Calopteryx Splendens Research Articles

Selection on size and secondary sexual characters of the damselfly Calopteryx splendens when sympatric with the congener Calopteryx virgo

Male mating success is often determined by body size or secondary sexual characters because of female mate choice or competition for females. In addition to intraspecific interactions, interspecific interactions may interfere with intraspecific selection. In this study, we investigated sexual selection on size and sexual characters of male banded demoiselle ( Calopteryx splendens (Harris, 1780)) in wild populations sympatric with the beautiful demoiselle ( Calopteryx virgo (L., 1758)). As secondary sexual characters, male C. splendens have pigmented wing spots whose size appears to be under positive selection. Male C. virgo resemble male C. splendens that have the largest wing spots, leading to interspecific male–male aggression and possibly also to heterospecific matings via mistaken species recognition. If interspecific interactions interfere with intraspecific sexual selection on wing-spot size of C. splendens, their effects should increase with the increasing relative abundance of C. virgo. Our results did not show the expected positive selection on wing-spot size in C. splendens, suggesting that interspecific interactions might interfere with sexual selection. Also, we observed no relationship between the strength of interspecific sexual selection and the relative abundance of C. virgo. However, there was a positive intraspecific density-dependent sexual selection for larger size. Although the present results are tentative, we suggest that interspecific interactions should be considered along with intraspecific selection when studies of sexual selection are performed in the wild.

ФАУНА СТРЕКОЗ (ODONATA) ТУВЫ

The known odonate fauna of Tuva in Siberia, Russia, is documented. It includes 47 species. In the southern Ubsu-Nur depression 29 species were recorded (2 just there); in the Central Tuvinian depression 34 species (6 just there) and in the Todzha depression 32 species (9 just there). The fauna of the more humid taigaous region of Todzha contains lacks 7 species found elsewhere in Tuva. In spite of Todzha's position in the north-east, its fauna shows a more western character and includes a population of Calopteryx splendens with a high proportion of two morphs of androchromic females and a male morph with wings coloured to the tips. Todzha is inhabited by Enallagma c. cyathigerum with a variably melanised abdomen, while in the Central Tuvinian and Ubsu-Nur depressions, E. c. risi occurs. In Turan and the Upper Kaa-Khem basin, intergradation between both taxa takes place. In Todzha, Somatochlora exuberata and S. metallica abocanica are sympatric without intermediate forms and with habitat segregation, thus proving their status as separate species. Todzha is inhabited by Ophiogomphus obscurus while the rest of Tuva harbours O. spinicornis. The status of vicariant western/eastern pairs of taxa in the genus Leucorrhinia: dubia/orientalis and rubicunda/indermedia, is discussed in detail.

Seasonal variation of wing spot allometry in Calopteryx splendens (Odonata Calopterygidae)

In the genus Calopteryx, males generally have pigmented wing spots, a secondary sexual character. Constraints imposed by the advancing season influence the development of organisms and the effect of these constraints has been explored in insects. For example, the size of emerging insects and the fecundity of females which developed late in the season are often lower when compared with those which emerged early. This suggests that insects which develop later in the season have less energy to spend and that they need to adjust resource allocations accordingly. Hence it is expected that the allometry of costly secondary sexual characters, such as wing spots, should be influenced by seasonal constraints. In contrast the allometry of non-sexual traits (e.g. wing cell numbers) should be less affected. These hypotheses were tested using males of the damselfly Calopteryx splendens caught in May and in September. It was found that males caught later were on average smaller and that the allometric functions describing wing spots differed between the two groups, with males caught later having relatively smaller spots. In contrast, the allometry of wing cell numbers did not vary with season

