Wing length and asymmetry of male Tokunagayusurika akamusi chironomid midges using alternative mating tactics |
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Authors: | Takamura Kenzi |
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Institution: | National Institute for Environmental Studies, 16-2 Onogawa, Tukuba,
Ibaraki 305-0053, Japan |
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Abstract: | Male Tokunagayusurika akamusi chironomids have alternative mating
tactics.One is to search for females on vegetation (ground mating),and the
other is to wait for females in an aerial swarm (swarmmating). Simultaneous
sampling of ground-unpaired and ground-pairedmales and of swarm-unpaired and
swarm-paired males were performed.The average wing length and right-left wing
length difference(wing asymmetry) were compared between males from the four
differentcategories. Swarm-unpaired males were larger than ground-unpaired
ones,swarm-paired males were larger than swarm-unpaired ones, and
ground-pairedmales were not larger than ground-unpaired ones. Thus, large
malestended to aggregate in swarms, and larger swarming males matedmore
successfully. On the other hand, small males probably enjoyedmating on the
ground, especially when large males swarmed. Thewing asymmetry was not
significantly different between unpairedand paired males both within and
between tactics. There wasa flat or U-shaped relationship between wing length
and asymmetry,underpinning the lack of a symmetrical advantage of swarmingto
large males. The right-left difference was not normally distributedin four of
six samples of unpaired males but, in contrast, wasnot normally distributed
in only one of six samples of pairedmales. The non-normal distributions were
leptokurtic and includedoutliers. Removal of the outliers improved normality,
suggestingthat males with extremely asymmetric wings were not successfulin
mating. |
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Keywords: | chironomids alternative mating tactics fluctuating asymmetry normal distribution outliers swarm Tokunagayusurika akamusi wing length |
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