AP Syllabus focus:
‘Flower color, seasonal fur color, and similar traits can shift when environmental conditions such as soil pH or temperature change.’
Coloration is a visible phenotype shaped by pigments and tissue structure. In many organisms, environmental conditions alter pigment production, pigment chemistry, or hair/feather replacement patterns, changing appearance without changing DNA sequence.
Core idea: environment can shift colour phenotypes
Environmental variation can change colour by affecting:
Pigment synthesis (enzyme activity, gene expression, precursor availability)
Pigment chemistry (molecular form, binding partners, pH-dependent structure)
Pigment deposition (where and how much pigment accumulates)
Practice Questions
FAQ
Hydrangea colour often depends on complexes between petal pigments and metal ions.
More available aluminium in certain soil conditions can shift pigment complexes toward blue hues.
Soil chemistry affects aluminium solubility and transport into petals.
Yes. Structural colours depend on tissue microstructure.
Environmental stress during growth (nutrition, temperature) can alter the spacing/organisation of nanostructures in feathers or scales, shifting reflected wavelengths.
Some microbes alter pigment chemistry or host resources.
They can reduce available dietary pigments (e.g., carotenoids) by affecting digestion.
Inflammation can disrupt pigment deposition during feather or hair growth.
Not as DNA sequence changes, but some effects can persist via non-genetic mechanisms.
For example, epigenetic marks or maternal provisioning might influence offspring pigment production under similar conditions, though stability varies across taxa.
If snow cover duration changes faster than day length, photoperiod-driven moults may become mismatched.
This can produce periods where animals are white on snowless ground (or vice versa), increasing predation risk and potentially shifting selection on cue sensitivity.