A ROLE FOR LEARNING IN POPULATION DIVERGENCE OF MATE PREFERENCES

Learning and other forms of phenotypic plasticity have been suggested to enhance population divergence. Mate preferences can develop by learning, and species recognition might not be entirely genetic. We present data on female mate preferences of the banded demoiselle (Calopteryx splendens) that suggest a role for learning in population divergence and species recognition. Populations of this species are either allopatric or sympatric with a phenotypically similar congener (C. virgo). These two species differ mainly in the amount of wing melanization in males, and wing patches thus mediate sexual isolation. In sympatry, sexually experienced females discriminate against large melanin wing patches in heterospecific males. In contrast, in allopatric populations within the same geographic region, females show positive ("open-ended") preferences for such large wing patches. Virgin C. splendens females do not discriminate against heterospecific males. Moreover, physical exposure experiments of such virgin females to con- or hetero-specific males significantly influences their subsequent mate preferences. Species recognition is thus not entirely genetic and it is partly influenced by interactions with mates. Learning causes pronounced population divergence in mate preferences between these weakly genetically differentiated populations, and results in a highly divergent pattern of species recognition at a small geographic scale.

Predation selects for increased immune function in male damselflies, Calopteryx splendens.

Predation selects for numerous traits in many animal species, with sick or parasitized prey often being at high risk. When challenged by parasites and pathogens, prey with poor immune functions are thus likely to be at a selective disadvantage. We tested the hypothesis that predation by birds selects for increased immune function in a wild population of male damselflies Calopteryx splendens, while controlling for a trait known to be under selection by bird predation, dark wing-spots. We found that selection on both immune function and wing-spot size was significantly positive, and that selection on either trait was independent of selection on the other. We found no evidence of nonlinear quadratic or correlational selection. In contrast to previous studies, we found no phenotypic correlation between immune function and wing-spot size. There was also no difference in immune response between territorial and non-territorial males. Our study suggests that predation may be an important agent of selection on the immune systems of prey, and because the selection we detected was directional, has the potential to cause phenotypic change in populations.

Odonata of Tuva, Russia

Abstract The odonate fauna of Tuva in Siberia, Russia, is documented, based mainly on data from expeditions in 1990, 2000 and 2004, and examination of collections preserved in Novosibirsk. The checklist of Tuvinian Odonata presently includes 47 species. In the southern Ubsu-Nur depression 29 species were recorded (two just there); in the Central Tuvinian depression 34 species (six just there) and in the Todzha depression 32 species (nine just there). The fauna of the more humid taiga region of Todzha, separated from the arid remainder of Tuva by the Obruchev Mts, contained some forest species but lacked seven species found elsewhere in Tuva. In spite of Todzha's position in the north-east, its fauna showed a more western character and included a population of Calopteryx splendens with a high proportion of androchromic females and males with wings coloured to the tips. Todzha was also inhabited by Enallagma c. cyathigerum with a variably melanized abdomen, while in the Central Tuvinian and Ubsu-Nur depress...

A role for ecology in male mate discrimination of immigrant females in Calopteryx damselflies?

Sexual selection against immigrants is a mechanism that can regulate premating isolation between populations but, so far, few field studies have examined whether males can discriminate between immigrant and resident females. Males of the damselfly Calopteryx splendens show mate preferences and are able to force pre-copulatory tandems. We related male mate responses to the ecological characteristics of female origin, geographic distances between populations, and morphological traits of females to identify factors influencing male mate discrimination. Significant heterogeneity between populations in male mate responses towards females was found. In some populations, males discriminated strongly against immigrant females, whereas the pattern was reversed or nonsignificant in other populations. Immigrant females were particularly attractive to males when they came from populations with similar predation pressures and densities of conspecifics. By contrast, immigrant females from populations with strongly dissimilar predation pressures and conspecific densities were not attractive to males. Differences in the abiotic environment appeared to affect mating success to a lesser degree. This suggests that male mate discrimination is context-dependent and influenced by ecological differences between populations, a key prediction of ecological speciation theory. The results obtained in the present study suggest that gene-flow is facilitated between ecologically similar populations. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 506-518. (Less)

Condition and Phenotype-Dependent Dispersal in a Damselfly, Calopteryx splendens

Individual dispersal decisions may be affected by the internal state of the individual and the external information of its current environment. Here we estimated the influence of dispersal on survival and investigated if individual phenotype (sex and wing length) and environmental condition (conspecific density and sex-ratio) affected dispersal decisions in the banded damselfly, Calopteryx splendens. As suspected from the literature, we showed that the proportion of dispersing individuals was higher in females than in males. We also found negative-density dependent dispersal in both sexes and influence of sex-ratio on dispersal. Individuals moved less when sex-ratio was male biased. These results are consistent with a lek mating system where males aggregate in a place and hold mating territories. Contrary to our expectations, neither dispersal nor survival was affected by wing length. Nevertheless, mean adult survival was about 8% lower in dispersing individuals than in residents. This might reflect a mortality cost due to dispersal.

