María Ángeles Ortiz

Population structure of Hypochaeris salzmanniana DC. (Asteraceae), an endemic species to the Atlantic coast on both sides of the Strait of Gibraltar, in relation to Quaternary sea level changes

To detect potential Pleistocene refugia and colonization routes along the Atlantic coast, we analysed amplified fragment length polymorphisms (AFLPs) in 140 individuals from 14 populations of Hypochaeris salzmanniana (Asteraceae), an annual species endemic to the southwestern European and northwestern African coastal areas. Samples covered the total distributional range of the species, with eight populations in southwestern Spain and six populations in northwestern Morocco. Using nine primer combinations, we obtained 546 fragments in H. salzmanniana and its sister species H. arachnoidea of which 487 (89.2%) were polymorphic. The neighbour‐joining tree shows that the populations south of the Loukos river in Morocco are clearly differentiated, having more polymorphic, private, and rare fragments, and higher genetic diversity, than all the other populations. The southernmost populations in Morocco, south of the river Sebou, form a large panmictic population. They are probably the oldest populations that have been relatively unaffected by stochastic processes resulting from Pleistocene glaciations. Northward migration of populations during this period may have resulted in loss of genetic diversity in specific regions, perhaps due to bottlenecks caused by rise in sea level during interglacial periods, and, in some cases, by changes in the breeding system.

Self-incompatibility and floral parameters in Hypochaeris sect. Hypochaeris (Asteraceae)

We studied the relationships between self-incompatibility mechanisms and floral parameters in the genus Hypochaeris L. sect. Hypochaeris (consisting of H. glabra, H. radicata, H. arachnoidea, and H. salzmanniana). We assessed at intra- and interspecific levels (1) the self-incompatibility (SI) mechanism and its distribution among populations, (2) the relationship between SI and floral parameters, and (3) the relationship of SI to reproductive success. Hypochaeris salzmanniana is semi-incompatible, H. glabra is self-compatible, and H. arachnoidea and H. radicata are self-incompatible. Floral parameters differed among populations of H. salzmanniana: plants in self-compatible populations had fewer flowers per head, a smaller head diameter on the flower, and a shorter period of anthesis than self-incompatible populations. We also detected this pattern within a semi-compatible population of H. salzmanniana, and these differences were also found between species with different breeding mechanisms. Fruit to flower ratio in natural populations was generally high (>60%) in all species, regardless of breeding system. It is hypothesized that self-compatibility may have arisen through loss of allelic diversity at the S locus due to bottleneck events and genetic drift.

Pleistocene refugia and polytopic replacement of diploids by tetraploids in the Patagonian and Subantarctic plant Hypochaeris incana (Asteraceae, Cichorieae)

We report the phylogeographic pattern of the Patagonian and Subantarctic plant Hypochaeris incana endemic to southeastern South America. We applied amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and 32 populations, respectively, throughout its distributional range and assessed ploidy levels using flow cytometry. While cpDNA data suggest repeated or simultaneous parallel colonization of Patagonia and Tierra del Fuego by several haplotypes and/or hybridization, AFLPs reveal three clusters corresponding to geographic regions. The central and northern Patagonian clusters (∼38–51° S), which are closer to the outgroup, contain mainly tetraploid, isolated and highly differentiated populations with low genetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (∼51–55° S) contains mainly diploid populations with high genetic diversity and connected by high levels of gene flow. The data suggest that H. incana originated at the diploid level in central or northern Patagonia, from where it migrated south. All three areas, northern, central and southern, have similar levels of rare and private AFLP bands, suggesting that all three served as refugia for H. incana during glacial times. In southern Patagonia and Tierra del Fuego, the species seems to have expanded its populational system in postglacial times, when the climate became warmer and more humid. In central and northern Patagonia, the populations seem to have become restricted to favourable sites with increasing temperature and decreasing moisture and there was a parallel replacement of diploids by tetraploids in local populations.

