RESUMO

Spatial patterns of phylogenetic diversity (PD) are increasingly becoming relevant for conservation decisions. PD measures are based on phylogenies estimated from molecular data. This paper addresses the question of how different molecular markers impact PD spatial patterns. We first conducted a simple simulation to explore the effect of deep and shallow changes in topology (simulating variations in molecular markers), using ultrametric and non-ultrametric trees, and then used a dataset of Chilean flora with four sets of markers to assess potential differences in spatial patterns of PD ranks using different markers and types of trees. The simulation consistently showed that the difference in PD rank was lower for ultrametric trees than for phylograms. A similar trend was observed using the Chilean flora dataset, with among-markers variability in spatial patterns of the PD metrics lower for ultrametric than for non-ultrametric trees, depicted as top 2.5 and 5% hotspots. Frequency distribution of PD values differed among markers as well, with this variation less apparent for ultrametric trees. We conclude that the choice of markers impacts spatial patterns of PD, and these results vary more strongly for phylograms, suggesting that ultrametric trees are more robust to the choice of marker.

Assuntos

RESUMO

A national-scale study of outcrossing potential within Chilean vascular flora was conducted using an upgraded algorithm, which adds parameters such as pollinator agents, climate, and geographic conditions. Datasets were organized and linked in a Web platform (www.flujogenico.cl), in which the development of a total outcrossing potential (TOP) predictor was formulated. The TOP predictor is the engine in the Web platform, which models the effect of a type of agricultural practice on others (coexistence calculation mode) and on the environment (biodiversity calculation mode). The scale for TOP results uses quintiles in order to define outcrossing potential between species as "very low," "low," "medium," "high," or "very high." In a coexistence analysis considering 256 species (207 genera), the 10 highest TOP values were for genera Citrus, Prunus, Trifolium, Brassica, Allium, Eucalyptus, Cucurbita, Solanum, Lollium, and Lotus. The highest TOP for species in this analysis fell at "high" potential, 4.9% of the determined values. In biodiversity mode, seven out of 256 cultivated species (2.7%) were native, and 249 (97.3%) corresponded to introduced species. The highest TOP was obtained in the genera Senecio, Calceolaria, Viola, Solanum, Poa, Alstroemeria, Valeriana, Vicia, Atriplex, and Campanula, showing "high" potential in 4.9% of the values. On the other hand, 137 genetically modified species, including the commercial and pre-commercial developments, were included and represented 100 genera. Among these, 22 genera had relatives (i.e., members of the same genus) in the native/introduced group. The genera with the highest number of native/introduced relatives ranged from one (Ipomea, Limonium, Carica, Potentilla, Lotus, Castanea, and Daucus) to 66 species (Solanum). The highest TOP was obtained when the same species were coincident in both groups, such as for Carica chilensis, Prosopis tamarugo, and Solanum tuberosum. Results are discussed from the perspective of assessing the possible impact of cultivated species on Chilean flora biodiversity. The TOP predictor (http://epc.agroinformatica.cl/) is useful in the context of environmental risk assessment.

RESUMO

Current geographic patterns of biodiversity are a consequence of the evolutionary history of the lineages that comprise them. This study was aimed at exploring how evolutionary features of the vascular flora of Chile are distributed across the landscape. Using a phylogeny at the genus level for 87% of the Chilean vascular flora, and a geographic database of sample localities, we calculated phylogenetic diversity (PD), phylogenetic endemism (PE), relative PD (RPD), and relative PE (RPE). Categorical Analyses of Neo- and Paleo-Endemism (CANAPE) were also performed, using a spatial randomization to assess statistical significance. A cluster analysis using range-weighted phylogenetic turnover was used to compare among grid cells, and with known Chilean bioclimates. PD patterns were concordant with known centers of high taxon richness and the Chilean biodiversity hotspot. In addition, several other interesting areas of concentration of evolutionary history were revealed as potential conservation targets. The south of the country shows areas of significantly high RPD and a concentration of paleo-endemism, and the north shows areas of significantly low PD and RPD, and a concentration of neo-endemism. Range-weighted phylogenetic turnover shows high congruence with the main macrobioclimates of Chile. Even though the study was done at the genus level, the outcome provides an accurate outline of phylogenetic patterns that can be filled in as more fine-scaled information becomes available.

Assuntos

RESUMO

The potential impact of genetically modified (GM) crops on biodiversity is one of the main concerns in an environmental risk assessment (ERA). The likelihood of outcrossing and pollen-mediated gene flow from GM crops and non-GM crops are explained by the same principles and depend primarily on the biology of the species. We conducted a national-scale study of the likelihood of outcrossing between 11 GM crops and vascular plants in Chile by use of a systematized database that included cultivated, introduced and native plant species in Chile. The database included geographical distributions and key biological and agronomical characteristics for 3505 introduced, 4993 native and 257 cultivated (of which 11 were native and 246 were introduced) plant species. Out of the considered GM crops (cotton, soya bean, maize, grape, wheat, rice, sugar beet, alfalfa, canola, tomato and potato), only potato and tomato presented native relatives (66 species total). Introduced relative species showed that three GM groups were formed having: a) up to one introduced relative (cotton and soya bean), b) up to two (rice, grape, maize and wheat) and c) from two to seven (sugar beet, alfalfa, canola, tomato and potato). In particular, GM crops presenting introduced noncultivated relative species were canola (1 relative species), alfalfa (up to 4), rice (1), tomato (up to 2) and potato (up to 2). The outcrossing potential between species [OP; scaled from 'very low' (1) to 'very high' (5)] was developed, showing medium OPs (3) for GM-native relative interactions when they occurred, low (2) for GMs and introduced noncultivated and high (4) for the grape-Vitis vinifera GM-introduced cultivated interaction. This analytical tool might be useful for future ERA for unconfined GM crop release in Chile.

Assuntos