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1. Initial preference of oviposition sites: discrimination between living and dead plant material in Sympecma fusca and Coenagrion caerulescens (Odonata: Lestidae, Coenagrionidae)

Creator:
Martens, Andreas
Type:
article, model:article, and TEXT
Subject:
Odonata, Zygoptera, Lestidae, Coenagrionidae, Sympecma fusca, Coenagrion caerulescens, reproductive behaviour, oviposition site selection, and aggregation behaviour
Language:
English
Description:
Sympecma fusca and Coenagrion caerulescens mainly deposit their eggs into floating dead parts of emergent plants. In their initial choice of oviposition site (selection of landing site) S. fusca does not distinguish between fresh and dead plant material, whereas C. caerulescens significantly prefers dead material. In S. fusca, the missing discrimination of the plant condition in the choice of the landing site is explained by its oviposition period in the beginning of the vegetation period when the green plant material is rare. C. caerulescens reproduces in summer and finds dead and living plants side by side. I suggest that in the latter species an early recognition of dead material is advantageous because of the reduction of the expense in searching.
Rights:
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2. Long range movements by individuals as a vehicle for range expansion in Calopteryx splendens (Odonata: Zygoptera)

Creator:
Ward, Louise and Mill, Peter
Type:
article, model:article, and TEXT
Subject:
Zygoptera, Calopteryx splendens, dispersal, migratory movements, non-migratory movements, range expansion, and territoriality
Language:
English
Description:
1. Flight activity in zygopterans is generally restricted to short-range movements associated with foraging, reproductive activity and escape. Indeed, previous studies have suggested that Calopteryx species, including C. splendens, are relatively sedentary species, with a low tendency for long distance movements. 2. Recent observations suggest that C. splendens is expanding its northern range in the UK; in the northeast the species is now well established in Northumberland and, in the northwest, has recently spread into south-west Scotland. The current study aimed to investigate the mobility and dispersal tendency of C. splendens in a well-established breeding population in NE England. 3. A mark-release-recapture study was carried out on a population of C. splendens along a section of the River Wharfe, West Yorkshire, UK. 831 adult C. splendens were marked uniquely for individual identification in order to monitor the day-to-day, and overall, distance and direction of movement for each individual. Of these 381 were recaptured at least once. 4. The majority of males (85%) and females (88%) moved a distance of 100 m or less and only five of the recaptured individuals (1.3%) moved a minimum distance in excess of 500 m. Although the median distance moved by males was greater than that for females, this was not significant. In addition, there was no significant difference in the number of either males or females moving upstream as opposed to downstream. 5. The results are compared with those from other studies on calopterygid movement. Although most individual C. splendens stay within a suggested home range of approximately 300 m, clearly individuals have the potential to cover relatively long distances, and it is these latter movements that play a fundamental role in increasing the range of the species.
Rights:
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3. Preference of larvae of Enallagma cyathigerum (Odonata: Coenagrionidae) for habitats of varying structural complexity

Creator:
Verdonschot, Ralf C.M. and Peeters, Edwin T.H.M
Type:
article, články, model:article, and TEXT
Subject:
Zoologie, zoologie, entomologie, Enallagma cyathigerum, habitat complexity, macroinvertebrate-macrophyte interaction, Zygoptera, phytomacrofauna, two-choice experiment, 2, and 59
Language:
English
Description:
n macrophyte-rich lentic ecosystems, higher numbers of damselfly larvae occur in areas where there is structurally complex vegetation than in those where the plant architecture is relatively simple. Biotic interactions rather than morphological constraints are considered to underlie this pattern. We investigated whether the preference of the larvae of the damselfly Enallagma cyathigerum for a particular habitat was retained in absence of prey, predators and/or conspecifics. A series of laboratory choice experiments was conducted in which combinations of sediment and artificial plants differing in structural complexity were offered simultaneously to the larvae. Larvae preferred patches with structurally complex vegetation over patches with simply structured vegetation or lacking vegetation. Patches with simply structured vegetation were preferred over those with bare sediment, but the number of larvae showing a clear choice, which is regarded as an indication of the strength of the preference for a particular habitat, was relatively low compared to the number of individuals responding when complex vegetation was present. Based on the results presented, we conclude that the preference of E. cyathigerum larvae for structurally complex vegetation is independent of the presence of predators, prey or competitors. This suggests that this behaviour of the larvae is either learned or an innate response., Ralf C.M. Verdonschot, Edwin T.H.M. Peeters., and Obsahuje seznam literatury
Rights:
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4. The development of sexual differences in body size in Odonata in relation to mating systems

Creator:
Serrano-Meneses, Martin-Alejandro, Azpilicueta-Amorín, Mónica, Székely, Tamás, and Córdoba-Aguilar, Alex
Type:
article, model:article, and TEXT
Subject:
Odonata, Anisoptera, Anax imperator, Cordulegaster boltonii, Onychogomphus uncatus, Oxygastra curtisii, Zygoptera, Cercion lindeni, Ischnura graellsii, Platycnemis acutipennis, and sexual size dimorphism
Language:
English
Description:
Adult body size is the result of important environmental, maternal and/or genetic effects acting on animals during development. Here we investigate how sexual size dimorphism (SSD) develops in seven species of Odonata: Anax imperator, Cordulegaster boltonii, Onychogomphus uncatus, Oxygastra curtisii (Anisoptera), Cercion lindeni, Ischnura graellsii and Platycnemis acutipennis (Zygoptera). SSD of both the last larval and adult stages of the same individuals, which were reared under laboratory conditions, was measured. The aims were to investigate (i) whether SSD develops during the larval stage, (ii) the direction of larval and adult SSD, and (iii) whether the direction of adult SSD can be predicted by the mating system of a given species (e.g. males of territorial species being larger than females and the opposite for non-territorial species). We found that although larval differences in size may be present between the sexes, these are not necessarily shown in the adult stage (they may change or disappear). Also, the mating system was not related to patterns of adult SSD. Differences in SSD in larvae may be caused by differential use of resources via differential niche-utilisation or sex-specific growth patterns. We highlight the fact that sexual selection favouring large male size and fecundity selection, which selects for large females may be acting on the observed patterns in SSD in adults.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public