Abstract
Studies on 2 sympatric morphologically identical populations ofAphytis mytilaspidis Le Baron frpm Greece were conducted on their mating behavior, reproductive isolation, hybridization in the laboratory, host preferences and adult survivorships at different temperatures. These studies revealed that the 2 populations were partially reproductively isolated and qualify at least for the rank of strong “semispecies” with respect to one another. Marked differences were also recorded in their host preferences and adult survivorships at different temperatures. Gene flow among these populations in nature is likely to occur only in one direction. Differences in host preference may further reduce gene flow by providing ecological reproductive isolation. Also hybrid sterility is indicated which if complete would prove these 2 forms to be sibling species. Based on the experimental evidence, an hypothesis is presented that these 2 populations represent a case of incipient if not complete sympatric speciation, with the presumed descendant population (R-69-120) possessing a broader host range and better adult longevity, in comparison to the proposed progenitor population (R-63-63-4).
Résumé
L'étude de deux populations sympatriques identiques au point de vue morphologie deAphytis mytilaspidis Le Baron originaires de Grèce a été réalisée à propos de leur comportement d'accouplement, leur isolement sexuel, leur hybridation en laboratoire, le préférence en hôtes et la longévité des adultes à différentes températures. Il apparaît que les deux populations sont partiellement isolées au point de vue reproduction et peuvent être qualifiées au moins de «demi espèces» l'une par rapport à l'autre. Des différences notables se manifestent également dans les préférences pour tel ou tel hôte et dans les survies des adultes selon les températures. Le flux de gènes dans ces populations dans la nature se produit vraisemblablement seulement dans une direction. Les différences dans les préférences vis-à-vis des hôtes peuvent en outre réduire le flux de gènes en assurant un isolement écologique de la reproduction. La stérilité des hybrides si elle était complète prouverait que ces deux formes sont des espèces sœurs.
A partir de ces faits expérimentaux l'hypothèse est formulée que ces deux populations correspondent à un début sinon à une spéciation sympatrique complète, avec une population descendante présumée (“R-69-120”) ayant une gamme d'hôtes plus large et une plus grande longévité imaginale par rapport à la population proposée comme géniteur (“R-63-63-4”).
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This study was a part of the Ph. D. dissertation of the senior author submitted to the University of California, Riversiae. Financial support through grant Nos. GB 7444 and GB 17829 of the Nional Science Foundation awarded toP. DeBach is gratefully acknowledged.
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Khasimuddin, S., DeBach, P. Biosystematic and evolutionary statuses of two sympatric populations ofAphytis mytilaspidis [Hym.: Aphelinidae] . Entomophaga 21, 113–122 (1976). https://doi.org/10.1007/BF02372022
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DOI: https://doi.org/10.1007/BF02372022