Genetic diversity, population structure and taxonomy of Calopteryx splendens (Odonata: Calopterygidae): An AFLP analysis

Calopteryx splendens is a widely distributed palaearctic damselfly with a remarkably uniform morphology. Variation in the size and shape of the pigmented spot on the wing is the main diagnostic character used to discriminate subspecies across its huge geographic range. Here, AFLP analysis was used to assess the genetic structure and diversity of nine populations representing 3 putative subspecies and evaluate the pigment spot as a taxonomic marker. Genetic diversity was high, with the number of polymorphic loci per population ranging from 141 to 280 out of a total of 333 variable sites (42.3-84.1%) and Nei's gene diversity from 0.160 to 0.283 (overall 0.299). Overall population genetic differentiation (FST = 0.2766) suggests limited gene flow and adaptation to local environments. Restricted gene flow and genetic differentiation among populations are supported by significant FST estimates. High levels of gene flow (Nm >1) were only recorded among three Asian populations (Russia - Kazakhstan - Turkey). The patterns of genotypic diversity suggest that a given wing spot size and shape may arise from the hybridization of a limited number, possibly not more than four, ancestral gene pools in different ways and at different times. Clearly, the sample analyzed was not sufficient to capture all of the complex history of C. splendens, but sufficient to indicate the taxa ancilla, waterstoni, and orientalis possibly represent three of the four ancestral gene pools, and originated in western Asia. The origin of the fourth, xanthostoma, is the western Mediterranean.

Immune system activation interacts with territory-holding potential and increases predation of the damselfly Calopteryx splendens by birds

Activation of the immune system in insects has been shown to be costly in the laboratory setting, but experimental studies in the field are lacking. The costs of immunity in the wild may be different to those in the laboratory because animals in the wild are simultaneously subjected to a suite of selective agents. We have measured the costs of immune system activation in a wild population of the territorial damselfly Calopteryx splendens. Immune-challenged males were found to be less likely to be territorial and had lower overall survival rates than control or sham-manipulated males. Because territorial males have a higher mating success than nonterritorial males, this result suggests that immune-challenged males are also likely to suffer reduced mating success. However, the activation of the immune system as such did not increase predation risk; this occurred due to a combination of the former with a reduced territory-holding potential. As such, immune-challenged males not holding a territory were most susceptible to predation by birds. The size of the wing spots, a known sexually selected male trait, predicted territorial behaviour in control and sham-manipulated males, but not in immune-challenged males. Our data show that immune system activation can have several costs acting in unison and that ubiquitous ecological interactions, such as predation, may affect trade-offs between immunity and other life history traits.

Dragonflies from northern Syria

Nineteen stations distributed across the northern part of Syria were inventoried for dragonflies between 2006 and 2010. About 37 species were recorded, and four species are added to the list of known Syrian species. Because of a generalized decrease in the water quality of Syrian rivers, and an increasing number of rivers falling dry, lotic species such as the calopterygids have suffered and the remaining populations have become reduced to disjunct islands. Calopteryx splendens hyalina, once extending from Lake Hula to the Wadi Afrin, now appears to have become extinct in the Orontes valley, and only survives in few short Syrian coastal rivers.

Alternative reproductive tactics and the propensity of hybridization

One explanation for hybridization between species is the fitness benefits it occasionally confers to the hybridizing individuals. This explanation is possible in species that have evolved alternative male reproductive tactics: individuals with inferior tactics might be more prone to hybridization provided it increases their reproductive success and fitness. Here we experimentally tested whether the propensity of hybridization in the wild depends on male reproductive tactic in Calopteryx splendens damselflies. Counter to our expectation, it was males adopting the superior reproductive tactic (territoriality) that had greatest propensity to hybridize than males adopting the inferior tactics (sneakers and floaters). Moreover, among the territorial males, the most ornamented males had greatest propensity to hybridize whereas the pattern was reversed in the sneaker males. Our results suggest that there is fluctuating selection on male mate discrimination against heterospecific females depending on both ornament size and the male's reproductive tactic.

