Molecular population divergence and sexual selection on morphology in the banded demoiselle (Calopteryx splendens)

Insect monitoring with fluorescence lidar techniques: feasibility study

We investigate the possibilities of light detection and ranging (lidar) techniques to study migration of the damselfly species Calopteryx splendens and C. virgo. Laboratory and testing-range measurements at a distance of 60 m were performed using dried, mounted damselfly specimens. Laboratory measurements, including color photography in polarized light and spectroscopy of reflectance and induced fluorescence, reveal that damselflies exhibit reflectance and fluorescence properties that are closely tied to the generation of structural color. Lidar studies on C. splendens of both genders show that gender can be remotely determined, especially for specimens that were marked with Coumarin 102 and Rhodamine 6G dyes. The results obtained in this study will be useful for future field experiments, and provide guidelines for studying damselflies in their natural habitat using lidar to survey the air above the river surface. The findings will be applicable for many other insect species and should, therefore, bring new insights into migration and movement patterns of insects in general.

Carcinosarcomas (malignant mixed Müllerian tumor) of the uterus: advances in elucidation of biologic and clinical characteristics

Carcinosarcoma of the uterus (malignant mixed Müllerian tumor [MMMT]) is an uncommon, typically extremely aggressive neoplasm histologically composed of malignant epithelial and mesenchymal (stromal) elements. Although the literature contains some debate, most authors now agree that most MMMTs derive from sarcomatous differentiation in a high-grade carcinoma. This article reviews the clinical and histopathologic features of this interesting neoplasm, with particular emphasis on recent data supporting MMMTs as primarily epithelial malignant neoplasms with areas of mesenchymal/spindle cell differentiation.

In-stream and overland dispersal across a river network influences gene flow in a freshwater insect, Calopteryx splendens

Gene flow in riverine species is constrained by the dendritic (branching) structure of the river network. Spatial genetic structure (SGS) of freshwater insects is particularly influenced by catchment characteristics and land use in the surroundings of the river. Gene flow also depends on the life cycle of organisms. Aquatic larvae mainly drift downstream whereas flying adults can disperse actively overland and along watercourses. In-stream movements can generate isolation by distance (IBD) at a local scale and differentiation between subcatchments. However, these patterns can be disrupted by overland dispersal. We studied SGS across the Loire River in the damselfly Calopteryx splendens which is able to disperse along and between watercourses. Our sampling design allowed us to test for overland dispersal effects on genetic differentiation between watercourses. Amplified fragment length polymorphism markers revealed high genetic differentiation at the catchment scale but the genetic structure did not reflect the geographical structure of sampling sites. We observed IBD patterns when considering the distance following the watercourse but also the Euclidean distance, i.e. the shortest distance, between pairs of sites. Altogether, our results support the hypothesis of overland dispersal between watercourses. From a conservation perspective, attention should be paid to the actual pathways of gene flow across complex landscapes such as river networks.

Differentiation of morphology, genetics and electric signals in a region of sympatry between sister species of African electric fish (Mormyridae)

Mormyrid fishes produce and sense weak electric organ discharges (EODs) for object detection and communication, and they have been increasingly recognized as useful model organisms for studying signal evolution and speciation. EOD waveform variation can provide important clues to sympatric species boundaries between otherwise similar or morphologically cryptic forms. Endemic to the watersheds of Gabon (Central Africa), Ivindomyrus marchei and Ivindomyrus opdenboschi are morphologically similar to one another. Using morphometric, electrophysiological and molecular characters [cytochrome b sequences and amplified fragment length polymorphism (AFLP) genotypes], we investigated to what extent these nominal mormyrid species have diverged into biological species. Our sampling covered the known distribution of each species with a focus on the Ivindo River, where the two taxa co-occur. An overall pattern of congruence among datasets suggests that I. opdenboschi and I. marchei are mostly distinct. Electric signal analysis showed that EODs of I. opdenboschi tend to have a smaller initial head-positive peak than those of I. marchei, and they often possess a small third waveform peak that is typically absent in EODs of I. marchei. Analysis of sympatric I. opdenboschi and I. marchei populations revealed slight, but significant, genetic partitioning between populations based on AFLP data (F(ST) approximately 0.04). Taken separately, however, none of the characters we evaluated allowed us to discriminate two completely distinct or monophyletic groups. Lack of robust separation on the basis of any single character set may be a consequence of incomplete lineage sorting due to recent ancestry and/or introgressive hybridization. Incongruence between genetic datasets in one individual, which exhibited a mitochondrial haplotype characteristic of I. marchei but nevertheless fell within a genetic cluster of I. opdenboschi based on AFLP genotypes, suggests that a low level of recent hybridization may also be contributing to patterns of character variation in sympatry. Nevertheless, despite less than perfect separability based on any one dataset and inconclusive evidence for complete reproductive isolation between them in the Ivindo River, we find sufficient evidence to support the existence of two distinctive species, I. opdenboschi and I. marchei, even if not 'biological species' in the Mayrian sense.

