SBI3U Biology - Unit 4

Evolution

The process by which significant changes occur in the genetic makeup of a species over time

List: The Five Ideas Presented in the Evolutionary Theory

1. Fossil Records

2. Geographic Distribution of Species

3. Comparative Anatomy & Embryology

4. Biochemistry

5. Genetic Principles

Species

Organisms that resemble each other in appearance, behavior, chemistry and genetic makeup enough that they can be interbred and produce fertile offspring

Hardy-Weinberg Principle

A Mathematical Calculation that is used to show that allelic and genotype frequencies remain constant in a population.

List: Four Ideas that can affect the Hardy-Weinberg Principle

1. Mutation

2. Immigration

3. Emigration

4. Natural Selection

Gene Pool

The total of all alleles within a population

Allelic Frequency

The proportion of gene copies for an allele in a population

List: The Five Fingers of Evolution

1. Small-Sized Populations

2. Non-Random Mating

3. Mutations

4. Movement of Individuals (Gene Flow)

   1. Adaptation

Genetic Drift

A change in the allelic frequency simply due to chance, which is common in smaller populations, and reduces genetic diversity.

Bottleneck Effect

A dramatic reduction in population size which causes significant genetic drift, often created through hunting and severe weather conditions, and reduces genetic diversity.

Founder Effect

The creation of a new, small population that is separated from a larger one, with reduced genetic diversity.

List: The Three Effects that can cause a reduction in genetic diversity

1. Genetic Drift

2. Bottleneck Effect

3. Founder Effect

Natural Selection (Survival of the Fittest)

A Theory created by Darwin which states that individuals with traits that are best suited for their environment are more likely to survive & pass on their genes.

List: The Four Main Types of Natural Selection

1. Stabilizing Selection

2. Directional Selection

3. Disruptive Selection

4. Sexual Selection

Stabilizing Selection

One type of natural selection where the average trait is favored in an environment.

Directional Selection

One type of natural selection where one extreme trait is favored in an environment

Disruptive Selection

One type of natural selection where both extreme traits are favored in an environment

Sexual Selection

One type of natural selection that favors traits that aid in mating success

Artificial Selection

An example of a non-natural selection, where humans choose which traits they want in an organism.

List: The Three Types of Mutations

1. Harmful

2. Beneficial

3. Neutral

Speciation

The process by which one species splits off into two separate species such that they can no longer interbreed.

Prezygotic Mechanisms

One of the two reproductive barriers that prevents two species from breeding, occurring before a zygote is formed.

Postzygotic Mechanisms

One of the two reproductive barriers that prevents two species from breeding, occurring after a zygote is formed.

List: The Four Prezygotic Mechanisms

1. Ecological Isolation

2. Temporal Isolation

3. Behavioral Isolation

4. Mechanical Isolation

Ecological Isolations

One of the four prezygotic mechanisms that prevents different species from producing fertile offspring due to their differing habitats.

Temporal Isolation

One of the four prezygotic mechanisms that prevents different species from producing fertile offspring due to their differing mating periods.

Behavioral Isolation

One of the four prezygotic mechanisms that prevents different species from producing fertile offspring due to their differing attraction signals.

Mechanical Isolation

One of the four prezygotic mechanisms that prevents different species from producing fertile offspring due to their differing reproductive organs.

List: The Three Postzygotic Mechanisms

1. Mortality of Zygotes

2. Hybrid Inviability

3. Hybrid Infertility

Mortality of Zygotes

One of the three postzygotic mechanisms that prevents different species from producing fertile offspring due to the zygote dying, often called a miscarriage.

Hybrid Inviability

One of the three postzygotic mechanisms that prevents different species from producing fertile offspring due to the offspring yielding health problems that kill it before it can reproduce.

Hybrid Infertility

One of the three postzygotic mechanisms that prevents different species from producing fertile offspring due to the offspring being sterile.

List: The Two Modes of Speciation

1. Allopatric Speciation

2. Sympatric Speciation

Allopatric Speciation

The mode of speciation that occurs when a new species forms with geographic separation, resulting in two separate populations that evolve separately.

Sympatric Speciation

The mode of speciation that occurs when a new species forms without any geographic separation, likely due to behavioral changes or mutations between the two groups.

List: The Two Pathways of Evolution

1. Divergent Evolution

2. Convergent Evolution

Divergent Evolution

A pathway of evolution that occurs when two or more related species develop increasingly different traits, usually due to different selective pressures.

Convergent Evolution

A pathway of evolution that occurs when two or more species develop increasingly similar traits, usually due to similar selective pressures.

Coevolution

A process where two species are completely dependent on each other for survival

Adaptive Radiation

The Rapid Evolution of many different species from a common ancestor, often when a species colonizes a new environment with various niches, leading to a variety of different species.

Phylogeny

The evolutionary history of a group of species, demonstrating how they are related through a common ancestor.

Clade

A group of organisms that all share a common ancestor

Cladogram

A diagram that shows the evolutionary relationships between a group of species based on shared traits (synapomorphies)

Synapomorphies

Shared traits that are present in two or more species, inherited from a common ancestor.

Ingroup

The members of a clade that have one or more synapomorphies.

Outgroup

The first group to have diverged from the other members of a clade

LINEs (Long Interspersed Nuclear Elements)

Long Non-Coding DNA elements that are sometimes found as part of cladograms that show the genetic relation between two or more species.

SINEs (Short Interspersed Nuclear Elements

Short Non-Coding DNA elements that are sometimes found as part of cladograms that show the genetic relation between two or more species.

Fossils

The Preserved remains of an organism or its activity.

