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Artificial selection

The process of direct breeding to produce offspring with desired traits, also referred to as selective breeding.

Ex. Pigeons produced with fan shaped tails.

Ex. Also used by humans to create new breeds of dogs as well as other species.

Natrual selection

The process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated.The central theme of evolution.
All organisms must be equally adapted to their environment, which is a rare occurrence.


Cumulative changes in groups of organisms through time, originally proposed by Charles Darwin in his book, the origin of the species.

Origin of the species

Charles Darwin's book explaining the theory of evolution and evidence for it.

Derived traits

Newly evolved features, such as feathers, that do not appear in fossils of common ancestors.

Ex. Feathers in the species archaeopteryx.

Ancestral traits

More primitive features such as teeth and tails, that do appear in fossils of common ancestors.

Homologous structures

Anatomically similar structures inherited from a common ancestor. Modifications of the ancestors body parts not entirely new parts.

Ex. Birds wings

Ex. Reptiles limbs

Vestigial structures

Structures that are reduced forms of functional structures in other organisms. Once a body part is no longer needed it will slowly become smaller until it will disappear.

Analogous structures

Structure that has the same function but different construction and was not inherited by a common ancestor.

Ex. An eagle's wings compared to a beetles.


An early, pre birth, stage to an organisms's development. Vertebrate embryos exhibit homologous structure during certain phases of development, but become totally different structures in adult form.


An enzyme that is essential for respiration in highly conserved animals. Even though there are slight changes in the amino acid sequence, the molecule changes little over time.


The study of the distribution of plants and animals across the world


A trait shaped by natural selection that increases an organisms reproductive success


The measure of the relative contribution that an individual trait makes to the next generation.


The evolved morphological adaptations that allow a species to blend in with their environment


The process in which one species evolves to look like another.
Ex. Western coral snake, California king snake


A consequence of an adaptation
Ex. Helplessness of human babies

Hardy Weinberg principle

Showed mathematically that evolution will not occur in a population unless allelic frequencies are acted upon by forces that cause change. With the absences of these forces, the allelic frequency remains the same and evolution doesn't occur.

5 conditions have to occur for this principle to work

No genetic drift, no gene flow, no mutation,mating must be at random,and there must be no natural selection.

Genetic drift

Any change in allelic frequencies in a population that results from chance.

The allele affected is chosen through independent assortment. Not as noticeable in large populations, but drastic in smaller ones.

The founder effect

An extreme example of genetic drift, results in a small population that settles in a location separated from the rest of the population.

A trait that is uncommon in the original population can be common in this population

Ex. Amish persons


Another extreme example of genetic drift, occurs when a population stoops to low numbers then rebounds.

The rebound gene pool is often genetically similar

Ex. Cheetahs

Genetic equilibrium

A closed system, with no new genes entering the population, and no new genes leaving the population.

Gene flow

The introduction of new genes, to new populations.

Non random mating

The belief that the mating process of organisms usually occurs in a close proximity, and can lead to inbreeding, and can lead to allelic proportions favoring homozygous individuals.

Helpful mutations throughout species

If a helpful mutation is selected, the trait is know to become more common, and continue to be passed from generation to generation.

Stabilizing selection

The most common form of natural selection, operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness.

Ex. Baby birth weight survival rate.

Directional selection

Increases the expression of an extreme trait in a population.
Ex. Peppered moth changes
See peppered moth survey sheet.
Ex. Galapagos finches.

Disruptive selection

Splits a population in to two groups. Tends to remove individuals with average traits and replace them with individuals with extreme traits at both ends of the continuum.

Ex. Various colors of snakes according to habitat

Sexual selection

Change in frequency of a trait in order to attract a mate. Often occurs in populations in which males and females greatly differ.

Ex. Peacocks, peahens.

Prezygotic isolating mechanisms

Prevents gene flow throughout a population, operates before fertilization occurs.
Makes fertilization unlikely.prevent the genotype from entering the gene pool.

Ex. Eastern and western meadowlarks

Postzygotic isolating mechanisms

Prevent gene flow throughout a population, operates after fertilization has occurred to ensure that the resulting hybrid remains infertile.
Has occurred when a hybrid offspring cannot develop or reproduce.

Ex. Liger

Allopatric speciation

A physical barrier between two similar organisms

Ex. Grand canyon separating Albert and kaibab species of squirrels.

Sympatric specification

A species that evolves into a new species without a physical barrier. The ancestor species as well as the new species live side by side during this process.

Ex. Apple maggot flies, appear to be diverging depending on which fruit they eat.

Ex. Plants mutated with polyploidy.

