Natural Selection

Define evolution

The change in heritable characteristics of a population over time

What is Lamarckism

Stuctures used frequently will strengthen and develop, while structures that are not used will weaken and deteriorate. These acquired characteristics are inherited.

What is Darwininian Evolution?

Heritable variations that benefit an individual’s survival and reproduction are passed on more often so that the frequency of helpful variation increases.

What are the ecological observations made that contributed to natural selection?

1. Populations have the potential to grow exponentially

2. Populations stabilize at the carrying capacity

3. Natural resources are timited

What are the hereditary observations made that contributed to natural selection?

1. Individuals in the population vary in many characteristics

2. Many characteristics are heritable

What does it mean for a trait to be heritable?

A trait can be passed from parent to offspring

What does it mean for a trait to be acquired?

Changes that occur during the lifetime of the individual that do not change the DNA of the reproductive cells (injuries, somatic mutations, etc)

What is inductive reasoning?

Using observations to form a conclusion

In Darwinian evolution, traits must be _____

Heritable

What causes variation?

1. Mutation

2. Gene Flow

3. Crossing Over

4. Independent Assortment

5. Random Fertilization

What does the rate of mutation depend on?

Reproductive rate

What does natural selection act on?

Variation

What kind of property is evolution?

An emergent property

What level of organization does evolution appear at?

Population level

What is the most common type of mutation?

Single nucleotide polymorphism (SNP)

What is a single nucleotide polymorphism?

A change in a single nucleotide (ex: Base substitution)

What kind of mutations are selected for in a population?

Beneficial mutations

What kind of mutations are selected against in a population?

Harmful mutations

Lactose tolerance is what kind of mutation?

Beneficial mutation

A mutation to the CFTR gene causes what?

Cystic fibrosis

The CFTR gene code for what protein?

Cystic Fibrosis Transmembrane Conductance Regulator

What is the role of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)?

Channel protein for chloride and bicarbonate ions

What kind of mutations have no effect on a population?

Neutral mutation

Free or attached earlobe is what kind of muation?

Neutral muation

Sickle cell is what kind of mutation?

Harmful Mutation

What is required for continuation of a species?

Some offspring to survive to adulthood and reproduce

Why do organisms overproduce offspring?

1. Increases odds some will survive to adulthood

2. Increases genetic variation

What are the two population growth models?

Exponential and Logistic

Which population growth model increases to infinity?

Exponential Growth Model

Which population growth model levels off?

Logistic Growth

What is the point logistic growth levels off called?

The carrying capacity (k)

What are the two kinds of selection pressures?

Biotic and Abiotic Pressures

Which kind of selection pressure is density dependent?

Biotic pressure

Which kind of selection pressure is density independent?

Abiotic pressure

Biotic pressure comes from what?

Living things

Abtiotic pressure comes from what?

Non-living things

What are some examples of biotic pressures?

• Predation

• Competition

• Disease

• Finding/Attracting Mates

• Availability of Food

What are some examples of abiotic pressures?

• Temperature

• Water availability

• Light availability

• Oxygen and Carbon Dioxide Concentrations

• Natural Disasters

• Pollutants

• Wind

What are the two kinds of competition?

Direct and Indirect competition

What is direct competition?

When 2+ members of the same species fight for a resource

What is indirect competition?

When individuals deplete shared resources, but do not directly fight

What are the 2 kinds of sexual selection?

Intersexual and Intrasexual Selection

What is intersexual selection?

One sex chooses which of the other sex they want to mate with (typically females choose)

What is intrasexual selection?

2+ members of the same sex fight for mating rights with the other sex (typically males fight)

What is biological fitness?

A measure of how likely an individual can survive to reproductive age

What is differential survival and reproduction?

Individuals with helpful variations will survive and reproduce more often, increasing the frequency of their alleles.

What does natural selection result in?

Adaptation

What is an adaptation?

A phenotype that is maintained through natural selection

What is artificial selection?

Humans deliberately breed organisms with particular traits

Today’s domestic sheep evolved from what?

Mouflon (Ovis orientalis)

Today’s corn evolved from what?

Teosinte

What is Brassica oleracea?

Wild Cabbage

Artifical selection in Brassica oleracea created which crops?

Brocolli, Cabbage, Turnips, Kale, Cauliflower, Kohlrabi

What is continuous variation?

Variation on a spectrum (no definite categories)

What is discrete variation?

Variation in categories

What kind of variation is height (in humans)?

Continuous variation

What kind of variation is blood type?

Discrete variation

Which type of variation is controlled by very few or one gene?

Discrete variation

Which type of variation is controlled by many genes?

Continuous Variation

What are the five premises of natural selection?

1. Heritable Traits

2. Variation

3. Selection Pressure

4. Differential Survival and Reproduction

5. Change in Population

What is the gene pool?

The collection of the genes and alleles of a population

What is gene flow?

Any movement of individuals and their genes from one population to another

What is the allele frequency?

Prevalence of an allele in a gene pool

All the allele frequencies in a gene pool must sum to what?

1.00

What is neo-darwinism?

The combination of genetics and evolution

What is the Hardy-Weinburg principle of equilibrium?

If the allele frequency of a specific gene remains stable, the gene is not evolving.

What affects allele frequency?

• Gene flow

• Non-random mating

• Genetic drift

• Selection

What is non-random mating?

Mates are chosen based on specific properties (ex: proximity, genetic traits, etc.)

What is genetic drift?

Change in allele frequency by random chance.

What are two examples of genetic drift?

Founder effect and bottleneck effect

What is the founder effect?

A small portion of an existing population break off an form their own population.

What is the bottleneck effect?

A large portion of a population is killed, leaving a small portion to continue the population.

What is a species?

Members of a population that actually or potentially interbreed in nature.

Who created the first formal system of grouping organisms?

Linnaeus

What is convergent evolution?

Independent evolution of similar features in two separate species that were not present in the last common ancestor of the two groups.

What branch of biology focuses on classifying things?

Taxonomy

What is the current organization method for grouping species?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is the binomial system for naming organisms?

Scientific names

The scientific name for a species uses what two taxonomical groups?

Genus and species

Scientific names are written how?

In italics with the genus capitalized

What group was added to Linnaeus’s system to create today’s organization?

Domain

What are the benefits of the taxonomical organization system?

• Clear communication

• Predictability of Characteristics Based on Grouping

• Information on Evolution of a Species

What is an organism?

Any biological system that is an independent life form

What is a population?

A group of organisms of the same species in the same area at the same time

Do members of a population vary?

Yes

What is a community?

Two or more populations of different species in the same area at the same time

What is variation?

Differences between members of a group

What is sexual dimorphism?

A large difference between males and females.

Sexual dimorphism is caused by what kind of selection?

Intersexual Selection

What is a hybrid zone?

A zone where two species can interbreed and make hybrids naturally.