Title: Adaptation of Mimulus guttatus Phrymaceae to serpentine soil
1 Adaptation of Mimulus guttatus (Phrymaceae) to
serpentine soil Kristy U. BradyDepartment of
Biology University of Washington
2Many Thanks! Toby Bradshaw Meade Krosby Liz
Van Volkenburgh Suzie Graham Josh
Tewksbury Christina Pince Sarah
Reichard David Haak Art
Kruckeberg Margaret Hendrick Dick Walker Joe
Callizo, Paul Aigner Cathy Koehler Doug Ewing,
Jeanette Milne, Paul Beeman Judy Farrow,
Patti Owens, Dave King Biology Staff
3Adaptive Evolution
Adaptation to novel environments leads to
speciation.
4- Serpentine Systems are Great for Studying
Adaptive Evolution - Extensive literature available
- Strong selection imposed by factors amenable to
manipulative experiments in the field,
greenhouse, and lab - Differential adaptation demonstrated by
reciprocal transplants - Physiological differences between serpentine and
non-serpentine races and sister taxa permit
investigation of speciation mechanisms and
evolutionary trajectories
5- Serpentine Soil
- Originates in the Earths mantle
- Adverse chemical conditions including
- Low CaMg
- Low levels of nutrients (e.g., P, K)
- High levels of heavy metals (e.g., Ni, Cr, Fe)
- Rocky and often steep with sparse vegetative
cover - Plant morphological responses include
- Reduced stature
- Xeromorphic foliage
- Highly developed root systems
- High rates of plant endemism
6Insight Into Mineral Nutrition Physiology
Magnesium deposits at White Seep, McLaughlin
Natural Reserve, California, USA
7Insight Into Endemism
- In California, USA, serpentine soil comprises
1.5 of landscape, but hosts 13 of endemic
plant species. - 11 of CA plant taxa listed as threatened or
endangered are serpentine endemics. - (Safford, Viers, Harrison, 2005, MadroƱo.)
8Serpentinized Rock in Architecture
9Kruckeberg (1985) Two Strategies for Serpentine
Tolerance
- Endemic species
- Restricted to serpentine soil
- Bodenvag or indifferent species
- Widely distributed species with populations or
races occurring on serpentine soil.
10- Mimulus guttatus
- (Common Monkeyflower, Yellow Monkeyflower, Seep
Monkeyflower) - Wide-ranging distribution.
- Found in seeps, riparian areas.
- A bodenvag species populations on and off
serpentine soil. - Thrives in a greenhouse environment.
11Mimulus as a study system
- Long history of study
- Phylogeny
- Genetic genomic tools
12Location
13Survival After 6 Weeks on Serpentine Soil (n11)
Photos taken 6 days after transplanting onto
treatment soil.
14Segregating Population
15Segregating Population
NP
F2
SP
F2
F2
16First Transplant
17Transplant Details
- Serpentine soil collected from McLaughlin Natural
Reserve, CA. - Plants germinated on greenhouse soil.
- Transplanted onto treatment soil 2 weeks after
germination. - Growth, flowering, and red phenotype data
collected every other day for 4-5 weeks after
transplanting.
18Flowering as a Fitness Indicator
- Proportion of Individuals that Flowered
Mode of inheritance F1s suggest dominance
19Red Phenotype as a Fitness Indicator
- Mean red score for last 11 days of transplant
Number of effective factors (Lande 1981)
6.5Maximum magnitude of leading factor 39
20Second Transplant
21Soil Elemental Differences Examined
22Two Sets of Hypotheses Tested
- Mechanistic hypotheses
- Adaptive differences between serpentine plants
(SP) and non-serpentine plants (NP) that enable
SP to survive on serpentine soil. - Ca-limiting hypotheses
- Testing whether supplementing serpentine soil
with Ca enables NP to survive.
23Hypotheses
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg High Mg requirement Mg
toxicity avoidance Heavy metal toxicity avoidance
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg Mg toxicity susceptibility Heavy metal
toxicity susceptibility
24Transplant Details
- Serpentine soil collected from McLaughlin Natural
Reserve, CA. - Plants germinated on greenhouse soil.
- Transplanted onto treatment soil approx. 2 weeks
after germination. - Plants watered with dH2O or a 4mM Ca(NO3)2
solution. - 10 days after transplanting onto treatment soil,
leaf tissue collected for ICP-MS.
25Hypothesis 1 CaMg
- Mechanistic Loew May (1901) low CaMg of
serpentine soil problematic for non-serpentine
plants. - SP tolerate the low CaMg ratio in serpentine
soil better than NP. - Prediction SP preserve a higher CaMg in
their leaf tissue than NP when grown on
serpentine soil.
- Ca-limiting Kruckeberg (1954) addition of Ca
(CaSO4) to serpentine soil permitted
non-serpentine strains of Phacelia californica to
survive on serpentine soil. - Supplementing Ca to serpentine soil ameliorates
the serpentine effect by increasing Ca
availability. - Prediction NP have a higher CaMg in their
leaf tissue when grown on serpentine soil
supplemented with Ca.