Adaptive radiation

Also called divergent evolution, occurs when one species gives rise to many new species in response to the creation of a new habitat or other ecological opportunity. Occurs in a relatively short period of time

Ex. Cichlid fish in africa's Lake Victoria.


When the similarities between two species is so similar ones species evolution affects the other.

Ex. Comet orchids and moths which pollinate them.

Convergent evolution

When unrelated species evolve similar traits even though they live in separate parts of the world. Occurs in environments that are far apart but ecologically similar.

Ex. The mara and the English rabbit.


The scientific theory that evolutionary traits evolve gradually in small, gradual steps.
Some exceptions according to fossil record.

Punctuated equilibrium

Attempts to explain abrupt transactions in the fossil record. Rapid spurts of genetic change cause a species to diverge quickly, these periods last longer depending on how drastic the change is.

Tempo evolution

One of the most active areas of evolutionary research today. The study of the question, does most evolution occur gradually or in short bursts?

Opposeable first digit

Either the thumb or big toe, most common among monkeys and other primates.

Allows for a strong grip.

Binocular Vision

Overlapping fields of vision. Caused by the occurrence of bony eye sockets, and the placing of the eyes in front of the face.


Active during the day. Common among primates


Active in the night. Common for these species to have black and white vision. Also, causes a decreased sense of smell. Also, the degree of binocular vision is increased.


The ability to have and maintain a flexible body. Useful for primates who swing tree to tree.

Common characteristics of a large brain

Fewer areas devoted to smell
More areas devoted to vision
Larger areas devoted to memory and coordination of arm and leg movement
Aloes for problem solving abilities, and well developed social behaviors.
Complex ways of communication

Primate reproductive rate

The rate at which primates reproduce ( obviously ) allows for increased learning ability in cultures. Birth is a much slower process with one infant being born at a time.


Tree dwelling. Most arboreal primates live in warm tropical forest environments.


Organisms that live on the ground.


Also called the 'wet nosed primates.' one of the most basic classification groups. Identified by their large eyes and ears. Most are found in Madagascar and nearby islands.

Ex. The lemur


Another one of the most basic primate groups, also called ' the dry nosed primates.' much larger than the strepsirrhines. Have brains realitive to their body size. Likely diurnal.

Ex. Tarsiers, monkeys, apes, gorillas, chimpanzees, etc.


A sub group of haplorhines, a group of large brained, diurnal monkeys , and hominoids.

New world monkeys

Smallest group of unique monkeys. Include marmosets and tamarins. Neither species has an opposable first digit or fingernails. Also includes squirrel and spider monkeys, as well as capuchin monkeys. Some of these monkeys have opposable first digits, most are diurnal, and live in social bands.

Prehensile tail

Acts as a 5th limb to primates. Often used to grasp to trees or other objects, and to support the monkeys weight.

Old world monkeys

Similar to new world monkeys, in the fact that they are diurnal, and live in large social groups. However, old world monkeys are usually larger and have narrower noses. Spend more time on the ground, no prehensile tail, or no tail at all, and most have opposable first digits.


Includes two groups lesser and greater apes. Have longer arms than legs, barrel shaped chests, no tails, and flexible wrists.

Lesser apes

The Asian gibbons and most of their relatives. Generally move from branch to branch swinging even though they have the ability to walk.

Great apes

Includes the family of orangoutangs. Lives exclusively in Asia. Also includes the family of gorillas. The chimpanzees are socially, and physically most similar to humans. Also includes other hominins,


Human like primates that appear to be more closely related to present day humans. Larger brains than hominoids, also have a thinner and flatter face than hominoids. Hominins also have manual dexterity, and are bipedal.

Ex. Neanderthal


Includes all non monkey anthropoids, gibbons, orangutans, chimpanzees, gorillas, and humans. The largest of the primates, excluding hominins their arms are longer than their legs. The best known fossil of a hominoid is the proconsul


The ability to walk upright on two legs. An ability mainly used by hominins.


The species where the first true bipedalism was discovered. Was a small, ape like creature that lived in eastern and southern Africa about 4.2 to 1 mya. Had human like joints and teeth. However, had ape like brains and jaws.

Genus homo

The genus that includes living and extinct humans.
Homo habilis, homo ergaster, homo erectus, homo neanderthalensis, and homo sapiens.


Evolved exclusively in Europe and Asia around 200,000 years ago, likely from homo erectus or homo intermediary. Were shorter yet had more muscle mass than humans do. Had similar brain size and sometimes larger brains. However, their brains were likely organized in different ways than modern humans. Lived near the end of the ice age, and even had a basic language.

