Linking ecomechanical models and functional traits to understand phenotypic diversity.

Physical principles and laws determine the set of possible organismal phenotypes. Constraints arising from development, the environment, and evolutionary history then yield workable, integrated phenotypes. We propose a theoretical and practical framework that considers the role of changing environments. This 'ecomechanical approach' integrates functional organismal traits with the ecological variables. This approach informs our ability to predict species shifts in survival and distribution and provides critical insights into phenotypic diversity. We outline how to use the ecomechanical paradigm using drag-induced bending in trees as an example. Our approach can be incorporated into existing research and help build interdisciplinary bridges. Finally, we identify key factors needed for mass data collection, analysis, and the dissemination of models relevant to this framework.

Individual asymmetry as a predictor of fitness in the bat Carollia perspicillata.

The measurement of fitness in wild populations is a challenging task, and a number of proxies have been proposed with different degrees of success. Developmental instability/stability (DI) is an organismal property associated with variance in bilateral asymmetry (fluctuating asymmetry-FA) and a correlated effect on fitness. This study provides evidence to corroborate the hypothesis that asymmetry partly reflects DI and is correlated with a reduction in fitness measured by survival and reproduction in bats. We studied two colonies of the bat Carollia perspicillata in southeastern Brazil over 5 years, marking and recapturing individuals. Gaussian mixture models for signed Forearm Asymmetry (ForA) distribution indicated that ~20% of asymmetry variation was due to DI heterogeneity among individuals. ForA, body condition (Scaled Mass Index-SMI) and Forearm Length (ForL) were used as predictors of survival probability in Cormack-Jolly-Seber models. Asymmetry was negatively associated with survival, whereas SMI and ForL were positively associated. The male C. perspicillata defend sites within the roost that are favoured by female harems, but there are mating opportunities for bachelor males, leading to both territorial disputes and sperm competition. As predicted by sexual selection, ForA was negatively associated with relative Testicle Length, a measure of reproductive potential. In females, ForA was negatively associated with the probability of two pregnancies (as opposed to one) in a given breeding season. The effect magnitudes and directions of associations suggest that asymmetry, even though not perfectly reflecting DI variation, is a useful predictor for fitness components in C. perspicillata.

Morphometrics and allometry of the larvae of five Characiformes species in the Paraíba do Sul River Basin.

The aim of this study was to analyse the morphology and allometry of larvae belonging to five potamodromous species. Five breeding species belonging to the order Characiformes [Salminus brasiliensis (Cuvier, 1816), Leporinus steindachneri, Eigenmann, 1907, Prochilodus lineatus (Valenciennes, 1837), Prochilodus vimboides (Kner,1859) and Brycon insignis, Steindachner, 1877] were used to obtain larvae samples during the pre-flexing, post-flexing, and juvenile developmental stages. When we observed the degree-hour (DH) amplitude time values, we found three developmental groups based on allometry and morphometrics within the period between the pre-flexing and post-flexing phases. Group 1 consists of the species S. brasiliensis and B. insignis, Group 2 consists of P. lineatus and P. vimboides, and Group 3 consists of L. steindachneri. Group 1 requires less development time and has more slender larvae. Group 2 has a moderate development time and larvae with a more rounded shape. Group 3 presents a greater development time and an intermediate larval morphology. It was possible to classify the larvae through cross-validated discriminant analyses based on seven morphometric variables with 90% accuracy in B. insignis, 83% in L. steindachneri, 91% in P. lineatus, 80% in P. vimboides, and 96% in S. brasiliensis. These results indicate larval characteristics that can be used for the taxonomic identification of the icthyoplankton.

Early development and allometric growth patterns of the grumatã (Prochilodus vimboides Kner, 1859).

