Juli Caujapé-Castells

Allozyme diversity in three endemic species of Cistus (Cistaceae) from the Canary Islands: intraspecific and interspecific comparisons and implications for genetic conservation.

Patterns of variation at 13 isozyme loci were examined in 11 populations in three Cistus species strictly endemic to the Canary Islands. Cistus osbaeckiaefolius and C. chinamadensis display low levels of isozyme variation associated with moderate to high interpopulation differentiation, which probably arose through historical bottlenecks in a landscape of habitat fragmentation, grazing, and human influence. By contrast, C. symphytifolius ranks among the subset of narrow endemics with high levels of isozyme variation and features different degrees of genetic structuring that are closely associated with taxonomic ascription. Low interpopulation differentiation in var. leucophyllus is possibly a reflection of its recent origin or of moderate levels of gene flow between its populations. High interpopulation differentiation in var. symphytifolius probably arose due to slight ecological differences between populations coupled with low levels of gene flow. Interpretation of neighbor-joining trees in the light of geological data substantiates the hypothesis that C. symphytifolius (or a very close relative) might be the ancestor of the other stands of Cistus in the islands. Conservation implications of our survey are the identification of the two populations of C. chinamadensis with the highest allele and genotype richness for preservation on genetic grounds and advice to prevent artificial gene flow in this taxon lest it might disrupt locally adapted gene combinations. All populations of C. osbaeckiaefolius should be given conservation priority on ecological grounds despite their genetic depauperation.

A local dormancy cline is related to the seed maturation environment, population genetic composition and climate

BACKGROUND AND AIMS Seed dormancy varies within species in response to climate, both in the long term (through ecotypes or clines) and in the short term (through the influence of the seed maturation environment). Disentangling both processes is crucial to understand plant adaptation to environmental changes. In this study, the local patterns of seed dormancy were investigated in a narrow endemic species, Centaurium somedanum, in order to determine the influence of the seed maturation environment, population genetic composition and climate. METHODS Laboratory germination experiments were performed to measure dormancy in (1) seeds collected from different wild populations along a local altitudinal gradient and (2) seeds of a subsequent generation produced in a common garden. The genetic composition of the original populations was characterized using intersimple sequence repeat (ISSR) PCR and principal co-ordinate analysis (PCoA), and its correlation with the dormancy patterns of both generations was analysed. The effect of the local climate on dormancy was also modelled. KEY RESULTS An altitudinal dormancy cline was found in the wild populations, which was maintained by the plants grown in the common garden. However, seeds from the common garden responded better to stratification, and their release from dormancy was more intense. The patterns of dormancy variation were correlated with genetic composition, whereas lower temperature and summer precipitation at the population sites predicted higher dormancy in the seeds of both generations. CONCLUSIONS The dormancy cline in C. somedanum is related to a local climatic gradient and also corresponds to genetic differentiation among populations. This cline is further affected by the weather conditions during seed maturation, which influence the receptiveness to dormancy-breaking factors. These results show that dormancy is influenced by both long-and short-term climatic variation. Such processes at such a reduced spatial scale highlight the potential of plants to adapt to fast environmental changes.

The biology of island floras.

