Biology journal 1 25 2010
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Biology Journal 1/25/2010. Think about a salmon and an elephant. What would some derived traits for the fish and the elephant? What conserved traits do they have?. Biology Journal 1/18/2013. What are the 4 steps of natural selection? What happens in each step?.

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Biology Journal 1/25/2010

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Biology Journal 1/25/2010

Think about a salmon and an elephant. What would some derived traits for the fish and the elephant? What conserved traits do they have?


Biology Journal 1/18/2013

What are the 4 steps of natural selection? What happens in each step?


What is environ-mental pressure?

What could be some examples of it?


What can happen if environmental pressure gets too great?


Evolution

Why are there so many different kinds of things?


Alfred Wallace and Charles Darwin: designers of the theories of Natural Selection and Evolution

Charles Darwin

(1809-1882)

Alfred Russel Wallace

(1823-1913)


These scientists observed slight differences in animals and wondered: what’s the deal?


Stops on Darwin’s Evolution Revolution World Tour 1831-1836


The Galapagos Islands: a group of islands named after some Spanish stuff.


Darwin noticed subtle differences between the Finches on the Galapagos Islands


Why do so many different kinds of Finches exist???


Environmental pressure shaped the finches on the Galapagos Islands to be good at getting a specific food.


The more quickly you can reproduce and go through a generation, the more quickly you can evolve.

Bacteria evolve in days; fruit flies evolve in months; polar bears evolve in millions of years.


For most organisms, evolution takes a long time. They’re just changing due to natural selection.

and that’s how this kind of stuff happens


What up, cuz?

Populations (not individuals!) change based on what’s an advantage


Great moments in evolution


What is evolution?

Evolution is the development of new types of organisms from preexisting types.

  • It takes place because of changes in the genes in a population, over time.


Humans can try to influence natural selection and evolution by controlling who reproduces and with whom. This is called artificial selection.

Through thousands of years of artificial selection, humans turned wolfs, majestic symbols of nature and independence, into helpless, dumb poodles.


What did we artificially select these dogs to do?

Greyhound

Golden

Retriever

Siberian Husky

Bloodhound

St. Bernard

German

Shepherd

Pit Bull

Foxhound


What are some other animals we’ve artificially selected?

Holstein

Texas longhorn

Black Angus

Ponies

Draft Horses

Thoroughbreds


Artificial selection is how all of our crops and food animals have become big, resistant to the environment, delicious and nutritious!

Sometimes too big


Doing this to humans is called “eugenics” and is usually just an excuse for a racist agenda.


Jessie Owens, a black US track and field athlete, defeated the Germans, winning 4 gold medals in the 1936 Olympics held in Berlin, Germany.

Who’s the inferior race now?


Another great moment in evolution


Biology Journal 1/26/2010

Compare and contrast natural selection and artificial selection in a Venn diagram.


Evolution is a theory

  • Evolution is supported by evidence and experiment.

  • Natural selection, however, is undeniable, because we can see it happen.

So here’s the evidence…


Fossils

The truth is under there.


1. Fossil Record

As the rocks get older, we can track what kinds of organisms were alive at different time periods over all of earth’s history.


Homologous structures

Organs that do different things, but all have the same structures.

These animals all must be related to a single species in the past.


Homologous structures

Organs that do different things, but all have the same structures.


Homologous structures

Organs that do different things, but all have the same structures.


Analogous Structures do the same thing, but are not related by evolution, and therefore have different structures.


Vestigial Structures

  • Vestigial organs are ones that are present but have no purpose.

Why are they there?


Vestigial Structures in Humans

  • Appendix: Attached to your small intestine. Does nothing. Then it gets infected and kills you.


Vestigial Structures in Humans

  • Coccyx: it used to be individual bones of a tail. Now is one fused mass.


Vestigial Structures in Whales


Similarities in DNA shows how closely related two species are.

Humans have up to 33% the same DNA as some single-celled organisms.

Humans and chimps have 98.8% the same DNA


Embryonic Similarities

As many animals grow up in the uterus, they all share the same development and structures.

Why would they do that???


Embryonic Similarities


  • And every once in a while, genetic mutations happen that allow us to understand how new structures could form. But they’re not always an advantage…

A dolphin with hind-leg flippers


An “extra” arm on an 11 year old boy.


  • Mutations help move along evolution by creating diversity. Some traits will be good. Some will be bad…


Evolution: Change that Matters


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