Phylogeography of the invasive weed Hypochaeris radicata (Asteraceae): from Moroccan origin to worldwide introduced populations

In an attempt to delineate the area of origin and migratory expansion of the highly successful invasive weedy species Hypochaeris radicata, we analysed amplified fragment length polymorphisms from samples taken from 44 populations. Population sampling focused on the central and western Mediterranean area, but also included sites from Northern Spain, Western and Central Europe, Southeast Asia and South America. The six primer combinations applied to 213 individuals generated a total of 517 fragments of which 513 (99.2%) were polymorphic. The neighbour‐joining tree presented five clusters and these divisions were supported by the results of Bayesian analyses: plants in the Moroccan, Betic Sierras (Southern Spain), and central Mediterranean clusters are all heterocarpic. The north and central Spanish, southwestern Sierra Morena, and Central European, Asian and South American cluster contain both heterocarpic (southwestern Sierra Morena) and homocarpic populations (all other populations). The Doñana cluster includes two homocarpic populations. Analyses of fragment parameters indicate that the oldest populations of H. radicata are located in Morocco and that the species expanded from this area in the Late Quaternary via at least three migratory routes, the earliest of which seems to have been to the southwestern Iberian Peninsula, with subsequent colonizations to the central Mediterranean area and the Betic Sierras. Homocarpic populations originated in the southwestern Iberian Peninsula and subsequently spread across north and central Spain, Central Europe and worldwide, where they became a highly successful weed.

Phylogeography of SW Mediterranean firs: Different European origins for the North African Abies species

The current distribution of Western Mediterranean Abies species is a result of complex geodynamic processes and climatic oscillations that occurred in the past. Abies sect. Piceaster offers a good study model to explore how geo-climatic oscillations might have influenced its expansion and diversification on both sides of the W Mediterranean basin. We investigated the genetic variation within and among nine populations from five Abies species by molecular markers with high and low mutation rates and contrasting inheritance (AFLP and cpSSR). Analyses revealed the opening of the Strait of Gibraltar as an effective barrier against gene flow between the Southern Iberian (A. pinsapo) and North African (A. marocana and A. tazaotana) firs. The A. pinsapo populations in Spain and likewise those of the A. marocana - A. tazaotana population complex were not differentiated, and no evidence was found to distinguish A. tazaotana at the species level. Diversification of Abies across North Africa could occur by way of at least two vicariant events from Europe, in the west, giving rise to the A. marocana - A. tazaotana complex, and in the east, giving A. numidica. Secondary contacts among species from Abies sect. Piceaster (A. pinsapo and A. numidica), and with A. alba (Abies sect. Abies) are also indicated. However, there is a closer relationship between the Algerian fir (A. numidica) and the North Mediterranean widespread A. alba, than with the Moroccan firs (A. marocana and A. tazaotana) or the Southern Iberian (A. pinsapo). We also discuss the distribution range of these taxa in its paleogeological and paleoclimatic context, and propose that part of the modern geography of the South-Western Mediterranean firs might be traced back to the Tertiary.

AFLP and breeding system studies indicate vicariance origin for scattered populations and enigmatic low fecundity in the Moroccan endemic Hypochaeris angustifolia (Asteraceae), sister taxon to all of the South American Hypochaeris species.

We used Amplified Fragment Length Polymorphism markers (AFLP) and breeding system studies to investigate the population structure and reproductive biology of Hypochaeris angustifolia (Asteraceae: Cichorieae). This species is endemic to altiplanos of the Atlas Mountains (Morocco) where it occurs in scattered populations, and it is the sister species to c. 40 species of this genus in South America. PCoA, NJ, and Bayesian clustering, revealed that the populations are very isolated whilst AFLP parameters show that almost all populations have marked genetic divergence. We contend that these features are more in accord with a vicariance origin for the scattered populations of H. angustifolia, rather than establishment by long-distance dispersal. The breeding system studies revealed that H. angustifolia is a self-incompatible species, with low fecundity in natural and in experimental crosses, probably due to a low frequency of compatible phenotypes within and between the populations.

Molecular phylogeny and systematics of the highly polymorphic Rumex bucephalophorus complex (Polygonaceae)

Rumex bucephalophorus is a very polymorphic species that has been subjected to various taxonomic studies in which diverse infraspecific taxa have been recognised on the basis of diaspore traits. In this study we used molecular markers (ITS and AFLP) to explore this remarkable diversity, to test previous hypotheses of classification, and attempt to explain biogeographic patterns. Results show that R. bucephalophorus forms a monophyletic group in which diversification began around 4.2 Mya, at the end of Messinian Salinity Crisis. The two molecular markers clearly show a deep divergence separating subsp. bucephalophorus from all other subspecific taxa, among which subsp. canariensis also constitutes a separate and well distinguishable unit. In contrast, subspecies hispanicus and subsp. gallicus constitute a monophyletic group in which three subgroups can be recognised: subsp. hispanicus, subsp. gallicus var. gallicus and subsp. gallicus var. subaegeus. However, these three subgroups are not clearly distinguished genetically or morphologically, so that in formal classification it would be preferable to treat them at the varietal level.

