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Opposite environmental and genetic influences on body size in North American Drosophila pseudoobscura.

Taylor ML, Skeats A, Wilson AJ, Price TA, Wedell N - BMC Evol. Biol. (2015)

Bottom Line: However, it is rarely known whether these differences are associated with genetic variation and evolved differences between populations, or are instead simply a plastic response to environmental differences experienced by the populations.However, we also found a genetic signature that was counter to this pattern as flies originating from the northern, cooler population were consistently smaller than conspecifics from more southern, warmer populations when reared under the same laboratory conditions.We conclude that local selection on body size appears to be acting counter to the environmental effect of temperature.

View Article: PubMed Central - PubMed

Affiliation: College of Life and Environmental Sciences, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK. m.l.taylor@exeter.ac.uk.

ABSTRACT

Background: Populations of a species often differ in key traits. However, it is rarely known whether these differences are associated with genetic variation and evolved differences between populations, or are instead simply a plastic response to environmental differences experienced by the populations. Here we examine the interplay of plasticity and direct genetic control by investigating temperature-size relationships in populations of Drosophila pseudoobscura from North America. We used 27 isolines from three populations and exposed them to four temperature regimes (16°C, 20°C, 23°C, 26°C) to examine environmental, genetic and genotype-by-environment sources of variance in wing size.

Results: By far the largest contribution to variation in wing size came from rearing temperature, with the largest flies emerging from the coolest temperatures. However, we also found a genetic signature that was counter to this pattern as flies originating from the northern, cooler population were consistently smaller than conspecifics from more southern, warmer populations when reared under the same laboratory conditions.

Conclusions: We conclude that local selection on body size appears to be acting counter to the environmental effect of temperature. We find no evidence that local adaptation in phenotypic plasticity can explain this result, and suggest indirect selection on traits closely linked with body size, or patterns of chromosome inversion may instead be driving this relationship.

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Related in: MedlinePlus

Mean wing size of three populations at four temperatures. Mean wing size (mm ± 1 se) scored across four developmental temperatures in three populations of flies. Lewistown (northern population) = black lines/square markers; Show Low (southern population) = grey lines/circle; Chiricahua (southernmost population) = grey lines/triangle markers.
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Fig2: Mean wing size of three populations at four temperatures. Mean wing size (mm ± 1 se) scored across four developmental temperatures in three populations of flies. Lewistown (northern population) = black lines/square markers; Show Low (southern population) = grey lines/circle; Chiricahua (southernmost population) = grey lines/triangle markers.

Mentions: We measured wing sizes in a total of 439 flies from 27 isolines across four temperatures. Summary statistics for wing sizes at different rearing temperatures and in different isolines are given in Table 1 and displayed in Figure 2. A full explanation of data analysis is included in the methods section. Briefly, wing length (WL) was scaled to standard deviation units prior to analysis and then modelled as: WL = μ + Year + T + Pop + T. Pop + T. Year + ISO + T. ISO + ε.Table 1


Opposite environmental and genetic influences on body size in North American Drosophila pseudoobscura.

Taylor ML, Skeats A, Wilson AJ, Price TA, Wedell N - BMC Evol. Biol. (2015)

Mean wing size of three populations at four temperatures. Mean wing size (mm ± 1 se) scored across four developmental temperatures in three populations of flies. Lewistown (northern population) = black lines/square markers; Show Low (southern population) = grey lines/circle; Chiricahua (southernmost population) = grey lines/triangle markers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374297&req=5

Fig2: Mean wing size of three populations at four temperatures. Mean wing size (mm ± 1 se) scored across four developmental temperatures in three populations of flies. Lewistown (northern population) = black lines/square markers; Show Low (southern population) = grey lines/circle; Chiricahua (southernmost population) = grey lines/triangle markers.
Mentions: We measured wing sizes in a total of 439 flies from 27 isolines across four temperatures. Summary statistics for wing sizes at different rearing temperatures and in different isolines are given in Table 1 and displayed in Figure 2. A full explanation of data analysis is included in the methods section. Briefly, wing length (WL) was scaled to standard deviation units prior to analysis and then modelled as: WL = μ + Year + T + Pop + T. Pop + T. Year + ISO + T. ISO + ε.Table 1

Bottom Line: However, it is rarely known whether these differences are associated with genetic variation and evolved differences between populations, or are instead simply a plastic response to environmental differences experienced by the populations.However, we also found a genetic signature that was counter to this pattern as flies originating from the northern, cooler population were consistently smaller than conspecifics from more southern, warmer populations when reared under the same laboratory conditions.We conclude that local selection on body size appears to be acting counter to the environmental effect of temperature.

View Article: PubMed Central - PubMed

Affiliation: College of Life and Environmental Sciences, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK. m.l.taylor@exeter.ac.uk.

ABSTRACT

Background: Populations of a species often differ in key traits. However, it is rarely known whether these differences are associated with genetic variation and evolved differences between populations, or are instead simply a plastic response to environmental differences experienced by the populations. Here we examine the interplay of plasticity and direct genetic control by investigating temperature-size relationships in populations of Drosophila pseudoobscura from North America. We used 27 isolines from three populations and exposed them to four temperature regimes (16°C, 20°C, 23°C, 26°C) to examine environmental, genetic and genotype-by-environment sources of variance in wing size.

Results: By far the largest contribution to variation in wing size came from rearing temperature, with the largest flies emerging from the coolest temperatures. However, we also found a genetic signature that was counter to this pattern as flies originating from the northern, cooler population were consistently smaller than conspecifics from more southern, warmer populations when reared under the same laboratory conditions.

Conclusions: We conclude that local selection on body size appears to be acting counter to the environmental effect of temperature. We find no evidence that local adaptation in phenotypic plasticity can explain this result, and suggest indirect selection on traits closely linked with body size, or patterns of chromosome inversion may instead be driving this relationship.

Show MeSH
Related in: MedlinePlus