Biology-Darwin and Evolution

Evolution

Change over time; the process by which modern organisms have descended from ancient organisms.

Fossil

Preserved remains or traces of ancient organisms.

Speciation

Formation of a new species.

Fitness

How well an organism can survive and reproduce in it's environment.

Adaptation

Heritable characteristics that increase an ogranism's ability to survive and reproduce in an environment.

Natural Selection

Process by which organisms that are most suited to their environment survive and reproduce most successfully. Survival of the fittest.

Analagous Structure

Body parts that share a common function, but not structure.

Vestigial Organ/Structure

Body parts that share a common function, but not structure.

Homologous Structure

Structures that are similar in different species of common ancestry.

Reproductive Isolation

Separation of a species or popularion so that they no longer interbreed an evolve into tewo seperare species.

Behavioral Isolation

Form of reproductive isolation in which two populations develop differences in courtship rituals or other behaviors that prevent them from breeding.

Geographic Isolation

Form of reproductive isolation in which two populations are seperated by geographic barriers such as rivers, mountains, or bodies of water, leading to the formation of two seperate species.

Temporal Isolation

Form of reproductive isolation in which two or more species reproduces at different times.

Species

A group of similar organisms that can breed and produce fertile offspring.

Gene Pool

All the genes, including all the different alleles for each gene, that are present in a population at any one time.

Allele Frequency

Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene.

Genetic Equilibirum

Situation in which allele frequencies in a population remain the same.

Genetic Drift

Random change in allele frequency caused by a series of chance occurences that an allele to become more or less common in a population.

Adaptation

Heritable characteristics that increase an organism's ability to survive and reproduce in an environment.

Artificial Selection

Humans selecting which variations of a species are useful.

Mutation

A change in the genetic material of a cell.

Natural Variations

Differences among individuals within a population, in all types of organisms.

Selective Breeding

Improving a species by allowing only those with desired characteristics to reproduce.

Fossils are found in ________ rock.

Sedimentary.

Give 4 different types of fossils.

Shells, bones, teeth, leaves.

According to Darwin, are traits inherited or acquired?

Inherited.

What part of the Galapagos finches did Darwin see as a factor that caused speciation?

Beaks.

By linking today's organisms with fossils of the past shows the presence of a common ________ that will link them together.

Ancestor.

Darwin's theory of evolution links natural ________ with natural _______.

Selection, variations.

According to Darwin a species must _____ to its environment.

Adapt.

What differences did Darwin notice about the tortises on the Galapagos Islands?

The turtles had different shapes of their shells and different neck lengths.

Define Homologous structures.

Structures that are similar in different species of common ancestry.

Define Analagous structures.

Body parts that share a common function, but not structure.

Define Vestigial organs.

Structure that is inherited from ancestors but has lost much of it's original function.

What was the name of Darwin's book?

The Origin of a Species by Natural Selection.

What are the two types of adaptations?

Physical and behavioral.

Define Coevolution.

When two species evolve in response to changes in another.

Name the two sources of variation in a population.

Mutations and gene shuffling.

What is gene shuffling?

Sexual reproduction shuffling genes as families mix genetic information.

What does Common Descent mean?

All species, living and extinct, came from the same common ancestor.

Individuals in a species ____.

Vary

Those best adapted will survive to _____.

Reproduce.

Darwin referred to survival of the fittest as ______ _______.

Natural Selection.

Define Population.

A group of individuals of the same species living in the same area.

Relative Frequency

Number of times an allele occurs in a gene pool.

Adaptive Radiation

When several species evolve from one group.

Traits gained during a lifetime are passed to the _______.

Offspring.

Darwin published "The Origin of a Species by Natural Selection" in ____.

1859.

Entirely _____ species living on different continents have similar _____ and _____ characteristics.

Different, physical, behavioral.

Biochemistry

The metabolism of various organisms is based on the same biochemical compounds.

Influences on Darwin: Thomas Malthus

Populations grow faster than resources, leading to competition.

Influences on Darwin: Charles Lyell

Earth's surface changes gradually over time (Uniformitarianism).

Influences on Darwin: Jean-Baptiste Lamarck

Proposed evolution but incorrectly (inheritance of acquired traits).

Stabilizing Selection

Intermediate traits are favored; extremes are selected against.

• Example: Heterozygous sickle cell carriers (Hh) resist malaria without having the disease.

Disruptive Selection

Both extreme traits are favored over the intermediate trait.

• Example: Mice in a habitat with light sand and dark rocks—light and dark-colored mice survive, medium-colored mice are eaten.

Directional Selection

One extreme phenotype is favored due to environmental changes.

• Example: Peppered moths in England—before the Industrial Revolution, light moths were camouflaged; after soot covered trees, darker moths had an advantage.

Artificial Selection

Humans selectively breed for traits (e.g., crops, purebred dogs).

• Pros: Improves crops, enhances food production, desirable traits in animals.

• Cons: Reduces genetic diversity, increases disease susceptibility.

Natural Selection

The environment "selects" traits that help survival.

Important Notes on Evolution

• Individuals do not evolve—populations do.

• Evolution is a change in allele frequencies over time.

• Only heritable traits can be passed down.

• Evolution is not goal-directed—it is shaped by environmental conditions.

Microevolution

• Definition: Small changes in allele frequencies over time within a population.

• Leads to adaptations that can accumulate into larger evolutionary changes.

• Example: Antibiotic resistance in bacteria. (if you haven’t heard about antimicrobial resistance, ask me… I did a special research project on this and its nightmare fuel)

Phylogenetics

Study of evolutionary relationships between species.

Shared Traits & Relatedness

More shared traits = closer evolutionary relationship.

Common Descent

All living organisms share a common ancestor.