The objective of this study was to characterize the early development and allometric growth of the grumatã (Prochilodus vimboides). We describe a sample of 266 eggs and larvae obtained through induced spawning. The eggs were spherical (mean 3.7 mm diameter), exhibited a yellow yolk and were non-adhesive and pelagic after fertilization and hydration. The time elapsed between the early cleavage and post-flexion stages was considered short (328 hours, 8054 hour-degrees) in regard to the development times of other Neotropical rheophilic species, but time to hatching was considerably longer than in other Prochilodus species. The most notable anatomical changes were observed between the end of the yolk larval stage and the beginning of the pre-flexion stage, when the larvae displayed directed swimming and the digestive system became functional, enabling the transition from endogenous to exogenous feeding. After hatching, the larvae grew from 6.04 to 15.15 mm in total length average. Two growth phases were observed at this stage: a non-linear asymptotic curve in yolk-sac larvae, and a linear constant-rate growth phase after exogenous feeding started. Allometric growth related to standard length was positive for head length, negative for eye diameter, and switched between phases from negative to positive in body depth and head height. Morphological development and allometric growth in different larval phases impose drastic anatomical and physiological changes that are synchronic with habitat changes and the flood cycles during the reproductive period.

Defense response in non-genomic model species: methyl jasmonate exposure reveals the passion fruit leaves' ability to assemble a cocktail of functionally diversified Kunitz-type trypsin inhibitors and recruit two of them against papain.

MAIN CONCLUSION: Multiplicity of protease inhibitors induced by predators may increase the understanding of a plant's intelligent behavior toward environmental challenges. Information about defense mechanisms of non-genomic model plant passion fruit (Passiflora edulis Sims) in response to predator attack is still limited. Here, via biochemical approaches, we showed its flexibility to build-up a broad repertoire of potent Kunitz-type trypsin inhibitors (KTIs) in response to methyl jasmonate. Seven inhibitors (20-25 kDa) were purified from exposed leaves by chromatographic techniques. Interestingly, the KTIs possessed truncated Kunitz motif in their N-terminus and some of them also presented non-consensus residues. Gelatin-Native-PAGE established multiple isoforms for each inhibitor. Significant differences regarding inhibitors' activity toward trypsin and chymotrypsin were observed, indicating functional polymorphism. Despite its rarity, two of them also inhibited papain, and such bifunctionality suggests a recruiting process onto another mechanistic class of target protease (cysteine-type). All inhibitors acted strongly on midgut proteases from sugarcane borer, Diatraea saccharalis (a lepidopteran insect) while in vivo assays supported their insecticide properties. Moreover, the bifunctional inhibitors displayed activity toward midgut proteases from cowpea weevil, Callosobruchus maculatus (a coleopteran insect). Unexpectedly, all inhibitors were highly effective against midgut proteases from Aedes aegypti a dipteran insect (vector of neglected tropical diseases) opening new avenues for plant-derived PIs for vector control-oriented research. Our results reflect the KTIs' complexities in passion fruit which could be wisely exploited by influencing plant defense conditions. Therefore, the potential of passion fruit as source of bioactive compounds with diversified biotechnological application was strengthened.

Type I error rates for testing genetic drift with phenotypic covariance matrices: a simulation study.

Studies of evolutionary divergence using quantitative genetic methods are centered on the additive genetic variance-covariance matrix (G) of correlated traits. However, estimating G properly requires large samples and complicated experimental designs. Multivariate tests for neutral evolution commonly replace average G by the pooled phenotypic within-group variance-covariance matrix (W) for evolutionary inferences, but this approach has been criticized due to the lack of exact proportionality between genetic and phenotypic matrices. In this study, we examined the consequence, in terms of type I error rates, of replacing average G by W in a test of neutral evolution that measures the regression slope between among-population variances and within-population eigenvalues (the Ackermann and Cheverud [AC] test) using a simulation approach to generate random observations under genetic drift. Our results indicate that the type I error rates for the genetic drift test are acceptable when using W instead of average G when the matrix correlation between the ancestral G and P is higher than 0.6, the average character heritability is above 0.7, and the matrices share principal components. For less-similar G and P matrices, the type I error rates would still be acceptable if the ratio between the number of generations since divergence and the effective population size (t/N(e)) is smaller than 0.01 (large populations that diverged recently). When G is not known in real data, a simulation approach to estimate expected slopes for the AC test under genetic drift is discussed.

