Search results for "odonata"

Why are wasps so intimidating: field experiments on hunting dragonflies (Odonata: Aeshna grandis)

2003

Abstract The mechanisms of aposematism (unprofitability of prey combined with a conspicuous signal) have mainly been studied with reference to vertebrate predators, especially birds. We investigated whether dragonflies, Aeshna grandis, avoid attacking wasps, Vespula norwegica, which are an unprofitable group of prey for most predators. As a control we used flies that were painted either black or with yellow and black stripes. The dragonflies showed greater aversion to wasps than to flies. Black-and-yellow-striped flies were avoided more than black ones, suggesting that aposematic coloration on a harmless fly provides a selective advantage against invertebrate predators. There was no signifi…

Interactions and patterns between species diversity and genetic diversity

2015

Risk of Local Extinction of Odonata Freshwater Habitat Generalists and Specialists

2014

Understanding the risk of a local extinction in a single population relative to the habitat requirements of a species is important in both theoretical and applied ecology. Local extinction risk depends on several factors, such as habitat requirements, range size of species, and habitat quality. We studied the local extinctions among 31 dragonfly and damselfly species from 1930 to 1975 and from 1995 to 2003 in Central Finland. We tested whether habitat specialists had a higher local extinction rate than generalist species. Approximately 30% of the local dragonfly and damselfly populations were extirpated during the 2 study periods. The size of the geographical range of the species was negati…

Heterogenic aquatic vegetation promotes abundance and species richness of Odonata (Insecta) in constructed agricultural wetlands

2019

Regional variations in occupancy frequency distributions patterns between odonate assemblages in Fennoscandia

2018

Odonate (damselfly and dragonfly) species richness and species occupancy frequency distributions (SOFD) were analysed in relation to geographical location in standing waters (lakes and ponds) in Fennoscandia, from southern Sweden to central Finland. In total, 46 dragonfly and damselfly species were recorded from 292 waterbodies. Species richness decreased to the north and increased with waterbody area in central Finland, but not in southern Finland or in Sweden. Species occupancy ranged from 1 up to 209 lakes and ponds. Over 50% of the species occurred in less than 10% of the waterbodies, although this proportion decreased to the north. In the southern lakes and ponds, none of the species o…

Odonats del País Valencià: diversitat, factors implicats en la composició de les seues comunitats i respostes als senyals de risc durant la fase d'ou

2017

Libèl·lules i espiadimonis són els noms comuns emprats per a anomenar eixos insectes que tan familiars en resulten i que configuren l’ordre escollit per a la realització d’aquesta tesi doctoral: el dels odonats. D’entre les característiques taxonòmiques que el configuren com a grup, cal destacar dos trets diagnòstics: un de la fase adulta i l’altre de la fase larvària. Un és l’òrgan copulador dels mascles adults, el qual s’ubica en el segon segment abdominal; aquesta característica determina un comportament reproductor exclusiu: durant l’aparellament el mascle doblega l’abdomen per a poder arribar a l’orifici genital de la femella. L’altre tret és la modificació del llavi inferior de les la…

Do allopatric male Calopteryx virgo damselflies learn species recognition?

2012

There is a growing amount of empirical evidence that premating reproductive isolation of two closely related species can be reinforced by natural selection arising from avoidance of maladaptive hybridization. However, as an alternative for this popular reinforcement theory, it has been suggested that learning to prefer conspecifics or to discriminate heterospecifics could cause a similar pattern of reinforced premating isolation, but this possibility is much less studied. Here, we report results of a field experiment in which we examined (i) whether allopatric Calopteryx virgo damselfly males that have not encountered heterospecific females of the congener C. splendens initially show discri…