Can morphotaxa be assessed with photographs? Estimating the accuracy of two-dimensional cranial geometric morphometrics for the study of threatened populations of African monkeys

The classification of most mammalian orders and families is under debate and the number of species is likely greater than currently recognized. Improving taxonomic knowledge is crucial, as biodiversity is in rapid decline. Morphology is a source of taxonomic knowledge, and geometric morphometrics applied to two dimensional (2D) photographs of anatomical structures is commonly employed for quantifying differences within and among lineages. Photographs are informative, easy to obtain, and low cost. 2D analyses, however, introduce a large source of measurement error when applied to crania and other highly three dimensional (3D) structures. To explore the potential of 2D analyses for assessing taxonomic diversity, we use patas monkeys (Erythrocebus), a genus of large, semi-terrestrial, African guenons, as a case study. By applying a range of tests to compare ventral views of adult crania measured both in 2D and 3D, we show that, despite inaccuracies accounting for up to one-fourth of individual shape differences, results in 2D almost perfectly mirror those in 3D. This apparent paradox might be explained by the small strength of covariation in the component of shape variance related to measurement error. A rigorous standardization of photographic settings and the choice of almost coplanar landmarks are likely to further improve the correspondence of 2D to 3D shapes. 2D geometric morphometrics is, thus, appropriate for taxonomic comparisons of patas ventral crania. Although it is too early to generalize, our results corroborate similar findings from previous research in mammals, and suggest that 2D shape analyses are an effective heuristic tool for morphological investigation of small differences

Self-limitation as an explanation for species\u27 relative abundances and the long-term persistence of rare species

Much of ecological theory describes species interactions. These interactions often play an important theoretical role in facilitating coexistence. In particular, rarity in ecological communities, though often observed, provides a significant challenge to theoretical and empirical ecologists alike. I use a plant community model to simulate the effect of stronger negative frequency dependence on the long-term persistence of the rare species in a simulated community. This strong self-limitation produces long persistence times for the rare competitor, which otherwise succumb quickly to stochastic extinction. The results suggest that the mechanism causing species to be rare in this case is the same mechanism allowing those species to persist. To determine if ecological communities generally show the theoretical pattern, I estimate the strength of frequency-dependent population dynamics using species abundance data from 90 communities across a broad range of environments and taxonomic groups. In approximately half of the analyzed communities, rare species showed disproportionately strong negative frequency dependence. In particular, a pattern of increasing frequency dependence with decreasing relative abundance was seen in these communities, signaling the importance of this mechanism for rare species specifically. Insight into the special population dynamics of rare species will inform conservation efforts in response to climate change and other disturbance. Further difficulties in the detection of theoretical patterns in ecological data may be a result of the ecological currency used. Though ecologists typically use abundance data to test theories, energy use is another ecological currency that may be more relevant in some cases. In particular when detecting patterns that are a result of species interactions, the currency used should be the one in which those interactions actually operate. I compare the results of using abundance and energy use to detect two processes with well-defined expectations. The first is a description of population dynamics, the above described relationship between relative abundance and self-limitation. The second, compensatory dynamics, is a description of community-level dynamics. I find that the currency used alters the results, and thus the species-level implications. It does not, however, alter the overall pattern that would have theoretical implications. Results in both currencies support the pattern of strong self-limitation for persistent rare species

Determinantes ecológicos da diversidade beta de árvores em florestas atlânticas no sul do Brasil

