Final answer:
Environmental signals can produce stable changes in gene activity that regulate physiology and behavior. Factors like nutrient deficiency and exposure to ultraviolet light can modify gene expression. Epigenetic changes influenced by environmental exposure and mutations can also impact gene expression and be passed on to future generations.
Step-by-step explanation:
Environmental signals can affect development by producing stable changes in the activity of genes that regulate physiology and behavior. These signals can come in the form of chemicals in the air, water, or extracellular fluids, as well as hormones released at specific times during development or in response to nutrient levels. For example, exposure to ultraviolet light or nutrient deficiency can modify gene expression and lead to changes in phenotype.
Environmental factors, such as sunlight and food availability, can influence how genes are expressed in an organism's phenotype. These factors can impact various characteristics in individuals. For instance, a fetus that experiences famine during pregnancy may have different environmental signals compared to a fetus that receives an appropriate food supply, which can lead to long-term changes in gene activity and affect the individual's physiology and behavior.
Epigenetic changes, which involve alterations in gene expression during an individual's lifetime, can also be influenced by environmental exposure and mutations. Trauma and exposure to certain substances, like smoking, can result in heritable changes in DNA and affect outwardly expressed traits. These changes can be passed on to future generations, showcasing how environmental signals can have lasting effects on gene activity and its regulation.