Chromosomal evidence for a hybrid origin of diploid parthenogenetic females from the unisexual-bisexual Lepidodactylus lugubris complex (Reptilia, Gekkonidae).

Chromosome banding analysis of seven diploid parthenogenetic females from Polynesian and Southeast Asian populations of the unisexual-bisexual Lepidodactylus lugubris complex (Reptilia, Gekkonidae) showed that the unisexual karyotype consists of two different haploid sets. Similar analysis of an L. lugubris male from a bisexually reproducing population revealed two identical chromosome complements, the banding pattern generally matching that of the females, although many chromosomes were obviously different. These observations suggest that the gonochoristic males belong to a taxon related to the parthenogenetic female taxon but are not a direct ancestor of the latter. The data also offer strong evidence for a hybrid origin of diploid parthenogenetic females in L. lugubris and suggest that a high degree of chromosomal heterogeneity may be the leading reason for the evolutionary selection of a modified meiotic process in this species, allowing production of unreduced oocytes and, consequently, of a unisexual mode of reproduction.

Presumptive sex chromosomes of a unisexual homomorphic species of lizards, Lepidodactylus lugubris.

Incorporation of 5-bromo-2'-deoxyuridine (BrdU) in prometaphasic chromosomes allows active from inactivated X chromosomes in female mammalian cells to be distinguished. We have applied the technique to the all-female, chromosomally homomorphic gecko Lepidodactylus lugubris. Similar differences to those obtained between the two female sex chromosomes of mammals are observed in the patterns of chromosome pair 1. It is argued that this is more likely to reflect incipient ZW heterogamety than female (XX) homogamety.

[A pullulation cycle with violent crash in a tropical lizard]. / Dynamique des populations.

According to a succession of samples taken at Ihotry, Madagascar, Lygodactylus tuberifer, a very rare gecko in the biotope sampled for Lygodactylus verticillatus in 1965, invaded the latter's habitat until its population reached, in the sampled biotope and using the L. verticillatus population as a gauge, an almost 700-fold increase by the end of 1972. Population growth then stopped abruptly, and a steep crash brought L. tuberifer down to 31 times less individuals within six months, whereupon sampling was discontinued.