Hugo A. Benítez

Bat Species Comparisons Based on External Morphology : A Test of Traditional versus Geometric Morphometric Approaches

External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species – in this case European horseshoe bats (Rhinolophidae, Chiroptera) – based on morphology of the wing, body and tail. In addition to comparing morphometric methods, we used geometric morphometrics to detect interspecies differences as shape changes. Geometric morphometrics yielded improved species discrimination relative to traditional methods. The predicted shape for the variation along the between group principal components revealed that the largest differences between species lay in the extent to which the wing reaches in the direction of the head. This strong trend in interspecific shape variation is associated with size, which we interpret as an evolutionary allometry pattern.

Ecomorphological Variation of the Wireworm Cephalic Capsule: Studying the Interaction of Environment and Geometric Shape

Studying the association between organismal morphology and environmental conditions has been very useful to test hypothesis regarding the influence of climate on shape. It has been long recognized that different environments produce dissimilar stress levels in insects, which can be reflected on the ability of an individual to overcome these pressures and spread further. Agriotes (Coleoptera: Elateridae) species infest agricultural fields in different parts of Croatia, inhabiting different climatic conditions. Previous biological studies have indicated that there is a relationship between some Agriotes biological parameters such as density and climatic conditions such as soil moisture and temperature. However, it is still unknown how these environmental properties influence the wireworm morphological structure. This is highly relevant because the head of this species is directly involved in the mobility in the soil, thus affecting the invasive capacity of this insect. Therefore the aim of this study was to assess the association between different climatic conditions and the morphological variation of Agriotes cephalic capsule. Advanced multivariate analysis and geometric morphometric tool were applied to study the covariation between shape and environmental variables. Partial Least Squares methods were used in order to analyse the association between the wireworm head shape and three different climatic conditions: soil type, temperature and rainfall. Our results showed that there is a high covariation between the wireworm head shape and the climatic conditions. It was suggested that the observed shape–environment association could be result of the high plasticity of this species in relation to its invasive capacity.

Morphological variation on isolated populations of Praocis ( Praocis ) spinolai

Abstract In this study, the morphological variations of four geographically isolated populations of Praocis (Praocis) spinolai Gay & Solier (Coleoptera: Tenebrionidae) in the transitional coastal desert, Chile, were studied. The study was conducted in the coastal area of Punta de Choros and Los Choros-Archipelago, which includes three islands: Choros, Damas, and Gaviota. 113 specimens of the species P. (P.) spinolai belonging to the four locations sampled were collected analyzed with geometric morphometrics techniques to explore the pattern of shape variation on the different isolated environments. The principal component analysis revealed a well-defined pattern of variation between the populations analyzed. Moreover, differences between populations emerged also from the canonical variation analysis and were confirmed by the Procrustes ANOVA. All analyses performed confirmed the existence of a pattern of variation, due to the isolation of the populations and to environmental effects. The islands are subject to more arid pressures than the continent, where there is a more stable environment and the presence of coastal wetlands and the coastal range of mountains act together and enable fog condensation. This study indicates the existence of a clear pattern of variation, which indicates an evolutionary trend among the population examined.

Assessment of patterns of fluctuating asymmetry and sexual dimorphism in carabid body shape.

The measurement tool most used to estimate developmental stability (DS) is fluctuating asymmetry (FA), which is a measure of the small random deviations that occur between the left and right sides of bilaterally symmetrical traits. In the Biobío Region of Chile, forest plantations are a widely extended phenomenon, which affect 27% of the surface area of the region and which are dominated by the monoculture of Pinus radiata. This study evaluated the presence of FA in the body shape of two populations of Ceroglossus chilensis (Eschscholtz) in two 13-year-old forest plantations (commercial thinning) using insects collected with interception traps. Since the biotic and abiotic components of forest plantations are subject to continual anthropic modifications that affect almost all ecological processes, including population dynamics, community composition, and material and energy flows, these characteristics are reflected in the DS of individuals. The results showed that there was greater precision using geometric morphometrics to detect the presence of asymmetry in plantations due to shape analysis, as proposed by studies in antennal morphology using traditional measures. It should be noted that the populations were exposed to different environments; the population in the Coast Range is more humid, while the Andes Foothills population is in a drier area with drier soils. In spite of this, there was minimum phenotypic variation detected at the population level, which reflected the different environments and may be associated with patterns of environmental phenotypic plasticity.

Sexual shape and size dimorphism in carabid beetles of the genus Ceroglossus: is geometric body size similar between sexes due to sex ratio?

Insects in many species vary greatly in the expression of secondary sexual traits, resulting in sexual dimorphism, which has been proposed to be a consequence of differences in sexual selection. In this study, we analyze the occurrence of sexual shape dimorphism and the correlation between geometric body size in males and females and sex ratio in the genus Ceroglossus (Coleoptera: Carabidae) using geometric morphometrics and randomization analysis. Our results show a positive relationship between the centroid size of males and females and sex ratio. However, we also observed a trend to maintain a “similar” body shape between sexes and species due to characteristics associated with sexual selection of the group in which the scarcity of outstanding morphological characters does not restrict reproduction capacity. The trend in sexual proportions was found to be near 1:1 for the eight species. We propose that the observed differences between sexes associated with the sex ratio are due to an energy cost caused by sexual selection; nevertheless, since proportions are similar for all the species, it is really not relevant to generate more conspicuous structures for a stronger male-male competence.

