Ant Human Evolution Test #1 Mechanisms

Front 1

Microevolution vs. macroevolution

Back 1

Microevolution is the individual adaptive changes which cause a species to change over time
Macroevolution is the evolution of an entirely new species

Front 2

How natural selection leads to complex adaptations

Back 2

• Fitness impacts allelic survival (frequencies)
• small adaptations lead to increased fitness and the passing on of these changes
• Complex adaptations are the sum of many small adaptations
• ie. the eyeball

Front 3

Speciation
Species

Back 3

Speciation = creation of a new species
Species = organisms clustered into distinct types

Front 4

Biological species concept

Back 4

Defines a species by a population which is reproductively isolated from other groups

Front 5

Ecological species concept

Back 5

Defines a species by organisms' morphological and behavioral proximity
Reproductive isolation is not a factor

Front 6

2 barriers to gene flow
Pre-zygotic
Post-zygotic

Back 6

Pre-zygotic = complications that arise before fertilization ie. cats and dogs don't mate
Post-zygotic = complications that arise after fertilization ie. still born

Front 7

Allopatric speciation

Back 7

When a species is divided by a physical barrier so that they adapt to different environments

Front 8

Sympatric speciation

Back 8

When a species diverges because different members adapt to different niches in one environment

Front 9

Parapatric speciation

Back 9

• when 2 populations of a species inhabit different environments, so that they only come into contact on occasion
• over time they eventually adapt enough to their individual habitats so that they can no longer interbreed

Front 10

Reinforcement

Back 10

Helps along speciation
when reduced hybrid viability leads to further reproductive isolation

Front 11

Character displacement

Back 11

Helps along speciation
competition between 2 species causes members to become more morphologically or behaviorally different

Front 12

Fitness

Back 12

Ability to pass on ones genes to the next generations

Front 13

Gene flow

Back 13

the movement of alleles within and between 2 populations via:
migration → increases diversity
nonrandom mating → decreases diversity

Front 14

Nonrandom mating

Back 14

A mechanism of gene flow
inbreeding = individuals of subunit mate with one another
assortative mating = when individuals seek mates with similar traits

Front 15

Genetic drift & Founder Effect

Back 15

Genetic drift = random changes in gene frequencies within a population, due to sampling variations
Founder Effect = when a small population colonizes a new habitat there are amplified random genetic changes
**Genetic drift is most powerful in a small population**

Increases between group diversity, decreases in group diversity

Front 16

Mutation

Back 16

changes in the chemical structure of DNA due to a coding error
Only source of absolutely new genes - variation

Front 17

Spontaneous mutation
Induced mutation

Back 17

Spontaneous mutation = errors in DNA replication
Induced mutation = due to some exogenous source