Salvador Talavera

Range-wide phylogeography of Juniperus thurifera L., a presumptive keystone species of western Mediterranean vegetation during cold stages of the Pleistocene.

We investigate the range-wide population structure and phylogeography of thuriferous juniper (Juniperus thurifera L.), a species with a highly disjunct distribution in the western Mediterranean. We genotyped a total of 327 individuals from 20 populations using amplified fragment length polymorphisms (AFLP). Different analyses such as principal co-ordinate analysis (PCoA), nonmetric multidimensional scaling of F(ST) distances among populations, unweighted pair group method with arithmetic mean (UPGMA), and Bayesian clustering revealed that the Strait of Gibraltar acted as an efficient barrier against gene flow between the Moroccan and European populations for a very long time, and consequently support that the Moroccan populations should be recognised as a distinct subspecies (J. thurifera L. subsp. africana (Maire) Romo and Boratyńsky). The Algerian population was genetically more closely related to the European than to the Moroccan ones, probably due to dispersal events from Europe to Algeria. With respect to the mainland European populations, our data are not conclusive to reject any of the two following hypotheses: (1) the Iberian Peninsula was subdivided into different gene pools, and was the source for the colonisation of the Pyrenees and the Alps; and (2) the pattern we see today is partly the result of immigration into the Iberian Peninsula, e.g. from the Alps. Finally, the Corsican population was closely related genetically to two northern Iberian populations most probably due to relatively recent long-distance dispersal.

Reproductive biology ofCistus ladanifer (Cistaceae)

The phenology, major floral characteristics, fruiting levels, and breeding system ofCistus ladanifer L. (Cistaceae), a common western Mediterranean shrub species, were studied in a southern Spanish population. The white, large (64 mm in diameter) flowers of this shrub appear during spring (March–May) and produce abundant pollen and nectar. In the year of study, flowers lasted up to three days, during which they were visited by a diverse array of insects including beetles, flies, and bees. Hand-pollinations revealed that flowers do not set any seed unless cross pollen is applied to the stigma. Microscopical observations indicate that self pollen tubes grow down the stigma but invariably fail to induce fruit maturation. At the plant level, all estimates of fecundity investigated (number of seeds per capsule, proportion of ovules developing into seed, and proportion of flowers setting fruit) were highly dependent on nearest neighbour distance, with isolated plants setting as little as 0% fruit. In contrast, plants within a clump often transformed into fruit as much as 90% of the flowers. At the population level, seed output was estimated to range between 3,000 and 270,000 seeds per plant during 1991.

Contrasting breeding systems in twoEriotheca (Bombacaceae) species of the Brazilian cerrados

The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens.

Genetic diversity and population structure in natural populations of moroccan atlas cedar (Cedrus Atlantica; Pinaceae) determined with cpSSR markers

Atlas cedar (Cedrus atlantica) is an ecologically and economically important forest tree species of northern Africa and is considered one of the endangered conifer species in the region. Chloroplast microsatellites (cpSSR) were used to study genetic variation within and among populations and geographical structure in natural populations of C. atlantica throughout its entire distribution range in Morocco. A total of 25 chloroplast haplotypes and 66 cpSSR alleles were found among 162 individuals. The cpSSRs indicate that C. atlantica appears to maintain a high level of genetic diversity (mean H(e) = 0.95), as observed in most coniferous species. Values of mean pairwise distance within a population (D(2)(SH)) were related to the size and location of the populations. AMOVA analysis showed that most of the variation in C. atlantica occurs within populations and confirmed the general tendency of gymnosperms to display lower values of population differentiation than angiosperms. The distance-based clustering method (PCoA and neighbor-joining analysis) and the geographical structure revealed a poor structure among the six populations of Cedrus atlantica. Also, a Mantel test indicated a weak correlation between geographic and genetic distances (P = 0.106, r = 0.363). These results are also interpreted in the context of postglacial history of the region plus human impacts.

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.

Distribution and diversity of cytotypes in Dianthus broteri as evidenced by genome size variations.

