Evolution & the Origin of Species

Question 1

Theory

Answer 1

An explanation of large bodies of collected data and facts

Question 2

Hypothesis

Answer 2

An idea about how observed phenomenon works

Question 3

Natural Selection

Answer 3

The process by which a selective force (i.e. predator, parasite, abiotic feature) causes some individuals in a population to survive and reproduce to a greater degree than others, which can lead to evolutionary change.

Question 4

Evolution

Answer 4

A change in genotype frequencies in a population over time

Question 5

What is the adaptive mechanism of evolution?

Answer 5

Natural selection

Question 6

Natural selection happens to _________, while evolution happens to __________

Answer 6

individuals

populations

Question 7

What are the necessary aspects of natural selection?

Answer 7

1. Genetic variation (mutation, sexual reproduction)
2. Selective Force (alteration in background, parasite presence, etc.)
3. This causes differential survival that leads to differential reproduction. Some individuals are more successful at reproduction for a reason.
4. Leads to genotype frequency alterations in a population.

Question 8

Adaptation

Answer 8

Any trait that makes the organism more likely to survive and reproduce.

Question 9

Fitness

Answer 9

Individuals within populations that have adapted to their environment generally have a higher fitness.

Usually fitness is measured in terms of survival or reproductive success.

Question 10

Fecundity

Answer 10

Reproductive success is usually measured by counting the number of surviving offspring, this is called fecundity.

Question 11

Convergent Evolution

Answer 11

Similar conditions can cause the evolution of similar traits – even in unrelated organisms

Question 12

What is the main evidence for the evolution of species from common descent?

Answer 12

-Fossils
-Anatomy & Embryology (humans have pharyngeal arches and similar embryonic development to many other vertebrates)
-Biogeography (fossils in Antarctica that could not survive there today, continental drift theory)
-Molecular Biology (Same DNA structure, amino acid sequence for cytochrome C)

Question 13

Homologous structures

Answer 13

Structures that have similar parts due to shared common ancestry, which may or may not have similar functions.

Question 14

Vestigial structures

Answer 14

Structures that have no apparent function and are likely due to evolution from an ancestor that had a function for that structure.

Question 15

Microevolution

Answer 15

Changes within a species
Example: Pocket mouse coat evolution

Question 16

Macroevolution

Answer 16

Formation of a new species from pre-existing species.
Example: Modern dog species – reproductively isolated from ancestral wolf species

Question 17

Biological species concept, what is the problem with this concept?

Answer 17

A group of populations whose members have potential to interbreed in nature and produce fertile offspring.

Problem: Some populations produce asexually.

Also, some animals can be morphologically different and the same species according to this. (Ex: polar bears and grizzly bears, not same species according to ecological species concept)

Question 18

Morphological species concept

Answer 18

Defines species by physical traits; doesn’t require mating

Question 19

Ecological species concept

Answer 19

Defines species by their role within the environment

Question 20

Phylogenetic species concept

Answer 20

Any group of organisms that have shared common ancestry, also may use morphology (physical traits)

Question 21

Medical/micro species concept

Answer 21

Species, groups of similar organisms within a genus, are designated by biochemical and other phenotypic criteria and by DNA relatedness, which groups strains on the basis of their overall genetic similarity.

Question 22

Divergent Evolution

Answer 22

When two species (or more) evolve differently from a common ancestor. This leads to speciation.

Question 23

Speciation

Answer 23

When one group of organisms becomes isolated and evolves enough to become their own species.

Question 24

Allopatric speciation

Answer 24

When two populations are physically separated

Speciation happens gradually – ex: mountain range formation (takes thousands of years)

Or… quickly – ex: building of a road, digging of Panama Canal, or daming of a stream

Question 25

Sympatric speciation

Answer 25

When populations live in the same habitat but gene flow has been eliminated through reproductive isolation.

Question 26

Reproductive isolation

Answer 26

When two populations are no longer able to reproduce with each other. Causes rapid speciation.

Prezygotic barriers:
-Mating behavioral differences
-Breeding at different times (temporal)
-Live in different habitats
-Mechanical isolation – Ex: Mating structures are not compatible
-Gametic Isolation – Gametes unable to join

Postzygotic barriers:
-Hybrids – offspring between populations cannot survive or are not able to reproduce

Question 27

Hybrid Zones

Answer 27

Regions in which two species have the opportunity meet, mate, and produce some offspring.

Reinforcement: When hybrids are less fit (don’t survive or reproduce well) than parental species – maintains species

Fusion: When hybrids are more fit than parental species causing two species to fuse into one

Stability: When hybrids continue to be produced and are maintained