Evolutionary patterns and processes in the radiation of phyllostomid bats.

BACKGROUND: The phyllostomid bats present the most extensive ecological and phenotypic radiation known among mammal families. This group is an important model system for studies of cranial ecomorphology and functional optimisation because of the constraints imposed by the requirements of flight. A number of studies supporting phyllostomid adaptation have focused on qualitative descriptions or correlating functional variables and diet, but explicit tests of possible evolutionary mechanisms and scenarios for phenotypic diversification have not been performed. We used a combination of morphometric and comparative methods to test hypotheses regarding the evolutionary processes behind the diversification of phenotype (mandible shape and size) and diet during the phyllostomid radiation. RESULTS: The different phyllostomid lineages radiate in mandible shape space, with each feeding specialisation evolving towards different axes. Size and shape evolve quite independently, as the main directions of shape variation are associated with mandible elongation (nectarivores) or the relative size of tooth rows and mandibular processes (sanguivores and frugivores), which are not associated with size changes in the mandible. The early period of phyllostomid diversification is marked by a burst of shape, size, and diet disparity (before 20 Mya), larger than expected by neutral evolution models, settling later to a period of relative phenotypic and ecological stasis. The best fitting evolutionary model for both mandible shape and size divergence was an Ornstein-Uhlenbeck process with five adaptive peaks (insectivory, carnivory, sanguivory, nectarivory and frugivory). CONCLUSIONS: The radiation of phyllostomid bats presented adaptive and non-adaptive components nested together through the time frame of the family's evolution. The first 10 My of the radiation were marked by strong phenotypic and ecological divergence among ancestors of modern lineages, whereas the remaining 20 My were marked by stasis around a number of probable adaptive peaks. A considerable amount of cladogenesis and speciation in this period is likely to be the result of non-adaptive allopatric divergence or adaptations to peaks within major dietary categories.

The role of body size and shape in understanding competitive interactions within a community of Neotropical dung beetles.

Geometric morphometrics is helpful for understanding how body size and body shape influence the strength of inter-specific competitive interactions in a community. Dung beetles, characterized by their use of decomposing organic material, provide a useful model for understanding the structuring of ecological communities and the role of competition based on their size and morphology. The relationship between body size and shape in a dung beetle community from the Atlantic Forest in Serra do Japi, Brazil was analyzed for 39 species. Fifteen anatomical landmarks on three-dimensional Cartesian coordinates were used to describe both the shape and the size of the body of each species on the basis of the centroid located along homologous points in all of the species. The first vector of a principal components analysis explained 38.5% of the morphological variation among species, and represents a gradient of body shape from elongated, flattened bodies with narrow abdomen to rounded or convex bodies. The second component explained 17.8% of the remaining variation in body shape, which goes from species with an abdomen that is larger than the elytra to species with constricted abdomens and large elytra. The relationship between body size and shape was analyzed separately for diurnal and nocturnal species. In both guilds not only were there differences in body size, but also in body shape, suggesting a reduction in their level of competition.

Adaptive radiations, ecological specialization, and the evolutionary integration of complex morphological structures.

The evolutionary integration of complex morphological structures is a macroevolutionary pattern in which morphogenetic components evolve in a coordinated fashion, which can result from the interplay among processes of developmental, genetic integration, and different types of selection. We tested hypotheses of ecological versus developmental factors underlying patterns of within-species and evolutionary integration in the mandible of phyllostomid bats, during the most impressive ecological and morphological radiation among mammals. Shape variation of mandibular morphogenetic components was associated with diet, and the transition of integration patterns from developmental to within-species to evolutionary was examined. Within-species (as a proxy to genetic) integration in different lineages resembled developmental integration regardless of diet specialization, however, evolutionary integration patterns reflected selection in different mandibular components. For dietary specializations requiring extensive functional changes in mastication patterns or biting, such as frugivores and sanguivores, the evolutionary integration pattern was not associated with expected within-species or developmental integration. On the other hand, specializations with lower mastication demands or without major functional reorganization (such as nectarivores and carnivores), presented evolutionary integration patterns similar to the expected developmental pattern. These results show that evolutionary integration patterns are largely a result of independent selection on specific components regardless of developmental modules.

