Download Natural Selection - Northwest ISD Moodle

Warm-up questions:
• How could genetic mutations be
advantageous to a population?
Adaptations for survival
• Which type of trait is most likely to be
expressed by offspring? (dominant or
recessive)
Dominant
NATURAL SELECTION
“Survival of the Fittest”
Natural Selection:
The process in which organisms better adapted to
their environment tend to survive and produce more
offspring.
 First fully described by Charles Darwin.

Survival of the Fittest:


The continued existence of organisms that are best
adapted to their environment, with the extinction of
those that are not.
Term used to describe natural selection.
Mutations and Survival


If mutations are beneficial to living in the
environment, it is more likely to survive and pass on
this mutated trait.
Genetic diversity helps a population be more
varied and the likelihood of survival to be
increased.
Genetic Trait VS Acquired Trait


Genetic trait: a trait that is passed down from
parents through genetics.
Acquired trait: trait that has been adapted in order
to serve a, immediate need.
Directional Selection:

When natural selection
favors one extreme of
a trait. Over time, the
favored extreme will
become more common
and the other extreme
will be less common or
lost.
Stabilizing Selection:

Type of natural selection in which genetic diversity
decreases and the population mean stabilizes on a
particular trait value.
Disruptive Selection:


The make up of this type of population would show
phenotypes of both extremes, but have very few
individuals in the middle.
The rarest of the three types of natural selection.
Practice PBA



You will now fill out the graphs on your game
packet and write a practice PBA.
Practice Prompt: Is it more important to have a
large amount of genetic diversity within the starting
population, or to have many of the same traits
throughout?
Your PBA must used evidence from your graphs and
will be in the “Claim, Evidence, and Reasoning”
format.