Genome size in plants can vary by orders of magnitude, but this variation has long been considered to be of little to no functional consequence.
Studying three independent adaptations to high elevation in Zea mays, we find that genome size experiences parallel pressure from natural selection, causing a linear reduction in genome size with increasing altitude.
Though reductions in repetitive content are responsible for the genome size change, we find that repeats are not targeted uniformly, but that the same repetitive sequences are removed as Z. mays taxa move to higher altitude.
To identify the phenotype influenced by genome size, we study how 20% variation in genome size in a single teosinte population impacts leaf growth.
We find that genome size variation correlates negatively with cell production rate but not cell size, suggesting that individuals with larger genomes require longer to complete a mitotic cycle.
We reanalyze data from maize inbreds to show that slower cell production can lead to a delay in flowering time, suggesting that genome size can be used as a developmental clock to help adapt maize to different altitudes.
chemical bonding Essentials of Physical Chemistry2.pdf
Adaptive evolution of genome size across altitudinal clines in maize
1. Jeffrey Ross-Ibarra
@jrossibarra • www.rilab.org
Plant Sciences • Center for Population Biology • Genome Center
University of California Davis
Adaptive Clines in Genome Size in Maize
2. Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or
GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Genome Size
3. By Nr387241 - Own work, CC BY-SA 3.0, https://
commons.wikimedia.org/w/index.php?
curid=14945255
Mycoplasma (0.0006Gb)
Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or
GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Genome Size
4. By Gőtehal.jpg: Mathae derivative work: Bff (Gőtehal.jpg) [CC BY 2.5 (http://
creativecommons.org/licenses/by/2.5), CC-BY-SA-3.0 (http://
creativecommons.org/licenses/by-sa/3.0/) or GFDL (http://www.gnu.org/
copyleft/fdl.html)], via Wikimedia Commons
Protopterus (130Gb)
By Nr387241 - Own work, CC BY-SA 3.0, https://
commons.wikimedia.org/w/index.php?
curid=14945255
Mycoplasma (0.0006Gb)
Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or
GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Genome Size
5. Genlisea (0.065Gb)
By Michal Rubeš [CC BY 3.0 cz
(http://creativecommons.org/
licenses/by/3.0/cz/deed.en)], via
Wikimedia Commons
By Gőtehal.jpg: Mathae derivative work: Bff (Gőtehal.jpg) [CC BY 2.5 (http://
creativecommons.org/licenses/by/2.5), CC-BY-SA-3.0 (http://
creativecommons.org/licenses/by-sa/3.0/) or GFDL (http://www.gnu.org/
copyleft/fdl.html)], via Wikimedia Commons
Protopterus (130Gb)
By Nr387241 - Own work, CC BY-SA 3.0, https://
commons.wikimedia.org/w/index.php?
curid=14945255
Mycoplasma (0.0006Gb)
Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or
GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Genome Size
6. By alpsdake - Own work, CC0, https://commons.wikimedia.org/w/index.php?
curid=12228596
Paris (150Gb)
Genlisea (0.065Gb)
By Michal Rubeš [CC BY 3.0 cz
(http://creativecommons.org/
licenses/by/3.0/cz/deed.en)], via
Wikimedia Commons
By Gőtehal.jpg: Mathae derivative work: Bff (Gőtehal.jpg) [CC BY 2.5 (http://
creativecommons.org/licenses/by/2.5), CC-BY-SA-3.0 (http://
creativecommons.org/licenses/by-sa/3.0/) or GFDL (http://www.gnu.org/
copyleft/fdl.html)], via Wikimedia Commons
Protopterus (130Gb)
By Nr387241 - Own work, CC BY-SA 3.0, https://
commons.wikimedia.org/w/index.php?
curid=14945255
Mycoplasma (0.0006Gb)
Abizar at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or
GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
Genome Size
8. Lynch and Connnery (2003) Science Lefébure et al. (2017) Genome Research
genome size (pg)dN/dS
surface
subterannean
9. Whitney et al. (2010) Evolution
Contrast in Ne
ContrastinGenomeSize
10. Seed Weight (+)
Leaf Size (-)
Knight (2005) Ann Bot
Genome Size (2C pg)
Seed Weight
GenomeSize(2Cpg)specificleafarea
Whitney et al. (2010) Evolution
Contrast in Ne
ContrastinGenomeSize
11. Kang et al. (2015) Sci Reports
GenomeSize
SoilNitrogen
Seed Weight (+)
Leaf Size (-)
Knight (2005) Ann Bot
Primulinaspp.
