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trabalhos:abstracts [2021/12/08 00:44] jennifervasconcelosjdsv2 |
trabalhos:abstracts [2021/12/08 00:58] jennifervasconcelosjdsv2 |
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| **Abstract:** Niche and dispersal limitation are important coexistence mechanisms that can spatially structure tree communities. We aimed to verify the influence of environmental heterogeneity in the relative importance of those processes. We used data from ForestGEO plots with different environmental heterogeneity (Colombia-CO < Brazil-BR < Ecuador-EQ). We selected the most plausible of four concurrent spatial models: Randomness (CSR), Niche (NH), Dispersal Limitation (DL), and both (NH+DL). BR e EQ didn't diverge in the probability of model selection, having 85,6% and 83% of niche models selected (NH and NH+DL), while in CO only 57,5% were observed. The proportion of no model selected was four times higher in CO than in BR and EQ. We attribute these differences to CO's lesser environmental heterogeneity and conclude that it influences the relative importance of processes. Plots with a higher proportion of coexistence mechanisms are also significantly more diverse (BR and EQ > CO). | **Abstract:** Niche and dispersal limitation are important coexistence mechanisms that can spatially structure tree communities. We aimed to verify the influence of environmental heterogeneity in the relative importance of those processes. We used data from ForestGEO plots with different environmental heterogeneity (Colombia-CO < Brazil-BR < Ecuador-EQ). We selected the most plausible of four concurrent spatial models: Randomness (CSR), Niche (NH), Dispersal Limitation (DL), and both (NH+DL). BR e EQ didn't diverge in the probability of model selection, having 85,6% and 83% of niche models selected (NH and NH+DL), while in CO only 57,5% were observed. The proportion of no model selected was four times higher in CO than in BR and EQ. We attribute these differences to CO's lesser environmental heterogeneity and conclude that it influences the relative importance of processes. Plots with a higher proportion of coexistence mechanisms are also significantly more diverse (BR and EQ > CO). | ||
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| + | === ROSA, Matheus Guthierris Bitencourt === | ||
| + | |||
| + | **Phylogenetic structure of seedling communities in Restinga forests with different environmental conditions** | ||
| + | |||
| + | **Abstract:** Ecological communities often differ in species richness, composition and abundance, | ||
| + | reflecting different assembly processes. Niche-determined processes and neutral | ||
| + | processes may interact in the role of structuring different communities. Assessing the | ||
| + | phylogenetic structure of communities should allow us to infer niche-related | ||
| + | processes with respect to neutral processes, if the phylogenetic distances between | ||
| + | co-ocurring species reflects niche differences. On one hand, if species tolerance to | ||
| + | abiotic conditions are phyllogenetically conserved, intense environmental filtering is | ||
| + | expected to promote community assemblages more phyllogenetically related than | ||
| + | chance. On the other hand, negative interactions between neighbouring species can | ||
| + | limit niche similarity in local assembly, if species interactions, such as competition for | ||
| + | limited resources, is stronger between species that share the niche of a common | ||
| + | ancestor. In the stage of seedlings, competition may not be able to impose a non- | ||
| + | random signal on the phylogenetic structure of the entire habitat, but it may drive the | ||
| + | assembly of local neighbourhoods. We therefore intend to infer the relative | ||
| + | importance of different assembly processes by comparing the phylogenetic structure | ||
| + | of seedlings communities in different Restinga forest physiognomies from the Parque | ||
| + | Estadual da Ilha do Cardoso (Restinga Alta Alagada - RAA, Restinga Alta Drenada - | ||
| + | RAD e Restinga Baixa – RB), at the scale of the entire habitat and the scale of local | ||
| + | neighbourhoods. We describe phylogenetic structure of the entire habitat and local | ||
| + | neighborhoods by calculating the mean pairwise phylogenetic distances between co- | ||
| + | occuring species, both weighted and unweighted by species abundances. At the | ||
| + | scale of the entire habitat, we ask if species composition at each forest type differs | ||
| + | from null expectations, we test this by comparing the observed MPD value for each | ||
| + | Restinga forest with a null distribution of communities generated by drawing species | ||
| + | by chance from an adult tree species pool. We found that different Restinga forests | ||
| + | show random phylogenetic structure at this scale. And, at the scale of local | ||
| + | neighbourhoods, we ask if the distribution of MPD per triad differs between Restinga | ||
| + | forests physiognomies, by comparing the F statistics from a simple Analysis of | ||
| + | Variance with the distribution of F generated by permutations of MPD between | ||
| + | habitats. We then conducted a post-hoc test to evaluate the absolute differences | ||
| + | between groups of neighbourhoods in different Restinga forest types. We found that | ||
| + | the distribution of MPD per triad in Restinga Baixa differs from the distribution of both | ||
| + | Restinga Alta forests, but the Restinga Alta Alagada (flooded habitat) and Restinga | ||
| + | Alta Drenada (drained habitat) don’t differ from each other. Our results therefore | ||
| + | suggest that neutral processes are more important than niche processes to | ||
| + | determine the assembly of seedlings communities at the entire habitat scale, | ||
| + | however, niche-related processes, such as habitat filtering and competition may have | ||
| + | a secondary role by determining local differences in the phylogenetic structure of | ||
| + | neighbouring species. | ||
| === PEREIRA, Thiago === | === PEREIRA, Thiago === | ||
trabalhos/abstracts.txt · Última modificação: 2021/12/08 01:28 por jennifervasconcelosjdsv2
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