Selective Predation on Wing Morphology in Sympatric Damselflies

Although predation is thought to affect species divergence, the effects of predator-mediated natural selection on species divergence and in nonadaptive radiations have seldom been studied. Wing melanization in Calopteryx damselflies has important functions in sexual selection and interspecific interactions and in species recognition. The genus Calopteryx and other damselfly genera have also been put forward as examples of radiations driven by sexual selection. We show that avian predation strongly affects natural selection on wing morphology and male wing melanization in two congeneric and sympatric species of this genus (Calopteryx splendens and Calopteryx virgo). Predation risk was almost three times higher for C. virgo, which has an exaggerated degree of wing melanization, than it was for the less exaggerated, sympatric congener C. splendens. Selective predation on the exaggerated species C. virgo favored a reduction and redistribution of the wing melanin patch. There was evidence for nonlinear selection involving wing patch size, wing patch darkness, and wing length and width in C. splendens but weaker nonlinear selection on the same trait combinations in C. virgo. Selective predation could interfere with species divergence by sexual selection and may thus indirectly affect male interspecific interactions, reproductive isolation, and species coexistence in this genus.

Rapid courtship evolution in grouse (Tetraonidae): contrasting patterns of acceleration between the Eurasian and North American polygynous clades

Sexual selection is thought to be a powerful diversifying force, based on large ornamental differences between sexually dimorphic species. This assumes that unornamented phenotypes represent evolution without sexual selection. If sexual selection is more powerful than other forms of selection, then two effects would be: rapid divergence of sexually selected traits and a correlation between these divergence rates and variance in mating success in the ornamented sex. I tested for these effects in grouse (Tetraonidae). For three species pairs, within and among polygynous clades, male courtship characters had significantly greater divergence than other characters. This was most pronounced for two species in Tympanuchus. In the Eurasian polygynous clade, relative courtship divergence gradually increased with nucleotide divergence, suggesting a less dramatic acceleration. Increase in relative courtship divergence was associated with mating systems having higher variance in male mating success. These results suggest that sexual selection has accelerated courtship evolution among grouse, although the microevolutionary details appear to vary among clades.

Effects of early resource-limiting conditions on patterns of growth, growth efficiency, and immune function at emergence in a damselfly (Odonata: Coenagrionidae)

Periods of restricted growth during early development are expected to have detrimental effects on subsequent metrics of fitness, most prominently increases in age and decreases in size at maturity. However, in some cases, animals may compensate by altering foraging effort, growth efficiency, or patterns of resource allocation between critical traits prior to maturation. Yet, even when compensation for age and size is complete, brief periods of restricted growth may carry costs persisting in the long term, and compensatory tactics may themselves be costly. We investigated the long-term costs of early growth restriction and mechanisms of compensatory growth in the damselfly Ischnura verticalis (Say, 1839). Larvae were temporarily exposed to one of three feeding regimes in the early stages of development, after which food levels were restored. In the period of unrestricted growth prior to emergence, partial compensation for structural size in the lowest food treatment was observed, while both resource-limited groups accelerated mass gain relative to controls. Changes in food consumption and food conversion efficiency were ruled out as mechanisms for accelerating growth following diet restriction. We tested for changes in resource allocation patterns that could explain the observed compensatory growth and found that adult body shape may depend on early growth conditions in females. There was no evidence of detrimental effects on immune function at emergence, although males tended to have higher phenoloxidase activity (a measure of immunocompetence) than females.

Ten years of AFLP in ecology and evolution: why so few animals?

Researchers in the field of molecular ecology and evolution require versatile and low-cost genetic typing methods. The AFLP (amplified fragment length polymorphism) method was introduced 10 years ago and shows many features that fulfil these requirements. With good quality genomic DNA at hand, it is relatively easy to generate anonymous multilocus DNA profiles in most species and the start-up time before data can be generated is often less than a week. Built-in dynamic, yet simple modifications make it possible to find a protocol suitable to the genome size of the species and to screen thousands of loci in hundreds of individuals for a relatively low cost. Until now, the method has primarily been applied in studies of plants, bacteria and fungi, with a strong bias towards economically important cultivated species and their pests. In this review we identify a number of research areas in the study of wild species of animals where the AFLP method, presently very much underused, should be a very valuable tool. These aspects include classical problems such as studies of population genetic structure and phylogenetic reconstructions, and also new challenges such as finding markers for genes governing adaptations in wild populations and modifications of the protocol that makes it possible to measure expression variation of multiple genes (cDNA-AFLP) and the distribution of DNA methylation. We hope this review will help molecular ecologists to identify when AFLP is likely to be superior to other more established methods, such as microsatellites, SNP (single nucleotide polymorphism) analyses and multigene DNA sequencing.

Female Polymorphism, Frequency Dependence, and Rapid Evolutionary Dynamics in Natural Populations

Rapid evolutionary change over a few generations has been documented in natural populations. Such changes are observed as organisms invade new environments, and they are often triggered by changed interspecific interactions, such as differences in predation regimes. However, in spite of increased recognition of antagonistic male-female mating interactions, there is very limited evidence that such intraspecific interactions could cause rapid evolutionary dynamics in nature. This is because ecological and longitudinal data from natural populations have been lacking. Here we show that in a color-polymorphic damselfly species, male-female mating interactions lead to rapid evolutionary change in morph frequencies between generations. Field data and computer simulations indicate that these changes are driven by sexual conflict, in which morph fecundities are negatively affected by frequency- and density-dependent male mating harassment. These frequency-dependent processes prevent population divergence by maintaining a female polymorphism in most populations. Although these results contrast with the traditional view of how sexual conflict enhances the rate of population divergence, they are consistent with a recent theoretical model of how females may form discrete genetic clusters in response to male mating harassment.