26Hypothesis 1 CaMg
n11, one-tailed t-test, experiment-wise P
0.05, Bonferroni corrected
27Conclusions for M. guttatus
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg
?
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg
?
? hypothesis not supported by data ?
hypothesis supported by data
28Hypothesis 2 Mg requirement
- Mechanistic Madhok Walker (1969) The
serpentine sunflower Helianthus bolanderi ssp.
exilis requires high external levels of Mg for
optimal growth. - For optimal growth, SP require higher levels of
Mg externally than NP. - Prediction Without high levels of Mg
externally, SP will experience a reduced growth
rate.
29Hypothesis 2 Mg requirement
n11, one-tailed t-test, experiment-wise P
0.05, Bonferroni corrected
30Conclusions for M. guttatus
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg High Mg requirement
? ?
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg
?
? hypothesis not supported by data ?
hypothesis supported by data
31Hypothesis 3 Mg toxicity
- Mechanistic Proctor (1970 1971)
non-serpentine plants are susceptible to Mg
toxicity on serpentine soil. - SP avoid Mg toxicity whereas NP are susceptible
to Mg toxicity on serpentine soil. - Prediction SP maintain lower levels of Mg in
their leaf tissue than NP when grown on
serpentine soil.
- Ca-limiting Proctor (1971) addition of Ca
(CaSO4 or CaCO3) to serpentine soil ameliorated
Mg toxicity in oats (Avena sativa var.
Victory). - Supplementing Ca to serpentine soil decreases
amount of Mg taken up by NP. - Prediction NP contain lower levels of Mg in
their leaf tissue when grown on serpentine soil
supplemented with Ca.
32Hypothesis 3 Mg toxicity
n11, one-tailed t-test, experiment-wise P
0.05, Bonferroni corrected
33Conclusions for M. guttatus
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg High Mg requirement Mg
toxicity avoidance
? ? ?
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg Mg toxicity susceptibility
? ?
? hypothesis not supported by data ?
hypothesis supported by data
34Hypothesis 4 Heavy metal toxicity
- Mechanistic
- SP exclude potentially toxic heavy metals present
at high levels in serpentine soil (Cr, Ni) better
than NP. - Prediction SP maintain lower levels of toxic
heavy metals in their leaf tissue than NP when
both are grown on serpentine soil.
Ca-limiting b. Supplementing Ca to serpentine
soil decreases the quantity of potentially toxic
heavy metals taken up by NP, thus ameliorating
the serpentine effect. Prediction NP
contain lower levels of heavy metals in their
leaf tissue when grown on serpentine soil
supplemented with Ca.
35Hypothesis 4 Heavy metal toxicity
n11, one-tailed t-test, experiment-wise P
0.05, Bonferroni corrected
36Conclusions for M. guttatus
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg High Mg requirement Mg
toxicity avoidance Heavy metal toxicity
avoidance
? ? ? ?
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg Mg toxicity susceptibility Heavy metal
toxicity susceptibility
? ? ? Cr ? Ni
? hypothesis not supported by data ?
hypothesis supported by data
37Conclusions for M. guttatus
Mechanistic SP are able to survive on serpentine
soil because they are equipped with one or more
of the following traits, which NP lack
Tolerance of low CaMg High Mg requirement Mg
toxicity avoidance Heavy metal toxicity
avoidance
? ? ? ?
Ca-limiting Supplementing serpentine soil with
Ca ameliorates serpentine conditions for NP by
altering the following
Low CaMg Mg toxicity susceptibility Heavy metal
toxicity susceptibility
? ? ? Cr ? Ni
? hypothesis not supported by data ?
hypothesis supported by data
38More than one way to solve a problem Nectar
feeding birds
39More than one way to solve a problem Serpentine
tolerance
- Likely to be more than one physiological
mechanism that confers tolerance to serpentine
soil. - Ion uptake discrimination
- Ion translocation and/or sequestration properties
- Chelation
40- Future Work
- Investigate serpentine tolerance at the root
level using chemically-defined nutrient
solutions. - What is happening at the root-soil interface?
- How does membrane permeability differ between
serpentine and non-serpentine plants? - How are elements stored in the root?
- Investigate genetic component of serpentine
tolerance. - Generate a QTL map
- Develop NILs
41- Future Work
- Investigate evolutionary trajectories of
different serpentine populations. - Do different populations arrive at the same
solution to the serpentine problem or are there
multiple pathways to tolerance within a species?
- In California, USA, serpentine soil comprises
1.5 of landscape, but hosts 13 of endemic
plant species. - 11 of CA plant taxa listed as threatened or
endangered are serpentine endemics.
42Many Thanks!
43Soil Elemental Differences (Complete Table)
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