To test the hypotheses that fruit-feeding nymphalid butterflies are randomly distributed in space and time, a community of fruit-feeding nymphalid butterflies was sampled at monthly intervals for one year by trapping 6690 individuals of 130 species in the canopy and understory of four forest habitats: primary, higraded, secondary, and edge. The overall species abundance distribution was well described by a lognormal distribution. Total species diversity (?-diversity) was partitioned into additive components within and among community subdivisions (a-diversity and 8-diversity) in vertical, horizontal and temporal dimensions. Although community subdivisions showed high similarity (1 -/l-diversity/y-diversity), significant 8-diversity existed in each dimension. Individual abundance and observed species richness was lower in the canopy than in the understory. However, rarefaction analysis and species accumulation curves revealed that canopy had higher species richness than understory. Observed species richness was roughly equal in all habitats, but individual abundance was much greater in edge, largely due to a.single, specialist species. Rarefaction analysis and species accumulation curves showed that edge had significantly lower species richness than all other habitats. Samples from a single habitat, height and time contained only a small fraction of the total community species richness. This study demonstrates the feasibility, and necessity, of large-scale, long-term sampling in multiple dimensions for accurately measuring species richness and diversity in tropical forest communities. We discuss the importance of such studies in conservation biology. 0 1997 The Linnean Swiety of London ADDITIONAL

Aim Differentiation of sites or communities is often measured by partitioning regional or gamma diversity into additive or multiplicative alpha and beta components. The beta component and the ratio of within-group to total diversity (alpha/gamma) are then used to infer the compositional differentiation or similarity of the sites. There is debate about the appropriate measures and partitioning formulas for this purpose. We test the main partitioning methods, using empirical and simulated data, to see if some of these methods lead to false conclusions, and we show how to resolve the problems that we uncover. Location South America, Ecuador, Orellana province, Rio Shiripuno. Methods We construct sets of real and simulated tropical butterfly communities that can be unambiguously ranked according to their degree of differentiation. We then test whether beta and similarity measures from the different partitioning approaches rank these datasets correctly. Results The ratio of within-group diversity to total diversity does not reflect compositional similarity, when the Gini-Simpson index or Shannon entropy are used to measure diversity. Additive beta diversity based on the Gini-Simpson index does not reflect the degree of differentiation between N sites or communities. Main conclusions The ratio of within-group to total diversity (alpha/gamma) should not be used to measure the compositional similarity of groups, if diversity is equated with Shannon entropy or the Gini-Simpson index. Conversion of these measures to effective number of species solves these problems. Additive Gini-Simpson beta diversity does not directly reflect the differentiation of N samples or communities. However, when properly transformed onto the unit interval so as to remove the dependence on alpha and N, additive and multiplicative beta measures yield identical normalized measures of relative similarity and differentiation

~ ~ ~To test the veracity of previous studies and illuminate major community patterns from an intact community, a guild of nymphalid butterflies was sampled at monthly intervals for five consecutive years by trapping in the canopy and understorey of five contiguous forest plots in the same rainforest. Significant numbers of species belonged to either the canopy or understorey fauna, confirming fundamental vertical stratification, and showing that sampling in one vertical position is a poor estimator of diversity. Significant monthly variation showed that intermittent or short-term sampling would underestimate diversity, and significant variation among years and areas showed that diversity was strongly influenced by sampling year. Even when the underlying communities were the same, temporal interactions strongly affected species diversity in both horizontal and vertical dimensions. An unprecedented seasonal inversion of species richness and abundance was detected between the canopy and understorey that occurred at the onset of all rainy seasons. This investigation suggests that long-term studies evaluating spatial and temporal patterns of species diversity among many sites may be required for a better understanding of tropical communities and how best t o conserve them.

Summary1. Flight is a key innovation in the evolution of insects that is crucial to their dispersal, migration, territoriality, courtship and predator avoidance. Male butterflies have characteristic territoriality and courtship flight behaviours, and females use a characteristic flight behaviour when searching for host plants. This implies that selection acts on wing morphology to maximize flight performance for conducting important behaviours among sexes. 2. Butterflies in the genus Morpho are obvious components of neotropical forests, and many observations indicate that they show two broad categories of flight behaviour and flight height. Although species can be categorized as using gliding or flapping flight, and flying at either canopy or understorey height, the association of flight behaviour and flight height with wing shape evolution has never been explored. 3. Two clades within Morpho differ in flight behaviour and height. Males and females of one clade inhabit the forest understorey and use flapping flight, whereas in the other clade, males use gliding flight at canopy level and females use flapping flight in both canopy and understorey. 4. We used independent contrasts to answer whether wing shape is associated with flight behaviour and height. Given a single switch to canopy habitation and gliding flight, we compared contrasts for the node at which the switch to canopy flight occurred with the distribution of values in the two focal clades. We found significant changes in wing shape at the transition to canopy flight only in males, and no change in size for either sex. A second node within the canopy clade suggests that other factors may also be involved in wing shape evolution. Our results reinforce the hypothesis that natural selection acts differently on male and female butterfly wing shape and indicate that the transition to canopy flight cannot explain all wing shape diversity in Morpho. 5. This study provides a starting point for characterizing evolution of wing morphology in forest butterflies in the contexts of habitat selection and flight behaviour. Further, these observations suggest that exploring wing shape evolution for canopy and understorey species in other insects may help understand the effects of habitat destruction on biological diversity.

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