Explore how short- and long-term environmental changes affect organisms and traits in subsequent populations
Heredity or Environment?
In a later unit we will be discussing how genetics and DNA allows us to
understand and predict how traits are passed from parents to offspring
during reproduction. Some traits, however, are affected by both genetics
and interactions with the environment. For example, identical twins have
exactly the same genes but could develop differently if their nutrition or
other conditions in the environment are not the same.
Today we will look at how environmental conditions, such as amount
of sunlight, chemicals and pH, temperature and nutrition, can effect or
change the expression of some genetic traits. Temperature plays an
important role in the development of dark points on the legs, tail, and face
of some cat breeds. Siamese cats are born almost completely white, and
develop dark points as they get older because of body temperature
differences. The cooler areas of the cat’s body, such as nose, ears, legs and
tail, get darker. The torso area of the cat remains lighter because body
temperature is warmer. This is one example of how an environmental factor,
temperature, plays a role in the expression of an inherited trait.
Temperature can also cause the color of an arctic fox’s or arctic
hare’s coat to change according to the season. Temperature-sensitive
chemicals in the skin of these animals produce pigments that darken the
coat during the warm summer months. During the cold winter months, the
pigments are not produced, which results in a white winter coat for the arctic
animals. The change in color helps to camouflage the animals during each
season because the white winter coat blends in with the snow and the brown
summer coat blends in with the grasses and soil.
The amount of light is another factor that can affect the coat
conditions of animals. Providing extra hours of artificial light during fall and
winter can prevent animals from growing a thick winter coat. People who
raise and show livestock often regulate the amount of light in the animal’s
stall to maintain a sleek show coat throughout the year. They must also
blanket the animal to keep them warm during the cold months which also
prevents the growth of a long winter coat.
Plant growth and coloration are also affected by environmental
conditions. Most plants grow toward light because it is needed for
photosynthesis. Many flowering plants bloom during the summer while
receiving many hours of sunlight. Other flowering plants bloom when days
are shorter such as in the fall season. Chemicals in the soil can also affect
growth and blooming in plants. Some plants, like hydrangeas, will bloom in
different colors depending on the chemistry of the soil.
So although genetics plays the largest role in an organism’s looks and
behaviors, the environment can also have an impact. Some impacts are
positive and help an organism survive, while others may be negative and
cause species to have mutations or die out.
Explore how short- and long-term environmental changes affect organisms and traits in subsequent populations
Heredity or Environment?
Read the article above and then finish the following statements.
Three environmental factors that can affect the expression of an organisms traits
are _______________________________________________________________
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Temperatures can affect organisms by ___________________________________
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The advantages of changing coat color are ________________________________
__________________________________________________________________.
When flowers bloom depends on ________________________________________
__________________________________________________________________.
The color of hydrangea blooms can ______________________________________
__________________________________________________________________.
Identical twins with identical genes can be different because __________________
__________________________________________________________________
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