Monitoring techniques of the western corn rootworm are the precursor to effective IPM strategies

BACKGROUND The western corn rootworm (WCR) is economically the most important pest of maize in Croatia. To predict WCR adult population abundance and variability, traditional, genetic and morphometric monitoring of populations was conducted over time through each phase of the WCR invasion process in Croatia. RESULTS Through traditional monitoring it was shown that WCR established their current population and reached economic densities after 14 years persisting in the study area. Regression-tree-based modelling showed that the best predictor of WCR adult abundance was the total amount of rainfall. Genetic monitoring indicated that genetic differentiation increased over time at the intrapopulation level, and morphometric monitoring indicated that wing morphotypes varied according to edaphic landscape changes. CONCLUSION Traditional population metric surveys are important in WCR integrated pest management (IPM), as such surveys can be effectively used to predict population abundances. Novel-use monitoring techniques such as genetics and geometric morphometrics can be used to provide valuable information on variation within and among populations. The monitoring techniques presented herein provide sound data to assist in the understanding of both WCR ecology and population genetics and may provide more information than that currently available using traditional techniques (e.g. sticky traps), and as such these additional techniques should be written into IPM for WCR.

Modelando la Varianza de la Forma: Morfometría Geométrica Aplicaciones en Biología Evolutiva

La comparacion de caracteres anatomicos entre organismos ha sido un elemento central de la biologia comparada. Historicamente, la clasificacion taxonomica y la comprension de la diversidad biologica se han basado en descripciones morfologicas. En base a una revolucion matematica cuantitativa, el estudio de la morfologia ha tenido un importante enfasis gracias al desarrollo del analisis de la forma mediante la combinacion de metodos estadisticos multivariados y nuevas maneras de visualizacion. El objetivo de la presente revision es dar una vision actualizada sobre los avances del estudio de la morfometria geometrica (MG) en biologia evolutiva, asi como introducir a tematicas en fuerte desarrollo (e.g. estabilidad del desarrollo, integracion y modularidad morfologicas, entre otras). Se espera proporcionar una vision amplia del uso de la MG en biologia evolutiva, destacando la necesidad de aumentar el esfuerzo de investigacion en esta disciplina, junto con llamar la atencion acerca de la utilidad de la MG como una herramienta efectiva, precisa, amigable y barata para cuantificar y estudiar la variacion morfologica.

A gregarine from the gut of cat flea, Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) in Taiwan: Dynamic of infection patterns

An understanding on host-parasite interaction is essential for control of disease causing organisms in domestic animals. The cat flea, Ctenocephalides felis (Bouché) is the predominant flea infesting dogs and cats in Taiwan. It was collected from 933 dogs and 197 cats from Taiwan. A total of 5878 C. felis adults were recovered; 14.6% fleas were observed to harbor Steinina ctenocephali. Female fleas were more susceptible to gregarine infection than males. Further, fleas were more likely to be infected with the gregarine at high temperatures, particularly during March-July with high parasite prevalence and intensity. Fleas harboring gregarines infection were higher in dogs than cats. Our study may help in development and application of appropriate flea control measures in Taiwan.

Allometric and Non-Allometric Patterns in Sexual Dimorphism Discrimination of Wing Shape in Ophion intricatus: Might Two Male Morphotypes Coexist?

Abstract Bees and wasps could exhibit shape and size sexual dimorphism, and most of their morphological variation could depend on phenotypic responses due to environmental pressure during ontogenetic development. More complex measurement techniques related to size and shape rather than simply to mass and length should be required to analyze such a complex sexual dimorphism. In this study, differences related to wing shape and size of males and females of Ophion intricatus Brullé (Hymenoptera: Ichneumonidae) were evaluated using geometric morphometrics. Right and left wings of specimens were used, and a photographic matrix was constructed in which 18 morphological landmarks based on shape and vein patterns of the wings were digitalized. A multivariate analysis of wing shape showed significant differences between sexes and sites. The geometric variation demonstrated that the points at the intersection of radial and cubital-anal veins might be key characters to differentiate between sexes. This study also showed the presence of two clearly different male morphotypes coexisting in the same study site. However, it should be noted that the results of this study showed that the variation in wing shape is an analytical character in the determination of sexual differences in the family Ichneumonidae. These differences raise the question of whether sexual dimorphism of wing shape may be modulated by natural selection.

Erratum to: Left–right asymmetry and morphological consequences of a host shift in the oligophagous Neotropical moth Macaria mirthae (Lepidoptera: Geometridae)

Phytophagous insects are excellent model organisms to study the genetic and ecological components of adaptation and morphological divergence, because their host plants are one of the main environmental factors influencing their early life stages. Although many lepidopterans are highly specialized in their host use, shifts to exotic plants have been reported for some species. Macaria mirthae is a native moth from Northern Chile that feeds preferentially on the Fabacea species Acacia macracantha, however due to habitat loss a host shift has recently been observed to the introduced fabacean Leucaena leucocephala. We studied the impact that different host plants have on the developmental instability levels in the moth’s wing morphology evaluating both fluctuating asymmetry (FA) and directional asymmetry (DA). FA measures the small random deviations existing between the left and right sides of bilaterally symmetrical traits and it widely used as a biomonitor of environmental quality. DA refers to the tendency for a trait to be consistently developed in a different manner on the right and left sides of the body. It has been recently shown that subtle DA patterns seem to be a ubiquitous phenomenon among bilaterian animals. Our results confirmed the presence of FA in M. mirthae forewings by applying geometric morphometric techniques. Furthermore, it was found that the individuals feeding on the endemic tree (A. macracantha) showed marked DA levels, while the specimens inhabiting the exotic plant (L. leucocephala) did not. The absence of DA in the individuals occupying the exotic plant is striking, because it has been established that this asymmetry pattern is widespread among insect wings. This phenomenon could be related to the influence of L. leucocephala on normal wing development. Despite the reduced quality of L. leucocephala as host plant, its wider presence in the Azapa valley (Chile) could explain the host shift made by M. mirthae.