Limits...
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.

Show MeSH

Related in: MedlinePlus

Mean monthly temperature at each collection site. Mean monthly temperatures in the three geographic locations relative to the experimental temperatures used in the experiment. Climate data from 1981–2010 is from the archives of the National Climatic Data Centre (National Oceanic and Atmospheric Administration).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig1: Mean monthly temperature at each collection site. Mean monthly temperatures in the three geographic locations relative to the experimental temperatures used in the experiment. Climate data from 1981–2010 is from the archives of the National Climatic Data Centre (National Oceanic and Atmospheric Administration).

Mentions: Here we examine temperature-size relationships in Drosophila pseudoobscura. The geographic range of this fruit fly extends from Canada at the northern end of North America, through the USA into Guatemala (approximately 35 degrees of latitude, or 3800 km). Previous work has shown that phenotypic plasticity in body size occurs in this species [19]. Experimental work has also demonstrated the potential for evolutionary divergence between populations as plasticity in body sizes can stabilize over time under laboratory conditions [27,28]. Additionally, strong latitudinal distributions of other traits, such as sex ratio distortion and polyandry in this species have been observed but not yet conclusively explained [29]. One potential explanation is that phenotypic plasticity in body size, driven by temperature, underpins the latitudinal patterns already established in other traits. For example, larger females developing in cooler climates may produce substantially more offspring, requiring multiple matings to gain sufficient supplies of viable sperm for complete fertilization. Our aims are to investigate the variation in body size due to environmental, genetic, and genotype-by-environment (GxEs) influences. To achieve this, we examined 27 isolines representing three populations spanning a 1770 km latitudinal section of the geographic range across the USA. These populations experience an average of 5°C difference in mean monthly peak temperatures (Figure 1).Figure 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 monthly temperature at each collection site. Mean monthly temperatures in the three geographic locations relative to the experimental temperatures used in the experiment. Climate data from 1981–2010 is from the archives of the National Climatic Data Centre (National Oceanic and Atmospheric Administration).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig1: Mean monthly temperature at each collection site. Mean monthly temperatures in the three geographic locations relative to the experimental temperatures used in the experiment. Climate data from 1981–2010 is from the archives of the National Climatic Data Centre (National Oceanic and Atmospheric Administration).
Mentions: Here we examine temperature-size relationships in Drosophila pseudoobscura. The geographic range of this fruit fly extends from Canada at the northern end of North America, through the USA into Guatemala (approximately 35 degrees of latitude, or 3800 km). Previous work has shown that phenotypic plasticity in body size occurs in this species [19]. Experimental work has also demonstrated the potential for evolutionary divergence between populations as plasticity in body sizes can stabilize over time under laboratory conditions [27,28]. Additionally, strong latitudinal distributions of other traits, such as sex ratio distortion and polyandry in this species have been observed but not yet conclusively explained [29]. One potential explanation is that phenotypic plasticity in body size, driven by temperature, underpins the latitudinal patterns already established in other traits. For example, larger females developing in cooler climates may produce substantially more offspring, requiring multiple matings to gain sufficient supplies of viable sperm for complete fertilization. Our aims are to investigate the variation in body size due to environmental, genetic, and genotype-by-environment (GxEs) influences. To achieve this, we examined 27 isolines representing three populations spanning a 1770 km latitudinal section of the geographic range across the USA. These populations experience an average of 5°C difference in mean monthly peak temperatures (Figure 1).Figure 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