Unit 3: Biological Evolution (The History of Evolutionary Thought…
The History of Evolutionary Thought
The idea that GOD created all organisms on Earth perfectly and that they did not change. This was widely accepted as truth for a long time!
Law of Use & Disuse
Inheritance of Acquired Characteristics
This was proven to be false! Jean Baptiste de Lamarck was teased for his ideas! Very few people agreed with him.
Today, there are still many Lamarckian Misconceptions based on his ideas.
Punctuated Equilibrium Vs. Phyletic Gradualism
Hypotheses from looking at ROCK STRATA - proved that perhaps organisms could change over time & contradicted creationism.
Alfred Wallace also independently came to the same conclusions about natural selection! He often does not get credit for his ideas, though :unamused:
Wallace led Darwin to publish his work!
Should evolution be taught in schools?
Inherit The Wind - Book/Play read in 7th Grade!
Very controversial, even still today
Evidence for Evolution
Fossil evidence found in rock strata
Laws of Superposition, Original Horizontality, Lateral Continuity
It was seen by geologists that fossils in newer layers of rock looked different than fossils in older layers of rock - could species change over time?
The same fossils/species were found on different continents that were oceans apart! Did the continents move over time?
Types of Fossils
Casts & Molds
Often found in sedimentary rock
3 types of rock
Examples of Natural Selection in Real Life & studied in class
Polar Bear Example
Environment = Thousands of years ago, in the cold, snowy arctic
Selective force = the white and cold snow
Adaptation over time = lighter, thicker fur, increased fitness to be able to stay warm and camouflage
Galapagos Finches Example
Environment = Island Daphne Major on the Galapagos Islands, Ecuador
Selective Force = an 18-month drought, causing a change in the available seeds on the islands (to be larger & harder shelled)
Adaptation over time = larger break size, increased fitness to be able to eat the bigger/harder seeds
Rock Pocket Mouse Example
Adaptation over time = dark colored fur, increased fitness
Selective force = dark colored ground from lava flows
Environment = Valley of Fire, New Mexico
Labs from Class
Environment = a new, uninhabited island on Earth
Selective Force = a Cat (the predator)
Adaptation over time = faster moving mice (moving on orange lines) had greater fitness, so their population increased over many generations
Environment = While fishing in a pond of both gold fish and brown fish
Selective Force = Fishermen prefer to eat gold fish
Adaptation over time = gold fish population increased, while brown fish population decreased
Antibiotic and Pesticide Resistance
Environment = Farms, the Human Body, Anywhere antibiotics/pesticides are used
Selective Force = use of antibiotics/pesticides
Adaptation over time = resistance to pesticides and antibiotics - the bacteria become more fit (and our medicine is no longer effective for treatment) - the insects become more fit (and our crops may become infested with pests)
Takeaway = use antibiotics more responsibly
Peppered Moth Example
Environment = The Industrial Revolution between London and the Countryside
Selective Force = Soot covered the trees in the woods, due to factory smoke
Adaptation over time = dark -grey colored wings of moths became more common in the population, as it increased the fitness of the species due to camouflage from predators
DNA evidence in closely related species
More Shared DNA = More Closely Related = More Recent the Closest Ancestor
Example = We share about 99% of our DNA with chimpanzees
Our most recent common ancestor lived about 8 million years ago!
Looking at homologous and analogous structures
Occurs when selective forces are very different, creating different looking adaptations with different functions (despite being closely related) - homologous structures
Example = The LIMBS of tetrapods are homologous structures
Creates the "Tree of Life" where all species are related to one another.
This gives BIODIVERSITY on for our planet.
The Galapagos Islands are uniquely biodiverse - this is why it was the perfect spot for Darwin to study nature (he was a naturalist!) and come up with natural selection!
He traveled to the Galapagos on a boat called the HMS Beagle
Biodiversity = a large variety of types of organisms in a given location (bio = life, diversity = many different kinds)
Species that are cloer together on the tree of life are more closely related & have a more recent common ancestor
Ancestor - in past generations
Descendant - in future generations
Not all related species look alike!
Occurs when selective forces are very similar, creating similar adaptations (analogous structures)
Example = Flying Squirrels & Sugar Gliders (they are distantly related, but have very similar adaptations)
Example = Dolphins & Sharks (they are distantly related, but have similar adaptations of streamlined bodies and dorsal fins, since they both live in the ocean!)
Similarity in Embryos of Related Species
Embryo = an unborn or unhatched offspring in the process of development
What is Evolution?
HOW does evolution work?
Idea proposed by Charles Darwin
Over many generations, the inherited characteristics of a population change, which results in creased fitness of the species
Fitness = the ability to survive and reproduce
"Survival of the fit!"
Humans are the Selective Force
Humans choose traits that are desirable to us! This does not necessarily increase species' fitness.
Just because we can, does that mean we should?
Topics: Stem Cells, Cloning, Designer Babies, Genetic Testing/Screening, GMO Foods, CRISPR-Cas9
Definition: Evolution is the process where different species have developed and diversified from earlier forms during the history of the earth.
Also called "Descent with Modification"
Written in Charles Darwin's Book: The Origin of Species
What conditions MUST be present in order for evolution to occur?
Variation of traits in the population!
Can be behavioral or physical
Traits affect the fitness of the individual
trait INCREASES fitness
adaptation (favorable trait)
trait DECREASES fitness
trait DOES NOT AFFECT fitness
Comes from mutations in DNA
Can sometimes create Dominant and Recessive Traits
Traits are expressed = PHENOTYPE
Can predict offspring using Punnett Squares
One allele is given by each parent.
The combination of parent alleles (BB, Bb, bb) is called the GENOTYPE.
Studied by Gregor Mendel - an Austrian Monk
Only mutations in alleles that are INHERITED can be passed down to offspring. Most mutations are neutral (do not affect offspring's fitness).
Unequal reproduction between individuals in the population
the MORE FIT individuals are more LIKELY to survive and reproduce
If a species is not fit for the environment, it may become EXTINCT.
The frequency of traits in the population will change. The adaptation will be come more common over time.
A selective force is changed in the environment
A struggle for existence between individuals
may be for food, shelter, mates, territory, getting away from a predator, etc...
Time - Evolution takes many generations
Types of Evolution
Misconceptions about Evolution
Evolution is NOT just a theory. It is a scientific theory!
There is a lot of evidence that supports evolution.
A scientific theory is well-substantiated, supported idea, that has been repeatedly proven.
Evolution is NOT random. It can be predicted by the variation of traits of the species and the selective forces in the environment
Genetic Mutations ARE random and very uncommon.
Humans did not evolve FROM apes/monkeys. However, there is a tree of life and we are closely related to them. We have a very recent common ancestor about 8 million years ago.
Organisms evolve because they want or need to change.
One organism can change in its own lifetime.