Experimental evidence that thermal selection shapes mitochondrial genome evolution
Zdeněk Lajbner, Reuven Pnini, M. Florencia Camus, Jonathan Miller & Damian K. Dowling
Scientific Reports volume 8, Article number: 9500 (2018)
Fruit flies exhibit sexual dimorphism. Males are smaller, they have bristle on their forelegs, their abdomen is blunt, and their stripes meld together and become dark toward the back of the abdomen. Females are larger, and their abdomen is longer, pointed, and striped until the end. The sexes differ in many aspects. In this study, researchers reveal that male fruit flies respond to environmental temperatures differently than females that bear the same mtDNA variant.
Source/Fonte: Science Daily
Abstract
Mitochondria are essential organelles, found within eukaryotic cells, which contain their own DNA. Mitochondrial DNA (mtDNA) has traditionally been used in population genetic and biogeographic studies as a maternally-inherited and evolutionary-neutral genetic marker. However, it is now clear that polymorphisms within the mtDNA sequence are routinely non-neutral, and furthermore several studies have suggested that such mtDNA polymorphisms are also sensitive to thermal selection. These observations led to the formulation of the “mitochondrial climatic adaptation” hypothesis, for which all published evidence to date is correlational. Here, we use laboratory-based experimental evolution in the fruit fly, Drosophila melanogaster, to test whether thermal selection can shift population frequencies of two mtDNA haplogroups whose natural frequencies exhibit clinal associations with latitude along the Australian east-coast. We present experimental evidence that the thermal regime in which the laboratory populations were maintained drove changes in haplogroup frequencies across generations. Our results strengthen the emerging view that intra-specific mtDNA variants are sensitive to selection, and suggest spatial distributions of mtDNA variants in natural populations of metazoans might reflect adaptation to climatic environments rather than within-population coalescence and diffusion of selectively-neutral haplotypes across populations.
Acknowledgements
We thank Vanessa Kellerman and Winston Yee for assistance with wild sample collection, and Mary Ann Price, Carla Sgrò, Ritsuko Suyama, Garth Illsley, Richard Lee, Nicholas Luscombe, Pavel Munclinger, Takeshi Noda, and Oleg Simakov for helpful advice. We thank Yuan Liu for her assistance with artwork design. This work was supported by the Physics and Biology Unit of the Okinawa Institute of Science and Technology Graduate University (J.M.) and JSPS P12751 + 24 2751 to Z.L. and J.M., the Hermon-Slade Foundation (HSF 15/2) and the Australian Research Council (FT160100022 and DP170100165) to D.K.D. Initial stages of the study were funded by Go8EURFA11 2011003556 to Z.L. and D.K.D.
Author information
Affiliations
Physics and Biology Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Okinawa, 904-0945, Japan
Zdeněk Lajbner, Reuven Pnini & Jonathan Miller
School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
M. Florencia Camus & Damian K. Dowling
Department of Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK
M. Florencia Camus
Contributions
Z.L. and D.K.D. designed the experiment. Z.L. performed the experiment. Z.L. and M.F.C. provided mitogenomic sequences. Z.L., R.P., D.K.D., M.F.C. and J.M. contributed to the data analyses. Z.L., D.K.D., R.P., J.M. and M.F.C. wrote the manuscript.
Competing Interests
The authors declare no competing interests.
Corresponding author
Correspondence to Zdeněk Lajbner.
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