Chapter 2: Natural Selection

Question 1

Organizing biodiversity
Systematics
-branch of science concerned with organizing and classifying organisms
-2 distinct branches:
1. taxonomy
2. phylogenetics

Question 2

Where did this biodiversity come from?
-What are the mechanisms driving biodiversity?
-Happen in many ways (different _________) but they all describe one of the defining characteristics of life
-___________

Answer 2

-mechanisms
-evolution

Question 3

Evolution
-heritable change in ___________ of populations over time

Microevolution:
-changes in allele frequencies with ____ population

-but how did evolution happen?

Answer 3

-characteristics
-one

Question 4

Mechanisms of evolution
1. Natural Selection
2. Genetic Drift
3. Genetic __________
4. Gene Flow (__________)
5. __________ Mating

Answer 4

• mutations
• migrating
• nonrandom

Question 5

Charles Darwin & Natural Selection
-Charles Darwin published his book “On the Origin of Species” in 1859
-this was the first well supported mechanism of how organisms ______________
-Darwin hypothesized that ___________ took place through a process called ____________

Answer 5

-change over time
-evolution
-natural selection

Question 6

A Key Observation
-Darwin’s hypothesis was based on a fundamental assumption derived from Thomas Malthus’ work:
-________________ mean not every ____________ in a population _________ to reproduce

Answer 6

-limited resources
-individual
-will survive

Question 7

Survival of the Fittest
-Darwin’s theory of natural selection describes how __________ characteristics are selected for and passed down to ______________
-4 ____________ need to be met for evolution to take place by means of natural selection

Answer 7

-favorable
-future generations
-conditions

Question 8

1. Natural Variation
   -variation must be present in the members of a population
   -some variations may give individuals an ______ in their environment (_______________)

Answer 8

-edge
-higher fitness

Question 9

2. Heritability (genetic inheritance)
   *Only variations that are genetically ___________ are relevant to natural selection
   -variations that are heritable are the traits that can be ______________ from parents to offspring

Answer 9

-heritable
-passed down

Question 10

3. Differential Survival
4. Differential Reproduction
   -not all individuals survive to reproduce
   -individuals with the _________________ are more likely to survive and reproduce

Answer 10

-best variations

Question 11

Selection in Action
-The Peppered Moth (Biston betularia) is a widely distributed species in England
-________ to blend in with lichen on trees during the day (___________)
-variations in coloration
-peppered color
-melanistic (black)

Answer 11

-adapted
-camouflage

Question 12

Changing Environments
-Before 1800s, most moths were peppered (very few were _______)
-During the Industrial Revolution in 1840s, ________ cause black soot from factories to coat tress that were previously lichen colored
-caused a shift in which variations were ___________ (now _________ moths were better at blending in with darker trees)

Answer 12

-black
-pollution
-favorable
-melanistic

Question 13

Quick Review of Genetics
Chromosomes:
-carry ________ information in form of genes

Genes:
-portions of genetic information that code for ______________

Allele:
-__________ forms of genes (ex. A, a)

Answer 13

-genetic
-certain traits
-alternate

Question 14

Quick Review of Genetics
Allele:
Alternate forms of genes (ex. A, a)

Allele Frequencies:
Describe what proportion of a population carries a particular allele.
***The sum of allele frequencies for a gene always add up to 1

Question 15

Definitions:
Genotype:
_______________ of an organism, or what alleles an individual has (ex. AA, Aa, aa)

Phenotype:
_________________ of a gene (ex. hair color, height, tail length, etc.)

_________ determines ___________

Answer 15

-genetic makeup
-physical expression
-genotype
-phenotype