Abordagens integrativas considerando diferentes dimensões da diversidade (p.ex., taxonômica, funcional, ou filogenética) cada vez mais estão sendo utilizadas para (1) avançar o nosso conhecimento sobre os mecanismos que criam e mantém a biodiversidade, e (2) elucidar a distribuição da biodiversidade tanto em áreas geográficas de interesse como dentro de áreas protegidas. De fato, entender como a biodiversidade se distribui no espaço e como ela é mantida ao longo do tempo é fundamental para embasar o planejamento de áreas protegidas e corredores ecológicos, assim como auxiliar no manejo de espécies invasoras, restauração de habitats degradados e manejo de ecossistemas. Nessa perspectiva, os objetivos centrais desta tese foram: (1) avaliar os mecanismos ecológicos e evolutivos, que potencialmente influenciam a diversidade beta taxonômica e filogenética de árvores nas florestas Atlânticas do sul do Brasil, e (2) avaliar como os componentes taxonômicos e filogenéticos se distribuem ao longo destas florestas, e como eles são representados dentro da rede regional de áreas protegidas. Para tal, utilizei modelagem de equações estruturais (capítulo 1) para testar a validade de uma rede de hipóteses ligando dados e teoria. No capítulo 1, avaliei a relação entre a diversidade beta taxonômica e filogenética, e como elas se relacionam com a riqueza de espécies, filtragem ambiental, espaço geográfico e estrutura filogenética (agrupamento filogenético). Nesse capítulo, concluí que a diversidade beta taxonômica é influenciada principalmente pelos gradientes altitudinais e climáticos, enquanto que a diversidade beta filogenética é determinada também pelo grau de agrupamento filogenético, em nível local, que provavelmente reflete o conservadorismo de nicho dentro das linhagens e distúrbio humano, que historicamente tem conduzido as florestas estudadas a um processo de homogeneização biótica. Em relação ao segundo objetivo, utilizei uma abordagem integrativa para predizer e mapear os componentes taxonômicos e filogenéticos da diversidade de árvores e, em seguida, avaliar a efetividade da rede de áreas protegidas em representar tais componentes nas florestas Atlânticas do sul Brasil. Nesse capítulo, concluí que as áreas protegidas são insuficientes para preservar adequadamente a biodiversidade de árvores nestas florestas. Sugeri que a expansão da rede em direção as áreas de alta singularidade taxonômica e filogenética, como definidas aqui, poderia aumentar, ao mesmo tempo, a representação da riqueza de espécies, da diversidade beta e da história evolutiva das espécies estudadas. Sugeri também que a inclusão de áreas de alta insubstituibilidade, em termos de história evolutiva, poderia ajudar a aumentar a proteção da diversidade de características e do potencial evolutivo das espécies.Integrative approaches considering different dimensions of biodiversity are increasingly being used in ecology and conservation to (1) advance our knowledge about the mechanisms underlying current patterns of biological diversity, and (2) elucidate the distribution of biodiversity in geographical areas of interest, and within the protected areas. Indeed, understanding how biodiversity is distributed in space and how it is maintained over time is critical to support the planning of protected areas and ecological corridors as well as assist the management of invasive species, the restoration of degraded areas and ecosystem management. In this perspective, the central goals of this thesis were: (1) to evaluate the ecological and evolutionary mechanisms that potentially influence the tree taxonomic and phylogenetic beta diversity in Atlantic forests located in southern Brazil, and (2) to evaluate how the taxonomic and phylogenetic diversity components are distributed across these forests, and how they are represented within the regional network of protected areas. For this, I used structural equation modeling (chapter 1) to test the validity of a network of hypotheses linking data and theory. In the chapter 1, I evaluate the relationship between taxonomic and phylogenetic beta diversity, and how they are related to species richness, environmental filtering, geographical space and phylogenetic structure (phylogenetic clustering). In this chapter, I conclude that taxonomic beta diversity (at the study scale) is mainly driven by the altitudinal and climatic gradients, while phylogenetic beta diversity is also determined by the degree of phylogenetic clustering at local level, more likely reflecting niche conservatism within lineages and human disturbance that has historically conducted the studied forests to a process of biotic homogenization. In relation to the second goal, I used an integrative approach to predict and map the taxonomic and phylogenetic components of tree diversity, and to assess the effectiveness of the protected areas network in representing these components in the Atlantic forests. In this chapter, I conclude that protected areas are insufficient to adequately preserve the tree biodiversity in these forests. I suggest that expanding the network towards the areas of taxonomic and phylogenetic uniqueness, as defined here, could increase the representation of species richness, beta diversity and evolutionary history of angiosperm trees at the same time. Furthermore, the inclusion of areas of high irreplaceability in terms of evolutionary history could help to improve the protection of feature diversity and evolutionary potential of species