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2030-01-01
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- IOC - Artigos de Periódicos [12973]
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MORPHOLOGICAL, GENETIC, AND CHROMOSOMAL VARIATION AT A SMALL SPATIAL SCALE WITHIN A MOSAIC HYBRID ZONE OF THE GRASSHOPPER DICHROPLUS PRATENSIS BRUNER (ACRIDIDAE)
Affilliation
Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Cátedra de Genética Evolutiva. Posadas, Misiones, Argentina / Universidade Federal de São Carlos. Departamento de Genética e Evolução. São Carlos, SP, Brasil.
Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Genética de Poblaciones y Evolución. Córdoba, Argentina.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia e Parasitologia de Mamíferos Silvestres Reservatórios. Rio de Janeiro, RJ, Brasil.
Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Genética de Poblaciones y Evolución. Córdoba, Argentina.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia e Parasitologia de Mamíferos Silvestres Reservatórios. Rio de Janeiro, RJ, Brasil.
Abstract
Hybrid zones are regions where genetically different populations meet and mate, resulting in offspring of mixed
characteristics. In organisms with limited dispersal, such as melanopline grasshoppers, hybrid zones can occur at small
spatial scales (i.e., ,500 m). We assessed levels of morphological, chromosomal, and molecular variability in adult males of
the grasshopper Dichroplus pratensis Bruner (N 5 137 males, 188 females) collected at 12 sites within a mosaic hybrid zone in
a heterogeneous environment in Sierra de la Ventana, Argentina. In this hybrid zone, 2 Robertsonian chromosomal races,
polymorphic for different centric fusions, meet (the ‘‘Northern race’’ at low altitudes and the ‘‘Southern race’’ at higher
altitudes), forming hybrids that show monobrachial homologies during meiosis. High morphometric variation in 6 traits was
revealed among grasshoppers of both sexes, with male body size positively and significantly correlated with increasing
altitude. Frequency of Robertsonian fusions characteristic of the Southern race increased significantly with altitude.
Moreover, fusion frequencies covaried between samples. Considerable genetic variation was revealed by random
amplification of polymorphic DNA markers, with heterozygosity ranging from 0.3477 to 0.3745. Insects from low-altitude
and high-altitude populations showed significant genetic differentiation, as indicated by FST values. The proposed model for
D. pratensis, involving the generation and maintenance by chromosomal fusions, of gene complexes adaptive in different
environments, could explain the observed clinal patterns within the contact zone.
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