Introduction to Natural Selection
True or False: Natural selection acts on genotypes
False, it acts on Phenotypes
True or false: a trait that is “selected for” is a trait that is good and/or helpful to the individual.
False, traits can also be harmful or not beneficial
Natural selection is a theory that states the environments will force selection of the best:
a. physical skills
b. heritable traits
c. location
d. predato
Who Was Charles Darwin?
An English naturalist/scientist/father of evolution
Define natural selection
A process in which individuals that have certain traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Which of the following would most likely
not lead to natural selection?
a. birds with longer beaks get the more
food
b. longer whales mate more
successfully
c. a monkey finds an easy source of
food
d. darker tigers are selected as mates
more often
c. a monkey finds an easy source of
food
What idea(s) did Charles Darwin propose?
Descent with modification and Natural Selection
Some organisms, like the kangaroo rat, live in very hot environments. These mice are only active at night when it’s cool and have highly efficient kidneys to absorb as much water from their food sources as possible. These traits are known as __________
Adaptations
In a population of sea turtles all of the following could be examples of natural selection except
a. large females lay more eggs than small
females.
b. large males have more wounds from
fights than small males.
c. large males mate with more females than
small males.
d. small females are more likely to be killed
by sharks than large females.
b. large males have more wounds from
fights than small males.
Define evolution
Evolution is the change in the genetic makeup of a population over time
Contrast between artificial and natural selection
Artificial selection is human selection for traits vs nature in natural selection
How does an environment's stability or fluctuation affect the rate and direction of evolution?
Stable environments result in lower rates of evolution while fluctuating conditions increase selective pressure on populations causing faster rates of evolution.
A fire burns down part of a forest region in South America. Due to the fire, a native species of lizard loses much of its food source. The lizard subsequently loses weight. The food scarcity is present for several years and subsequent generations of lizards are much thinner than in previous years. Is this an example of natural selection? Explain your answer.
No because no trait was being selected for. The lizard loss weight due to a food scarcity, there was no change to its phenotypes for natural selection to select for.
What does “fitness” refer (in terms of natural selection)?
An organisms ability to survive and reproduce
What are the three major propositions of Charles Darwin's Theory of Evolution?
Species change over time, divergent species share a common ancestor, and natural selection is the mechanism that produces these changes.