Relationship of Hypochaeris salzmanniana (Asteraceae, Lactuceae), an endangered species of the Iberian Peninsula, to H. radicata and H. glabra and biogeographical implications

Hypochaeris salzmanniana DC. (Asteraceae, Lactuceae) is an endangered species on the Iberian Peninsula, known from only eight coastal populations. Most authors have treated it as a variety, subspecies or simply as a synonym of H. glabra L. On the basis of morphological and cytological characters, Talavera recently separated H. salzmanniana (2n = 8) from H. glabra (2n = 10). Material of H. salzmanniana, H. glabra and H. radicata was collected from Spain, Italy, Sicily and Tunisia in order to assess taxonomic status and population relationships. Amplified Fragment Length Polymorphism (AFLP) analysis revealed three well-differentiated species. A close relationship between H. salzmanniana and H. radicata is also confirmed by AFLP analysis and chromosome number (2n = 8), morphology, and rDNA localization (FISH, fluorescence in situ hybridization). Hypochaeris salzmanniana and H. radicata share three fixed diagnostic AFLP fragments out of 348 fragments scored. The population structure of H. salzmanniana reveals distinct groups in southern Spain that are separated geographically. High differentiation among a western (Conil to Zahara), an intermediate (Punta Paloma and Los Algarbes) and an eastern (Algeciras and La Línea) group may reflect ancient separation. Population sizes and genetic compatibility differ greatly among populations and can be used to explain levels of within-population genetic diversity, together with recent documented loss of habitats resulting from tourist developments. Population structures of H. radicata and H. glabra show a similar geographical patterning: strongly differentiated populations from the Betic Cordillera and from the Iberian Massif, which are separated at present by the Guadalquivir river. Geological events at the end of the Tertiary (Tortonian-Messinian Miocene) might help explain patterns of differentiation in these three species of sect. Hypochaeris.Austrian Science Foundation FWF P-15225Ministerio de Ciencia y Tecnología PB96-1352, REN2002-04634-C05-03, REN2002-04354-C02-0

Towards a glacial-sensitive model of island biogeography

Although the role that Pleistocene glacial cycles have played in shaping the present biota of oceanic islands world-wide has long been recognized, their geographical, biogeographical and ecological implications have not yet been fully incorporated within existing biogeographical models. Here we summarize the different types of impacts that glacial cycles may have had on oceanic islands, including cyclic changes in climate, shifts in marine currents and wind regimes and, especially, cycles of sea level change. The latter have affected geographical parameters such as island area, isolation and elevation. They have also influenced the configurations of archipelagos via island fusion and fission, and cycles of seamount emergence and submergence. We hypothesize that these sea level cycles have had significant impacts on the biogeographical processes shaping oceanic island biotas, influencing the rates and patterns of immigration and extinction and hence species richness. Here we provide a first step toward the development of a glacial-sensitive model of island biogeography, representing the tentative temporal evolution of those biogeographical parameters during the last glacial cycle. From this reasoning we attempt to derive predictions regarding the imprint of sea level cycles on genetic, demographic or biogeographical patterns within remote island biotas

Sertum polynesicum 3 : un Bidens (Asteraceae) nouveau de l'île de Nukuhiva (Marquises, Polynésie Française)

#Bidens teikiteetinii$ est décrit de la forêt hygrophile d'altitude de Nukuhiva (Marquises, Polynésie Française). Il apparaît avoir d'étroites affinités avec les espèces de Rapa (archipel des Australes), à 1500 km au Sud. (Résumé d'auteur

Allozyme Variation and Evolutionary Relationships among Three Species of Wahlenbergia (Campanulaceae) in the Juan Fernandez Islands

