Francisco J. Valtueña

Phylogeography of a Tertiary relict plant, Meconopsis cambrica (Papaveraceae), implies the existence of northern refugia for a temperate herb

The perennial herb Meconopsis cambrica, a western European endemic, is the only European species of the otherwise Himalayan genus Meconopsis and has been interpreted as a Tertiary relict species. Using rbcL and ITS sequence variation, we date the split between M. cambrica and its sister clade Papaver s.str. to the Middle to Upper Miocene (12.8 Myr, 6.4–19.2 Myr HPD). Within M. cambrica, cpDNA sequence variation reveals the existence of two groups of populations with a comparable level of genetic variation: a northern group from Great Britain, the Massif Central, the western Pyrenees and the Iberian System, and a southern group from the central and eastern Pyrenees. Populations from the Cantabrian Mountains were placed in both groups. Based on ITS sequence variation, the divergence between these two groups can be dated to 1.5 Myr (0.4–2.8 Myr HPD), and the age of the British populations is estimated as 0.37 Myr (0.0–0.9 Myr HPD). Amplified fragment length polymorphism results confirm the distinctive nature of the populations from Britain, the Massif Central and the central and eastern Pyrenees. These patterns of latitudinal variation of M. cambrica differ from patterns of longitudinal differentiation found in many other temperate species and imply glacial survival of the northern populations in northerly refugia. The primary differentiation into northern and southern cpDNA groups dates to near the onset of the Quaternary and suggests that an ancient phylogeographic pattern has survived through several glacial periods. Our data provide evidence that the species has persisted for a long period with a highly fragmented and probably very localized distribution.

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).

Nectar Production in Anagyris foetida (Fabaceae): Two Types of Concentration in Flowers with Hanging Droplet

In Anagyris foetida, a shrubby legume with autumn–winter flowering, the flowers produce great amounts of very dilute nectar during the first half of their life, consonant with their pollination by passeriforms. With advancing age, the volume of nectar diminishes and the concentration increases to values characteristic of bee‐pollinated flowers. The daily nectar secretion is greatest in volume early in the morning, damping during the day, whereas the concentration usually undergoes a gradual rise from morning to evening. The flowers visited for the first time in any day in the first half of anthesis have greater accumulated final nectar volumes than those first visited in the second half of anthesis. The accumulated nectar per flower is less in flowers that receive one visit per day than in those that receive three visits per day and is less in shrubby plants than in arboreal plants. In unvisited flowers, the rate of production of nectar depends on the environmental conditions, and at the end of their life there is a major loss of volume due to evaporation and of solutes possibly due to reabsorption. These flowers usually present a large hanging droplet of nectar that has a greater concentration and sugar content than does the nectar inside the calyx. The sugar, hexose dominant, is homogeneous in both locations.

Self-sterility in two Cytisus species (Leguminosae, Papilionoideae) due to early-acting inbreeding depression

In most angiosperms, the endosperm develops before the embryo, but with harmony between the two structures until final seed formation. In an embryological study, we show that inbreeding depression causes disharmony in development of the two structures in two Leguminosae shrubs, Cytisus multiflorus and C. striatus. Our main objective was to test the causes of self-sterility in the two species by comparing the embryological development of the self seeds with that of cross seeds. In developing selfed seeds of C. multiflorus, the embryo reaches at most the globular stage and never forms mature seeds, while in C. striatus a few mature selfed seeds are formed. In both species, the main cause of abortion of developing selfed seeds is diminished endosperm development (low values of the ratio of endosperm to embryo), which triggers collapse of the endosperm and embryo. The results indicate that self-sterility in C. striatus is postzygotic because of strong, early inbreeding depression, while in C. multiflorus there exists a mixed pre- and postzygotic mechanism; the prezygotic mechanism causes rejection of some self-pollen tubes in the style/ovary, and the early inbreeding depression triggers abortion of fertilized ovules that escaped that action.

Is Welsh Poppy, Meconopsis cambrica (L.) Vig. (Papaveraceae), truly a Meconopsis?

