Summary:

Quantifying change in species and phylogenetic composition across biogeographic regions or environmental gradients (β-diversity and β-phylodiversity respectively) provides insight into the ecological and evolutionary processes that shape biodiversity. Here we investigated the entire angiosperm flora of the mountains of the Baetic range in Andalusia, one of the most diverse regions within the Mediterranean Basin Biodiversity Hotspot, quantifying β-phylodiversity between bioclimatic elevational belts while accounting for differences in species β-diversity. We also measured phylogenetic structure within each bioclimatic elevational belt, to assess how phylogenetic composition changes along the elevational gradients. We found β-phylodiversity turnover was very strong among elevational ranges both within and between Sierras, but was significantly lower between floras of the same elevational range from different Sierras. This pattern was strongest within the Core Eudicots, but broke down in the Monocots and ancient Dicots. At medium to high elevations the flora was phylogenetically clustered, but was random with respect to phylogeny at low elevations. Once again this differed between the Core Eudicots and Monocots-ancient Dicots when analysed independently, the former being random with respect to phylogeny at all elevational ranges and the latter being clustered at high elevations. These results indicate that deep phylogenetic signal is driving the spatial distribution of angiosperm plants along elevational gradients in the Baetic mountains, and suggests that species occuring at high elevations, and thus likely more vulnerable to climate change, are non-random with respect to phylogeny.

Summary:

Linum (Fam. Linaceae) is a subcosmopolitan genus, which includes about 250 species, and it is widely distributed in temperate and subtropical regions. The genus is organized in five taxonomic sections: Linum, Cathartolinum, Syllinum, Dasylinum and Linopsis. While all the sections are relatively well represented in the North of Africa, Linopsis appears to be the only section represented in the Southern Africa, and it is particularly abundant (in number of species) in South Africa (mostly in the Cape Region). South African Linum is represented by 14 species displaying a comparatively low variation in floral and vegetative traits, which has made difficult taxonomic treatment. Heterostyly has been known in Linum for long, but it was supposed to be restricted to Old World northern hemisphere. Our field sampling has shown that heterostyly and monomorphism is present in some populations and species in South Africa. Linum species of Cape Region are related with South American lineages where heterostyly is absent, rather than to Mediterranean *Linum, where this style polymorphism is common. We explore the extent to which heterostyly is a newly acquired trait in this southern lineage, and what are the ancestral and derived conditions within the variability of traits related to heterostyly shown by this small group of taxa. To do that, we present data on cpDNA and nuclear sequences from 50 populations of this group of species from South Africa and reconstruct trait evolution on the recovered phylogenetic relationships.

Summary:

Heterostylous plant populations usually undergo high level of disassortative mating due to differentiated pollen transfer and heteromorphic incompatibility system. Stylar dimorphism lacks perfect reciprocity between morphs, thus it is considered unstable. However, it is very frequent in Narcissus. We hypothesize that enough level of disassortative pollen transfer might account for its maintenance. We investigated mating patterns in style dimorphic Narcissus papyraceus, a species with dimorphic and monomorphic populations for the long-styled morph. We set twelve experimental populations in two different sites within the dimorphic and the monomorphic regions and exposed them to natural pollinators. Two different approaches based on paternity analysis revealed increased rates of disassortative mating in most of experimental populations. In a second experiment, we assessed the role of different types of floral visitors on pollen transfer. We set emasculated (receptive) and intact (donor) flowers of each morph in the field, and collected single-visited receptive flowers to examine the pollen load deposited on stigmas. Long-tongued pollinators enhanced disassortative pollen transfer to the short-styled morph, in agreement with paternity experiment. In contrast, short-tongued insects were low efficient pollinators of the long-styled morph, and incapable to pollinate the short-styled morph. Our study provides empirical support for the hypothesis that disassortative mating maintains stylar dimorphism in the genus Narcissus. Despite of our first approach could not explain the loss of the short-styled morph in the north range of distribution of the species, the second experiment points out to a possible role of short-tongued insects, as previous correlational studies had proposed.

Summary:

The increasing availability of phylogenetic reconstructions presents the opportunity to test relevant hypotheses about the origin and diversity of plant sexual polymorphisms. Heterostyly, a pervasive discrete floral polymorphism across lineages of flowering plants, has attracted the interest of evolutionary biologists since Darwin’s book The different forms of flowers.... Early evolutionary models based on genetics explained the origin and maintenance of heterostyly as an anti-selfing mechanism. The genetic hypothesis contrasted with Darwinian views, which considered heterostyly as a device to promote outcrossing in hermaphroditic plants without the constraints imposed by self-interference between male and female functions and lack of precision in pollen transfer in hermaphroditic flowers. The mostly ecological Darwinian hypothesis posits a key role for particular pollinators, which are able to efficiently transfer pollen between different morphs. Both hypotheses agree on the fact that heterostyly is a typical mechanism for disassortative mating and is governed by negative frequency-dependent selection, although the factors proposed as important for the evolution of the trait differ. We surveyed occurrence of heterostyly across angiosperms families and genera to trace its evolution across the phylogeny. We determined the number of independent evolutionary transitions from monomorphism to heterostyly, and also the ancestral condition of heterostyly (approach herkogamy or non-herkogamy as suggested by the two competing evolutionary models). Finally we analysed whether the presence of heterostyly is evolutionarily correlated with flower architecture and developmental constraints, such as (1) tubular flowers which restrict pollinator movements and ensure more exact pollen deposition on their bodies, (2) regular flowers which do not restrict pollinator movements within the flower, and (3) flower with free stamens (not connate to the perianth).