Studies from a wide diversity of taxa have shown a negative relationship between genetic compatibility and the divergence time of hybridizing genomes. Theory predicts the main breakdown of fitness to happen after the F1 hybrid generation, when heterosis subsides and recessive allelic (Dobzhansky-Muller) incompatibilities are increasingly unmasked. We measured the fitness of F2 hybrids of Africa...

Crosses between Betula nana and B. utilis 'Doorenbos' were undertaken in order to obtain interspecific hybrids which could be characterized by wide spreading stems, strong branching habit, decorative clear white bark and an interesting shape of purple leaves. The research purpose was to examine genetic diversity of the 16 F1 and F2 putative progenies by using the RAPD-PCR method and the ploidy ...

Both chromosomal rearrangements and negative interactions among loci (Dobzhansky-Muller incompatibilities) have been advanced as the genetic mechanism underlying the sterility of interspecific hybrids. These alternatives invoke very different evolutionary histories during speciation and also predict different patterns of sterility in artificial hybrids. Chromosomal rearrangements require drift,...

The haplodiploid wasp genus Nasonia is a promising model for studying the evolution of genic incompatibilities due to the existence of interfertile species and haploid males. The latter allows for significantly reducing the sample size required to detect and map recessive dysfunctional genic interactions. We exploited these features to study the genetics of intrinsic hybrid inviability in male ...

Circulating interferon production, induced by Newcastle disease virus, is about seven times higher in C57 Black mice than in Balb/c/Gif mice. A Mendelian analysis was carried out and circulating interferon production was measured in reciprocal F1 hybrids, in the F2 generation, in progeny of backcrosses of F1 hybrids to either parent strain, and in second backcross progeny. The results indicate ...

Hybrids between Rhipicephalus appendiculatus and R. zambeziensis were reared and glucose-phosphate-isomerase isoenzymes were resolved by agarose electrophoresis. By phenotyping hybrids in F1 and F2 generations autosomal transmission of 2 GPI genes was demonstrated. Identification of a hybrid phenotype provides a method for identifying hybrids in field collections.

The reproductive capacity between Triatoma lenti and Triatoma sherlocki was observed in order to verify the fertility and viability of the offspring. Cytogenetic, morphological and morphometric approaches were used to analyze the differences that were inherited. Experimental crosses were performed in both directions. The fertility rate of the eggs in crosses involving T. sherlocki females was 6...

Interpopulation hybridization can lead to outbreeding depression within affected populations due to breakdown of coadapted gene complexes or heterosis in hybrid populations. One of the principal methods commonly used to estimate the level of developmental instability (DI) is fluctuating asymmetry (FA). We used three genetically differentiated Drosophila subobscura populations according to inver...

The cytogenetic characteristics of Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum and their F1, F2 and backcross hybrids were assessed by using chromosome banding techniques. The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes. Nucleol...

aegilops triuncialis l. (2n=4x=28; ctctutut) is one of the tetraploid aegilops species harboring valuable genes for resistance to many biotic and abiotic stresses. in the present study the bread wheat cultivars mv17, navid, omid, pishgam, zarin were crossed with an accession of ae. triuncialis and the resulted f1 and f2 (obtained by the selfing of f1 plants) hybrids studied using the convention...