List of contributors Preface Juli Caujape-Castells 1. Introduction, islands and plants David Bramwell 2. The reproductive biology of island plants Daniel J. Crawford, Gregory J. Anderson and Gabriel Bernardello 3. Spatial methodology in historic biogeography of islands Paula Posadas, Jorge V. Crisci and Liliana Katinas 4. Origin and evolution of Hawaiian endemics: new patterns revealed by molecular studies Sterling C. Keeley and Vicky A. Funk 5. Origins and evolution of Galapagos endemic vascular plants Alan Tye and Javier Francisco-Ortega 6. The plants of the Caribbean Islands: a review of the biogeography, diversity and conservation of a storm-battered biodiversity hot-spot Michael Maunder, Melissa Abdo, Rosalina Berazain, Colin Clubbe, Francisco Jimenez, Angela Leiva, Eugenio Santiago-Valentin, Brett Jestrow and Javier Francisco-Ortega 7. The biogeography of Madagascar palms John Dransfield and Mijoro Racotoarinivo 8. Evolution and biogeography of the flora of the Socotra Archipelago (Yemen) Lisa M. Banfield, Kay Van Damme and Anthony G. Miller 9. Biogeography and conservation of the flora of New Caledonia David Bramwell 10. Phytogeography and relationships of the Pitcairn Islands flora Steve Waldren and Naomi Kingston 11. Chromosomes and evolution in New Zealand endemic Angiosperms and Gymnosperms Brian G. Murray and Peter J. de Lange 12. Jesters, red queens, boomerangs and surfers: a molecular outlook to the diversity of the Canarian endemic flora Juli Caujape-Castells 13. Endemism and evolution in Macaronesian and Mediterranean Limonium taxa M. Dolores Lledo, Per O. Karis, Manuel B. Crespo, Michael F. Fay and Mark W. Chase 14. Dispersal, diversity and evolution in the Macaronesian Cryptogamic floras Alain Vanderpoorten, Ben Laenen, Rosalina Gabriel, Juana M. Gonzalez-Mancebo, Fred J. Rumsey and Mark A. Carine 15. Invasive alien species and islands Michael Kiehn 16. Ecology, demography and conservation in the Galapagos Islands flora Ole Hamann 17. New directions and challenges for the conservation of the flora of Madagascar Stuart Cable 18. Climate change and island floras David Bramwell 19. Conservation status of endemic plants on Isla de Coco, Costa Rica: applying IUCN red list criteria on a small island Jennifer L. Trusty, Herbert C. Kesler, Jorge Rodriguez and Javier Francisco-Ortega 20. Botanical gardens and the conservation of island floras Sara Oldfield 21. The hazardous future of island floras Vernon H. Heywood Index.

Molecular evidence of hybridisation between the endemic Phoenix canariensis and the widespread P. dactylifera with Random Amplified Polymorphic DNA (RAPD) markers

Abstract.We used RAPD markers to test whether morphologically intermediate individuals between the Canarian endemic Phoenix canariensis and the widespread P. dactylifera correspond to hybrids. Consistent with previous allozyme evidence, the scarcity of appropriate RAPD markers to distinguish P. dactylifera and P. canariensis indicated a close genetic relationship among these species. Only two of the 54 ten-mer primers (OPM-8 and OPK-14) tested in 221 individuals from 7 localities in different islands enabled us to unambiguously identify both species. While P. canariensis possesses two exclusive monomorphic bands of 1000 bp and 750 bp (for OPM-8 and OPM-14, respectively), dactylifera is characterised by two bands of 900 bp and 950 bp for the same primers. The additivity of these taxon-specific bands in the individuals that were morphologically intermediate provided, for the first time, firm evidence for their hybrid origin. Because these hybridisation capabilities pose clear threats to the survival of the endemic P. canariensis and some individuals that had been morphologically characterised as pure P. canariensis revealed later a hybrid nature in the RAPD analysis, we suggest that RAPD markers be used to estimate the possible incidence of introgression in the scarce extant natural populations of P. canariensis. This procedure will provide a straightforward means to select target populations to implement the “in situ” conservation strategies suggested previously on the basis of allozyme research.

The influence of the Miocene Mediterranean desiccation on the geographical expansion and genetic variation of Androcymbium gramineum (Cav.) McBride (Colchicaceae)

