Environmental Effects on Phenotype Study Guide


Scientists have long recognized the importance of environmental variables in developing animal features. Diet, temperature, light cycles, humidity, oxygen levels, and the presence of mutagens may all influence an animal’s genes, thereby affecting the animal’s phenotype. As a result, scientists studying the genetics of modern organisms usually try to minimize the environmental effects by keeping the species under investigation in the same habitat. Even genetically identical creatures subjected to controlled experimental circumstances can exhibit distinct phenotypes, demonstrating the impact of minor environmental variations on gene expression.

Genetic differentiation and variable environmental circumstances among populations and ecosystems can be linked to phenotypic diversity within a species. The link between environmental circumstances and phenotypic expression can alter evolutionary potential, possibly affecting speciation rates or displacement of ecological character.

The expression of genes in an organism can be influenced by the environment, including the external world in which the organism is located or develops and its inner world, including hormones and metabolism. One significant internal environmental influence that affects gene expression is gender. Similarly, temperature, chemicals, drugs, and light are the external environmental factors that can determine which genes are turned on and off, thereby influencing how an organism develops and functions.

Effects of Environment on Phenotype

  • Genes have a vital role in phenotype development, but they are not the sole factor. Phenotypes are influenced by environmental factors like temperature and nutrition availability. In Siamese cats, for example, coat color is affected by temperature.

Effects of Environment on PhenotypeSource

  • The timing of the transition from vegetative to reproductive growth stages, the allocation of more resources to the roots in soils with low nutrient concentrations, the size of the seeds an individual produces depending on the environment, and the alteration of leaf shape, size, and thickness are all examples of phenotypic plasticity in plants.
  • A mutation in an enzyme involved in melanin formation causes the pointed pattern, which is a kind of partial albinism. The heat-sensitive mutant enzyme cannot function at average body temperatures, and it is, nevertheless, active in the skin’s colder regions. As demonstrated in the Figure above, this causes dark pigmentation in the cat’s coldest areas, such as the lower limbs and face. The flow of air via the nose cools the cat’s face. Adult Siamese cats with lighter coats live in warmer areas than those with darker coats.

How does the environment influence phenotypes?

  • Epigenetic mechanisms are frequently blamed for phenotypic variations caused by the parental origin of alleles. The most well-known example is genomic imprinting, in which gene dosage is influenced by a gene’s monoallelic expression owing to local epigenetic suppression of transcription on one chromosome. Furthermore, the entire genotype of parents can occasionally impact the phenotype of kids, such as through the mothers in utero influences.
  • It can be difficult to tell the difference between parental genotype effects and parent-of-origin effects caused by genomic imprinting. About 1% of the genes in the human genome are thought to be affected by genomic imprinting.
  • Genes and the environment both influence color. The pigment gene must be present in flowers. The color of the bloom is influenced by the pH of the soil. Some flowers have a color preference.
  • Treatments like fertilizer can be used to modify the color and adjust the pH. As a result, the flower’s color becomes more saturated, making it more appealing to sell (various meanings/symbols). Plant colors are only one aspect of epigenetics.
  • The health of organisms can be influenced by the environment. Not every creature goes through the same experiences as others, which might cause health issues. Some people design surroundings with the intent of altering an organism’s physical manifestation.
  • The skin includes a range of macromolecules that readily absorb UVB photons, such as RNA, DNA, and proteins. Practically, all UVB photons are absorbed by the macromolecules in the epidermis. UVA radiation gets through the epidermis and enters the dermis because these macromolecules are less effective in absorbing UVA radiation. The epidermis and dermis absorb very little visible and infrared light, allowing them to penetrate deep into the human cavity and bathe interior organs.


  • Environmental factors can alter an organism’s phenotype, and environmental factors triggers can play a role in developing a disease in those who are genetically susceptible to it.
  • Twin studies help scientists determine how environmental and genetic factors impact individual characteristics and behaviors.


1. Can the environment change phenotype?

Yes, by adapting to changes in the environment, organisms change their phenotypes, including physical and behavioral features.

2. How does the environment affect genes?

Exposure to chemicals in the external environment alters which genes are switched “on” or “off,”. This can modify how cells operate and, as a result, a person’s vulnerability to disease. Epigenetic regulation is the result of this chemical alteration.

3. How does the environment affect genotype?

Although spontaneous mutations can cause it to alter, the genotype remains typically stable in different environments. However, when the same genotype is exposed to various circumstances, it can create a wide variety of phenotypes.

4. How do environmental factors affect the relationship between genotype and phenotype?

Phenotypic plasticity refers to the degree to which your genotype determines your phenotype, and phenotypic plasticity is high when environmental variables have a substantial impact.

5. What are two environmental factors likely to affect gene expression?

Temperature and light, in addition to medications and chemicals, are external environmental variables that can alter gene expression in some species.

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  1. Environmental Effects on Phenotypes https://apcentral.collegeboard.org/pdf/ap-biology-course-and-exam-description-0.pdf?course=ap-biology Accessed on 30 Dec, 2021
  2. Environmental Effects on Phenotypes https://fiveable.me/ap-bio/unit-5/environmental-effects-on-phenotype/study-guide/hLZNliseyo0zAayZWnah Accessed on 30 Dec, 2021
  3. Phenotypes https://www.nature.com/scitable/topicpage/environmental-influences-on-gene-expression-536/ Accessed on 30 Dec, 2021
  4. Environmental Effects on Phenotypes https://www.jove.com/science-education/11977/background-and-environment-affect-phenotype Accessed on 30 Dec, 2021

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