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Sarkinen T.,Royal Botanic Garden Edinburgh | Sarkinen T.,University of Oxford | Sarkinen T.,Natural History Museum in London | Pennington R.T.,Royal Botanic Garden Edinburgh | And 4 more authors.
Journal of Biogeography | Year: 2012

Aim The tropical Andes are a world biodiversity hotspot. With diverse biomes and dramatic, geologically recent mountain uplift, they offer a system to study the relative contributions of geological and biome history to species richness. There are preliminary indications that historical species assembly in the Andes has been influenced by physiographical heterogeneity and that distinct biomes have evolved in relative isolation despite physical proximity. Here we test this 'Andean biotic separation hypothesis' by focusing on the low-elevation, seasonally dry tropical forest (SDTF) biome to determine whether patterns of plant diversification within the SDTF differ from those in mid- and high-elevation biomes. Location Tropical Andes, South America. Methods Densely sampled time-calibrated phylogenies for five legume genera (Amicia, Coursetia, Cyathostegia, Mimosa and Poissonia) containing species endemic to the Andean SDTF biome were used to investigate divergence times and levels of geographical structure. Geographical structure was measured using isolation-by-distance methods. Meta-analysis of time-calibrated phylogenies of Andean plant groups was used to compare the pattern and tempo of endemic species diversification between the major Andean biomes. Results Long-term persistence of SDTF in the Andes is suggested by old stem ages (5-27Ma) of endemic genera/clades within genera, and deep divergences coupled with strong geographical structure among and within species. Comparison of species diversification patterns among different biomes shows that the relatively old, geographically confined pattern of species diversification in SDTF contrasts with the high-elevation grasslands that show rapid and recent radiations driven by ecological opportunities. Main conclusions The SDTF biome has a long history in the Andes. We suggest that the diverse SDTF flora has been assembled gradually over the past c.19Ma from lineages exhibiting strong phylogenetic niche conservatism. These patterns suggest that Andean SDTFs have formed stable and strongly isolated 'islands' despite the upheavals of Andean uplift. Indeed, the Andean SDTFs may represent some of the most isolated and evolutionarily persistent continental plant communities, similar in many respects to floras of remote oceanic islands. © 2011 Blackwell Publishing Ltd.

Sarkinen T.,Natural History Museum in London | Iganci J.R.V.,Federal University of Rio Grande do Sul | Linares-Palomino R.,Agrarian National University | Simon M.F.,Embrapa Recursos Geneticos e Biotechnologia | Prado D.E.,National University of Rosario
BMC Ecology | Year: 2011

Background: South America is one of the most species diverse continents in the world. Within South America diversity is not distributed evenly at both local and continental scales and this has led to the recognition of various areas with unique species assemblages. Several schemes currently exist which divide the continental-level diversity into large species assemblages referred to as biomes. Here we review five currently available biome maps for South America, including the WWF Ecoregions, the Americas basemap, the Land Cover Map of South America, Morrone's Biogeographic regions of Latin America, and the Ecological Systems Map. The comparison is performed through a case study on the Seasonally Dry Tropical Forest (SDTF) biome using herbarium data of habitat specialist species.Results: Current biome maps of South America perform poorly in depicting SDTF distribution. The poor performance of the maps can be attributed to two main factors: (1) poor spatial resolution, and (2) poor biome delimitation. Poor spatial resolution strongly limits the use of some of the maps in GIS applications, especially for areas with heterogeneous landscape such as the Andes. Whilst the Land Cover Map did not suffer from poor spatial resolution, it showed poor delimitation of biomes. The results highlight that delimiting structurally heterogeneous vegetation is difficult based on remote sensed data alone. A new refined working map of South American SDTF biome is proposed, derived using the Biome Distribution Modelling (BDM) approach where georeferenced herbarium data is used in conjunction with bioclimatic data.Conclusions: Georeferenced specimen data play potentially an important role in biome mapping. Our study shows that herbarium data could be used as a way of ground-truthing biome maps in silico. The results also illustrate that herbarium data can be used to model vegetation maps through predictive modelling. The BDM approach is a promising new method in biome mapping, and could be particularly useful for mapping poorly known, fragmented, or degraded vegetation. We wish to highlight that biome delimitation is not an exact science, and that transparency is needed on how biomes are used as study units in macroevolutionary and ecological research. © 2011 Särkinen et al; licensee BioMed Central Ltd.

Baldoni A.B.,Embrapa Recursos Geneticos e Biotechnologia | Baldoni A.B.,University of Brasilia | Araujo A.C.G.,Embrapa Recursos Geneticos e Biotechnologia | de Carvalho M.H.,Embrapa Recursos Geneticos e Biotechnologia | And 3 more authors.
International Journal of Plant Biology | Year: 2010

Ricin is a dimeric glycoprotein that accumulates in protein storage vacuoles of endosperm cells of Ricinus communis L. (castor bean). The proricin travels through the Golgi appar-atus and co-localizes throughout its route to the storage vacuoles of developing castor bean endosperm. We report here the pattern of seed morphological and ultrastructural changes during various stages of seed development, associated with ricin accumulation. ELISA was used to compare the ricin content in mature seeds of four Brazilian commercial cultivars. ELISA and immunoelectron microscopy anal-ysis were used to study ricin accumulation during seed development from 10 to 60 days after pollination (DAP). Results have shown that no ricin could be localized in the endosperm cells in the early development stages (before 20 DAP) and only a few localization points could be observed at 30 DAP. However, a significant ricin localization signal was observed at 40 DAP in the matrix of the protein storage vacuoles. The signal increased significantly from 50 to 60 DAP, when ricin was observed in both the matrix and crystalloids of the protein storage vacuoles. Understanding ricin expression at the cellular level is fundamental for the development of strategies for gene suppression using molecular breeding approaches. © A.B. Baldoni et al., 2010.

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