The out of Africa hypothesis

First proposed by Christopher stringer and Peter Andrews of the British museum of natural history in 1988, humans first evolved from Africa, and then migrated to other parts of the world.

Cro magnons

The first homo sapiens to be hunter gatherers.


The biological grouping of objects based on certain criteria.

Aristotle's classification

The first widely accept way of biological classification. Classified animals according to the presence of red blood, animals were further classified according to their habitats and morphology. Plants were classified by average size and structure.

Linnaeus's system

Based on the study of morphology and the behavior of organisms. Similar to aristotle's system. The first classification system of taxonomy.

Ex. Organized birds into three separate groups.


A discipline of biology primarily concerned with identifying, naming, and classifying a certain species based on natural relationships
Taxonomy is included in a branch of biology called systematics, or the study of biological diversity with an emphasize on evolutionary history.

Binomial nomenclature

Another name for Linnaeus method, gives each organism a scientific name composing of two parts, the first part is the genus, and the second is the specific epithet, or specific name that identifies the species.

Modern classification

A classification system based on that of Linnaeus, but including evolutionary naming.


A named group of organisms.


A group of species that are closely related to a common ancestor.

Ex. Ursus americanas, Ursus ursinus, Ursus thibetanus.


Consisting of similar related genra.

Ex. Family ursidae


Contains related families


Contains related orders.


Contains related hardware


Contains related phyla


The broadest of all taxa, contains one or more kingdoms.

Charles Darwin

Hypothesized the theory of evolution,after his trip to the Galapagos islands. The theory is explained in his book 'the origin of the species.'


The preserved evidence of an organism. Mostly found in various rock layers, greatly supports the theory of evolution.


A scientist who studies fossils.

Relative dating

A method used to compare the age of fossils compared to other layers.

Law of superposition

States that younger layers of rock are positioned above lower layers.

Radiometric dating

Uses the decay of radioactive isotopes to measure the date of a rock.

Half life

The amount of time it takes half of the original isotope to decay, is required in radio metric dating. The relative amount of radioactive isotope and its decay product must also be known.

Geologic time scale

The record of earths history . Major geological and biological events in earths history can be seen hare

Ex. Mass extinction kt boundary


The smallest unit of geological time, lasts several million years.


Last 10s of millions of years, consisting of two epochs.


Lasts hundreds of millions of years. Consists of two or more periods.


The longest geological time unit, consists of billions of years.

Cambrian explosion

The epoch in which ancestors of most modern animals diversified across the planet.

Kt boundary

Where the majority of the earths iridium is found. Indicating that there was a meteorite impact that led to mass extinction.

Plate tectonics

Describes the movement of several large plates that make up the surface of the earth. Includes the theory of continental drift.

Spontaneous generation

The idea that life arises from non life. The belief of how humans originated, until disproved in the 17th century by Francisco Redi.

Theory of biogenesis

States that living organisms can only come from living organisms. First proposed by Louis Pasteur.

Endosymbiont theory

States that ancestors of prokaryotic cells lived among the ancestors of eukaryotic cells. Proposed by Lynn Margulis.


The evolutionary history of a species.


Inherited features that are inherited among species.morphological or biochemical.

Ex. Eagles with hooked beaks.

Molecular clock

A model used to compare DNA or amino acid sequences from two different species to estimate how long the species have been evolving since they divulged from a common ancestor.


A method that classifies organisms in the order they divulged from a common ancestor.


A branching diagram that represents the proposed phylogeny or evolutionary history of a species or group.

Domain archea

More ancient than domain bacteria yet more closely related to eukaryotic bacteria. Very diverse, and most are heterotrophic. Can live in extreme environments.. Cell walls do not contain peptidoglycan, and they have some of the same proteins eukaryotes do.

Kingdom Protista and Protists

Organisms that can be unicellular, colonial, or multicellular. No organs. Classified into 3 broad groups, protozoans,algae, and euglenoids.

Kingdom fungi and fungus

Multicellular or unicellular organisms that absorb organic nutrients in the environment. The members of kingdom fungi lack the ability to move, also all fungi are dependent on hyphae.


Threadlike structures that make up a fungus. The fungus is dependent of these for growth, feeding, and reproduction.

Kingdom plantae and plants

The base of all terrestrial habitats. All plants are multicellular, and have cell walls composed of cellulose. Most plants are autotrophic because of photosynthesis, but there are a few such as the parasitic dodder extracts it's food from host plants through suckers.

Kingdom and animals

All animals are heterotrophic , multicellular eukaryotes. Organized into tissues, organs, then organ systems. Animals live on all terrains.

Virus classification

Virus' are no living creatures, therefore they are not classified in any kingdom or domain.

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