Dainty damselfly

Dainty damselfly
Male C. scitulum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Suborder: Zygoptera
Family: Coenagrionidae
Genus: Coenagrion
Species: C. scitulum
Binomial name
Coenagrion scitulum
(Rambur, 1842)
Male Dainty Damselfly

The Dainty damselfly (Coenagrion scitulum), also known as the Dainty bluet, is a blue damselfly of the family Coenagrionidae. This is a scarce species found mainly in southern Europe, northern Africa, southwest Asia, and Central America. Coenagrion scitulum are Odonata (dragonflies & damselfly's) predators that can reach a length of 30–33 mm at maturity and have hind-wing lengths of 15–20 mm.[1] The males and females do exhibit differing features through their colouration making them easily distinguishable. As shown in the photo to the left, segment eight is blue in colour followed by black markings on segment nine, whereas the females are mostly black near the rear with smaller blue markings.[2] Although they are relatively simple to sex, they are easily confused with the Common Blue Damselfly.[2]

Habitat

Coenagrion scitulum are found in large and generally stagnant,[3] ponds with abundant vegetation including water-milfoil and hornwort, they can also be found in flooded ditches.[1] It has also been discovered that constructed wetlands are an important habitat and sanctuary for Coenagrion scitulum. This is because these areas lack fish that prey on insects giving the Dainty damselfly a safe habitat to live and reproduce in.[4] They are most easily spotted during the months of June and July and males can be most easily observed perched on floating vegetation in open water.[1] Although Dainty damselfly's are quite small they do have the ability to travel distances between ponds if resources become sparse and if the benefits outweighs the cost.[5] We also see evidence of their movement through the recolonisation of the lost population in Britain.

Reproduction

Mating damselflies

Coenagrion scitulum exhibits unique mating habits than other Odonates. In damselfly reproduction there is indirect insemination. The male damselfly will pass their sperm from the testes to the penis in order for the female to obtain it from them.[6] This translocation of sperm only happens once in all other species of damselflies. In Coenagrion scitulum this process happens upwards to six times during the copulation cycle.[6] There are a few hypothesis as to why this process may occur one of them being that several sperm translocation's may be needed to achieve full insemination.[6] After this process is done and the female has successfully fertilized her eggs she then lays them. The male is usually still attached the female at this point to stop other males from removing their sperm, although sperm removal is harder in C. scitulum as they do not have the spines on the horns of their penis as other damselflies do. The dainty damselfly seems to be univoltine in their core populations and in their expansion populations, this was exhibited when ponds were sampled and they showed that each was a separate population.[7]

The photo to the left shows the mating embrace that damselflies exhibit. Please note that these are not Dainty Damselflies, they are more likely to be Common Blue Damselflies.

Status

Male C. scitulum

The Dainty Damselfly was formerly recorded as a breeding species in Britain and had thought to have become locally extinct after the North Sea flood of 1953.[8][9] There was a large viable population in East Anglia, but after the flood many seasons passed by without any sightings of the Dainty Damselfly leading to the conclusion that they had gone extinct. In 2010, after 57 years without sightings, it had been positively identified and rediscovered in Kent.[8][9][10] This meant that there had to of been a viable population all along, it just had diminished to critical numbers. The Dainty Damselfly is able to disperse quite widely so it is a possibility that a neighbouring population made its way back into the area.

The current status of C. scitulum according to IUCN Red List is of 'least concern', meaning that they feel the population is exhibiting stable characteristics and is following an increasing population trend.[11]

Distribution & Geographic Movement

Distribution

The Dainty Damselfly is mostly found in Western Europe, Northwest Africa, Western Caspian and the South Caucasus regions.[11] There seems to be another population of Coenagrion scitulum in Central Asia and its not clear if this is a separate species or if they travelled from the European population across the mountains of Afghanistan and Northern Iran.[11]

Geographic Movement

Male C. scitulum

There are many factors contributing to the geographic movement of Coenagrion scitulum some of these include changing temperatures, land disruption and decreasing water levels. The number one cause of dispersal in Dainty damselflies is rising temperatures as they tract their optimal thermal niche to new locations.[12] In the 1990s the most Northern Edge of their range was located in Northern France.[7] Due to climate change though there has been an increased poleward distribution, and now the Dainty damselflies populations have expanded from historical ranges and has founded edge populations in a northward, eastward and westward direction.[7][13][14]

This poleward expansion has been associated with rapid phenotypic change and founder effects including reduction in genetic diversity and increases in genetic differentiation.[7][15] It has been found that the new edge populations are genetically differentiated from the core populations and all of the new populations were differentiated from each other giving indication that each range expansion is independent.[15] There are some issues with the changes in genetic diversity though. There has been studies completed on the Dainty damselfly showing that genetic diversity can influence the success of colonisation and can decrease resistance to stress and disease.[7] This can make the insect more susceptible to toxins such as pesticides which in turn also affects the Dainty damselflies ability to continue their dispersal through slow movement, reduced population growth and flight ability.[12] The Dainty damselflies are being exposed to pesticides more frequently due to their dispersal and need to cross agricultural land to reach new habitats. Its not just dispersal due to climate change that causes the genetic changes in the Dainty damselfly though, it can also happen due to natural range expansion as well.[7] The genetic diversity and structure of Dainty damselflies are shaped by both historical rapid range expansions and contemporary processed causing dispersal like environmental factors (climate change).[13]

