Phenotypic Plasticity and
Maternal Effects
Short-term responses to changing
climates?
Changing Thermal Environments
Current Climate Models Predict
an Increasingly Warmer World
Organismal response to rising
temperatures
Ecological Response
Shifts in Distribution
Δ Phenology
Evolutionary Response:
Adaptation
Failure to Adapt
Extinction
Creative Commons/Bart Heird
Another response (short term)
&
Maternal Effects
Adaptive Plasticity in Novel Environments
Reaction Norms –
low cost to fitness
persistence of plasticity
φ
Novel Low
Normal Range of
Developmental Temperatures
Novel High
“Release” of cryptic variation
in novel environments.
Selection on G x E..
after Ghalambor et al. 2007. Functional Ecology 21:397
Acclimitization is one form of
Plasticity
B. CIB
Fitness
A. BAH
Cool
Warm
Test Temperature
C. HIB
Cool
Warm
Test Temperature
Fitness
D. LAH
Cool
Warm
Test Temperature
Cool
Warm
Test Temperature
BAH, CIB, etc.
• Most tests of these hypotheses involve
Developmental Plasticity
– i.e., irreversible phenotypic changes induced by
rearing conditions
Plasticity in Reproduction
• How do gravid (pregnant) females respond to
warming?
Reproductive Plasticity in Females
Manipulation of thermal regime
experienced by gravid females
Developmental stage is sensitive to
thermal conditions experienced by
gravid females
Reproductive Investment
Why Females?
Females can manipulate the phenotype of her offspring depending on intrinsic and
extrinsic conditions
Hormones (Cort, Androgens), Tb of dam
How can females affect offspring
phenotype?
• Hormones
• Offspring Provisioning
• Incubation Temperatures during embryonic
development
– Viviparous Lizards
• Maternal Tb
– Oviparous Lizards
• Nest Site Selection
How does elevated CORT
Altered niche
attributes initiate effects and costs of
immune response mediate
stress response
offspring quality
Population dynamics
Consequences
Rising
Temperatures
Extended
Warm Spells
Maternal
Condition
ReproSuccess/
Offspring
Traits
Decreasing
rainfall
Adaptive maternal effects (mainly
organizational effect of hormones and
immunity products) modify individual strategy
and survival later on. One outcome is the
induction of offspring phenotypes to cope with
novel environments.
Altered
Population
Dynamics
Maternal Effects & Developmental
Plasticity
Stressor
CORT
Could be Ta
Energy Stores
¥
Maternal Survival
Clutch Size/Offspring Size
Trade-off
Offspring “Quality”
Dispersal
Philopatry
Growth Rate
Body size affected by incubation
temperature
Speed is sensitive to incubation
temperature
Hormones and Offspring
Phenotype
CORT treated lizards remained in
shelters longer than controls
Plasticity in Dorsal Pattern
Zootoca (=Lacerta) vivipara
Mechanism of Induction
Juvenile dorsal pattern affected by:
May Ta during Gestation
August Ta year before pregnancy
x
Significance of Dorsal Pattern
Behavior and performance covary with dorsal pattern
Brodie 1992 Evolution
Temporal variation in % reticulated
morphs
Frequency of
Reticulate females
decreased with
elevation only in
2008
“Cool” Year
Evidence for plasticity in morphs
Maximum velocity increased with
habitat openness
F3,349 = 3.05, p < 0.02
Speed differed between
years
F3,349 = 7.82, p < 0.001
Speed differed between
morphs
F3,349 = 3.35, p < 0.01
Number of stops
increases with habitat
openness
Reticulate females
stopped more
frequently than linear
females
Chi-square = 5.42, P < 0.01
Conclusions
• Climate can induce variation in reproductive
performance
• Variation in conditions experienced by females
can affect offspring phenotype
– Whether female manipulation benefits offspring
depends on conditions at hatching (birth)