Pacheco, P. Departament of Botany, University of Talca, Talca, Chile.Enzyme electrophoresis was employed to measure variation within and divergence among three species of Wahlenbergia (W. berteroi, W. fernandeziana, and W. masafuerae) endemic to the Juan Fernandez Islands at gene loci encoding soluble enzymes. Two species, W. berteroi and W. fernandeziana, occur only on the older island of Masatierra while W. masafuerae is endemic to the younger island, Masafuera. A high genetic identity (.947) was calculated for W. berteroi and W. masafuerae, with both species monomorphic for the same allele at all loci except one, where the latter species has a novel allele. Wahlenbergia fernandeziana exhibits lowered identities (ca. .680-.770) with the other two species. This divergence results from W. berteroi and W. masafuerae having only a subset of the allelic variation detected in W. fernandeziana. That is, the former two species contain a limited extraction of the variation found in the latter. Isozyme data are concordant with morphological information in suggesting a close relationship between W. berteroi and W. masafuerae. The electrophoretic data also support the hypothesis, based on morphology and geographic distribution, that W. berteroi was derived from W. fernandeziana (or an ancestor of it) and that W. masafuerae evolved from W. berteroi following dispersal to Masafuera. Founder events associated with speciation probably account for the lowered variation in W. berteroi and W. masafuerae. In the present study, chromosome counts of n = 11 were determined for W. berteroi, the same number as previously reported for W. fernandeziana and W. masafuerae. Six new populational counts are also reported here for the latter species. Electrophoretic banding patterns suggest that the number of isozymes detected for several enzymes is greater than the expected minimal conserved number for diploid plants. This suggests either that the plants are diploid with extensive gene duplications or that they are polyploids

Radiation of the Hypochaeris apargioides complex (Asteraceae: Cichorieae) of southern South America

Penailillo, P (Penailillo, Patricio). Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Radiation into different environments is a common evolutionary phenomenon in plants. This process has been extensively documented in oceanic islands and to a lesser extent in continental areas. The genus Hypochaeris (Asteraceae: Cichorieae) contains 41 species in South America that have evolved during the past one million years. Dispersal of propagules to new regions followed by speciation at the diploid level into different ecological zones has resulted in radiated groups. One such group, the H. apargioides complex, consists of four closely related species, H. apargioides, H. gayana, H. spathulata, and H. thrincioides, all of which are distributed in central-south Chile and adjacent Argentina. Morphometric and molecular (AFLP) data were used to help reveal processes involved in the evolution of the complex. A total of 54 populations were sampled: 34 were analyzed morphometrically and 45 were examined for genetic variation and divergence using AFLP methodology. Morphometric analysis shows that two species, H. gayana and H. spathulata, are clearly separated phenotypically from the others, but that H. apargioides and H. thrincioides are more similar to each other. The principal environmental conditions influencing morphology and distribution of species in the H. apargioides complex appear to be salinity and elevation in H. spathulata and H. gayana, respectively, and climate in H. apargioides and H. thrincioides. The overall pattern in the evolution of the complex is one of subtle morphological divergence in response to environmental selection, perhaps reflecting initial stages of adaptive radiation. The low level of molecular divergence among species also suggests rapid speciation

Genetic variation (AFLPS and nuclear microsatellites) in two anagenetically derived endemic species of Myrceugenia (MYRTACEAE) on the Juan Fernandez Islands, Chile

Penailillo, P (Penailillo, Patricio). Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, ChilePremise of the study: Anagenesis (or phyletic evolution) is one mode of speciation that occurs in the evolution of plants on oceanic islands. Of two endemic species on the Juan Fernandez Islands (Chile), Myrceugenia fernandeziana and M. schulzei (Myrtaceae), believed to have originated anagenetically from different continental progenitors, the first is endemic to Robinson Crusoe Island and has no clear tie to continental relatives; the last is endemic to the younger island, Alejandro Selkirk Island, and has close affinity to M. colchaguensis in mainland Chile. Methods: Using AFLPs and six nuclear microsatellites from 381 individuals representing 33 populations, we determined patterns of genetic variation within and among populations on both islands and between those of the islands and mainland. Key results: Considerable genetic variation was found within populations on both islands. The level of gene diversity within M. schulzei was equivalent to that of its close continental relative M. colchaguensis. Genetic diversity was not partitioned geographically in M. fernandeziana and was weakly so and nonsignificantly in M. schulzei. Conclusions: The high genetic variation in both taxa is most likely due to anagenetic speciation. Subsidence of the older island Robinson Crusoe, landscape erosion, and restructuring of communities have severely reduced the overall island population to a single panmictic system. On the younger and less modified Alejandro Selkirk Island, slightly stronger patterns of genetic divergence are seen in M. schulzei. Because both species are genetically diverse and number in the thousands of individuals, neither is presently endangered in the archipelago