PL SC 324 Lecture 3: Stress Responses & Phenotypic Plasticity

Stress

Is any phenomena that limits the biomass production of plants

Disturbance

Any phenomena that removes or destroys plant biomass

Resistance

Is the ability of a plant to withstand a stress

Resilience

Is the ability of a plant to recover from stress

Draw the Time Scale of Plant Response

Stress Response

Immediate detrimental effect of stress on a plant process (Photosynthesis, growth, etc.)

Acclimation

Morphological and physiological adjustment by individual plants to compensate for the decline in performance due to a stress (ex: Synthesis of new proteins).

Adaptation

Evolutionary response that results from genetic changes in populations leading to morphological and physiological compensation (genetic changes in populations).

Population

All of the individuals of the same species and living in the same area

Adaptation is the result of

natural selection (or selective breeding)

Long-term stress will lead to selection of — survival strategies as opposed to — strategies

Phenotypic Plasticity:

Ability of a single genotype to produce more than one phenotype. We can demonstrate this by examining genetically similar individuals grown in different environments.

Genotype

The genes of an individual, or the particular alleles of a gene.

Phenotype

The observable characteristics of an individual.

T/F Plasticity can happen in virtually any plant trait

True

Plasticity may thus be advantageous when the environment varies on an intermediate scale, between scales somewhat larger than the size of the response unit and somewhat smaller than the dispersal range of offspring. Amplitude: the degree to which an environmental factor varies over a given distant. Plasticity is likely to be advantageous over an intermediate rage of amplitude in heterogenicity. With a small amplitude, the environmental variation has no effect on performance, plasticity will have no advantage. When the amplitude of environment is so great that plasticity cannot enable a genotype to survive in more than one environment, plasticity should have no advantage.

Plasticity is expected to be advantageous only in a trait that responds quickly relative to the duration of environmental states. When the ability to change matches the duration of the environmental state, there will be a lag.

Plasticity may be more advantageous when the environment is more predictable, expect that plasticity should have no advantage when the environment is completely predictable.