title: [Assortative mating and maintenance of intrapopulation polymorphism in wild populations and laboratory cultures of insects].
abstract: Speciation as a micro-evolutionary process begins with emerging of intraspecies differentiation, which is associated with establishment of reproductive isolation. One of intrinsic isolation factors ensuring physiological isolation is assortative mating. In course of long-term field observations in the Southern Urals (Republic of Bashkortostan) and prolonged laboratory experiments, we have detected assortative mating in populations of potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). Three morphotypes were singled out by the extent of integument melanization, namely achromists (A), melanists (M), and intermediate type (I), and frequency of occurrence of these morphotypes imago pairs significantly deviated from random distribution, thus manifesting the assortative mating. Under in copulo conditions, mating between achromist males (A) and melanist females (M) where active choice belonged to males was not registered. In.laboratory experiments, in the sample of 40 artificially formed pairs, there were detected significant differences in longevity and fecundity of different morphotype imagoes. Achromists and melanists had significantly (almost two times) higher longevity as compared with intermediate type. Females of intermediate type were significantly more fecund in homonomous crossings than achromists and melanists. It is shown that pairs offspring also differs significantly in viability, with highest viability being characteristic for offspring from females of A- and I-type. The differences revealed are indicative of different reproductive strategies that exist in populations. In laboratory line S of house fly Musca domestica L. (Diptera: Muscidae) the presence of individuals with different reproductive strategies related to longevity is detected. Maximum longevity in inbred lines Sh28 (short living) and L2 (long living), isolated from the line S, significantly differed almost twofold. In the line of short living flies, mass reproduction occurs on the first-second week of imago stage, while in long living flies it is put off to the third-fourth week. In reciprocal crossings between the lines, drastic reduction in females fecundity is observed as well as reduction in viability of females from hybrid offspring. The results obtained are indicative of substantial role of assortative mating and frequency-dependent selection in maintenance of intrapopulation diversity.
authors: G V
authors: GV
authors: Benkovskaya
authors: Yu M
authors: YM
authors: Nikonorov
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001517:Coleoptera / Q000235:genetics / Q000502:physiology; D005260:Female; D005298:Fertility / Q000235:genetics; D049810:Genetic Speciation; D005828:Genetics, Population; D008136:Longevity / Q000235:genetics* / Q000502:physiology; D008297:Male; D011110:Polymorphism, Genetic; D060047:Reproductive Isolation; D012641:Selection, Genetic / Q000235:genetics*; D012726:Sexual Behavior, Animal