Fossilization

The process by which traces of past organisms become part of rock layers, volcanic ash, etc.

Paleontology

The study of fossil remains, started by Cuvier

Cuvier

A scientist who starter the study of Paleontology & developed the theory of Catastrophism

Catastrophism

A theory derived by Cuvier that suggests that numerous global catastrophes in the passed had caused the extinction of multiple species, and ultimately became replaced by new life forms.

Relative Age

The estimated age of a rock or fossil specimen

Absolute Age

The actual age of a rock or fossil specimen, usually determined through radiometric dating.

Radiometric Dating

Method used to determine the age of a fossil by measuring the amount of a radioisotope from a sample

Radioisotopes

Radioactive isotopes that are unstable due to an unordinary number of neutrons, such as carbon-14.

Half-Life

The time it takes 50% of a simple of a parent isotope to decay to its daughter isotope.

Kelvin

A scientist who developed the mathematical calculation for the age of earth

Hutton

A scientist who developed the theory of actualism, which states that earth’s features were formed gradually.

Lyell

A scientist who developed the theory of uniformitarianism, which states that Earth’s structure changes slowly over time through natural processes.

Buffon

Developed the theory that organisms evolve over time.

Linnaeus

A scientist who created the binomial nomenclature system.

Lamarck

A scientist who came up with the theory of inheritance of acquired characteristics, which states that traits acquired by an organism during its lifetime can be passed down to its offspring. His claims were replaced with Darwin’s theory of natural selection.

Malthus

A scientist who developed the theory that when populations grow at an exponential rate, food does not, which leads to the death of organisms in the population due to a lack of food.

Wallace

A scientist who worked with Darwin on Natural Selection, particularly looking at monkeys/chimpanzees in the southeast.

Darwin

A scientist who developed the theory of evolution by Natural Selection, particularly looking at finches in the Galapagos islands.

Hardy-Weinberg

Mathematicians who developed the hardy-weinberg principle to determine allelic & genotype frequencies

Homologous Features

Structures in two or more species that have a similar structure & evolutionary origin, but have differing functions. For example, the forelimbs of humans & whales are homologous.

Analogous Features

Structures in two or more species that have similar functions, but a different structure & a different evolutionary origin. For example, the wings of a bird & insects are analogous.

Vestigial Features

A structure with no function anymore, making it useless. For example, the human appendix is vestigial.

Primordial Earth

The time period where earth was just formed, said to be 4.6 billion years ago

Primary Abiogenesis

A theory which states that the first living things on Earth arose from non-living material

Primordial Soup

A term used to describe the hypothetical mixture of material that are thought to be life’s origin. It consists of essential sugars, the 20 amino acids and the nitrogenous bases.

Polymerization

The process of which the material from the primordial soup combine

Protocells

Simple cell-like structures that are said to be the first step in the origin of life.

Liposomes

Liquid filled spheres that act as a boundary between the protocell and the environment

Stromatolites

Mats of prokaryotic cells trapped in sediment, that are said to be the oldest fossils on Earth that date 3.5 billion years ago

List: The Original Gasses of Earth’s atmosphere

Nitrogen, CO2, CO and Hydrogen Compounds

Prokaryotic cells

Simple cells that must have lacked O2, oldest ones date to 3.5 billion years ago

Eukaryotic Cells

Cells with membrane bound organelles and specialized functions, said to date at 1.85 to 2.1 billion years ago

Endosymbiosis

A relationship where a single celled organism lives within another cell, which is said to have created eukaryotes

Cambrian Explosion

An event that occurred 565 to 640 million years ago, where there was a massive increased in animal diversity

List: The Two Theories about how the Pace of evolution occurs.

1. Gradualism

2. Theory of Punctuated Equilibrium

Gradualism

A theory about how the pace of evolution occurred, stating that evolutionary changes in species accumulated slowly (Creeps)

Theory of Punctuated Equilibrium

A theory about how the pace of evolution occurred, stating there were rapid spurts of evolutionary change, followed by long periods of no change (Jerks)

Human Evolution

It is said to have begun 60 million years ago, with the earliest ancestral primate who had a large snout, sharp teeth and very large eyes.

Prosminian Lineage

The lineage that humans did not branch off from, creating lemurs.

Anthropoidian Lineage

The lineage that humans evolved from, creating higher primates including us, apes and monkeys. It split up a number of times 30 million years ago, creating old world and new world monkeys, and hominoids.

Hominoids

A group that was created from the anthropoidian lineage splitting up, creating humans, gorillas, chimpanzees and gibbons, which all lack tails.

Hominids

A group that was separated from the hominoid lineage, which contained humans, apes, but notably, not gibbons.

List: The Two Theories that explain the most recent chapter of human evolution

1. Multi Regional Hypothesis

2. Monogenesis Hypothesis

Multi Regional Hypothesis

A theory that states that humans evolved in a number of different regions.

Monogenesis Hypothesis

A theory that states that homo sapiens evolved in Africa, and then migrated out. This hypothesis is heavily favored to be true.

Karyotype

A visual display of all chromosomes in a cell, often taken when they are in metaphase

List: The Three Factors that determine the order of a chromosome on a karyotype

1. Size

2. Banding Pattern

3. Centromeric Position

Giesma

A chemical used to stain bands on a karyotype, creating G-Bands

G-Bands

The Bands of a karyotype. Darker ones are tightly condensed, while lighter ones are less condensed.

List: The Three Centromeric Positions

1. Metacentric

2. Acrocentric

3. Telocentric

Metacentric

A centromeric position where the centromere is in the very middle of the chromosome.