Module 2

Evolution

Evolution

change in the heritable characteristics of biological populations over successive generations

Evolution

These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction.

biological evolution

The central idea of _______ is that all life on Earth shares a common ancestor.

Population

A group of individuals of the same species living in a particular area at the same time

Gene Pool

All alleles of a population’s genes

Allele Frequency

The percentage of any one specific allele

Variations

differences among members of a species

Genetic Equilibrium

If the allelic frequency stays the same over many generations.

Mechanisms in Evolution

Anything that changes the frequency of alleles in a population is a ___________________.

Natural Selection

Individuals with the best adapted phenotypes will survive and pass on their genes to the next generation.

Mutation

A mutation in a parent’s DNA could result in offspring with different alleles. Changing the allele frequency of the population.

Genetic Drift

Occurs when the allele frequency of a population changes by chance.

Gene Flow (Migration)

Gene flow is any movement of genes from one population to another.

Non-Random Mating

If organisms can choose their mating partners, then the more desirable alleles will have a higher frequency in future populations

Selection

process whereby organisms that are better adapted to their environment survive and reproduce while those less adapted fail to do so.

Natural Selection

Is a biological theory that explains why organisms seem to match their environmental niches so well

Artificial Selection

process of intentional or unintentional modification of a species through human actions that encourage the breeding of certain traits over others

Charles Darwin

He proposed the theory of natural selection in his publication, on the origin of species

Fitness

term describes how successful an organism has been at passing on its genes.

Fitness

Has a great influence on which trait will be passed on to the next generation.

Stabilizing Selection

Favors intermediate variants.

Stabilizing Selection

The intermediate states become more common and each extreme variation will become less common or lost

Disruptive Selection

Favors individuals at both extremes of a characteristic range.

Directional Selection

Occurs when a certain allele has greater fitness than others resulting in an increase in the frequency of that allele until it is fixed in the population gene pool.

Sexual Selection

Special kind of selection that acts on traits that help animals increase their chances of mating

Polymorphism

Many different phenotypes found in a population, each group represents a morph (form).

Artificial Selection

the process of intentional or unintentional modification of a species through human actions that encourage the breeding of certain traits over others

Negative effects of Artificial Breeding

It removes variation in a population.

Negative effects of Artificial Breeding

Organisms can be susceptible to disease or changes in the environment

What is EVOLUTION

Organisms can be susceptible to disease or changes in the environment

GENETIC DRIFT

is change in allele frequencies in a population from generation to generation that occurs due to chance (randomness) events

GENETIC DRIFT

change due to "sampling error" in selecting the alleles for the next generation from the gene pool of the current generation.

GENETIC DRIFT

Assuming there is more than one allele, any allele is about equally likely to increase or decrease in frequency in one generation by sampling error

CONSEQUENCES OF GENETIC DRIFT

Drift can cause big changes in allele frequency over time

CONSEQUENCES OF GENETIC DRIFT

may reduce genetic viability in small populations and may inflict fixation in an allele

CONSEQUENCES OF GENETIC DRIFT

fixation refers to the elimination of the allele

CONSEQUENCES OF GENETIC DRIFT

Drift is strongest in small populations.

CONSEQUENCES OF GENETIC DRIFT

Drift is neither predictable in direction in one generation nor exactly replicable in degree

CONSEQUENCES OF GENETIC DRIFT

Under exact same conditions, get different results from genetic drift

BOTTLENECK EFFECT

happens when the size of a population is severely reduced. Events like natural disasters (earthquakes, floods, fires) can decimate a population, killing most individuals and leaving behind a small, random assortment of survivors.

FOUNDER EFFECT

occurring when a small group in a population splinters off from the original population and forms a new one. When a newly formed colony is small, its founders can strongly affect the population's genetic makeup far into the future.

INTRASPECIFIC SPECIATION

comes from one species

INTERSPECIFIC SPECIATION/ HYBRID

comes from two species.

ALLOPATRIC SPECIATION

Occurs when there is an imbalance of gene flow between two populations due to physical barriers.

Geographic Isolation

Allopatric Speciation rises from what type of isolation?

SYMPATRIC SPECIATION

Occurs when there is an overlapping range of the two diverging species within a region or locality.

Temporal Isolation

when population reproduce at different time

Behavioral Isolation

populations have different rituals or behavior involved

PALEONTOLOGY/FOSSIL RECORDS

Fossils are body parts of living organisms that are buried for a long period of time. Fossil records gave Darwin ideas about the inhabitants of the earth and their anatomy.

PALEONTOLOGY/FOSSIL RECORDS

Age can be identified by carbon dating.

GEOGRAPHICAL DISTRIBUTION

is believed that the world consists of a large mass of continent called Pangaea.

GEOGRAPHICAL DISTRIBUTION

because of continental drift, the supercontinent splits

GEOGRAPHICAL DISTRIBUTION

there are fossil records and species of the same origins that can be found in places that were believed once connected

Jean Baptiste Lamarck

LAMARCK'S THEORY/LAMARCKISM is by

LAMARCK'S THEORY/LAMARCKISM

● the main concept in Lamarckism is the Inheritance of Acquired Traits

LAMARCK'S THEORY/LAMARCKISM

According to his theory, the bodies of living organisms were modified through the use and disuse of certain body parts based on the need of the organism to adapt to an ever changing environment.

LAMARCK'S THEORY/LAMARCKISM

This theory lacks evidence to support the acquired characteristic today.

DARWIN-WALLACE THEORY

most believed theory

DARWIN-WALLACE THEORY

Natural Selection as a mechanism of evolution

DARWIN-WALLACE THEORY

Both Alfred Wallace and Charles Darwin have the same conclusion.

COMPARATIVE ANATOMY

Similarity in biological structures and function gave rise to the study of ______________________

Homologous Structures

same structures different function

Vestigial Structures

structure of animals that disappear or deteriorate over a period of time due to adaptation.

Analogous structure

Same function, different structures of body parts.

COMPARATIVE EMBRYOLOGY

The early development of most vertebrate embryos are alike. However, in later stages the similarities are lost

BIOCHEMISTRY

Studies comparing the biochemistry of different organisms gives the most persuasive evidence that all organisms give the most persuasive evidence that all organisms evolved from a common ancestor.

Comparative biochemistry thus far has revealed that:

the nucleic acids in almost all organisms have the same genetic code

Comparative biochemistry thus far has revealed that:

the metabolic pathways of physiological processes like respiration is very similar

Comparative biochemistry thus far has revealed that:

the universal energy used is ATP

MODERN SYNTHESIS THEORY

Fusion between Gregor Mendel's Theory of Inheritance and Darwin's Natural Selection Population Genetics as a basis for inheritance including genetic variation, natural selection and mendelian inheritance

Modern Synthesis and Darwinism differs in 3 main points:

The modern synthesis theory recognizes several different possible mechanisms of evolution such as genetic drift, gene flow, mutation pressure versus Darwinism that only believes in natural selection as the basis of evolution.

Modern Synthesis and Darwinism differs in 3 main points:

Modern synthesis theory argues that characteristics are passed down from parent to offspring on the parts of DNA called genes. however multiple allelism may cause mutations and variations.

Modern Synthesis and Darwinism differs in 3 main points:

Modern synthesis theory hypothesizes that speciation is most likely due to the gradual accumulation of mutations in the gene level.