Fossil berries reveal global radiation of the nightshade family by the early Cenozoic.

Fossil discoveries can transform our understanding of plant diversification over time and space. Recently described fossils in many plant families have pushed their known records farther back in time, pointing to alternative scenarios for their origin and spread. Here, we describe two new Eocene fossil berries of the nightshade family (Solanaceae) from the Esmeraldas Formation in Colombia and the Green River Formation in Colorado (USA). The placement of the fossils was assessed using clustering and parsimony analyses based on 10 discrete and five continuous characters, which were also scored in 291 extant taxa. The Colombian fossil grouped with members of the tomatillo subtribe, and the Coloradan fossil aligned with the chili pepper tribe. Along with two previously reported early Eocene fossils from the tomatillo genus, these findings indicate that Solanaceae were distributed at least from southern South America to northwestern North America by the early Eocene. Together with two other recently discovered Eocene berries, these fossils demonstrate that the diverse berry clade and, in turn, the entire nightshade family, is much older and was much more widespread in the past than previously thought.

Habitat fragmentation reduces plant progeny quality: a global synthesis.

Most of the world's land surface is currently under human use and natural habitats remain as fragmented samples of the original landscapes. Measuring the quality of plant progeny sired in these pervasive environments represents a fundamental endeavour for predicting the evolutionary potential of plant populations remaining in fragmented habitats and thus their ability to adapt to changing environments. By means of hierarchical and phylogenetically independent meta-analyses we reviewed habitat fragmentation effects on the genetic and biological characteristics of progenies across 179 plant species. Progeny sired in fragmented habitats showed overall genetic erosion in contrast with progeny sired in continuous habitats, with the exception of plants pollinated by vertebrates. Similarly, plant progeny in fragmented habitats showed reduced germination, survival and growth. Habitat fragmentation had stronger negative effects on the progeny vigour of outcrossing- than mixed-mating plant species, except for vertebrate-pollinated species. Finally, we observed that increased inbreeding coefficients due to fragmentation correlated negatively with progeny vigour. Our findings reveal a gloomy future for angiosperms remaining in fragmented habitats as fewer sired progeny of lower quality may decrease recruitment of plant populations, thereby increasing their probability of extinction.

Pollen-pistil relationships and pollen size-number trade-off in species of the tribe Lycieae (Solanaceae).

Pollen volume may be involved in different associations with other floral traits. Particularly, the literature indicates that pollen volume can be implicated in a functional relationship with pistil length, and that it may be affected by a trade-off with pollen number because of the subdivision of limited resources. To assess these associations, pollen volume was subjected to correlation analyses with pollen number and pistil length in 20 Argentinean and Chilean taxa of the monophyletic tribe Lycieae. Depending on the mechanisms operating on pollen size and number, the variability of these traits may be different. Therefore, their coefficients of variation were compared. Pistil length and pollen volume showed a strong positive correlation. In contrast, pollen grain size and number were significantly correlated at neither inter- nor intraspecific levels. Results suggest that pollen size and pistil length may co-evolve. The central role of this interaction is discussed. The lack of a correlated variation in pollen size and number may be related to the similar constraints experienced by the species and/or because constraints are operating at the plant level and not at the species level. Lower variance in pollen size compared with pollen number denotes that pollen size may be the main trait subjected to natural selection.

Reproductive biology of the dioecious Canary Islands endemic Withania aristata (Solanaceae).

We confirmed functional dioecy of Withania aristata via field and greenhouse studies. Male flowers are significantly larger. Female flowers bear stamens with no pollen; males bear 220 000 grains. Stigmata of male flowers senesce in buds. Anatomical observations confirm more ovules in females and an ovarian nectary in both sexes. We detected nectar in female flowers in the greenhouse but found no nectar in males. Thus, males offer pollen and females nectar. Females bear large numbers of fruits and, infrequently, male plants bear few significantly smaller fruits with few seeds. Outcrosses of females (self crosses impossible without pollen) yielded fruits in young buds, older buds, and open flowers. Self crosses of male flowers succeeded only with very young buds. Although functionally dioecious, this species manifests self-compatibility; however, no fruits are produced autonomously. Bee species (Lassioglossum, Amegilla, Apis) visit flowers and mature buds. Bud visits in which bees force petal tips apart, coupled with self-compatibility, may explain infrequent fruit on males. Thus, dioecy in W. aristata seems to have evolved from self-compatible ancestors, that leaky dioecy may have been favored during colonization, and, that despite autogamy and a low floral visition rate, this endemic enjoys a high rate of reproductive success.

Floral nectaries, nectar production dynamics and chemical composition in six ipomoea species (convolvulaceae) in relation to pollinators.

BACKGROUND AND AIMS: Floral nectaries and nectar features were compared between six Argentinian Ipomoea species with differences in their pollinator guilds: I. alba, I. rubriflora, I. cairica, I. hieronymi var. hieronymi, I. indica, and I. purpurea. METHODS: Pollinators were recorded in natural populations. The morpho-anatomical study was carried out through scanning electron and light microscopy. Nectar sugars were identified via gas chromatography. Nectar production and the effect of its removal on total nectar sugar amount were determined by using sets of bagged flowers. KEY RESULTS: Hymenopterans were visitors of most species, while hummingbirds visited I. rubriflora and sphingids I. alba. All the species had a vascularized discoidal nectary surrounding the ovary base with numerous open stomata with a species-specific distribution. All nectar samples contained amino acids and sugars. Most species had sucrose-dominant nectars. Flowers lasted a few hours. Mean nectar sugar concentration throughout the lifetime of the flower ranged from 34.28 to 39.42 %, except for I. cairica (49.25 %) and I. rubriflora (25.18 %). Ipomoea alba had the highest nectar volume secreted per flower (50.12 microL), while in the other taxa it ranged from 2.42 to 12.00 microL. Nectar secretion began as soon as the flowers opened and lasted for a few hours (in I. purpurea, I. rubriflora) or it was continuous during the lifetime of the flower (in the remaining species). There was an increase of total sugar production after removals in I. cairica, I. indica and I. purpurea, whereas in I. alba and I. rubriflora removals had no effect, and in I. hieronymi there was a decrease in total sugar production. CONCLUSIONS: The chemical composition, production dynamics and removal effects of nectar could not be related to the pollinator guild of these species. Flower length was correlated with nectary size and total volume of nectar secreted, suggesting that structural constraints may play a major role in the determination of nectar traits of these species.

The reproductive biology of Sophora fernandeziana (Leguminosae), a vulnerable endemic species from Isla Robinson Crusoe.

Sophora fernandeziana is the only legume endemic to Isla Robinson Crusoe (Archipelago Juan Fernández, Chile); it is uncommon and becoming rare. Although its preservation status is listed as "vulnerable," as with many species, little is known of its reproductive biology. Flowering phenology, floral morphology, nectar features, breeding system, and visitors were analyzed in two populations. Flowering is from late winter to early spring. Flowers last 6 d and have a number of ornithophilous features. A floral nectary begins to secrete highly concentrated nectar 48 h after flowers open. Nectar secretion increases as the flower ages but culminates in active nectar reabsorption as the flower senesces. Nectar production is negatively affected by nectar removal. Self-pollen germinates and tubes grow down the style. However, pollen tubes were only observed to enter the ovaries in open pollinated styles, suggesting the possibility of an ovarian self-incompatibility mechanism. Both sexes of the two hummingbird species that inhabit the island are regular visitors. Low fruit and seed set, low genetic diversity, and a shrinking number of populations all contribute to increased concern about the future of this species-and perhaps the hummingbirds that depend on it.