Cold Resistance of Karyotypes in Drosophila persimilis from Timberline of California

Genetic Capacity for Adaptation to Cold Resistance at Different Developmental Stages of Drosophila melanogaster

“…Laboratory studies on the genetics of cold resistance in Drosophila are not numerous (e.g., Kamshilov, 1941-cited after Kamshilov, 1972Dubinin andTiniakov, 1945, 1946;Heuts, 1948;Parsons, 1959;Mohn and Spiess, 1963;Marinkovic et al, 1969). In most cases it has been found that genotypes react differently when exposed to temperature treatments.…”

“…Data suggest that in some species of Drosophila seasonal variation in gene arrangement frequencies are related to temperature adaptation. Dubinin andTiniakov (1945, 1946) in D. funebris, Dobzhansky (1948Dobzhansky ( , 1956Dobzhansky ( , 1958 in D. pseudoobscura, Levitan (1951) in D. robusta, and Mohn and Spiess (1963) in D. persimilis have provided evidence that particular chromosomal segments (marked by inversions) may be responsible for the control of resistance to low temperature. Marinkovic et al (1969) have provided evidence in D. pseudoobscura that cold resistance is associated with certain chromosomal inversion types.…”

How does Drosophila melanogaster overwinter?

“…In the population cage at La Venta, the adult phase was the most resistant to cold and freezing temperatures in accordance with other results at constant temperatures (Crumpacker & Marinko-vic, 1967;Tucic, 1979;Cuesta & Comendador, 1982), although apparently higher resistance was found under natural conditions. Other developmental stages are in principle also resistant to cold and freezing (Mohn & Spiess, 1963;Crumpacker etal., 1977;Tucic, 1979;Krunic et al, 1980;Cuesta & Comendador, 1982) but those stages of D. melanogaster could not overwintering in La Venta. We might ask why.…”

FITNESS OF KARYOTYPES IN DROSOPHILA PSEUDOOBSCURA

“…Implicit in all of this is that selection must take place at the chromosome level. Indeed, although it is often difficult to demonstrate, particular gene orders have been shown to be generally adapted to a particular type of environment such as temperature or rainfall (MOHN and SPIESS 1963;STRICKBERGER and WILLS 1966;MAYHEW et al 1966). Moreover, unlike genic selection, where only heterosis can ensure a balanced polymorphism, at the chromosome level, frequency-dependent selection, or annidation as well as heterosis is sufficient to produce a balanced polymorphism.…”