Download Evolution of Populations Scavenger Hunt

Evolution of Populations Scavenger Hunt
16-1 Genes and Variation (pages 393-396)
Name ___________________________
Period _______
Darwin’s Ideas Revisited
Darwin did not understand Heredity so he had no understanding of
1. ____________________________________________________________________________________
____________________________________________________________________________________
2. ____________________________________________________________________________________
____________________________________________________________________________________
Gene Pools
*What is a population? _______________________________________________________________________
*A gene pool typically contains ___________ or ____________ alleles for each inheritable trait.
*The number of times an allele occurs in a gene pool compared with the number of times other alleles occur is
known as ____________________ ________________________.
Sources of Genetic Variation
*The two main sources of genetic variation are ____________________ and ____________________
____________________ that results from sexual reproduction.
Single Gene and Polygenic Traits
*The number of ___________________ produced for a given _____________ depends on how many
_____________ control the trait.
*______________ ____________ is an example of a single-gene trait because you either have it or you don’t.
*______________ in humans is an example of a polygenic trait because there are many phenotypic variations.
*A __________________ bell-like shape curve is a typical representation of polygenic traits.
*A bell-shape curve is also called a _______________ _______________________.
16-2 Evolution as Genetic Change (pages 397-402)
*Natural selection determines which ____________ are passed from one ___________________ to the next.
*This causes a change in the ______________ __________________ of alleles in a
______________________ over time.
*Whenever an individual in a population _________ without _________________, its __________ are
removed from the population.
*But it an individual produces many ____________, the proportion of that individual’s ___________ in the
gene pool will _____________.
Natural Selection on Single-Gene Traits
*Natural selection on ____________- ____________ traits can lead to ______________ in allele frequencies
and thus to ____________________.
Natural Selection on Polygenic Traits
*Fitness of individuals ___________ to one another on the bell-curve is not very ______________________.
*But fitness can __________ a great deal from one ________ of a curve to the ____________.
*Where _____________ varies, _______________ ________________ can act.
1.Directional Selection
*When individuals at one end of the cure have higher fitness than individuals in the middle or the other end it
is called ___________________ _____________________.
*This situation causes the __________ curve to move as the character ___________ changes.
*An example of this would be the ___________ in the average size of ________ on Galápagos ____________.
2.Stabilizing Selection
*When individuals near the center of the curve have higher fitness than individuals at either end of the curve it
is called __________________ _______________.
*This situation keeps the ____________ of the curve at its ____________ position, but it ______________ the
overall graph.
*An example of this would be the _____________ _______________of human ____________.
3.Disruptive Selection
*When individuals at the upper and lower ends of the curve have higher fitness than individuals near the
middle it is called _________________ __________________.
*If the pressure of ______________ ________________ is strong enough and lasts long enough, this situation
can cause the _____________ curve to split into __________.
*An example of this would be the disappearance of _______________ sized seeds, resulting in high fitness for
birds with ____________ or ____________ beaks.
Genetic Drift
*In ___________ populations, individuals that carry a particular _____________ may leave more descendants
than other __________________, just by chance. Over time, a series of ____________ occurrences of this
type can cause an _____________ to become __________________ in a population.
*A situation in which _____________ frequencies change as a result of the _________________ of a small
subgroup of a __________________ is known as the _________________ __________________.
Evolution Versus Genetic Equilibrium
*The ________________-_________________principle states that allele frequencies in a population will
remain ______________ unless one or more ____________ cause those frequencies to change.
*The five conditions required to maintain genetic equilibrium from generation to generation are:
1.__________________________________________
4._____________________________________
2.__________________________________________
5._____________________________________
3.__________________________________________