Orthetrum Coerulescens Research Articles

A tale of two Skimmers: complex relationships between DNA barcodes, distributions and taxonomy in European Orthetrum cancellatum and O. coerulescens

We explore the genetic diversity and phylogeography of the dragonflies Orthetrum cancellatum and O. coerulescens in Europe based on mitochondrial and nuclear DNA. Orthetrum cancellatum has a clear division between a group comprising Maltese, Italian, and central and northern European populations, and a group comprising mainly populations from southwestern and southeastern Europe, as well as some northern European specimens. We propose that the two groups represent two different Glacial refugia, one in the Italian Peninsula and one in the Balkans where the species survived during the Weichsel Glaciation. Orthetrum coerulescens shows a more complex pattern, although it too can be divided into two groups. One group comprise all the specimens we have identified as O. coerulescens anceps from their phenotype as well as specimens from Spain, Montenegro, and Pakistan, and some specimens from Italiy, Poland and Bulgaria. The other group comprise all other specimens from central and northern Europe, almost all specimens from Italy and Bulgaria, and all specimens from Malta. We propose that the latter group represents an Italian Glacial refugium from which the species spread to both central Europe, Malta and southern Balkan (Bulgaria) after the end of the Weichsel Glaciation. As specimens from Spain and Bulgaria, which were identified as O. coerulescens coerulescens group with specimens identified as O. coerulescens anceps we conclude that the two subspecies mix more or less freely across the Mediterranean and question the validity of two subspecies.

Long-term genetic monitoring of a riverine dragonfly, Orthetrum coerulescens (Odonata: Libellulidae]: Direct anthropogenic impact versus climate change effects.

Modern conservationists call for long term genetic monitoring datasets to evaluate and understand the impact of human activities on natural ecosystems and species on a global but also local scale. However, long-term monitoring datasets are still rare but in high demand to correctly identify, evaluate and respond to environmental changes. In the presented study, a population of the riverine dragonfly, Orthetrum coerulescens (Odonata: Libellulidae), was monitored over a time period from 1989 to 2013. Study site was an artificial irrigation ditch in one of the last European stone steppes and “nature heritage”, the Crau in Southern France. This artificial riverine habitat has an unusual high diversity of odonate species, prominent indicators for evaluating freshwater habitats. A clearing of the canal and destruction of the bank vegetation in 1996 was assumed to have great negative impact on the odonate larval and adult populations. Two mitochondrial markers (CO1 & ND1) and a panel of nuclear microsatellite loci were used to assess the genetic diversity. Over time they revealed a dramatic decline in diversity parameters between the years 2004 and 2007, however not between 1996 and 1997. From 2007 onwards the population shows a stabilizing trend but has not reached the amount of genetic variation found at the beginning of this survey. This decline cannot be referred to the clearing of the canal or any other direct anthropogenic impact. Instead, it is most likely that the populations’ decay was due to by extreme weather conditions during the specific years. A severe drought was recorded for the summer months of these years, leading to reduced water levels in the canal causing also other water parameters to change, and therefore impacting temperature sensitive riverine habitat specialists like the O. coerulescens in a significant way. The data provide important insights into population genetic dynamics and metrics not always congruent with traditional monitoring data (e.g. abundance); a fact that should be regarded with caution when management plans for developed landscapes are designed.

Lifetime egg production of captive libellulids (Odonata)

The estimation of lifetime egg production (LEP) is a central question in ecology, since the number of eggs produced determines the potential size of the following generation. In this study, I tried to obtain a rough estimation of the LEPs in libellulids in outdoor cages. The main questions were: (1) does hand feeding influence females’ life history traits; (2) how long is the maturation period and the lifespan; (3) does the quality/quantity of eggs vary with female age or size; and (4) how many eggs do females lay in their lifetime? I installed two outdoor cages and kept individually marked specimens of Orthetrum coerulescens and Sympetrum striolatum under semi-natural circumstances. Orthetrum coerulescens had a longer life span in hand-fed specimens compared to not hand-fed. The maturation period, number of clutches, clutch size, egg circumference, and LEP did not differ between hand-fed and not hand-fed specimens. The median maturation period was shorter in O. coerulescens (24 days hand-fed; 20 days not...