External links

YouTube Video

References

  1. 1 2 3 Smallshire, David; Swash, Andy (2014). Britain's Dragonflies: A Field Guide to the Damselflies and Dragonflies of Britain and Ireland : A Field Guide to the Damselflies and Dragonflies of Britain and Ireland. p. 84 – via EBSCOhost.
  2. 1 2 3 "Dainty Damselfly | british-dragonflies.org.uk". www.british-dragonflies.org.uk. Retrieved 2016-11-23.
  3. 1 2 Dragonflypix.com. "Dainty Bluet: 20 Photos". www.dragonflypix.com. Retrieved 2016-11-24.
  4. ↑ Gallardo, Belinda; García, Mercedes; Cabezas, Álvaro; González, Eduardo; González, María; Ciancarelli, Cecilia; Comín, Francisco A. (2008-07-01). "Macroinvertebrate patterns along environmental gradients and hydrological connectivity within a regulated river-floodplain". Aquatic Sciences. 70 (3): 248–258. doi:10.1007/s00027-008-8024-2. ISSN 1015-1621.
  5. ↑ Angelibert, S; Giani, N (2003). "Dispersal characteristics of three odonate species in a patchy habitat". Ecography. 26: 13–20.
  6. 1 2 3 CORDERO, ADOLFO; SANTOLAMAZZA-CARBONE, SERENA; UTZERI, CARLO (1995-02-01). "Male disturbance, repeated insemination and sperm competition in the damselflyCoenagrion scitulum(Zygoptera: Coenagrionidae)". Animal Behaviour. 49 (2): 437–449. doi:10.1006/anbe.1995.0057.
  7. 1 2 3 4 5 6 Swaegers, Janne; Mergeay, Joachim; St-Martin, Audrey; De Knijf, Geert; Larmuseau, Maarten H. D.; Stoks, Robby (2015-08-01). "Genetic signature of the colonisation dynamics along a coastal expansion front in the damselfly Coenagrion scitulum". Ecological Entomology. 40 (4): 353–361. doi:10.1111/een.12189. ISSN 1365-2311.
  8. 1 2 "Coenagrion scitulum". British Dragonfly Society. Retrieved 27 May 2011.
  9. 1 2 Ettinger, P. "Wildlife Extra News - Absent damselfly re-discovered in Britain after 57 years". www.wildlifeextra.com.
  10. ↑ Richard, Black (21 July 2010). "Beautiful 'lost' insect turns up anew in UK". BBC News. Retrieved 9 August 2010.
  11. 1 2 3 4 "Coenagrion scitulum (Dainty Damselfly)". www.iucnredlist.org.
  12. 1 2 Dinh, Khuong Van; Janssens, Lizanne; Therry, Lieven; Gyulavári, Hajnalka A.; Bervoets, Lieven; Stoks, Robby (2016-03-01). "Rapid evolution of increased vulnerability to an insecticide at the expansion front in a poleward-moving damselfly". Evolutionary Applications. 9 (3): 450–461. doi:10.1111/eva.12347. ISSN 1752-4571. PMC 4778112Freely accessible. PMID 26989436.
  13. 1 2 Swaegers, J.; Mergeay, J.; Therry, L.; Bonte, D.; Larmuseau, M. H. D.; Stoks, R. (2014-04-01). "Unravelling the effects of contemporary and historical range expansion on the distribution of genetic diversity in the damselfly Coenagrion scitulum". Journal of Evolutionary Biology. 27 (4): 748–759. doi:10.1111/jeb.12347. ISSN 1420-9101.
  14. ↑ Swaegers, J.; Mergeay, J.; Therry, L.; Larmuseau, M. H. D.; Bonte, D.; Stoks, R. (2013-11-01). "Rapid range expansion increases genetic differentiation while causing limited reduction in genetic diversity in a damselfly". Heredity. 111 (5): 422–429. doi:10.1038/hdy.2013.64. ISSN 0018-067X. PMC 3806023Freely accessible. PMID 23820582.
  15. 1 2 Swaegers, J.; Mergeay, J.; Van Geystelen, A.; Therry, L.; Larmuseau, M. H. D.; Stoks, R. (2015-12-01). "Neutral and adaptive genomic signatures of rapid poleward range expansion". Molecular Ecology. 24 (24): 6163–6176. doi:10.1111/mec.13462. ISSN 1365-294X.
  16. ↑ "Dainty Bluet – Coenagrion scitulum –". dragonflyphotofavourites.co.uk. Retrieved 2016-11-24.
  17. ↑ Paul Hopkins (2011-06-20), Dainty Damselfly, retrieved 2016-11-23
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