Works matching Released time

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    Speciation by reinforcement, the process by which characters that increase assortative mating will be favoured because of selection against the production of less fit hybrids, is a much criticized evolutionary scenario, supported by little evidence. Previous studies have focused on hybrid zones, i.e. where different populations come into contact after diverging in allopatry, which might not be the optimal situation in which to look for reinforcement. We argue that reinforcement is more likely to occur in sympatrically diverging populations, like host races of phytophagous insects. In an attempt to demonstrate this we studied mate recognition of different life cycle forms, host races, sister species and more distantly related species of the aphid Cryptomyzus. All but one of these taxa mate on the same host plant, thus their mate recognition is subjected to similar ecological conditions, i.e. extrinsic selection pressures. The males of the life cycle forms and host races were not differentially attracted in an olfactometer by their respective females, which all released sex pheromones during the same period of the day. The females of the sister species, however, released sex pheromones at different times of the day, one 'calling' in the morning and the other in the afternoon. This difference is corroborated by a corresponding pattern of activity in the males, and a marked preference of the males for conspecific pheromone. It is argued that these sister species originated sympatrically following a shift in summer host plant utilization. As their hybrids are less viable than the Fl of intraspecific crosses reinforcement might have been a major force in the development of specific mate recognition, i.e. the specificity and difference in the daily cycle of release of the sex pheromones.

    Published in:
    Biological Journal of the Linnean Society, 1994, v. 52, n. 3, p. 287, doi. 10.1111/j.1095-8312.1994.tb00991.x
    By:
    • GULDEMOND, J. ADRIAAN;
    • DIXON, ANTHONY F. G.
    Publication type:
    Article
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