B. Malmqvist, How does wing length relate to distribution patterns of stoneflies (Plecoptera) and mayflies (Ephemeroptera)?, BIOL CONSER, 93(2), 2000, pp. 271-276
Short wings, and hence a potential for reduced dispersal capacity, can be o
ne of several reasons for rarity in freshwater insects. To test this hypoth
esis, I compared wing lengths, standardised for body length differences, of
stoneflies and mayflies based on published Swedish material. Taking 25% pr
esence as the limit between rare and not rare, rare species indeed had shor
ter wings than those that were classified as not rare. Wing length was not
the sole explanation for rarity as seen in the presence of rare species alo
ng the entire range of wing to body lengths. In both stoneflies and mayflie
s wing lengths were positively related to range sizes. Occupancy showed a p
ositive relationship with wing size in mayflies, whereas in stoneflies the
relationship was not significant, probably because there was no difference
in wing lengths over a range of occupancy values in the common species. Imp
lications for conservation include the importance to identify poor disperse
rs among these groups and describe their habitats, since it can be expected
that recolonisation by poor flyers can be very uncertain and slow after lo
cal extinction. Therefore, localities with rare, poorly-dispersing species
should be protected but if extinction occurs, re-introduction might offer a
possibility to re-establish such insects. (C) 2000 Elsevier Science Ltd. A
ll rights reserved.