Hand feeding: a method to increase the survival rate ofOrthetrum coerulescens(Odonata: Libellulidae) in outdoor enclosures

Food intake rate and diet composition have a high impact on all organisms and affect individual fitness, fecundity and mortality. Specimens in enclosures have to be fed in an adequate way and with minimum stress for the specimens. Adult dragonflies are flying hunters. In enclosures, they are usually fed by adding different kinds of adult dipterans. In this study, I additionally fed specimens of Orthetrum coerulescens by hand. Each specimen received one house fly or up to six fruit flies per day. This was less than an adult dragonfly would normally consume; however, this additional hand feeding was enough to significantly increase the survival rate of individuals, especially within the first 12 days of adult life. The maximum life span (subadult and adult) observed was about 60 days, for both hand-fed adults and those that were not hand fed.

Abundance and diversity of dragonflies four years after the construction of a reservoir

Few studies have investigated the impacts of river impoundments on reservoir constructions. Reservoir construction deeply changes dragonflies' habitat structures, especially in relation to shoreline vegetation. This study investigated the effects ofthe impoundment of the Guadiana River and its tributaries on dragonflies four years after the construction of a reservoir. A total of 17 dragonfly species (11 Zygoptera and ten Anisoptera), representing six families, were recorded in 21 sites in the years 1999 and 2003. Aeshna mixta, Coenagrion caerulescens, Coenagrion scitulum, Sympetrum foscolombei, Sympetrum meridionale and Sympetrum striolatum were sampled just before the impoundment took place, and Anax parthenope, Onychogomphus forcipatus, Orthetrum coerulescens, Trithemis annulata, Platycnemis acutipennis and Platycnemis latipes were recorded only after the construction of the reservoir. We concluded that the construction of the Alqueva Reservoir four years earlier did not change the dragonfly species richness, possibly because of species overlap, but that the species composition was modified. Changes in marginal vegetation may have been important to new species compositions.

Habitat requirements ofOrthetrum coerulescensand management of a secondary habitat in a highly man-modified landscape (Odonata: Libellulidae)

Abstract Due to the destruction of its primary habitats, the West Palaearctic libellulid Orthetrum coerulescens has suffered much decline in central Europe. However, at the regional scale it has survived in a variety of secondary habitat, such as draining ditches. In order to find adequate measures for its conservation and promotion, habitat use and habitat recognition of O. coerulescens were investigated by description and experimentation at fenland ditches in a small nature reserve in the Swiss Plateau. This breeding habitat, which harbours a viable population, had been restored and maintained for 25 years. The most densely populated sites comprised small ditches between 40-70 cm wide, with rather sparse vegetation of narrow-leaved plants and that had parts of the water surface uncovered; the peaty, mud ground was partly overgrown with submerged pads of stonewort (Chara spp.). Water was mainly supplied by seepage springs with a mixture of local slow flow that were hardly recognizable and shallow sites, ...

Zur wirklichen Verbreitung von Orthetrum coerulescens (Fabricius) und O. ramburi (Selys) = O. anceps (Schneider) in Europa und die Konsequenzen für deren taxonomischen Rang (Odonata, Libellulidae) ‘Actual distribution and taxonomic rank of Orthetrum coeru

Orthetrum coerulescens (Fabricius) and O. anceps (Schneider) are very closely related forms, the first of which is distributed in Europe farther northwest than the latter. For the distinction of these two forms, only one reliable character (structure of lamina anterior of the 2nd abdominal segment in males) can be utilized. A review of the localities of museum specimens revealed that the two taxa are allopatric with a belt of secondary intergradation along the line of contact. Hybrid populations exist in Sicily as well as in Hungary and former Yugoslavia. Whereas the influence of Orthetrum coerulescens on the phenotypes decreases gradually from west to east on the Balkan peninsula (but is still recognizable even on Crete), the parental forms persist, isolated by the “Strait of Bonifacio”, on Sardinia and Corsica, respectively. Single hybrids have been found, however, far outside the zone of secondary intergradation. It is obvious, hence, that Orthetrum coerulescens and O. anceps are not full species but either members of a superspecies or even subspecies which would have to be united under the older name Orthetrum coerulescens (Fabricius).