Abstract Since the nineteenth century, the western European endemic Meconopsis cambrica has been regarded as the only European representative of the genus Meconopsis Vig. This genus, which is otherwise restricted to the Himalayas, differs from Papaver in having a style rather than a stigmatic disc. A phylogenetic reconstruction using 65 internal transcribed spacer sequences of 62 taxa of Old World Papaveroideae and three outgroup taxa shows that M. cambrica is not the closest relative of the remainder of Meconopsis but rather the closest sampled relative of Papaver s.str. This is consistent with morphological evidence which suggests that the style evolved independently in M. cambrica from a Papaver-like ancestor. We suggest that Meconopsis cambrica should revert to its former name, Papaver cambricum L. We also suggest that: (1) the Arctic-montane species of Papaver sect. Meconella need to be placed in their own genus; (2) Papaver sect. Argemonidium (including P. argemone and P. hybridum) should be included in Roemeria Medik.; and (3) the basal lineage of Asian Meconopsis needs to be treated as an independent genus, Cathcartia Hook.f. As Meconopsis cambrica is the type of Meconopsis, conservation of Meconopsis Vig. with a different type is required to avoid further nomenclatural changes. The evolutionary history of M. cambrica is briefly discussed.

Evolutionary significance of the invasion of introduced populations into the native range of Meconopsis cambrica

The long history of the deliberate or accidental and human‐mediated dispersal of flowering plants has led to the introduction of foreign genotypes of many species into areas of Europe hitherto occupied by potentially distinct native populations. Studies of the genetic and evolutionary consequences of such changes are handicapped by the difficulty of identifying the surviving native populations of many species in the absence of clear morphological differences. We investigated the relationship between putative native and introduced populations of the herbaceous perennial Meconopsis cambrica (Papaveraceae), as the isolated native populations of this species can be identified by historical and ecological evidence. In Britain, the species is scarce and declining as a native, but has become increasingly frequent in recent decades as a garden escape. Native populations from Spain and France were compared with native and introduced British populations using internal transcribed spacer and cpDNA sequences and amplified fragment length polymorphisms (AFLPs). Ten of the twelve British populations could be unambiguously assigned to native or introduced groups using cpDNA and AFLPs. The introduced plants appear to originate from the central and eastern Pyrenees rather than from native British sites. Two populations (including one previously considered native) cannot be classified unambiguously. There is unequivocal evidence for unidirectional gene flow from native plants into two of the introduced populations and possible evidence for hybridization in three other sites (two native). The absence of biological barriers to hybridization suggests that the native and introduced gene pools of M. cambrica in Britain might eventually merge.

Germination and seed bank biology in some Iberian populations of Anagyris foetida L. (Leguminosae)

In Anagyris foetida, the fruits are disseminated by fall under gravity. No dispersing agent is as yet known, so that the fruits are located near the mother plant. The species presents an important seed bank that differs between the two populations studied, probably due to their different production of seeds/individual and to the livestock pressure. The germination of control seeds was found to be null or very low, with no improvement following exposure to high temperatures, but reaching high values following scarification in all the populations studied. This indicates that the failure in germination must be attributed to the hardness of the testa, with the seeds presenting physical dormancy. Also, the browsing of sheep on ripe fruit increases germination to 48% due to mechanical scarification, with this being the only positive effect those animals have on these plants. There were differences in germination after scarification between populations and years which could have been due to intrinsic characteristics.

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.

Regulation of fruit and seed set in Anagyris foetida L. (Fabaceae): The role of intrinsic factors

Abstract We investigated the role of resource limitation, ovary reserve, and selective abortion in controlling flower and fruit set in the Mediterranean leguminous shrub Anagyris foetida. The removal of bracts, but not that of leaves, reduced the initiation of fruit with respect to controls. The removal of a large proportion (2/3 of the total) of preanthesic inflorescences increased the reproductive capacity of individuals via two different strategies: (1) maintaining the number of fruit-bearing inflorescences, but increasing the number of fruits per inflorescence and seeds per fruit; and (2) increasing the number of fruit-bearing inflorescences, while maintaining fruits/inflorescence and seeds/fruit ratios unchanged. At the level of the inflorescence, most of the ripe fruits were located on the basalmost whorls of the raceme. Within the legume, fertilization was independent of the position of ovules, although the more basal presented lower rates of fertilization than the more central-stylar. The same was observed for the probability of a fertilized ovule to develop into a mature seed.