Investigating the adaptive
potential of agricultural weeds
Dehnen-Schmutz, Bill Finch-Savage, Paul Neve
to increased temperatures Katharina
School of Life Sciences, University of Warwick, United Kingdom
+ 4 oC
+ 2 oC
Ambient
Growing A. myosuroides at
increased temperatures
Plants were grown in pots in
three zones in a purpose built
thermogradient tunnel equipped
with a heating and fan system
that creates a temperature
gradient ranging from ambient
temperature at one end of the
tunnel to +4oC at the other end
(total length 30 m).
Acknowledgements: this study is funded by the
UK Government Department for Environment,
Food and Rural Affairs.
210
ambient
plus 2
plus 4
B
ambient
plus 2
plus 4
200
Num ber of days
16
18
205
20
22
A
Temperature
195
190
510000
520000
530000
540000
510000
550000
520000
530000
540000
550000
Latitude
Latitude
Figure 1: Average time to emergence (A) and flowering (B) from the date of sowing at
ambient temperature, + 2oC above ambient and + 4oC for 18 populations of
A. myosuroides collected along a UK latitudinal gradient.
Fitness
As a measure of
fitness we used the
sum of the length
(cm) of all seed heads
produced per plant
multiplied
by
the
number
of
seeds
counted per cm seed
head
length.
In
general, fitness and
within
population Figure 2: Changes in fitness (average number
seed produced per plant) at ambient
variability
increased of
temperature, + 2oC above ambient and + 4oC
with temperature in all of 18 populations of A. myosuroides collected
along a UK latitudinal gradient.
populations.
Southern populations showed the greatest increase in
fitness at +2oC , whereas, the fitness of Northern
populations increased most at +4oC .
2000
Temperature
1800
ambient
plus 2
plus 4
1000
Num ber of seeds
1200
1400
1600
Study species and seed
collection
Alopecurus myosuroides L. is
an annual grass found more or
less exclusively as a weed on
arable land. In Britain, A.
myosuroides
has
been
introduced very early as an
archaeophyte. A. myosuroides
is considered one of the most
serious agricultural weeds in
Europe and has developed
resistances to a variety of
herbicides. We collected A.
mysuroides seeds from 18
locations across the main
distribution range of the species
in Great Britain.
Temperature
14
Research questions
We use Alopecurus myosuroides as an example to explore:
1. how increased temperatures impact on phenology and
reproductive success of the species
2. if populations from different origins along a UK
latitudinal gradient show different responses to increased
temperatures
3. if variability within these populations changes with increased
temperature and along the latitudinal gradient
Results
Emergence and flowering timing
For populations of northern origin time to emergence
increased with increasing temperature whereas
southern populations emergened faster in warmer
conditions. Flowering was advanced
for all
populations, but the effect was greatest with the +2oC
increase. The within population variability increased
with higher temperatures.
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Introduction
Agricultural weeds are the most important reason for crop losses
globally and their management is of crucial importance not just for
individual farmers but also for global food security. Climate change
will not only result in the introduction of new potentially serious
agricultural weeds it will also severely impact on weeds already
present. Populations of arable weeds exhibit a large degree of
inter- and intra-population variability. This variability dictates that
populations may respond in different ways to climate change and,
perhaps more importantly provides a means for populations to
adapt to changing management and changing environments.
510000
520000
530000
540000
550000
Latitude
Conclusions
Our results show significant differences in the effects of
warming between and within populations depending on
their geographic origin. Overall, the fitness of A.
myosuroides increased with temperature and the within
and between population variability suggests possible
adaptive potential in the face of future climate change.
These experimental results do not allow for any
predictions of possible future impacts for agriculture as
likely changes in precipitation and cultivation patterns,
as well as competition from crops and other species
would also have to be included. Nevertheless, the
methodology seems useful to analyse the adaptive
potential not just of the current most troublesome
weeds but also as a screening tool for newly introduced
weeds as well as for species already present that have
little impacts at current temperatures.