A panel of microsatellite markers to detect and monitor demographic bottlenecks in the riverine dragonflyOrthetrum coerulescensF.

Odonates (dragonflies and damselflies) are important indicators for monitoring anthropogenic impacts on freshwater ecosystems. We developed a panel of microsatellite loci for the keeled skimmer Orthetrum coerulescens, a libellulid dragonfly inhabiting small streams. By using two different isolation techniques, nine microsatellite loci have been isolated. Screening of 209 individuals resulted in an overall number of 88 alleles, ranging from three to 19 alleles per locus. The observed heterozygosity ranged from 0.37 to 0.83. One locus showed significant deviation from Hardy–Weinberg equilibrium.

Diel pattern of activity, mating, and flight behaviour inOnychogomphus uncatus(Odonata: Gomphidae)

Abstract The behaviour of Onychogomphus uncatus, including flight and mating activity, was studied at a fast-flowing irrigation canal. During the day, males perched in sections of the canal with a strong current and a turbulent water surface. During short flights, interactions with other con-specific and hetero-specific males occurred, particularly with Orthetrum coerulescens. Under conditions of high population density, the frequent occurrence and disturbances by this species often resulted in male O. uncatus leaving a particular section of the canal. In the late afternoon and evening, males concentrated on ground perches in the vicinity of the water. The reproductive system of O. uncatus was found to be ‘encounter limited’. The operational sex ratio of imagines at the water was always strongly biased in favour of the males. Individual females were observed at the water during the morning and evening hours. Following pair formation there was a prolonged period of copulation away from the water. Most pair...

Sex ratio estimation and survival analysis for Orthetrum coerulescens (Odonata, Libellulidae)

There is controversy over whether uneven sex ratios observed in mature dragonfly populations are a mere artifact resulting from the higher observability of males. Previous studies have at best made indirect inference about sex ratios by analysis of survival or recapture rates. Here, we obtain direct estimates of sex ratio from capture–recapture data based on the Cormack–Jolly–Seber model. We studied Orthetrum coerulescens (Fabricius, 1798) at three sites in the Swiss Jura Mountains over an entire activity period. Recapture rates per 5-day interval were 3.5 times greater for males (0.67, SE 0.02) than for females (0.19, SE 0.02). At two sites, recapture rate increased over the season for males and was constant for females, and at one site it decreased with precipitation for both sexes. In addition, recapture rate was higher with higher temperature for males only. We found no evidence for higher male survival rates in any population. Survival per 5-day interval for both sexes was estimated to be 0.77 (95% CI 0.75–0.79) without significant site-or time-specific variation. There were clear effects of temperature (positive) and precipitation (negative) on survival rate at two sites. Direct estimates of sex ratios were not significantly different from 1 for any time interval. Hence, the observed male-biased sex ratio in adult O. coerulescens was an artifact resulting from the better observability of males. The method presented in this paper is applicable to sex ratio estimation in any kind of animal.

TheOrthetrum coerulescenscomplex in Bulgaria (Odonata: Libellulidae)

Abstract Although there are many records of Orthetrum coerulescens in Bulgaria, the presence of the nominotypical subspecies is doubtful. A critical analysis of all specimens available revealed that they belong either to O. c. anceps or to intermediate forms, but not to O. c. coerulescens. The latter taxon is therefore omitted from the Bulgarian species list, bringing the number of recorded species to 66.

Risky Times? Mortality During Emergence in Two Species of Dragonflies (Odonata: Gomphidae, Libellulidae)

Mortality during emergence in two species of dragonfly, Onychogomphus uncatus and Orthetrum coerulescens, was studied at a Mediterranean irrigation canal in France. Overall mortality was 5.2% (n =1901) and 5.7% (n =611), respectively. Predation was low in both species. The prime cause of mortality was incomplete ecdysis resulting from different factors among which heavy wind was the most important in O. coerulescens and lack of suitable emergence supports in O. uncatus. Besides data on mortality the emergence curves of both species are provided.