Crystalline wax coverage of the imaginal cuticle inCalopteryx splendens(Odonata: Calopterygidae)

Abstract In this study we use high resolution SEM to describe the diversity of wax crystals and their distribution on different morphological structures in male individuals of Calopteryx splendens. The entire cuticle surface of this damselfly, with the exception of ommatidia and ocelli, is covered with crystalline wax in dimensions from submicron to micron range. It is shown that shape - rod-like, plate like, filamentous, etc. -, size, and density of crystals vary on different surfaces and in individuals of different ages. Additionally, we demonstrate different types of damage to the crystalline wax layer: scratches, compressions, wear, and contamination. The primary function of the wax crystalline coverage in odonates is, presumably, reduction of surface wettability by water (superhydrophobicity). However, other functions are also discussed, especially in such specialized body areas as postero-ventral parts of male abdomen, the so called ‘lantern’.

Males do not catch up with females in pursuing flight inCalopteryx splendens(Odonata: Calopterygidae)

Abstract In high densities males of Calopteryx splendens showed alternative reproductive behaviour at the river Oker in northern Germany. One of several tactics was to pursue females. Pursuing flight was filmed in summer 2006 in slow motion. Frame by frame analysis showed that males fly in irregular flight patterns: they showed different lengths of wing beat phases in comparison to females which fly more steadily. Females had significantly lower wing beat frequencies than males. The flight patterns of males depended on their position to other pursuing males and to the pursued female. The possible causes of these flight differences are discussed.

Variation in morphology between core and marginal populations of three British damselflies

As selective pressures are altered by the changing climate, species have been shown to shift their distributions. Here we investigate morphological variation in dispersal-related traits between core and marginal populations in three species of Odonata, a taxon that is known to be expanding polewards. We sampled individuals of (i) Calopteryx splendens, a species with a rapidly expanding range, (ii) Erythromma najas, a species with a slowly expanding range, and (iii) Pyrrhosoma nymphula, a species that does not exhibit a range margin in the UK (as a control). Only C. splendens exhibited consistent trends within two dispersal-related traits (wing:abdomen length ratio and aspect ratio). This result suggests that proximity to range margin alone does not account for variations in damselfly morphology, but that the rate of range expansion may also be important in determining variation.

SIMULATING RANGE EXPANSION: MALE SPECIES RECOGNITION AND LOSS OF PREMATING ISOLATION IN DAMSELFLIES

Prolonged periods of allopatry might result in loss of the ability to discriminate against other formerly sympatric species, and can lead to heterospecific matings and hybridization upon secondary contact. Loss of premating isolation during prolonged allopatry can operate in the opposite direction of reinforcement, but has until now been little explored. We investigated how premating isolation between two closely related damselfly species, Calopteryx splendens and C. virgo, might be affected by the expected future northward range expansion of C. splendens into the allopatric zone of C. virgo in northern Scandinavia. We simulated the expected secondary contact by presenting C. splendens females to C. virgo males in the northern allopatric populations in Finland. Premating isolation toward C. splendens in northern allopatric populations was compared to sympatric populations in southern Finland and southern Sweden. Male courtship responses of C. virgo toward conspecific females showed limited geographic variation, however, courtship attempts toward heterospecific C. splendens females increased significantly from sympatry to allopatry. Our results suggest that allopatric C. virgo males have partly lost their ability to discriminate against heterospecific females. Reduced premating isolation in allopatry might lead to increased heterospecific matings between taxa that are currently expanding and shifting their ranges in response to climate change.

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.

