Male Heterogamety and Chromosomal Variation in Caribbean Geckos

Abstract

ond largest family of lizards (approximately 650 species). Because of the high incidence of chromosomal variation in the few species that have been studied, continued investigation of gekkonid karyology is warranted. Chromosome numbers within the family range from 2n = 28 (King, 1973) to 2n = 46 (Makino and Momma, 1949). Typically, gekkonid karyotypes show a graded series of acrocentric chromosomes with few or no biarmed chromosomes and no distinct break between macrochromosomes and microchromosomes (Gorman, 1973). Robertsonian fission/fusions and pericentric inversions have played roles in the karyotypic evolution of gekkonids (Gorman, 1973; Bickham, 1984). Chromosomal races are known for nine species: Diplodactylus tessellatus, D. vittatus, Phyllodactylus marmoratus, Gehyra variegata, G. punctata, G. australis, G. purpurascens, Hemidactylus frenatus, and Heteronotia binoei (Bickham, 1984; Moritz, 1984b). Triploid parthenogenetic forms have been documented in Heteronotia and Hemidactylus (Moritz, 1984a; Kluge and Eckardt, 1969), and there are examples of both homogametic and female (ZW) heterogametic sex chromosomes in the family (Bickham, 1984; Moritz, 1984b). Because of the high degree of chromosomal variability expressed in only a few of its members, this family promises to be an excellent group for studies of cytosystematics and chromosomal evolution. This paper describes the chromosomal variability found in individuals of three species of Caribbean island geckos: Hemidactylus mabouia (Subfamily Gekkoninae), Gonatodes vittatus and G. ceciliae (Subfamily Sphaerodactylinae). Mitotic metaphase chromosomal spreads were prepared from bone marrow by the method of Baker et al. (1982). Animals were abdominally injected with 0.05 ml of 0.005% Velban 2 h prior to sacrifice. After