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34 Cards in this Set

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Descent With Modification
Biological evolution is defined as descent with modification. Descent with modification refers to the passing on of traits from parent organisms to their offspring

Evolution is the unifying theory of the life sciences.
Natural Selection
The mechanism for evolution or descent with modification.

The individuals with heritable traits best suited for the local environment will generally leave more surviving, fertile offspring.
The four pillars of Darwin's THeory
-Descent with modification
-Adaptation
-Phyolgenetic Tree
-Natural Selection
Adaptation
Adaptation - The features that have been developed through time (descent with modification) from parent organism to offspring from a challenge in the local environment
Phylogenetic Tree
is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics
Charles Darwin's life
-Was born in 1809
-Published Origin of Species in 1859

-Came from a family of doctors, his father especially.
-Went to University of Edinburgh, found it boring and distasteful, could not stand the sight of blood
-Dropped out and enrolled in Christ College at Cambridge University to become a minister
-After obtaining B.A degree in 1831, botany professor referred him to Captain Robert FitzRoy who was preparing a voyage around the world aboard the HMS Beagle, a military vessel.
Charles Darwin's Journeyq
Duration : 1831-1836
Main mission of voyage was to chart poorly the known stretches of South American Coastline, Darwin spent most of his time collecting specimens of fossils and living plants/animals.

-He noted the unique adaptations of organisms that inhabited such diverse environments.
-In spite of the unique adaptations of the specimens examined, all were very distinct from life forms in Europe.

The plants and animals living temperate regions of south america seemed more closely related to species living tropical regions of that continent than to species living in temperate regions of Europe.

These observations led Darwin to wonder if contemporary species in South America owned their features to an ancestral species on that continent

-Darwin made a stop a Galapagos islands

At the end of his journey Darwin seriously doubted that earth and all its living organims had been specially created only 6000 years earlier.
First set of Observations that led to Inference #1
Inference 1: There must be a struggle for existence in nature, with too many individuals and not enough resources.
Survival of The Fittest and Speciation
Inference 2: That struggle for existence is not random, but selective. Those individuals with the best set of traits will have the best chance for survival and reproduction (this is also known as the survival of the fittest)
Inference 3: In time, favored traits will pile up and unfavored traits will disappear from the population, and a new species may result. (speciation)
Observations
Obs 1: Species tend to produce more offspring than in necessary to replace the parents and maintain the population (no species really sticks with two kids per family)
Obs 2: Despite all the offspring making, adult populations of species stay fairly constant (hmmm…where are all those offspring going?)
Obs 3: There is a limited amount of resources in a habitat (that doesn’t sound good)
Obs 4: There is variation within populations…populations are not all clones of each other (true for plants, animals, etc.)
Obs 5: Much of this variation is heritable, meaning the offspring got their features from their parents (Darwin looked to farm animal breeding for insight into heritability of traits).
Spontaneous Creation
Spontaneous generation or Equivocal generation is an obsolete principle] regarding the origin of life from inanimate matter, which held that this process was a commonplace and everyday occurrence. Aristole theorized this

Then judeo christian views say that god makes each creature and they are unchanging, static populating a world only existing for 6000 years
Lemarkian Evolution Heritability of Acquired Characteristics
amarckism (or Lamarckian inheritance) is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring (also known as heritability of acquired characteristics or soft inheritance)

For example, a strength training program might build muscle mass beyond what would naturally occur from your genes, however you would not pass this environmentally induced physique to your offspring
Evolutionary Fitness
Populations are in competition, competition of resources to support reproduction.
Charles Lyell
(Darwin's Help)
Published Principles of Geology in 1830. Lyell also had paved the way for Darwin, stating that these geological processes that shape the world we know now are long processes taking millions of years, as opposed to the Judo Christian view of the world being only 6000 years old. Since natural selection also takes a very long time, the world must be more than 6000 years old.

Uniformitarianism
9These processes that have helped form the planet are the same as they were since the planet began.
Georges Cuvier
Theorized extinction, that animals do die out, that gods creation is not perfect.
Thomas Malthus
Thomas Malthus (right), an economist , published an essay in 1798 called An Essay on the Principles of Populations.

Malthus helped Darwin theorize that with limited resources and a growing population, there must be a struggle for existance. If all animals had great fitness they would reproduce endlessly, but nature has checks and balances.
Alfred Wallace
In 1857 Wallace sent Darwin his notion of evolution, bearing remarkable similarities they both had theorized natural selection. Wallace let Darwin publish Origin Of Species.
Common Ancestory
(Antogeny recapitulates Phylogeny)

Homologous Structures
States that during Embreyological development among vertebrae's, those organisms bear distinct similarities

-Example all vertebrae go through a stage of development in which structures called pharyngeal pouches appear on the sides of the throat.


