1. Chapter 16 Notes Spring 2006 Mr. Holmes

2.  Darwin’s problem was that he did not understand inheritance. Although Mendel’s work was published during Darwin’s lifetime, the work was not accepted at that time.

3. Frequency of Phenotype Phenotype (height)

4.  (copy)  All the genes in an organism makes up its total genetic makeup. A gene pool is a combination of all the genetic information of all the members of a particular population. It usually contains two or more alleles (or forms) of a gene. The relative frequency is the number of times an allele appears in a population.

5. Sample Population 48% heterozygous black 36% homozygous brown 16% homozygous black Frequency of Alleles allele for brown fur allele for black fur

6.  (copy)  The variations in genetic pools are due to mutations and genetic shuffling. Variations would lead to asking the question: Why aren’t all gene pools the same? Crossing over is a process that can lead to variation.

7.  A phenotype, or trait, can be due to the result of a single gene or it can be the result of more than one gene working together (polygenic)

8. Directional Selection Food becomes scarce. Key Low mortality, high fitness High mortality, low fitness

9. Key Percentage of Population Birth Weight Selection against both extremes keep curve narrow and in same place. Low mortality, high fitness High mortality, low fitness Stabilizing Selection

10. Disruptive Selection Largest and smallest seeds become more common. Number of Birds in Population Beak Size Population splits into two subgroups specializing in different seeds. Beak Size Number of Birds in Population Key Low mortality, high fitness High mortality, low fitness

11.  (copy)  Genetic drift is the idea that a certain trait disappears or appears in a population by chance and becomes common over time. The founder effect occurs when allele frequencies change as a result of the migration of a small subgroup of a population.

12. Sample of Original Population Founding Population A Founding Population B Descendants

13.  (copy)  Hardy-Weinberg equilibrium states that the allele frequencies in a population remains constant unless one or more factors causes a change. If this happens the situation is said to be at genetic equilibrium. The five conditions of Hardy- Weinberg equilibrium are: random mating large population no immigration or emigration no mutations no natural selection

14.  The formation of a new specie is caused speciation. What causes speciation?  The main reason is reproductive isolation behavioral isolation (differences in courtship rituals) geographic isolation (two species separation by geographic barriers) temporal isolation (different times of fertility)

15. results from which include produced by which result in Reproductive Isolation Isolating mechanisms Behavioral isolationTemporal isolation Geographic isolation Behavioral differencesDifferent mating times Physical separation Independently evolving populations Formation of new species