Phenotypic Plasticity and Maternal Effects

Short-term responses to changing climates?

Current Climate Models Predict an Increasingly Warmer World

Changing Thermal Environments

Organismal response to rising temperatures

Shifts in Distribution

Ecological Response

Δ Phenology

Evolutionary Response: Adaptation

ExtinctionFailure to Adapt

Creative Commons/Bart Heird

Another response (short term)

Maternal Effects

&

φ

Normal Range of Developmental Temperatures

Novel HighNovel Low

Adaptive Plasticity in Novel Environments

after Ghalambor et al. 2007. Functional Ecology 21:397

Reaction Norms – low cost to fitnesspersistence of plasticity

“Release” of cryptic variationin novel environments.Selection on G x E..

Acclimitization is one form of Plasticity

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

Repro- Success/Offspring

Traits

Repro- Success/Offspring

Traits

Maternal ConditionMaternal Condition

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.

Extended Warm Spells

Extended Warm Spells

Decreasingrainfall

Rising Temperatures

Altered Population Dynamics

Altered Population Dynamics

Altered niche attributes initiate stress response

How does elevated CORT effects and costs of immune response mediate offspring quality

Population dynamicsConsequences

Maternal Effects & Developmental Plasticity

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Stressor

Dispersal

Growth Rate

Philopatry

Maternal Survival

Energy Stores

Clutch Size/Offspring SizeTrade-off

CORT

Offspring “Quality”

Could be Ta

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

xAugust Ta year before pregnancy

Significance of Dorsal Pattern

Behavior and performance covary with dorsal pattern

Brodie 1992 Evolution

Frequency of Reticulate females decreased with elevation only in 2008“Cool” Year

Temporal variation in % reticulated morphs

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)