Nonrandom factors in modern human morphological diversification: a study of craniofacial variation in southern South american populations.

The causes of craniofacial variation among human populations have been the subject of controversy. In this work, we studied aboriginal populations from southern South America, the last continental region peopled by humans and with a wide range of ecological conditions. Because of these characteristics, southern South America provides a unique opportunity to study the relative importance of random and nonrandom factors in human diversification. Previous craniometric studies recognized remarkable differences among populations from this region, usually resorting to random factors as the main explanation. In contrast, here we suggest, using tests based on quantitative genetic models, that: (1) the rate of craniofacial divergence among these populations is too high and (2) the patterns of variation within and between populations are too different to be explained by genetic drift alone. In addition, the among-sample craniofacial variation is correlated with climate and diet but not with mtDNA variation. We suggest that the influence of nonrandom factors (e.g., plasticity, selection) on human craniofacial diversification in regions with large ecological variation is more important than generally acknowledged and capable to generate large craniofacial divergence in a short period of time. These results bring nonrandom factors into focus for the interpretation of human craniofacial variation.

Ontogenetic trajectories and hind tibia geometric morphometrics of Holymenia clavigera (Herbst) and Anisoscelis foliacea marginella (Dallas) (Hemiptera: Coreidae)

Holymenia clavigera (Herbst) e Anisoscelis foliacea marginella (Dallas) (Hemiptera: Coreidae: Anisoscelini) são hemípteros pouco estudados e que ocorrem no sul do Brasil. Observações preliminares indicam alta coexistência no uso de suas plantas hospedeiras (passifloráceas). Adicionalmente, há uma acentuada semelhança morfológica dos ovos e ninfas. Objetiva-se caracterizar e comparar as suas trajetórias ontogenéticas através de curvas de crescimento e da alometria ontogenética multivariada, uma vez que a única diferença aparente entre as espécies é uma dilatação da tíbia no terceiro par de pernas de A. foliacea marginella. Por não apresentarem as formas das tíbias distintas visualmente nos primeiro e segundo ínstares, as diferenças entre as espécies foram quantificadas pela função spline de placas finas, com o relaxamento do algoritmo para pontos em contorno. Em todos os ínstares, H. clavigera foi significativamente maior que A foliacea marginella. As trajetórias ontogenéticas dos coreídeos foram estatisticamente diferentes, e as estruturas mensuradas apresentaram coeficientes alométricos significativamente distintos. A forma das tíbias de H. clavigera e A. foliacea marginella não foi estatisticamente diferente no primeiro, mas sim no segundo instar. No terceiro instar, a forma da tíbia desses coreídeos torna-se distinta a olho nu. Ou seja, embora sejam espécies com imaturos quase idênticos morfologicamente, seus padrões de crescimento e tamanho diferem de forma significativa. Assim, o tamanho apresenta-se como parâmetro útil para a diferenciação desses estágios.

Holymenia clavigera (Herbst) e Anisoscelis foliacea marginella (Dallas) (Hemiptera: Coreidae: Anisoscelini) são hemípteros pouco estudados e que ocorrem no sul do Brasil. Observações preliminares indicam alta coexistência no uso de suas plantas hospedeiras (passifloráceas). Adicionalmente, há uma acentuada semelhança morfológica dos ovos e ninfas. Objetiva-se caracterizar e comparar as suas trajetórias ontogenéticas através de curvas de crescimento e da alometria ontogenética multivariada, uma vez que a única diferença aparente entre as espécies é uma dilatação da tíbia no terceiro par de pernas de A. foliacea marginella. Por não apresentarem as formas das tíbias distintas visualmente nos primeiro e segundo ínstares, as diferenças entre as espécies foram quantificadas pela função spline de placas finas, com o relaxamento do algoritmo para pontos em contorno. Em todos os ínstares, H. clavigera foi significativamente maior que A foliacea marginella. As trajetórias ontogenéticas dos coreídeos foram estatisticamente diferentes, e as estruturas mensuradas apresentaram coeficientes alométricos significativamente distintos. A forma das tíbias de H. clavigera e A. foliacea marginella não foi estatisticamente diferente no primeiro, mas sim no segundo instar. No terceiro instar, a forma da tíbia desses coreídeos torna-se distinta a olho nu. Ou seja, embora sejam espécies com imaturos quase idênticos morfologicamente, seus padrões de crescimento e tamanho diferem de forma significativa. Assim, o tamanho apresenta-se como parâmetro útil para a diferenciação desses estágios.

