Evolution

Biology 101 with Hogan at University of North Carolina - Chapel Hill

About this deck

By: Terra Swanson
Textbook:

Campbell Biology: Concepts & Connections with MasteringBiology� (7th Edition)

Chemistry: The Central Science with MasteringChemistry� (12th Edition) (MasteringChemistry Series)
Created: 2011-04-06
Size: 66 flashcards
Views: 25

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Key Observations by Darwin

1) Species tend to: over-reproduced, but don't all survive
2) Individuals in a population vary extensively
3) These varying traits are inherited

Natural Selection

Differential reproductive success. Individuals whose characteristics best adapt them to their current environment are most likely to survive and reproduce.

Successful/Fit Individual

Well adapted to environment, more likely to pass along genes

3 Key Points on NS

1. NS is an editing process, not a creative process
2. NS is contingent on time and place
3. Significant evolutionary change can occur in a short time

Modern Synthesis

The ideas of Darwin and Mendel put together

4 Processes of Evolution

1. Natural Selection
2. Genetic Drift
3. Gene Flow
4. Mutation

NS acts on _______________ but the effect is a change in the _____________

Individual, Population

Population

Group of organisms of the same species living in the same time/place

Microevolution

Allele frequencies in a population, change over time.

Hardy-Weinberg Model (non-evolution): 5 conditions

1. No mutations
2. Infinitely large
3. Complete Isolation (no immigration/emigration)
4. Random mating
5. Equal reproductive success (survive equally and have same number of offspring)

Do non-evolving populations exist?

Nope, only theoretical

Hardy-Weinburg Principle

Gene pool remains constant if these 5 conditions are met

Genotypic frequencies

p^2 + 2pq + q^2 = 1

Evidence that species had not been created "perfect"?

Sequence of complexity in species, Simple to complex

Cuvier

Anatomist, make sense of evolutions. Compared fossils with living organisms. Abrupt changes in fossil record=mass extinction (Catastrophism)

Lamarck

Hypothesized that offspring inherited traits from parents developed during lifetime. This is not true.
Ex. Stretched giraffe neck

Lyell

Wrote "Principles of Geology". Strange catastrophes not explained by earth's surface.

Wallace

"Father of Biology" - outlined Darwin's theory pre-Darwin.

Darwin

"Variations in traits can influence and individual's ability to secure limited resources and thus to survive and reproduce". Came up with idea of natural selection.

Mathus

Correlated populations size with famine, disease and war. Compete for resources.

_____________ do not evolve, _____________ do.

Individuals, populations

What created new alleles in a population?

Mutations

What shuffles alleles already existing in population?

Sexual reproduction

Mutations are not necessarily bad because...

They give rise to structural, functional, and behavioral alterations that increase changes of survival and reproduction.

Micro-evolution is when there are small changes in a population's...

Allele frequencies.

Five Types of Natural Selection

1. Directional Selection
2. Stabilizing Selection
3. Disruptive Selection
4. Sexual Selection
5. Balancing selection

Directional Selection

Environmental conditions can cause a shift in allele frequencies in a consistent direction.
Ex. White moths blend in to lichen

Stabilizing Selection

Intermediate traits favored, not extremes.
Ex. Over and underweight babies.

Disruptive Selection

Forms at both ends of a range of variation are favored, intermediate forms are selected against.
Ex. two typed of bills in species, for different plants.

Sexual Selection

Distinct male or female phenotype, sexual dimorphism.
Ex. Male more larger and more colorful, because genetic "winners" reproduce more.

Balancing Selection

Two or more alleles of gene persist at high frequencies. Heterozygotes are favored.
Ex. Sickle cell anemia, Heterozygote less likely to get malaria.

Natural Selection

Differential survival and reproduction among individuals of a population that vary in details of shared traits.

Mutation

Original Source of new Allele

Genetic Drift

Random change in allele frequencies brought about by chance.

Gene Flow

Individual (and allele) movement in between populations.

When all individuals have become homozygous for some allele?

Fixation - Genetic drift. Magnitude in genetic drift is larger for smaller populations.

Ernst Mayr's Biological Species Concept

A group of populations whose individuals have the potential to interbreed and produce fertile offspring.

5 Pre-zygotic Barriers

1. Temporal isolation
2. Behavioral Isolation
3. Ecological
4. Mechanical Isolation
5. Gamete Isolation

Temporal Isolation

Different reproduction times

Behavioral Isolation

Different mating rituals

Ecological Isolation

Physical barrier, based on habitats.

Mechanical Isolation

Sexual parts don't fit together.
Ex. Pollination by different birds.

Gametic Isolation

Sperm and Egg incompatible.

2 Post-Zygotic Barriers

1. Hybrid inviability
2. Hybrid Sterility

Hybrid Inviability

Zygote starts to divide and fails and dies.

Hybrid Sterility

Horse and donkey = Sterile mule

Divergence

Two species from one ancestral species

Adaptive Radiation

A burst of divergences from a single ancestor that leads to many new species each adapted to a new habitat.
(Honey Creepers in Hawaii)

Allopatric Speciation

"Other homeland", there is a geographical barrier causing speciation.

Sympatric Speciation

No geographic barrier.
Animals: Rare.
Plants: can become reproductively isolated in one generation due to polyploidy.

Polyploidy in Plants

Creates a tetraploid, a 4n cell, then to a triploid

D. Parapatric Speciation

One population that extends across a large diverse region. Populations at the edge of this region become different species.

Speciation occurs when...

Gene flow ends between populations

Punctuated Equilibrium

Occurs over brief time span followed by a long periods of no change.

Gradualism

Slight changes over long periods of time.

Microevolution

Changes in gene pool population over time - relatively small, not result in newer organisms being considered as a different species.

Macroevolution

Changes in organisms that are significant enough that new species arise.

Co-evolution

Process occurs when close ecological interactions among species cause them to evolve jointly. They can't survive without each other.

2 hypotheses on how life on earth began

1. Spontaneous
2. Formed in outer space (presence of amino acids in interstellar clouds)

Which came first, DNA or RNA? And proof?

RNA came first we think, RNA store genetic information and functioned like an enzyme in protein synthesis.

Prokaryotes gave rise to...

Eukaryotes

Advantage of nuclear envelope? How did it evolve?

Keep genes safe from foreign DNA ,and evolved keep genomes separate when two prokaryotes fused.

Hypothesis of Lynn Margulis?

Endosymbiosis; symbiont lives life inside host. Mitochondria is a symbiont of cell, was once separate. Also chloroplasts evolved in this way.