Rate of karyotype evolution and speciation in birds

The diploid number of chromosomes and the number of macro- and microchromosomes from 238 published bird karyotypes were used for calculation of the rate of karyotype evolution. From fossil data and numbers of extinct and living species the speciation rates in various bird orders have been calculated. Bird karyotypes can be divided into four groups characterized by the number of macro- and microchromosomes. The speciation and karyotype evolution rates in birds are low, except for the order Passeriformes. The data from the order Passeriformes are in agreement with the hypothesis of a high speciation rate in groups with a high rate of karyotype evolution but also with the hypothesis of younger groups having a higher rate of karyotypic diversity.