Resistance to ship‐induced waves of benthic invertebrates in various littoral habitats

Summary1. Ship‐induced waves disturb benthic invertebrate assemblages colonizing littoral zones of lakes and rivers. However, the impact of ship‐induced waves on invertebrates has rarely been quantified, and the influencing factors have not been addressed.2. In an experimental wave tank, five benthic invertebrate species, Bithynia tentaculata, Calopteryx splendens, Dikerogammarus villosus, Gammarus roeseli and Laccophilus hyalinus, were exposed to waves of increasing shear stress (0.43–2.19 N m−2). Mean number of detached individuals was recorded for five littoral habitats [coarse woody debris (CWD), reeds, sand, stones and tree roots], representing different levels of structural complexity as quantified by their fractal dimensions (FD).3. Results showed that detachment of invertebrates was significantly related to shear stress in all habitats except tree roots. Detachments averaged for the five species were significantly lower in habitats with a high degree of structural complexity, decreasing in the habitat sequence: sand, CWD, stones, reeds and tree roots.4. Consistent with their different morphologies and methods of attachment to substrates, the five species displayed differences in their response to hydraulic stress that were dependent on habitat.5. The increasing sheltering effect of structural habitat complexity was mirrored by increasing dissipation of the kinetic energy of waves; i.e. the FD of the habitat was positively correlated with shear stress reduction due to the flow resistance of the habitat.6. Network habitats such as tree roots provided the best sheltering conditions against hydraulic disturbance, because they combined good refuge availability for all studied invertebrate species and maximal dissipation of kinetic wave energy. Consequently, persistent anthropogenic impacts, such as lakeshore modification or long‐term exposure to ship‐induced waves, which cause disappearance of complex littoral habitats such as tree roots or dense reed belts, will drastically increase the adverse effects of boating and ship traffic on littoral invertebrate assemblages.

Hybridization in Calopteryx damselflies: the role of males

Females are often considered responsible for hybridization between two species because usually they are the choosier sex and their cooperation is needed for successful copulation. However, males can also be responsible for hybridization, for example in species in which males are able to force copulation. We studied the pattern of hybridization in two congeneric damselfly species, Calopteryx splendens and Calopteryx virgo, and provide evidence that F1 hybrids between the two damselfly species occur in the wild. According to mitochondrial DNA analysis, hybridization is reciprocal: five of seven hybrids were sired by C. splendens and two by C. virgo males. We conducted an experiment that revealed that males of both species have surprisingly poor premating reproductive isolation in that they accept heterospecific females, but C. splendens males were less discriminating against con- and heterospecific females than were C. virgo males. Moreover, our data on the number of hybrids sired by either species in the wild are congruent with the results of the discrimination experiment, supporting the conclusion that males may be responsible for the hybridization. Our results suggest that the males' role in hybridization studies should no longer be neglected.

Morphological clines in dendritic landscapes

Summary1. In complex landscapes such as river networks, organisms usually face spatio‐temporal heterogeneity and gradients in geomorphological, water, ecological or landscape characteristics are often observed at the catchment scale. These environmental variables determine developmental conditions for larval stages of freshwater insects and influence adult phenotypic characteristics. Environmental clines are therefore expected to generate morphological clines. Such a process has the potential to drive gradual geographical change in morphology‐dependent life history traits, such as dispersal.2. We studied the influence of aquatic and terrestrial environmental factors on morphological variations in Calopteryx splendens across the Loire drainage. To investigate these effects we took explicitly into account the hierarchical structure of the river network.3. We analysed eight morphological traits. Results showed significant body size variation between tributaries and the presence of a morphological cline at the drainage scale. We observed an effect of pH and water temperature on body size. Individuals in downstream sites were larger than individuals in upstream sites, and adults whose larval stages were exposed to alkaline pH and high temperatures during summer were larger.4. Body size affects flight abilities in insects. Thus, our results suggest that morphological clines may generate an asymmetric dispersal pattern along the downstream–upstream axis, downstream populations dispersing farther than upstream ones. Such a process is expected to influence population genetic structure at the drainage scale if larval drift and floods do not balance an asymmetrical dispersal pattern of adults along the downstream–upstream gradient. To assess the influence of environmental gradients on the variation of life history traits it is important to understand the population biology of freshwater insects, and more generally of riverine organisms. It is also essential to integrate such data in conservation or restoration programmes.