Evolutionary integration and morphological diversification in complex morphological structures: mandible shape divergence in spiny rats (Rodentia, Echimyidae).

The rodent mandible has become a paradigm for studies on the development and evolution of complex morphological structures. We use a combination of geometric and multivariate morphometric methods in order to assess the correspondence between integration patterns and a priori biological models in the context of evolutionary shape divergence in the mandible of rodents of the family Echimyidae. The correlation of shape distances among operational taxonomic units (individuals, species, genera) in separate morphogenetic components allowed the construction of integration matrices among mandible components for data sets corresponding to varying levels of genetic divergence (intergeneric, interspecific, and intrapopulational). The integration matrices were associated with a priori biological (developmental, genetical, modular) models, and the maximum integration axes (singular warps) were compared with realized axes of maximum interspecific variation (relative warps). The integration pattern and intensity were not stable in data sets with different levels of genetic divergence, and the varying functional demands during the ecological radiation in the family were probably responsible for the differences in observed integration patterns. Developmental and genetic models were significantly associated with the interspecific integration patterns observed, suggesting a role for neutral evolution during the evolutionary divergence of mandible shape. However, directional and stabilizing selection were not discarded as processes responsible for the generation of interspecific integration. The choreography of the morphogenetic components in the mandible is highly flexible and the integrated groups of components can be reorganized depending on functional demands during evolutionary shape changes.

Morphological divergence rate tests for natural selection: uncertainty of parameter estimation and robustness of results

In this study, we used a combination of geometric morphometric and evolutionary genetics methods for the inference of possible mechanisms of evolutionary divergence. A sensitivity analysis for the constant-heritability rate test results regarding variation in genetic and demographic parameters was performed, in order to assess the relative influence of uncertainty of parameter estimation on the robustness of test results. As an application, we present a study on body shape variation among populations of the poeciliine fish Poecilia vivipara inhabiting lagoons of the quaternary plains in northern Rio de Janeiro State, Brazil. The sensitivity analysis showed that, in general, the most important parameters are heritability, effective population size and number of generations since divergence. For this specific example, using a conservatively wide range of parameters, the neutral model of genetic drift could not be accepted as a sole cause for the observed magnitude of morphological divergence among populations. A mechanism of directional selection is suggested as the main cause of variation among populations in different habitats and lagoons. The implications of parameter estimation and biological assumptions and consequences are discussed.

Geometric estimates of heritability in biological shape.

The recently developed geometric morphometrics methods represent an important contribution of statistics and geometry to the study of biological shapes. We propose simple protocols using shape distances that incorporate geometric techniques into linear quantitative genetic models that should provide insights into the contribution of genetics to shape variation in organisms. The geometric approaches use Procrustes distances in a curved shape space and distances in tangent spaces within and among families to estimate shape heritability. We illustrate the protocols with an example of wing shape variation in the honeybee, Apis mellifera. The heritability of overall shape variation was small, but some localized components depicting shape changes on distal wing regions showed medium to large heritabilities. The genetic variance-covariance matrix of the geometric shape variables was significantly correlated with the phenotypic shape variance-covariance matrix. A comparison of the results of geometric methods with the traditional multivariate analysis of interlandmark distances indicated that even with a larger dimensionality, the interlandmark distances were not as rich in shape information as the landmark coordinates. Quantitative genetics studies of shape should greatly benefit from the application of geometric methods.