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The adaptive and evolutionary significance of wing polymorphism and parthenogenesis in Ptinella Motschulsky (Coleoptera: Ptiliidae)
Author(s) -
TAYLOR VICTORIA A.
Publication year - 1981
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1111/j.1365-2311.1981.tb00975.x
Subject(s) - alate , parthenogenesis , biology , fecundity , sex ratio , zoology , offspring , ecology , inbreeding , aphid , genetics , embryo , botany , aphididae , population , homoptera , pest analysis , demography , pregnancy , sociology
.1 The incidence of wing polymorphism varies seasonally in field populations of Ptinella aptera and Ptinella errabunda with alatae increasing in abundance in summer. 2 In laboratory cultures of P. aptera alate development varies with temperature. This implies that morph determination is based on a physiological switch sensitive to temperature and possibly other adaptively relevant environmental factors. 3 Alate P. aptera produce a higher proportion of alate offspring than do apterous parents suggesting an inherited component in polymorphism control, or some form of maternal effect. 4 The female biased sex ratio expected of a regularly inbreeding species was found only in the alate morph. Apterous beetles show a 1:1 sex ratio which is explained by the females' limited capacity to store sperm, the enormous size of the sperm, and the consequent need for multiple insemination. 5 Ptinella errabunda is thelytokous but fails to realize the potentially doubled fecundity associated with parthenogenesis. Both the number of eggs produced and their viability is lower than in bisexual congeners. 6 Enhanced colonizing ability, rather than energy economy, is considered to be the most important selective advantage of parthenogenesis to Ptinella in the subcortical habitat. 7 The spatial and temporal heterogeneity of the subcortical habitat is considered to have favoured the evolution and maintenance of parthenogenesis and wing polymorphism in Ptinella .