RESUMO

The effects of Pleistocene glaciations and geographical barriers on the phylogeographic patterns of lowland plant species in Mediterranean-climate areas of Central Chile are poorly understood. We used Dioscorea humilis (Dioscoreaceae), a dioecious geophyte extending 530 km from the Valparaíso to the Bío-Bío Regions, as a case study to disentangle the spatio-temporal evolution of populations in conjunction with latitudinal environmental changes since the Last Inter-Glacial (LIG) to the present. We used nuclear microsatellite loci, chloroplast (cpDNA) sequences and environmental niche modelling (ENM) to construct current and past scenarios from bioclimatic and geographical variables and to infer the evolutionary history of the taxa. We found strong genetic differentiation at nuclear microsatellite loci between the two subspecies of D. humilis, probably predating the LIG. Bayesian analyses of population structure revealed strong genetic differentiation of the widespread D. humilis subsp. humilis into northern and southern population groups, separated by the Maipo river. ENM revealed that the ecological niche differentiation of both groups have been maintained up to present times although their respective geographical distributions apparently fluctuated in concert with the climatic oscillations of the Last Glacial Maximum (LGM) and the Holocene. Genetic data revealed signatures of eastern and western postglacial expansion of the northern populations from the central Chilean depression, whereas the southern ones experienced a rapid southward expansion after the LGM. This study describes the complex evolutionary histories of lowland Mediterranean Chilean plants mediated by the summed effects of spatial isolation caused by riverine geographical barriers and the climatic changes of the Quaternary.

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RESUMO

The moss Entosthodon hungaricus (Boros) Loeske is an European endemic species typical of dry and saline soils extending from the Iberian Peninsula to Aral-Caspian steppes, similarly to some other xerothermic bryophytes. However, the distribution range is fragmented and localities are quite scattered and the species is considered as rare and vulnerable because of its ephemeral characteristics and specialized ecology. With the aim to develop an active protection plan for this species, the ex situ conservation requirements of E. hungaricus were developed. The axenic culture in in vitro conditions were established, and the optimal growth parameters were adjusted to achieve fully developed gametophytes ready to be reintroduced to its native range and other potentially native areas, where this species was once reported but has not been collected in recent times, suggesting its local extinction (i.e. some areas in Vojvodina, N. Serbia). Starting materials were derived from recent herbarium specimens and from fresh materials collected from Hungarian populations. Several means for sterilization of stating material and growing nutritive media were assayed in different regimes of light and temperature. Here we describe the conditions to achieve full plant development and for its micropropagation. Such materials are adequate for ex situ conservation purposes and for experimental introductions in native and potentially native areas. The first axenical culture of E. hungaricus was successfully established, and the first in vitro micropropagation of this rare and endangered species was achieved. Our study contributes to the conservation biology as well as for the potential use of this moss species in biotechnological research.

O musgo Entosthodon hungaricus (Boros) Loeske é uma espécie endêmica Européia típica de solos secos e salinos que se estendem da Península Ibérica até as estepes Aral-Cáspias, similar a outras briófitas de clima seco. Entretanto, a distribuição é bastante dispersa e fragmentada e a espécie é considerada muito rara e vulnerável devido às suas características efêmeras e ecologia especializada. Com o intuito de desenvolver um plano de proteção a essa espécie, foram elaborados os requisitos de preservação ex situ das E. hungaricus. As condições para a cultura axênica in vitro foram estabelecidas e os parâmetros ideais de crescimento foram atingidos para conseguir gametófitos completamente desenvolvidos, prontos para serem reintroduzidos em suas áreas nativas e em outras áreas potencialmente nativas, onde essa espécie já foi relatada. Porém, não houve coleta da mesma nos últimos anos, o que sugere uma extinção local (por exemplo, algumas áreas em Voivodina, Norte da Sérvia). Os materiais iniciais foram derivados de espécies recentes de herbários e de materiais frescos coletados de populações Húngaras. Várias formas de assepsia do material inicial e dos meios de crescimento nutritivo foram ensaiadas em diferentes regimes de luz e temperatura. No trabalho descrevemos as condições para obter desenvolvimento completo da planta e sua micropropagação. Os materiais são adequados para os fins de conservação ex situ e para as introduções experimentais em áreas nativas e/ou potencialmente nativas. O estudo contribui para a conservação biológica bem como para o potencial uso dessa espécie de musgo em pesquisas biotecnológicas.

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Divergence times and biogeographical analyses have been conducted within the Loliinae, one of the largest subtribes of temperate grasses. New sequence data from representatives of the almost unexplored New World, New Zealand, and Eastern Asian centres were added to those of the panMediterranean region and used to reconstruct the phylogeny of the group and to calculate the times of lineage-splitting using Bayesian approaches. The traditional separation between broad-leaved and fine-leaved Festuca species was still maintained, though several new broad-leaved lineages fell within the fine-leaved clade or were placed in an unsupported intermediate position. A strong biogeographical signal was detected for several Asian-American, American, Neozeylandic, and Macaronesian clades with different affinities to both the broad and the fine-leaved Festuca. Bayesian estimates of divergence and dispersal-vicariance analyses indicate that the broad-leaved and fine-leaved Loliinae likely originated in the Miocene (13My) in the panMediterranean-SW Asian region and then expanded towards C and E Asia from where they colonized the New World. Further expansions in America (10-3.8My) showed a predominant migratory route from North to South (N America<-->the Andes<-->Patagonia). This late Tertiary scenario of successive colonizations and secondary polyploid radiations in the southern hemisphere from the northern hemisphere was accompanied by occasional transcontinental long-distance dispersal events between South America and New Zealand. Multiple Pliocene dispersal events (3.6-2.5My) from the near SW European and NW African continents gave rise to the Macaronesian Loliinae flora, while a more recent Pleistocene origin (2-1My) is hypothesized for the high polyploid lineages that successfully colonized newly deglaciated areas in both hemispheres.

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