Chapter 4 - Organization of Life

Adapting to the Environment

Section 2.3 Adapting to the Environment

• Adaption - an inherited trait that increases an organism's chance of survival

• Factors in the environment, such as temperature, availabilty of food, and the number of predators, placedemands on the members of a species.

• Because there is natural varation among individuals of a species, some individuals may have hereditary characterisitc that enables them to better overcome the constraints imposed by the environment.   This individual will be more likely to survive and reproduce, thus causing the number of individuals wth the beneficial hereditary charateristic to increase with each generation.

• Evolution, simply, is change in the genetic characteristics of a population fromone generation to the next.

• Natural Selection is one process that results in evolution.
  • Individuals have the ability to produce more off spring than can possible surrive
  • Environment contains things that kill organisms.  Environment can be hostile, hot or cold, dry or flooded.  Predators are common, and the resources need to survive and reproduce are limited; therefore individuals compete for limited resources - Darwins "struggle for exsistance"
  • Individuals differ in traits - size, coloration, sunnings speed, resistance to disease - these traits must be inherited to influence natrual selection
  • Some inherited traits give indivduals advantage in coping with environmental challenges, allowing them to survive longer and produce more offspring.  Organisms with these traits ar "naturally selected for".
  • Because offspring with advantageous traits have more offspring, each new generation has more individuals with advantageous trait than the previous generaton, gradually over time population contains more individuals with advantageous trait.

• Coevolution occurs when two or more species evolve in response to one another.

• Darwins theory can be explained by looking at insects and insecticies.  There may be some indivdual insects with a hereditary characteristic that enables them to survive exposure to an insecticide.  Those insects will be able to survive and reproduce, and their offspring born with this characteristic will also survive and reproduce, those born without the characteristic will die, eventually the population will be largely immune to the effects of the insecticide.