Modeling body size evolution in Felidae under alternative phylogenetic hypotheses

The use of phylogenetic comparative methods in ecological research has advanced during the last twenty years, mainly due to accurate phylogenetic reconstructions based on molecular data and computational and statistical advances. We used phylogenetic correlograms and phylogenetic eigenvector regression (PVR) to model body size evolution in 35 worldwide Felidae (Mammalia, Carnivora) species using two alternative phylogenies and published body size data. The purpose was not to contrast the phylogenetic hypotheses but to evaluate how analyses of body size evolution patterns can be affected by the phylogeny used for comparative analyses (CA). Both phylogenies produced a strong phylogenetic pattern, with closely related species having similar body sizes and the similarity decreasing with increasing distances in time. The PVR explained 65% to 67% of body size variation and all Moran's I values for the PVR residuals were non-significant, indicating that both these models explained phylogenetic structures in trait variation. Even though our results did not suggest that any phylogeny can be used for CA with the same power, or that “good” phylogenies are unnecessary for the correct interpretation of the evolutionary dynamics of ecological, biogeographical, physiological or behavioral patterns, it does suggest that developments in CA can, and indeed should, proceed without waiting for perfect and fully resolved phylogenies

Plantas vasculares da região do Parque Estadual Cristalino, norte de Mato Grosso, Brasil

Os resultados do primeiro inventário botânico detalhado da região do Parque Estadual Cristalino, Mato Grosso, Brasil, são apresentados, incluindo uma lista de espécies. Um total de 1366 espécies de plantas vasculares distribuídas em 626 gêneros e 151 famílias foram registradas. As famílias com maior número de espécies foram Leguminosae, Rubiaceae, Melastomataceae, Malvaceae sensu lato e Moraceae. A flora inclui pelo menos sete novas espécies e diversos endemismos da região da Serra do Cachimbo, assim como muitos registros novos para o estado e alguns novos para o Brasil. Mais estudos provavelmente irão incrementar o número de espécies de forma significativa. Apesar da região apresentar uma diversidade alfa relativamente baixa em comparação a outras regiões já estudadas na Amazônia, a sua grande heterogeneidade de fitofisionomias é refletida numa elevada diversidade beta. Levando em conta esta riqueza biológica, situação importante mas ainda pouco estudada da margem ecotonal da Amazônia meridional, e sua posição estratégica com relação ao avanço sul-norte do deflorestamento, a região do Cristalino ocupa alta prioridade em termos de conservação.The results of the first detailed botanical inventory in the region of the Cristalino State Park, Mato Grosso, Brazil, are presented, including an annotated checklist. A total of 1366 species of vascular plants, representing 626 genera and 151 families, were recorded. The most species-diverse families included Leguminosae, Rubiaceae, Melastomataceae, Malvaceae (sens. lat.) and Moraceae. The flora includes at least seven new species and several endemics from the Serra do Cachimbo, as well as many new records for the State of Mato Grosso and several for Brazil. Further studies are likely to increase the number of species significantly. The region does not show high alpha-diversity by Amazonian standards but is ecologically diverse, resulting in high levels of beta-diversity. Considering this biological richness, its situation within the important yet relatively poorly studied ecotone of the Amazonian margin, and its strategic position at the advancing frontier of deforestation pushing northwards into the basin, Cristalino is a high priority for conservation

A new method of growth analysis for plants that experience periodic losses of leaf mass

1. A new method (the iterative approach) is presented by which growth analyses can be conducted on plants that have been subjected to significant losses in biomass and leaf area between harvests. The method is particularly useful to analyse the effects of defoliation on growth and biomass allocation. 2. Values for the following parameters can be estimated: absolute growth rate (g day-1), relative growth rate (RGR, g g-1 day-1), net assimilation rate (NAR, g m-2 day-1), leaf area ratio (LAR, m2 g-1), fraction of newly assimilated mass that is allocated to leaf lamina production (flam, g g-1), and daily fractional change in the average specific leaf area of plants (ρ, day-1). These parameters are determined by means of iterations. We defined a number of growth functions, and the values of NAR, flam and the SLA of newly produced leaves were changed until these functions correctly predicted the measured total plant mass, leaf lamina mass and leaf area at the end of the growth period. This avoids having to assume a constant relationship between leaf area and biomass (as in the 'classical' approach), and it avoids the use of polynomial functions to fit growth data (as in the 'functional' approach) that are unsuitable for fitting data sets exhibiting discontinuities such as abrupt changes in biomass. 3. The method was applied to a greenhouse experiment in which we analysed the effects of sustained defoliation on growth and biomass allocation in a tropical understorey palm, Chamaedorea elegans Mart. 4. We showed that C. elegans plants respond to defoliation with a considerable increase in the allocation of new assimilates to lamina growth (flam) and that, despite the repeated loss of leaf area and associated reductions in LAR, they had RGR values that were similar to those of undamaged plants.</p

Canopy-level photosynthetic compensation after defoliation in a tropical understorey palm

1. Increases in photosynthesis of leaves remaining after defoliation may result from shifts in leaf photosynthetic characteristics or from an improved light penetration in the canopy. However, few studies have tried to estimate the relative contribution of these factors to mitigating the negative effects of defoliation. We present a quantitative framework for such an analysis. 2. In a field and greenhouse experiment, plants of the rain forest understorey palm Chamaedorea elegans were subjected to three levels of defoliation (0, 50 or 66% of leaves removed) and, in the greenhouse, grown at two irradiances (5 or 16% of daylight, 'low light' and 'high light' hereafter). For each plant, leaf photosynthesis and light penetration in the canopy were measured and these data were used to calculate whole-canopy carbon gain. 3. Defoliation significantly increased the light available to the remaining leaves. In the field and in the 'high-light' greenhouse plants, defoliation also resulted in an increase in the light-saturated photosynthesis per unit leaf area (Pmax), although in the 'low-light' plants this was not the case. 4. A sensitivity analysis revealed that in the 'low-light' plants, a proportional increase in leaf Pmax did not result in increased canopy-level carbon gain, while in the 'high-light' and field plants, it did. This suggests that the lack of plasticity in Pmax in response to defoliation, at low light, may be the appropriate pattern to maximize carbon gain. 5. Defoliated plants had 10-18% more average photosynthesis per unit leaf area (Parea) than the control plants, and this increase was mostly the result of an improved light penetration in the canopy. 6. A relatively small fraction (5-30%) of the total estimated loss in canopy carbon gain caused by the removal of leaves was compensated for by an increase in Parea. This suggests that in rain forest understorey plants, an increase in diurnal photosynthesis of remaining leaves has limited potential for mitigating the negative effects of defoliation.</p