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Crossing experiment of Anopheles maculatus form K and Anopheles willmori (James) (Diptera: Culicidae)
Pradya Somboon1, Damrongpan Thongwat, Katy Morgan
1Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. psomboon@mail.med.cmu.ac.th
Abstract:
We recently reported crossing experiments between Anopheles maculatus form K and five members of the Maculatus group to support the specific status of form K. In the present study, we performed further crosses between form K and a sixth species of the Maculatus group, Anopheles willmori (James). Low viability was observed in hybrid males and females. All hybrid males were sterile with atrophied testes, or partially sterile with abnormal spermatozoa. The hybrid females showed normal ovaries. The ovarian nurse cell polytene chromosomes of the F1 hybrid females displayed complete asynapsis. Backcrossing showed low viability. All males were sterile with atrophied testes or partially sterile with abnormal spermatozoa, and the females showed varying degrees of atrophied ovaries. The results provide clear evidence that form K is not conspecific to A. willmori supporting previous studies that form K represents another species of the Maculatus group.
Insights
Anopheles maculatus form K is confirmed as a distinct species, not Anopheles willmori. Hybrid offspring exhibited low viability and sterility, supporting species separation in the Maculatus group.
Area of Science:
- Entomology
- Genetics
- Speciation studies
Background:
- Anopheles maculatus form K's specific status was previously investigated through crossing experiments with five Maculatus group members.
- Further research is needed to solidify the taxonomic classification of Anopheles maculatus form K.
Purpose of the Study:
- To determine if Anopheles maculatus form K is conspecific with Anopheles willmori through cross-breeding experiments.
- To provide additional evidence for the distinct species status of Anopheles maculatus form K within the Maculatus group.
Main Methods:
- Performed interspecific crosses between Anopheles maculatus form K and Anopheles willmori.
- Assessed viability and fertility of F1 hybrid males and females.
- Analyzed reproductive organs (testes and ovaries) and ovarian nurse cell polytene chromosomes in hybrids.
- Conducted backcrossing experiments to evaluate hybrid offspring viability and fertility.
Main Results:
- Hybrid males (F1 and backcrossed) showed sterility with atrophied testes or partial sterility with abnormal spermatozoa.
- Hybrid females (F1) had normal ovaries, but their ovarian nurse cell polytene chromosomes displayed complete asynapsis.
- Backcrossed females exhibited varying degrees of ovarian atrophy.
- Overall low viability was observed in both male and female hybrid offspring.
Conclusions:
- The reproductive incompatibilities observed between Anopheles maculatus form K and Anopheles willmori provide clear evidence of reproductive isolation.
- These findings strongly support that Anopheles maculatus form K is a distinct species, separate from Anopheles willmori.
- The study reinforces previous research classifying Anopheles maculatus form K as a unique species within the Maculatus group.