Chloroplast DNA (cpDNA) restriction site and isozyme data were combined to explore the spatial–temporal influence of the Messinian desiccation in the Mediterranean on the disjunct distribution of Androcymbium gramineum in Almería and Morocco (north and south of the straits of Gibraltar, respectively). Lack of evidence for different selective pressures, divergence time estimates based on the calibration of the isozyme molecular clock with the cpDNA data, the basal position of Almerian populations in the A. gramineum clade, and the much higher isozyme polymorphism in Almería suggest that (i) only a southern European range of A. gramineum existed before the Messinian [≈ 11.2 million years ago (Ma), in the middle Miocene] and (ii) the desiccation of the Mediterranean basin about 5.5–4.5 Ma induced the migration of A. gramineum from Almería to Morocco (between 4.9 and 4.6 Ma, according to our time estimates). After the split into two allopatric units following the refilling of the Mediterranean, the major influence of drift associated with Plio‐Pleistocene recurrent glaciation cycles and range expansions/contractions probably fostered the substantial interpopulation genetic differentiation observed within Almería (CGST = 0.41, average DNei = 0.185) and, to a lesser extent, within Morocco (CGST = 0.24, average DNei = 0.089), but did not hinder the maintenance of considerable levels of genetic variation in either geographical area (A = 2.14, HE = 0.230 and A = 1.90, HE = 0.213, respectively).

The colonization history of Juniperus brevifolia (Cupressaceae) in the Azores Islands.

Background A central aim of island biogeography is to understand the colonization history of insular species using current distributions, fossil records and genetic diversity. Here, we analyze five plastid DNA regions of the endangered Juniperus brevifolia, which is endemic to the Azores archipelago. Methodology/Principal Findings The phylogeny of the section Juniperus and the phylogeographic analyses of J. brevifolia based on the coalescence theory of allele (plastid) diversity suggest that: (1) a single introduction event likely occurred from Europe; (2) genetic diversification and inter-island dispersal postdated the emergence of the oldest island (Santa Maria, 8.12 Ma); (3) the genetic differentiation found in populations on the islands with higher age and smaller distance to the continent is significantly higher than that on the younger, more remote ones; (4) the high number of haplotypes observed (16), and the widespread distribution of the most frequent and ancestral ones across the archipelago, are indicating early diversification, demographic expansion, and recurrent dispersal. In contrast, restriction of six of the seven derived haplotypes to single islands is construed as reflecting significant isolation time prior to colonization. Conclusions/Significance Our phylogeographic reconstruction points to the sequence of island emergence as the key factor to explain the distribution of plastid DNA variation. The reproductive traits of this juniper species (anemophily, ornithochory, multi-seeded cones), together with its broad ecological range, appear to be largely responsible for recurrent inter-island colonization of ancestral haplotypes. In contrast, certain delay in colonization of new haplotypes may reflect intraspecific habitat competition on islands where this juniper was already present.

Population Structure and Genetic Diversity of Two Endangered Endemic Species of the Canarian Laurel Forest: Dorycnium spectabile (Fabaceae) and Isoplexis chalcantha (Scrophulariaceae)

We used random amplified polymorphic DNA (RAPD) markers to assess the levels and structuring of genetic variation in the Canarian laurel forest endangered endemics Dorycnium spectabile (Fabaceae) and Isoplexis chalcantha (Scrophulariaceae). Amplification of seven primers in the only two extant populations of each species resulted in 28 (D. spectabile) and 32 (I. chalcantha) markers that exhibited a polymorphism of 78% and 100%, respectively. The estimates of population subdivision show that ca. 75% and 25% of the total genetic variability of both species is explained by the within‐ and between‐population components, respectively. Our favored hypothesis to explain the high levels of genetic variation detected in both endemics is that they originated from multiple introductions of continental ancestors. The recent fragmentation and degradation of the Canarian laurel forest probably brought about a severe reduction of interpopulation gene flow in both species that might have disrupted the genetic cohesion of once more widespread geographic ranges. Intrapopulation spatial autocorrelation analyses indicate that the genetic variability of D. spectabile and I. chalcantha is structured in family clumps whose maintenance and enhancement is best explained by assortive mating and short‐range seed dispersal capabilities. Because of the extreme vulnerability of these two endemics and their high levels of interpopulation genetic differentiation, we recommend protecting all their natural areas of occurrence and avoiding mixing individuals from different populations. Patch size estimates derived from spatial autocorrelation were used to suggest seed collection strategies that minimize the probability of sampling genetically similar individuals.

