Biology Unit 6 - Evolution

Evolution

The process of biological change that makes descendants differ from their ancestors

The two types of evolution

Microevolution and Macroevolution

Microevolution

Evolution occurring on a small scale affecting a single population

Macroevolution

Evolution occurring on a large scale affecting changes in species across populations

What evolution is driven by

Natural selection

Natural selection

Organisms with better traits will survive and reproduce more

The 4 mechanisms of natural selection

Variation, overproduction, adaptation, and descent with modification

Variation

The differences in traits of organisms

Overproduction

Too much offspring for the environment, struggle for existence of resources

Adaptation

beneficial traits with higher chance for survival

Descent with modification

Change in gene frequency over time, organisms with better traits survive and inherit them to their offspring

The 3 mechanisms of microevolution

Genetic drift, gene flow, and sexual selection

Genetic drift

Random change in allele frequency over time

Gene flow

genes moving in and out of a population

The 7 mechanisms of macroevolution

Speciation, extinction, gradualism, punctuated equilibrium, divergent evolution (adaptive radiation), convergent evolution, and coevolution

Sexual selection

Choosing a specific other to mate with specific traits

Speciation

a new forming species from a pre-existing species

Extinction

a disappearance of a species

Gradualism

Slow change over a long period of time

Punctuated equilibrium

Change separated by bursts over a long time

Divergent evolution

Species sharing a common ancestor

Convergent evolution

Two unrelated species developing similar characteristics

Coevolution

Two organisms change in response to each other

Evidence of evolution

Anatomy, biogeography, embryology, paleontology and biochemistry

Anatomy

study of the structures of organisms

Biogeography

Where living things are located

Embryology

The study of organisms' embryos

Paleontology

The study of prehistoric life

Biochemistry

The study of chemical processes in an organism

Biochemistry helps create...

Phylogenetic trees

3 types of structures that provide evidence for anatomy

Homologous structures, analogous structures, and vestigial structures

Homologous structures and analogous structures result from...

Divergent evolution (adaptive radiation)

Analogous structures

Similar function, different structures, different ancestor

Vestigial structures

Structures that were useful to ancestors but not anymore to descendants

Homologous structures

Similar structure, same ancestor, different function

What do vestigial structures result from

Convergent evolution

Directional Selection

increases the abnormal trait in a population

(ex: darker moths survive more than lighter moths when they are able to blend in easier with tree bark = more dark color genes)

Disruptive Selection

removing average traits and favoring abnormal traits

(ex: gray snakes blend in with rocks, green snakes blend in with grass, normal colored snakes have a disadvantage because they are more visible to predators)

Stabilizing Selection

eliminating abnormal traits when the normal traits become more common

(ex: below-average and above-average baby weights have lower chances of survival than normal baby weights = little variation in birth weight)

Purpose of Hardy-Weinberg principle

Used to calculate allele frequencies for the dominant allele (p) and the recessive allele (q)

Formula to calculate the frequency of genotypes in a population

p² + 2pq + q² = 1

p² = homozygous dominant (AA)

2pq = heterozygous (Aa)

q² = homozygous recessive (aa)

Carolus Linnaeus

created binomial nomenclature

Charles Darwin

discovered the natural selection of evolution

Thomas Malthus

discovered the struggle for existence

Georges Cuvier

discovered catastrophism

James Hutton

discovered gradualism

Charles Lyell

discovered uniformitarianism, proposed Earth was more than thousands of years old

Jean Baptiste Lemark

discovered acquired trait inheritance

Aristotle

proposed organisms are perfectly adapted to the world and a Creator made everything

Gregor Mendel

created the concept of genetic