BACKGROUND AND AIMS Studying the spatial distribution of cytotypes and genome size in plants can provide valuable information about the evolution of polyploid complexes. Here, the spatial distribution of cytological races and the amount of DNA in Dianthus broteri, an Iberian carnation with several ploidy levels, is investigated. METHODS Sample chromosome counts and flow cytometry (using propidium iodide) were used to determine overall genome size (2C value) and ploidy level in 244 individuals of 25 populations. Both fresh and dried samples were investigated. Differences in 2C and 1Cx values among ploidy levels within biogeographical provinces were tested using ANOVA. Geographical correlations of genome size were also explored. KEY RESULTS Extensive variation in chromosomes numbers (2n = 2x = 30, 2n = 4x = 60, 2n = 6x = 90 and 2n = 12x =180) was detected, and the dodecaploid cytotype is reported for the first time in this genus. As regards cytotype distribution, six populations were diploid, 11 were tetraploid, three were hexaploid and five were dodecaploid. Except for one diploid population containing some triploid plants (2n = 45), the remaining populations showed a single cytotype. Diploids appeared in two disjunct areas (south-east and south-west), and so did tetraploids (although with a considerably wider geographic range). Dehydrated leaf samples provided reliable measurements of DNA content. Genome size varied significantly among some cytotypes, and also extensively within diploid (up to 1.17-fold) and tetraploid (1.22-fold) populations. Nevertheless, variations were not straightforwardly congruent with ecology and geographical distribution. CONCLUSIONS Dianthus broteri shows the highest diversity of cytotypes known to date in the genus Dianthus. Moreover, some cytotypes present remarkable internal genome size variation. The evolution of the complex is discussed in terms of autopolyploidy, with primary and secondary contact zones.

LOW REPRODUCTIVE SUCCESS IN TWO SUBSPECIES OF JUNIPERUS OXYCEDRUS L.

Mature seed cone and seed production were studied in six populations of Juniperus oxycedrus (three of subspecies oxycedrus and three of subspecies macrocarpa). In both subspecies, seed cone abortion took place mainly just after the pollination period, and most of the remaining seed cones reached full size. Percentage of mature cones was significantly higher in subspecies oxycedrus than in macrocarpa. In both taxa, seed cones developed fully in the absence of filled seeds. Both the number of full-sized seeds per cone and the seed viability were low, and they were similar in both subspecies. However, seed potential was markedly higher in subsp. macrocarpa (mean 4.1 ovules/cone) than in subspecies oxycedrus (mean 2.8 ovules/cone), indicating a lower seed efficiency in subspecies macrocarpa. Results indicate that deficient pollination and site quality can be causes of low seed cone production and low seed viability in both subspecies of J. oxycedrus.

Phenotypic consequences of polyploidy and genome size at the microevolutionary scale: a multivariate morphological approach

• Chromosomal duplications and increases in DNA amount have the potential to alter quantitative plant traits like flower number, plant stature or stomata size. This has been documented often across species, but information on whether such effects also occur within species (i.e. at the microevolutionary or population scale) is scarce. • We studied trait covariation associated with polyploidy and genome size (both monoploid and total) in 22 populations of Dianthus broteri s.l., a perennial herb with several cytotypes (2x, 4x, 6x and 12x) that do not coexist spatially. Principal component scores of organ size/number variations were assessed as correlates of polyploidy, and phylogenetic relatedness among populations was controlled using phylogenetic generalized least squares. • Polyploidy covaried with organ dimensions, causing multivariate characters to increase, remain unchanged, or decrease with DNA amount. Variations in monoploid DNA amount had detectable consequences on some phenotypic traits. According to the analyses, some traits would experience phenotypic selection, while others would not. • We show that polyploidy contributes to decouple variation among traits in D. broteri, and hypothesize that polyploids may experience an evolutionary advantage in this plant lineage, for example, if it helps to overcome the constraints imposed by trait integration.

Radiative evolution of polyploid races of the Iberian carnation Dianthus broteri (Caryophyllaceae)

SUMMARY *The micro-evolutionary mechanisms that drive large-scale radiations are not completely understood, partly because of a shortage of population-level studies aimed at identifying putative causes of rapid evolutionary change. The Dianthus broteri complex, representing the largest polyploid series known to date for any species in the genus (2x, 4x, 6x and 12x cytotypes), belongs to a lineage that was recently found to have diversified at unusually rapid rates. *We used a combination of genome sequencing (internal transcribed spacer (ITS), plus chloroplast DNA (cpDNA) regions trnH-psbA, psbA-trnK and trnK-matK) and amplified fragment length polymorphism (AFLP) fingerprinting in 25 populations to infer the evolutionary history of extant polyploid races. *The haplotype, ribotype and AFLP reconstructions showed a star-shaped arrangement suggesting a pattern of radiative evolution. The major, widespread haplotype occurred at all ploidy levels, whereas 20 minor haplotypes were restricted to single populations and cytotypes. In addition, AFLP analyses retrieved well-supported cytogeographic groups: six clades were clearly differentiated in terms of ploidy level and geography. Molecular data indicate that gene flow among different cytotypes is rare or nonexistent. *Our study supports a scenario of rapid diversification in carnations in which autopolyploidy and allopolyploidy, in interaction with geography and/or isolation, have played prominent roles.

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.