An Interaction Between Environmental Temperature and Genetic Variation for Body Size for the Fitness of Adult Female Drosophila melanogaster

Abstract

Drosophila and other ectotherms show geographic genetic variation in body size, with larger individuals at higher latitudes and altitudes. Temperature is implicated as an important selective agent because long-term laboratory culture of Drosophila leads to the evolution of larger body size at lower temperatures. In this paper, we tested the hypothesis that, in Drosophila melanogaster, larger size is favored at lower temperatures in part because of selection on adult females. We used replicated lines of D. melanogaster artificially selected for increased and decreased wing area with constant cell area. The resulting size differences between the selected lines were due solely to differences in cell number, and thereby were similar to the cellular basis of elinal variation in body size in nature. We examined life-history traits of adult females at 18 and 25°C. Rearing for two generations at the two temperatures did not affect the extent of the size differences between lines from the different selection regimes. There was a strong interaction between temperature and size selection for both survival and lifetime reproductive success, with larger females living significantly longer and producing more offspring over their lifetime only when reared and tested in the colder environment. There was also an increase in average daily progeny production in large-line females relative to the control and small lines again, only in the colder environment. Thus, the females from the large selection lines were relatively fitter at the colder temperature. At both experimental temperatures, especially the lower one, the small-line females rescheduled their progeny production to later ages. Larger body size may have evolved at higher latitudes and altitudes because of the advantages to the adult female of being larger at lower temperatures.

Factors affecting body size and fat content in a digger wasp

“…. There is evidence that in Drosophila, large body size is adaptive at low ambient temperatures (McCabe and Partridge 1997;. Females of the European beewolf depend on thermoregulation to carry their prey in flight (Strohm 1995), thermoregulation is obviously more important at low temperatures, and large size facilitates thermoregulation (Willmer 1985a(Willmer , 1985b.…”

“…Adult size is usually increased at lower temperatures (Kukal and Dawson 1989;Schroeder and Lawson 1992;Zwaan et al 1992;Atkinson 1994;Ayres and Scriber 1994;Blanckenhorn 1997;McCabe and Partridge 1997;Nylin and Gotthard 1998).…”

Genetic Architecture of Two Fitness-related Traits in Drosophila melanogaster: Ovariole Number and Thorax Length

“…Clinal variation and phenotypic plasticity for thorax length is well studied (Lemeunier, Tsacas & Ashburner, 1986;Capy et al, 1993;James, Azevedo & Partridge, 1995;Gilchrist & Partridge, 1999;van't Land et al, 1999); recurring latitudinal clines are most likely caused by natural selection (Berry & Kreitman, 1993). GEI has also been demonstrated for thorax length (McCabe & Partridge, 1997;French, Feast & Partridge, 1998;Gibert et al, 2004).…”

Effects of temperature and maternal and grandmaternal age on wing shape in parthenogenetic Drosophila mercatorum

“…The effect of temperature on wing size is well understood and has been commonly studied in laboratory experiments on thermal evolution, with lower temperature often resulting in increased wing size (a surrogate for body size) (McCabe and Partridge, 1997;Reeve et al, 2000;Nijhout, 2003;Pertoldi et al, 2005, David et al, 2006.…”