Although very closely related species can differ in their fine-scale patterns of recombination hotspots, variation in the average genomic recombination rate among recently diverged taxa has rarely been surveyed. We measured recombination rates in eight species that collectively represent several temporal scales of divergence within a single rodent family, Muridae. We used a cytological approach...

Karyotypic analysis of Tinospora cordifolia (Willd.) was carried out to determine the chromosomal classification by using “Aceto-orcine stain”. The plant is diploid with 2n=22 (18m+2Sm+2St) chromosomes and characterized in eleven pairs of chromosomes. The chromosomes are very short with a mean length 2.64 μm. and the total length of haploid complements was found 29.04 μm. The ideogram of Tinosp...

Three new karyotypes (2n=40, 44, 52) are described revealing what are probably new cryptic species of Ethiopian spiny mice. Two other diploid numbers have already been reported for the country (2n=36 and 68) and, overall, the five known karyotypic forms constitute a common lineage differentiated by a Robertsonian process. Such arrays of karyotypic forms are known as a 'Robertsonian fan'. This v...

D. n. nasuta and D. n. albomicana constitute a pair of chromosomal races with 2n=8 and 2n=6, respectively. The F(1) of these has 2n=7 and it is fertile. There exists a state of karyotypic mosaicism as evidenced by the presence of 26 types of chromosome combinations in F(2), F(3) and F(10) populations. In the midst of this karyotypic noise, the karyotype similar to that of F(1) reached 51% of th...

Karyotypic data are presented for two sympatric Corydoras species of the Lagoa Dourada, namely, C. ehrhadti and C. paleatus, which are found in the upper Tibagi river basin (Ponta Grossa, State of Paraná, Brazil). The same diploid number and karyotypic formula were observed in both species/populations. A great similarity in the constitutive heterochromatin distribution and in the activity of nu...