Cytogenetic Pathways in Beetle Speciation

Abstract

Investigations carried out over the past 50 years have made it abundantly clear that the chromosome, besides being a medium of evolutionary change, has an evolution of its own. In the animal kingdom, this has been elegantly proved by the extensive research onDrosophila(for a general review see Patterson and Stone, 1952), made possible largely by its possession of giant salivary gland chromosomes; by cytological analysis of hybrid rodents in the genusGerbillus(Wahrman and Zahavi, 1958) and newts of the genusTriturus(White, 1946; Spurway and Callan, 1950; Callan and Spurway, 1951); by investigations carried out on various Orthoptera, facilitated by the clarity of meiosis in interracial (White, 1957a), interspecific (Klingstedt, 1939), and “intergeneric” (Helwig, 1955) hybrids; and by studies on the mantid genusAmeles(Wahrman and O'Brien, 1956), through the credibility derived from cytophotometric measurement of desoxyribose nucleic acid content. Much of the evidence adduced elsewhere, for example, Manna and Smith's (1959) survey of the bark weevil genusPissodes, was based on comparative chromosome morphology, but, as will become evident later, our reasoning in this particular instance has so far proved correct.