Phylogeography above the species level for perennial species in a composite genus

Phylogeography above the species level is a powerful tool for investigating patterns and processes at the boundary between divergent and reticulate relationships. We examined the evolutionary history of perennial species in the western Mediterranean composite genus Helminthotheca using DNA sequence and fingerprint data. The origin of the group was in western North Africa, a region of intensive Pleistocene speciation. From here it expanded to the Iberian Peninsula and Sicily. The inferred evolutionary history is compatible with the concept of ecogeographic isolation, which refers to the fact that geographic ranges of diverging lineages are largely non-overlapping due to adaptive differentiation.

Karyotype studies on populations of two Hypochaeris species (H. catharinensis and H. lutea), Asteraceae, endemics to southern Brazil.

Hypochaeris is an excellent system for studying different modes of chromosome evolution in plants. We carried out a cytogenetic analysis on populations of 2 Hypochaeris species, comprising 10 populations of H. catharinensis and 5 of H. lutea, to assess possible changes on chromosome organization in this interesting genus. Conventional Feulgen staining and fluorescent banding revealed that the general aspects of chromosome morphology for all populations of both species were similar, evidence of the typical bimodal karyotypes with 2n = 8 chromosomes that characterize the South American Hypochaeris. Comparative analysis of the karyotypes identified minor variations in the absolute size and arm ratio of corresponding chromosome pairs. One population of H. lutea was entirely polyploid adding a novel cytotype to this species. Fluorescent banding revealed strong chromomycin A3 (CMA3)-positive signals on both arms of chromosomes 3 and 4 of H. catharinensis, revealing a new pattern for the distribution of GC-rich heterochromatin in Hypochaeris. A strong CMA-positive signal was observed on the short arm of chromosome 3 in one population of H. lutea, while the other populations validated the CMA3 pattern already described for this species. While the overall karyotype similarities of the 2 species are in compass with all South American Hypochaeris, the presence of unusual large blocks of GC-rich heterochromatin suggests that chromosome rearrangements, related to dispersion of heterochromatin, are taking place in the karyotype of H. catharinensis. The novel polyploid cytotype identified in H. lutea provides support that polyploidization is an active process in the mode of chromosome evolution in Hypochaeris.

Uncertain pollination environment promotes the evolution of a stable mixed reproductive system in the self-incompatible Hypochaeris salzmanniana (Asteraceae)

Background and aims The transition from outcrossing to selfing is a repeated pattern in angiosperm diversification and according to general theory this transition should occur quickly and mixed reproductive systems should be infrequent. However, a large proportion of flowering plants have mixed reproductive systems, even showing inbreeding depression. Recently, several theoretical studies have shown that mixed mating systems can be stable, but empirical studies supporting these assumptions are still scarce. Methods Hypochaeris salzmanniana, an annual species with populations differing in their self-incompatibility expression, was used as a study case to assess the stability of its mixed reproductive system. Here a descriptive study of the pollination environment was combined with measurements of the stability of the self-incompatibility system, outcrossing rate, reproductive assurance and inbreeding depression in four populations for two consecutive years. Key Results The reproductive system of populations exhibited a geographical pattern: the proportion of plants decreased from west to east. Pollinator environment also varied geographically, being less favourable from west to east. The self-incompatibility expression of some populations changed markedly in only one year. After selfing, progeny was mainly self-compatible, while after outcrossing both self-incompatible and self-compatible plants were produced. In general, both reproductive assurance and high inbreeding depression were found in all populations and years. The lowest values of inbreeding depression were found in 2014 in the easternmost populations, which experienced a marked increase in self-compatibility in 2015. Conclusions The mixed reproductive system of H. salzmanniana seems to be an evolutionarily stable strategy, with selfing conferring reproductive assurance when pollinator attendance is low, but strongly limited by inbreeding depression. The fact that the highest frequencies of self-compatible plants appeared in the environments most unfavourable to pollination suggests that these plants are selected in these sites, although high rates of inbreeding depression should impede the complete loss of self-incompatibility. In H. salzmanniana, year-to-year changes in the frequency of self-incompatible individuals are directly derived from the balance between reproductive assurance and inbreeding depression.