How does performance change through development?
Like the sea lion, capacity to store O2 undergoes a major developmental change as they mature into adulthood b/c concentration of hemoglobin in blood increases and enables each volume of blood to combine with more O2
Phenotypic plasticity due to genetically programmed responses
- programmed by a genetically coded physiological control system that determines which phenotypes are expressed under which environmental conditions.
- consequence of earlier menarche in European girls due to improved nutirion and health
Plasticity due to environmental forcing
working class kids in 1800’s were shorter than aristocratic kids because of harsh conditions they lived in
Describe polyphonic development
- phenomenon in which genetically identical individuals can assume two or more distinct body forms, induced by the environment
- butterflies in spring v. summer have different coloring to camouflage
- migratory locusts exhibit gregarious and solitary behavioral phenotypes.
Why do we say phenotypic plasticity is adaptive?
The control systems that determine the phenotypes are subject to natural selection over evolutionary time and represent adaptations
Identify mechanisms of epigenetic marking
- DNA methylation - attachment of methyl groups by covalent bonds to cytosine residues in structure of DNA
- covalent modification of histones - around which DNA is wrapped in the nucleosomes of the chromatin of a cell.
How are epigenetic marks transmitted to daughter cells?
When marks are replicated from cell to cell as cells divide, the marks induced by the environment are perpetuated throughout life and potentially into the offspring.
Describe the mechanism of genomic imprinting
-one allele form one of the parents is predominantly expressed over the other allele from the other parent
Define epigenetics
refers to modification of gene expression - with no change in DNA sequence - that are transmitted when genes replicate.
define gene expression
the appearance in a phenotype of a characteristic or effect attributed to a particular gene
When do mammals and birds achieve their full capacity of homeothermy?
At birth.
