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The gekko Phyllodactylus marmoratus has at least three distinct chromosome races; 2n=39, 2n=26 ZZ/ZW and 2n=34. Specimens from these races are morphologically distinguishable, have a degree of habitat specialization and occur in a defined distribution. The 2n=36 race found in Eastern Australia is the presumed primordial type. The 2n=34 race occurs in Western Australia and is regarded as a fusion derivative. The 2n=36 ZZ/ZW race, which is only found on the Murray River system in Eastern Australia has a heteromorphic sex chromosome system present in the female. Giemsa banding suggests that this heteromorphism is the result of a pericentric inversion.

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Comparative fluorescence studies on the chromosome of ten species of acridid grasshoppers, with varying amounts and locations of C-band positive heterochromatin, indicate that the only regions to fluoresce differentially are those that C-band. Within a given species there is a marked tendency for groups of chromosomes to accumulate heterochromatin with similar fluorescence behaviour at similar sites. This applies to all three major categories of heterochromatin - centric, interstitial and telomeric. Different sites within the same complement, however, tend to have different fluorescence properties. In particular, centric C-bands within a given species are regularly distinguishable in their behaviour from telomeric C-bands. Different species on the other hand, may show distinct forms of differential fluorescence at equilocal sites. These varying patterns of heterochromatin heterogeneity, both within and between species, indicate that whatever determines the differential response to fluorochromes has tended to operate both on an equilocal basis and in a concerted fashion. This is reinforced by the fact that structural rearrangements that lead to the relocation of centric C-bands, either within or between species, may also be accompanied by a change in fluorescence behaviour.

A karyotypic analysis of populations of the gekkos Gehyra variegata and G. punctata reveals three chromosome races in G. variegata (2n = 44; 2n = 40a; 2n = 40b), and three in G. punctata (2n = 44; 2n = 42; 2n = 38). The chromosome races have differentiated by a series of chromosome fusions. The ordered nature of these changes suggests that the phylogenetic relationships of the races cut across the current taxonomy, and it is argued that there is but one 2n = 44 race, occurring as a number of morphologically distinct populations, two of which were erroneously described as the separate Gehyra species. Isolated populations within a number of the chromosome races show pronounced morphological differences. It is believed that these gekkos are an ancient Australian group which differentiated chromosomally during a number of colonizing radiations. Since then, populations within each race have been isolated by geographic barriers and have speciated allopatrically. This suggests that the chromosome races are at least good species and may be of a higher taxon.