Mitochondrial DNA variation in the grasshopper Sinipta dalmani: application of long-PCR to the development of a homologous probe.

RFLP analysis of mtDNA in natural populations is a valuable tool for phylogeographic and population genetic studies. The amplification of long DNA fragments using universal primers may contribute to the development of novel homologous probes in species for which no previous genomic information is available. Here we report how we obtained the complete mtDNA genome of Sinipta dalmani (Orthoptera) in 2 fragments (7 and 9 kb) using primers of conserved regions.

Interaction among different heterocromatic variants in the grasshopper Dichroplus elongatus.

Simultaneous chromosome polymorphisms for supernumerary elements allow us to analyse the relationships among different forms of heterochromatic variation in nature. We report simultaneous variation patterns for supernumerary segments in chromosomes S10 (SS10), S9 (SS9) and S6 (SS6) and B chromosomes in nine populations of the grasshopper Dichroplus elongatus from two biogeographic provinces from east Argentina. Our results show spatial chromosome differentiation for three out of four supernumerary heterochromatic variants (B chromosomes, SS6 and SS10).

Chromosomal polymorphism, morphometric traits and mating success in Leptysma argentina Bruner (Orthoptera).

The South-American species Leptysma argentina Bruner is polymorphic for a centric fusion between chromosomal pairs 3 and 6 (fusion 3/6). Cytogenetic and morphological studies revealed that fusion 3/6 significantly increases some morphometric variables in males. A selection components study showed that the fusion is positively selected for longevity, the direct effect being exerted on thorax height.

Chromosomal polymorphism, morphological traits and male mating success in Leptysma argentina (Orthoptera).

Leptysma argentina (Acrididae: Orthoptera) is polymorphic for a centric fusion between pairs 3 and 6 of its basic chromosomal complement. With the aim of carrying out an analysis of selection components in this species, male mating success, in relation to karyotype and three morphometric traits, was assessed by using experimental contests with four males and one female per mating cage. Karyotype was assessed in terms of fused chromosome 3/6 dosage and coded as "0", "1" and "2" for unfused homozygotes, heterozygotes and fusion homozygotes, respectively.

Multivariate analysis of male mating success on morphometric traits and chromosome dosage in the grasshopper Sinipta dalmani.

Sinipta dalmani is a South American grasshopper that is chromosomally polymorphic for a pericentric inversion in the M4 pair. The inversion affects morphology, showing a negative average effect on body size. In the present work, male mating success was analysed in competition cages and possible correlations examined between this fitness component, body size and inversion polymorphism.