Hybrid sterility in crosses between two Brazilian sibling species of the Anopheles albitarsis complex.

Nathalia Giglio Fontoura,José Bento Pereira Lima,Alejandra Saori Araki,Renata Van Der Maas Azevedo,Allan Kardec Ribeiro Galardo,Alexandre Afranio Peixoto

doi:10.1186/s13071-014-0559-6

Abstract

BackgroundComplexes of cryptic species are common in several taxa and this is also the case in the Anopheles genus, a group including all known human malaria vectors. The Anopheles albitarsis complex comprises at least nine cryptic species, some of which are implicated as vectors of human malaria. Several different types of data have been generated for this species complex such as cytogenetics, alloenzymes, morphological and feeding behavioral, hybridization experiments, RAPD-PCR and RFLP and mitochondrial and nuclear markers. Studies focused on its postzygotic isolation are still somewhat rare in the literature despite their importance to understand the speciation process and the level of gene flow potentially occurring among the different sibling species.MethodsHybridization experiments between Anopheles albitarsis s.s. and Anopheles marajoara, as well as backcrosses between hybrids and Anopheles albitarsis s.s., were performed using the induced mating technique. Results were compared to intraspecific crosses. Larva-to-adult viability and sex ratio were also assessed.ResultsMale hybrids show very low insemination rates and nearly complete sterility, apparently due to abnormalities in their reproductive organs. Evidence of partial sterility among the hybrid females was also observed.ConclusionsOur data indicated that Anopheles albitarsis s.s. and Anopheles marajoara show a high level of postzygotic isolation with a strong hybrid male sterility. This result is consistent with the Haldane’s rule which states that in interspecific crosses the heterogametic sex is the first to be affected. However, the fact that the females are not completely sterile raises the possibility of introgression between these two siblings species.

Highlights

Complexes of cryptic species are common in several taxa [1,2] and this is the case in the Anopheles genus, a group including all known human malaria vectors [3,4]
The number of species within the Anopheles albitarsis complex can be even higher as An. deaneorum and An. marajoara might include more than one sibling species [9,25]
Specimens were identified as Anopheles albitarsis s.l. according to Faran & Linthicum [31] and were considered as An. marajoara based on Conn et al [7]

Summary

Introduction

Complexes of cryptic species are common in several taxa and this is the case in the Anopheles genus, a group including all known human malaria vectors. The Anopheles albitarsis complex comprises at least nine cryptic species, some of which are implicated as vectors of human malaria. Complexes of cryptic species are common in several taxa [1,2] and this is the case in the Anopheles genus, a group including all known human malaria vectors [3,4]. Anopheles albitarsis s.l. Lynch-Arribálzaga is widely distributed from northern Guatemala to northern Argentina [6] and is a complex of cryptic species that includes some. The number of species within the Anopheles albitarsis complex can be even higher as An. deaneorum and An. marajoara might include more than one sibling species [9,25]

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Results

Discussion

Conclusion