Determination of paternity in dragonflies by Random Amplified Polymorphic DNA fingerprinting.

We used Random Amplified Polymorphic DNA (RAPD) fingerprinting to address issues of paternity in two odonate species. Amplification artifacts of RAPD markers were controlled by assessing paternity patterns relative to the banding patterns generated by quantitative mixtures of DNA from putative parents ('synthetic offspring'). In the aeshnid dragonfly Anax parthenope, for which the mating histories of both males and females were unknown, we found strong evidence for complete paternity success for the contact guarding male. In the highly polygamous libellulid dragonfly Orthetrum coerulescens, we detected and quantified mixed paternity in sequentially produced offspring clutches and demonstrated that fertilization success is correlated with the duration of copulation. Our results suggest that RAPD fingerprinting is suitable to address issues of paternity in systems which are genetically uncharacterized and produce large offspring clutches.

Mechanisms of sperm removal and sperm transfer in Orthetrum coerulescens (Fabricius) (Odonata: Libellulidae)

ABSTRACT An account of the structure of the secondary genitalia of male Orthetrum coerulescens (Fabricius) is given together with an outline of the internal genitalia of the female. Observations on the experimental inflation of the penis are described. No sperm was released during fast inflations and deflations of the penis, but sustained inflation of the penis led to the release of a clear fluid followed by the slow discharge of sperm. Examination of natural copulations in the field has shown that rapid rhythmic movements at up to 5 Hz take place in the male's third abdominal segment throughout most of copulation, but towards the end they cease though inflation is maintained. It is suggested that the rapid movements coincide with the removal of rival sperm from the female and that sperm is transferred to the female only during the maintained inflation. Possible mechanisms of sperm translocation, sperm removal and sperm transfer are discussed with reference to male and female genital structures and the action of relevant muscles.

Autosomal fragmentations and fusions in Odonata and their evolutionary implications.

The fragmentation of autosomes in the karyotypes ofEnallagma cyathigerum (Charp.) (n=14→15),Mecistogaster sp. (n=15),Hetaerina rosea Sel. (n=14),Libellula depressa L. (n=12→13),Orthetrum coerulescens (Fabr.) (n=12→13),Diplacodes bipunctata (Br.) (n=13→15) andD. haematodes (Burm.) (n=12→13) is discussed. Original material ofMecistogaster andHetaerina was not available. Fragmentations were found to be the only way in which the recombination index is obligatorily changed (increased) in dragonflies. In at least five out of the seven cases considered the chromosome number is not stabilised: cells in which fragmentation occurred and those in which it did not are found in the same individual (Enallagma, Libellula, Orthetrum, Diplacodes). Fragmentation results in an increase of chromosome number (a) up to the family type number level (Libellula, Orthetrum, D. haematodes), (b) above the latter (Hetaerina) and (c) above any chromosome number ever reported in dragonflies (Mecistogaster, D. bipunctata). In our material the element or elements formed by fragmentation have always the size and usually also the heterochromatic features of the m-chromosomes, irrespective of the presence or absence of the latter in the original complement. A review of species in which fusions of autosomes were recorded or can be assumed is given.Orthetrum brachiale (Beauv.) (n=11) is added to the list. The situation in this species and inSympetrum eroticum Sel. is discussed in detail. The most essential differences between the fusion of (an) autosome (s) with the sex element on one hand (cf.Kiauta, 1969), and the fusion of two or more autosomes on the other, lies in the observations: (a) that in the former case, fused and unfused complements occur in one individual, whereas the latter is specifically characteristic and occurs in all cells, all individuals and all populations of the species, and (b) that autosomal fusion results in an increase of chiasma frequency, due to which the recombination index in secondarily low-n complements remains the same as it was in the primary high-n sets, or becomes even higher (O. brachiale, S. eroticum). Autosomal fragmentation (found so far in some advanced forms only) is considered as a character of phylogenetic advancement. Autosomal fusion, on the other hand, does not have any relation with phylogeny.