Genome Size (2C pg)
Seed Weight
GenomeSize(2Cpg)specificleafarea
Whitney et al. (2010) Evolution
Contrast in Ne
ContrastinGenomeSize
12. The small differences in genome size within
species seem generally to be of minor
importance compared to other components of
plant fitness. Šmarda & Petr Bureš (2010) Preslia
The ‘plastic genome’ seems to be an idea
rather than a defendable scientific
hypothesis; intraspecific variation is less
frequent than presently thought. Greilhuber (1998) Ann Bot
19. Domestication
10,000BP
Takuno et al. (2015) Genetics
Lowland
K=3K=4
Highland Lowland Highland
Mesoamerica South America
Lowland
A B
K=2K=3K=4
Highland Lowland Highland
Mesoamerica South America
Altitude
21. Domestication
10,000BP
Mexican Highlands
6,000BP
S. American lowlands
6,000BP
Takuno et al. (2015) Genetics
Lowland
K=3K=4
Highland Lowland Highland
Mesoamerica South America
Lowland
A B
K=2K=3K=4
Highland Lowland Highland
Mesoamerica South America
Altitude
22. Domestication
10,000BP
Mexican Highlands
6,000BP
S. American lowlands
6,000BP
Andes
4,000BP
Takuno et al. (2015) Genetics
Lowland
K=3K=4
Highland Lowland Highland
Mesoamerica South America
Lowland
A B
K=2K=3K=4
Highland Lowland Highland
Mesoamerica South America
Altitude
26. altitude
GenomeSize(Mb) 77 landraces
S. America
Mexico
teosinte
95 mexicana
altitude
P = µ + alt ⇤ A + g + "
g ⇠ MV N (0, VAK)
" ⇠ N (0, V✏)
Genome Size Altitude
Additive
Component
Berg and Coop (2014) Plos Gen
27. altitude
GenomeSize(Mb) 77 landraces
S. America
Mexico
teosinte
95 mexicana
altitude
P = µ + alt ⇤ A + g + "
g ⇠ MV N (0, VAK)
" ⇠ N (0, V✏)
Genome Size Altitude
Additive
Component
Berg and Coop (2014) Plos Gen
landraces
landraces
Kinship
Additive
Genetic Var.
28. altitude
GenomeSize(Mb) 77 landraces
S. America
Mexico
teosinte
95 mexicana
altitude
P = µ + alt ⇤ A + g + "
g ⇠ MV N (0, VAK)
" ⇠ N (0, V✏)
Genome Size Altitude
Additive
Component
Berg and Coop (2014) Plos Gen
landraces
landraces
Kinship
Additive
Genetic Var.
-110Kb/m
-260Kb/m
29. Rosado et al. (2005) Maize
Genetics Newsletter (shh, secret)
Knob180
KnobTR1
Maize TEs
Sorghum TEs
Jiao et al. (2017) Nature
copy
number
30. Rosado et al. (2005) Maize
Genetics Newsletter (shh, secret)
Knob180
KnobTR1
Maize TEs
Sorghum TEs
Jiao et al. (2017) Nature
copy
number
31. Rosado et al. (2005) Maize
Genetics Newsletter (shh, secret)
Knob180
KnobTR1
Maize TEs
Sorghum TEs
Jiao et al. (2017) Nature
copy
number
55. 1. Selection for earlier flowering leads to smaller genomes
across altitudinal gradients in maize and teosinte
2. Genome size is a quantitative trait that can affect fitness,
and observed intraspecific variation may be adaptive
3. Selection on genome size likely impacts the evolution of
individual repeat classes
56. Acknowledgements
UC Davis
U Georgia
U Missouri
Patrice Albert
Jim Birchler
Jeremy Berg
Paul Bilinski
Graham Coop
Mark Grote
Anne Lorant
Juvenal Quesada
Jinliang Yang
Kelly Dawe
Ed Buckler
Sherry Flint-Garcia
USDA
Cornell
Kelly Swarts
Plant Genome
Research Program
HiLo