Homologous structures are common structures in organisms that are the result of common ancestory.
New Synthesis
Gregor Mendel's idea's of heritable traits fused with Darwin's theory of natural selection was coined as New Synthesis.

-This happened in the 1900's
Key Elements of Natural Selection
Individual organisms do not evolve, populations do.Although natural selection affects an organism's survival and reproductive success the evolutionary impact is only apparent in a population overtime.

The environment is what provides the selective force or pressure on populations.

The enviornement may change, deeming organisms with great genetics suited for that environment may be obsolete as the environment has changed. An organism that has genes best suited for that enviornment might fail in a different enviornment.
Evolution begins with Mutations
-Neutral Mutations
-Deleterious Mutations, these vary in lethality
-Beneficial Mutations - The mutations that onset evolution.
Gene Pool
The total of all the alleles in the individuals making up the population.
Microevolution
Microevolution is a generation to generation change in a population's frequencies of alleles.
What can cause a change in Allele Frequencies (aka microevolution)
Mutations may establish in a gene pool and increase if beneficial, mad mutations will be selected.

Gene Flow - Refers to the movement of alleles between populations and is usually the result from migration

Sexual Selection - This is also known as sexual selection, as it it pertains to individuals selecting (or not selecting) their mates based on their characteristics.The outcome will likely be unequal reproduction.

Genetic Drift - When a random process (chance event) results in a change in the allele frequency of a population

Natural Selection - : Unequal reproduction by members of a population due to their characteristics.
Why do populations evolve, and not individual organisms?
There are two reasons: 1) evolution is the result of random changes in genetic material passed down from one generation to the next; gametic variations don't change the organism itself, and 2) organisms don't live long enough, since evolution of a species takes many, many generations.
Bottleneck Effect
(Component of Genetic Drift)
A random disaster will leave a population's gene pool completely different. Certain genes may be overrepresented and some may be underrepresented and some may be completely gone.

Bottlenecking usually reduces overall genetic variabllity in a population.
Founder Effect
(Component of Genetic Drift)
The type of genetic drift resulting from the establishment of a small, new population whose gene pool differs from that of the parent population


-Smaller populations are most susceptible to genetic drift

-The smaller the colony, the less its genetic makeup wil match the gene pool of the larger population from which the colonists originated from.
Three Types of Natural Selection
(Directional Selection)

-What is this
-When is it most common?
Shifts the overall makeup of a population by selecting in favor of one extreme phenotype.

-Most common when local environment changes or when organisms migrate to a new environment .
Three Types of Natural Selection
(Disruptive Selection)
A selection favoring two or more extreme variant phenotypes in a population

-A patchy environment, which favors different phenotypes in different patches

A polymorphism may occur due to a disruptive selection
Three Types of Natural Selection
(Stabilizing Selection)
Favors intermediate phenotypes

-Occurs in stable enviornments, where conditions tend to reduce physical variation.
Sexual Dimorphism
(Polymorphism)

-What is the is an example of?
-What is this?
What is the purpose?
Gender specific traits, noticable differences not directly associated with reproduction or survival.

-Secondary sex structures may be used to compete with members of the same sex (males) to compete for a mate (female)

-One reason may be that females see these secondary sex structures as good genes, and will pick the male with most prominent features.
The Idea of Fixed Species
-Who though of this theory?
-What is this called ?
-This actually occured, but is called something else, what is it?
-What fortified this idea?
-Aristole, who had major impact on western culture
-This is called spontaneous creation, the theory that living matter arises from non living matter all the time
-The notion is correct, it had to have been because the first molecules arose from non living matter this is called Abiogenesis
Lamarckian Evolution aka The Inheritance of Aquired Traits

-What was Lamarck the first to do?
-What does this notion say
-Why is it erroneous?
-Lamarckian evolution states that in an organisms lifetime, it may develop traits that are passed down its offspring

-Lamark was the first to propose the mechanism for evolution

-This is wrong because the physical traits it develops either through the environment or itself are not hard coded into its DNA, therefore it would not pass down to its offspring.

-The genes express their designated proteins which then form character/trait, nothing will divert this expression
Polymorphism

-What is Polymorphism
-What can lead to Polymorphism?
Polymorphism is when two or more clearly distinct phenotypes occur in a population of species

-Disruptive selection can lead to this, disruptive selection usually results in the same species dispersed throughout the environment in different patches, which usually results in polymorphism.