A review of the allozyme data set for the Canarian endemic flora: causes of the high genetic diversity levels and implications for conservation

Background and Aims Allozyme and reproductive data sets for the Canarian flora are updated in order to assess how the present levels and structuring of genetic variation have been influenced by the abiotic island traits and by phylogenetically determined biotic traits of the corresponding taxa; and in order to suggest conservation guidelines. Methods Kruskal-Wallis tests are conducted to assess the relationships of 27 variables with genetic diversity (estimated by A, P, Ho and He) and structuring (GST) of 123 taxa representing 309 populations and 16 families. Multiple linear regression analyses (MLRAs) are carried out to determine the relative influence of the less correlated significant abiotic and biotic factors on the genetic diversity levels. Key Results and Conclusions The interactions between biotic features of the colonizing taxa and the abiotic island features drive plant diversification in the Canarian flora. However, the lower weight of closeness to the mainland than of (respectively) high basic chromosome number, partial or total self-incompatibility and polyploidy in the MLRAs indicates substantial phylogenetic constraint; the importance of a high chromosome number is feasibly due to the generation of a larger number of linkage groups, which increase gametic and genotypic diversity. Genetic structure is also more influenced by biotic factors (long-range seed dispersal, basic chromosome number and partial or total self-incompatibility) than by distance to the mainland. Conservation-wise, genetic structure estimates (FST/GST) only reflect endangerment under intensive population sampling designs, and neutral genetic variation levels do not directly relate to threat status or to small population sizes. Habitat protection is emphasized, but the results suggest the need for urgent implementation of elementary reproductive studies in all cases, and for ex situ conservation measures for the most endangered taxa, even without prior studies. In non-endangered endemics, multidisciplinary research is needed before suggesting case-specific conservation strategies. The molecular information relevant for conservation should be conserved in a standardized format to facilitate further insight.

Patterns of genetic divergence of three Canarian endemic Lotus (Fabaceae): implications for the conservation of the endangered L. kunkelii

We examined data for 11 allozyme loci in 14 populations that represent the distribution of the endangered Lotus kunkelii, the narrowly distributed L. arinagensis (both endemic to Gran Canaria), and the broad-ranging L. lancerottensis (endemic to the easternmost Canary Islands, Fuerteventura and Lanzarote) to explore and construe patterns of genetic variation and use this data to assess the controversial taxonomic status of L. kunkelii relative to L. lancerottensis. While L. kunkelii maintains low levels of variation, presumably as a consequence of prolonged inbreeding due to very low population size and sharp geographic isolation, the other two taxa have much higher indicators of polymorphism than those reported for other oceanic island endemics. Lotus arinagensis has the highest genetic polymorphism and the lowest interpopulation differentiation, presumably because of its considerable antiquity and habitat stability, despite recent fragmentation. The high interpopulation differentiation in L. lancerottensis is attributed to the Atlantic acting as a barrier, reducing gene flow within islands. Evolutionary analysis of the allozyme evidence indicates that L. kunkelii is genetically closer to L. arinagensis than to L. lancerottensis, thereby dispelling the taxonomic uncertainty and supporting L. kunkelii as a distinct species, warranting legal protection in the forthcoming catalog of threatened Canarian species.

Comparative Micromorphology of Petals in Macaronesian Lotus (Leguminosae) Reveals a Loss of Papillose Conical Cells during the Evolution of Bird Pollination

Bird pollination has evolved in four species of Macaronesian Lotus from a bee-pollinated ancestor. The transition is associated with the modification of several floral traits, including flower color and size, relative size and orientation of the petals, and nectar composition and quantity. Here, we examine petal surface micromorphology in relation to pollination type, using SEM and LM. In the bee-pollinated Lotus (the majority of the genus), papillose conical cells (PCS) are the most abundant epidermal type on dorsal and lateral petals. However, bird-pollinated species completely lack PCS on their dorsal petals and have only a small patch of PCS in a highly localized region of the lateral petal. In the bee-pollinated species (including those most closely related to the bird-pollinated species), PCS develop early in floral development. In contrast, the small amount of residual PCS in bird-pollinated species forms later in development, after the other two major epidermal types have been formed. The almost complete elimination of PCS during the shift of pollination syndrome from bee to birds may be adaptively driven as a both probird and antibee trait.