Existe barreira de isolamento reprodutivo entre as espécies do subcomplexo vitticeps (Hemiptera, Triatominae)?
Carregando...
Data
2020-02-17
Autores
Sousa, Paulo Sergio de
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Triatoma melanocephala e T. vitticeps foram inicialmente agrupados no subcomplexo T. brasiliensis. Contudo, análises cariossistemáticas demonstraram que essas espécies não deveriam ter sido agrupadas com as espécies desse subcomplexo. Recentemente, T. melanocephala e T. vitticeps foram agrupadas em um novo subcomplexo intitulado T. vitticeps. Essas espécies são irmãs, compartilham características morfológicas e citogenéticas e, sobretudo, existem relatos de possíveis híbridos naturais ocorrendo na natureza. Como essas espécies estão isoladas reprodutivamente de todos os triatomíneos da América do Sul (pela divergência no número de cromossomos), consideramos importante realizar cruzamentos experimentais e avaliar se existem barreiras reprodutivas instaladas entre as espécies do subcomplexo T. vitticeps, pois acredita-se que diversos fatores, como as atuais mudanças climáticas e ambientais provocadas pelo homem, provavelmente, influenciarão no aumento da probabilidade de hibridação para as comunidades futuras, pois estão reorganizando as assembleias de espécies e derrubando as barreiras reprodutivas físicas, temporais e comportamentais, o que pode resultar em eventos de extinção, introgressão, ou, até mesmo, especiação. Assim, analisou-se se as espécies do subcomplexo T. vitticeps apresentam barreiras reprodutivas pré e/ou pós-zigóticas, por meio de cruzamentos experimentais e análise dos híbridos resultantes até a segunda geração (F2), com ênfase na análise da dinâmica evolutiva dos cruzamentos experimentais (cópula interespecífica, oviposição, eclosão e desenvolvimento dos híbridos), bem como na análise da viabilidade reprodutiva dos híbridos (espermatogênese e morfologia das gônadas masculinas e femininas). Os cruzamentos entre ♀ T. vitticeps x T. melanocephala ♂ não resultaram em híbridos, caracterizando, dessa forma, barreira pré-zigótica (possivelmente associada com isolamento gamético ou incompatibilidade genômica). Já os cruzamentos entre ♀ T. melanocephala x T. vitticeps ♂ produziram híbridos que, após chegar à fase adulta, foram estéreis (barreira pós-zigótica de esterilidade do híbrido) e apresentaram disgenesia gonadal bilateral (sem formação de gametas), confirmando o status específico de T. vitticeps e T. melanocephala, com base no conceito biológico de espécie.
Triatoma melanocephala and T. vitticeps were initially grouped in the T. brasiliensis subcomplex. However, karyosystematic analyzes showed that these species should not have been grouped with the species of this subcomplex. Recently, T. melanocephala and T. vitticeps have been grouped into a new subcomplex entitled T. vitticeps. These species are sisters, share morphological and cytogenetic characteristics and, above all, there are reports of possible natural hybrids occurring in nature. As these species are reproductively isolated from all triatomines in South America (due to the divergence in chromosome numbers), we consider it important to conduct experimental crosses and to evaluate if there are reproductive barriers installed between T. vitticeps subcomplex species, as it is believed that several factors, as the current climate and environmental changes caused by man, probably influence the increased likelihood of hybridization for future communities, as they are reorganizing the assemblies of species and breaking down the physical reproductive barriers, temporal and behavioral, which can result in events of extinction, introgression, or even speciation. Thus, we analyzed whether the species of the T. vitticeps subcomplex present pre and/or post-zygotic reproductive barriers through experimental crosses and analysis of the resulting hybrids until the second generation (F2), with emphasis on the evolutionary dynamics of the species. Experimental crosses (interspecific copulation, oviposition, hatching and development of hybrids), as well as the analysis of reproductive viability of hybrids (spermatogenesis and morphology of male and female gonads). Crossings between ♀ T. vitticeps x T. melanocephala ♂ did not result in hybrids characterizing prezygotic barrier (possibly associated with gametic isolation or genomic incompatibility). The crosses between ♀ T. melanocephala x T. vitticeps ♂ produced hybrids that, after reaching adulthood, were sterile (post-zygotic hybrid sterility barrier) and presented bilateral gonadal dysgenesis (without gamete formation), confirming the status of T. vitticeps and T. melanocephala, based on the biological species concept.
Triatoma melanocephala and T. vitticeps were initially grouped in the T. brasiliensis subcomplex. However, karyosystematic analyzes showed that these species should not have been grouped with the species of this subcomplex. Recently, T. melanocephala and T. vitticeps have been grouped into a new subcomplex entitled T. vitticeps. These species are sisters, share morphological and cytogenetic characteristics and, above all, there are reports of possible natural hybrids occurring in nature. As these species are reproductively isolated from all triatomines in South America (due to the divergence in chromosome numbers), we consider it important to conduct experimental crosses and to evaluate if there are reproductive barriers installed between T. vitticeps subcomplex species, as it is believed that several factors, as the current climate and environmental changes caused by man, probably influence the increased likelihood of hybridization for future communities, as they are reorganizing the assemblies of species and breaking down the physical reproductive barriers, temporal and behavioral, which can result in events of extinction, introgression, or even speciation. Thus, we analyzed whether the species of the T. vitticeps subcomplex present pre and/or post-zygotic reproductive barriers through experimental crosses and analysis of the resulting hybrids until the second generation (F2), with emphasis on the evolutionary dynamics of the species. Experimental crosses (interspecific copulation, oviposition, hatching and development of hybrids), as well as the analysis of reproductive viability of hybrids (spermatogenesis and morphology of male and female gonads). Crossings between ♀ T. vitticeps x T. melanocephala ♂ did not result in hybrids characterizing prezygotic barrier (possibly associated with gametic isolation or genomic incompatibility). The crosses between ♀ T. melanocephala x T. vitticeps ♂ produced hybrids that, after reaching adulthood, were sterile (post-zygotic hybrid sterility barrier) and presented bilateral gonadal dysgenesis (without gamete formation), confirming the status of T. vitticeps and T. melanocephala, based on the biological species concept.
Descrição
Palavras-chave
Triatomíneos, Híbridos, Cruzamentos experimentais, Doença de Chagas, Triatomines, Hybrids, Experimental crossings, Chagas disease