Behavioral Cycles Among Different Organisms

Behavioral Cycles in Plants

• Plant Dormancy– Is a temporary state of

reduced rate or no internal activity (Scott Freeman, 2003, pg.898) .

– Different chemicals (hormones) in the plant activate the plant to start growing and for it to go into dormancy.

Tree Dormancy • Both chlorophyll and carotenoids

are present in the chloroplasts of leaf cells throughout the growing season.

• During the growing season, chlorophyll is continually being produced and broken down and leaves appear green.

• As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed.

• The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

• This is what causes leaves to change color and for trees to lose their leaves for the winter (dormant).

http://www.na.fs.fed.us/fhp/pubs/leaves/leaves.shtm

Seed Dormancy

• Seed dormancy is the state seeds are in before they start growing.

• Seeds experience dormancy so they don’t start growing in conditions that won’t allow them to survive (drought, or winter).

• Dormancy is broken when optimal growing conditions are present.

• Water, sunlight, temperature are some ways to break dormancy (Scott Freeman, 2003, pg.926) .

Behavioral Cycles in Animals

• Hibernation occurs when temperatures lower and winter conditions cause food to become scarce.

• Animals (squirrels, voles, mice) must seek a well insulated shelter and reduce their internal activity (metabolic activity) which will lower their internal temperature (Scott Freeman, 2003, pg.948).

• During hibernation (torpor) animals reduce their internal temperature, heart rate, oxygen intake.

• This saves animals precious energy they need due to lack of resources.

How Organisms Migrate?• Migration is long-distance

movement of a population associated with a change of seasons. (Scott Freeman, 2003, pg.1148).– Examples:

• Arctic terns nest along the Atlantic coast of North America, fly south along the coast of Africa to Antarctica (total of 20,000 miles).

• Monarch butterflies travel from all over the North to Central Mexico or southwest California.

• Salmon when they hatch migrate to the ocean where after feeding and growing for several years return to where they spawn and then die.

How do Animals Migrate?• Piloting- Use familiar

Landmarks where offspring follow their parents and memorize the routes.

• Compass Orientation- Oriented in a specific direction based on the Sun during the day and the Stars at night.

• True Navigation- Birds can detect magnetism by their visual system and have small particles of magnetic iron. – Changes in the positions of

magnetic particles, in response to Earth’s magnetic field.

(Scott Freeman, 2003, pg.1149).

References

• Scott Freeman, S. (2003). Biological science. (2 ed., pp. 494-512). Upper Saddle River, New Jersey: Pearson Prentice Hall.

• http://www.na.fs.fed.us/fhp/pubs/leaves/leaves.shtm