumn-winter was less effective in drying the flowers when there was excess humidity. Also, significantly fewer inflorescences were lost from solitary plants than from clustered plants, probably reflecting the beneficial action of the wind and the greater light levels during flowering. Of the biotic factors analyzed, sheep predation was the most important, being worse in drought years. This predation, by affecting population density, could modify the plant-pollinator interaction and severely reduce the plant’s breeding success because of its pollen limitation.

Does the Scrophularia Staminode Influence Female and Male Functions during Pollination

Premise of research. Although approximately 30% of the genera in the Scrophulariaceae have staminodes, the functionality of this organ has been scarcely investigated in most of the largest genera. The majority of Scrophularia species have staminodes. Here, we investigated whether this organ acts as a pollinator attraction unit and enhances male and female flower functions. Methodology. We performed comparative experiments for 2 yr on two species with large staminodes (Scrophularia lyrata and Scrophularia scorodonia) and one with a tiny staminode (Scrophularia canina) from several Spanish populations involving control flowers with staminodes and flowers with staminodes manually removed. Pivotal results. The staminode acts as an attraction unit to the reward in S. lyrata and S. scorodonia but not in S. canina. However, the results do not support the second function after a single floral visit, because pollen reception on the stigma and pollen collection by pollinators on one side and seed set on the other were not treatment dependent. These results can be attributed to the need for several visits per flower to achieve an efficient reproductive success: in flowers under natural pollination conditions that were repeatedly visited, staminode removal decreased fruit or seed set after several pollinator visits in S. lyrata and S. scorodonia but not in S. canina. Conclusions. The presence of a tiny staminode located in the lower third of the corolla tube suggests that the fate of this organ is probably to disappear in S. canina, a species that has 10.5%–20% of flowers usually lacking staminodes and that is phylogenetically close to another species lacking staminodes (Scrophularia crithmifolia). Nevertheless, most Scrophularia species have a large staminode positioned on the upper third of the corolla tube (e.g., S. lyrata and S. scorodonia) that functions as a pollinator attraction unit and enhances female reproductive success.

Scabiosa galianoi Devesa, Ortega-Olivencia & J. Lopez, a new name for S. gracilis (Boiss.) Boiss. (Dipsacaceae)

Hispano-Lusitanian plants traditionally identified as Scabiosa semipapposa Salzm. ex DC. are recognized with a new name, Scabiosa galianoi Devesa, Ortega-Olivencia & J. LOpez, after it was found that they differ clearlyfrom the Moroccan plants on which De Candolles description was based.

Anatomical plasticity in species of Deschampsia P. Beauv. (Poaceae) in SW Europe (Iberian Peninsula)

Summary The utility of leaf anatomy in the taxonomy of the genus Deschampsia is discussed. To this end, the inter-and intra-populational variability of this character is analyzed in the taxa of the genus which are represented in the Iberian Peninsula (Deschampsia cespitosa (L.) Beauv. s.l., D. setacea (Huds.) Hack, and D. flexuosa (L.) Trin.), as well as in Holcus grandiflorus Boiss. and H. caespitosus Boiss., two Spanish endemic species which some authors include in Deschampsia. A critical analysis of their observed anatomical plasticity is given, evidencing the great intra-individual variability when wild plants are grown under experimental conditions.

Temporal and spatial intraspecific variation of primary seed dispersal in Scrophularia canina L., a widespread plant with unspecialised diaspores

Background: As seed dispersal can vary among years and individuals, studies that focus on a single year or on a few individuals may lead to erroneous conclusions. Aims: To study temporal and spatial intraspecific variation of seed dispersal in Scrophularia canina, a widespread species with capsule-type fruit. Methods: Primary seed dispersal was quantified by placing traps in each cardinal direction around 10 individuals during two consecutive years. We correlated several seed shadow parameters (modal dispersal distance, kurtosis, skewness, percentiles, slope, and seed percentage beneath the plant canopy) with three plant features (maximum height, lateral spread and seed production). Results: Scrophularia canina dispersed their seeds by boleochory, giving rise to a typical leptokurtic curve, but behaving as a barochorous species, because about 90% of seeds landed beneath the plant canopy. Temporal dispersal in S. canina included several seed waves associated with maximum wind speeds. Plant lateral spread was significantly positively correlated with seed percentiles and percentage of seeds beneath the plant canopy regardless of year. A seed production effect was only evident when both years were considered together. Conclusions: Although time-consuming, investigation of the dispersal process for more than 1 year provides more realistic information on seed dispersal. Lateral spread is the main plant feature determining seed shadow.

Peripatric speciation in an endemic Macaronesian plant after recent divergence from a widespread relative

The Macaronesian Scrophularia lowei is hypothesized to have arisen from the widespread S. arguta on the basis of several phylogenetic studies of the genus, but sampling has been limited. Although these two annual species are morphologically distinct, the origin of S. lowei is unclear because genetic studies focused on this Macaronesian species are lacking. We studied 5 S. lowei and 25 S. arguta populations to determine the relationship of both species and to infer the geographical origin of S. lowei. The timing of S. lowei divergence and differentiation was inferred by dating analysis of the ITS region. A phylogenetic analysis of two nuclear (ITS and ETS) and two chloroplast (psbJ–petA and psbA–trnH) DNA regions was performed to study the relationship between the two species, and genetic differentiation was analysed by AMOVA. Haplotype network construction and Bayesian phylogeographic analysis were conducted using chloroplast DNA regions and a spatial clustering analysis was carried out on a combined dataset of all studied regions. Our results indicate that both species constitute a well-supported clade that diverged in the Miocene and differentiated in the Late Miocene-Pleistocene. Although S. lowei constitutes a well-supported clade according to nDNA, cpDNA revealed a close relationship between S. lowei and western Canarian S. arguta, a finding supported by the spatial clustering analysis. Both species have strong population structure, with most genetic variability explained by inter-population differences. Our study therefore supports a recent peripatric speciation of S. lowei—a taxon that differs morphologically and genetically at the nDNA level from its closest relative, S. arguta, but not according to cpDNA, from the closest Macaronesian populations of that species. In addition, a recent dispersal of S. arguta to Madeira from Canary Islands or Selvagens Islands and a rapid morphological differentiation after the colonization to generate S. lowei is the most likely hypothesis to explain the origin of the last taxon.