Evolution and Taxonomy

"nothing in biology makes sense except in the light of evolution”

In science, theories are statements or models that have been tested and confirmed many times.

Theories have some important properties: They explain a wide variety of data and observations They can be used to make predictions They are not absolute, they serve as a model of thoughts for the world and can be changed as the world views changes

 In science, the term theory is used to represent ideas and explanations that have been confirmed through tests and observations

Photo courtesy of Swamibu, Flickr Creative Commons  The theory of evolution remains one of the most useful theories in biology because it answers many questions and observations

Lamarke's Theory of Acquired Characteristics Some thought that you would gain or lose features if you overused or didn't use them, PROVEN TO BE WRONG! Photo courtesy of ucumari, creative commons, flickr

 Logically it doesn’t work.  Imagine if you were in a car accident and had a leg amputated. This does not mean that your children will only have one leg. Features gained or lost during life are not passed on to children.  Or if you wore colored contacts, you could not pass that eye color down to your children.

 A lizard that didn’t use it legs would eventually not have legs and its offspring wouldn’t have legs  A giraffe stretched its neck to reach higher leaves, and this stretched neck would be a trait inherited by its offspring

Charles Darwin developed the THEORY OF EVOLUTION BY NATURAL SELECTION which explained how organisms changed over time or adapted)

Darwin was a naturalist (what we today call biologists) He traveled the world and made observations and sketches of many species His most famous travels were aboard a ship called the Beagle where he traveled to the Galapagos Islands

Marine Iguana, photo courtesy of mtchm, flickr creative commons Blue-footed booby, photo courtesy of stirwise, flickr creative commons

Giant tortoise, photo courtesy of Planetgordon, flickr creative commons Finch, photo courtesy of stirwise, flickr, creative commons

1. Variation exists among individuals in a species. 2. Individuals will compete for resources (food, mates, and space) 3. Competitions would lead to the death of some individuals while others would survive 4. Individuals that had advantageous variations are more likely to survive and reproduce. This process came to be known as Natural Selection The favorable variations are called Adaptations

Darwin noted that all the finches on the Galapagos Island looked about the same except for the shape of their beak. His observations lead to the conclusion that all the finches were descendents of the same original population. The shape of the beaks were adaptations for eating a particular type of food (Ex. long beaks were used for eating insects to assist the them with digging, short beaks for seeds)

Say in a species of blob….there exists blobs of all shapes and sizes (variation or varieties) Blobs eat the little purple organisms that live underground and on the surface.

During a particularly hot year, food became less abundant (so we get some competition for food), blobs that had the ability to dig into the soil to get food had a better chance of survival. Many blobs died that year…….

The ones that survived mated and passed their genes to the next generation through reproduction. Their particular variation of a pointed nose allowed them to survive over the others.

The next generation had more blobs with the pointed noses. That is NATURAL SELECTION. 1.Variation 2.Competition 3.Survival 4.Reproduction

Fossil Evidence If today’s species came from ancient species, the we should be able to find remains of those species that no longer exist. We have tons of fossils of creatures that no longer exist but are very similar in resemblance to creatures that do exist today. Carbon dating–gives an age of a sample based on the amount of radioactive carbon is in a sample. Fossil record creates a geologic time scale.

Dinosaurs have always fascinated us, movies such as Jurassic Park capitalize on that fascination. How do we know what dinosaurs looked like? We create a picture based on the bones we find (fossils) and use modern reptiles to guess at their texture and skin color.

 Homologous Structures–structures that are similar when there are developing, but have different functions, the wing of a bird and the forearm of a human  Vestigial Organs–seemingly functionless parts, snakes have tiny pelvic and limb bones, humans have a tail bone  Embryological development–Embryos of different species develop almost identically  Observation of species change- (wolves/dogs, peppered moths)  Biochemistry and DNA- lions and tigers are the same until the very last classification level

Homologous structures – these are parts of the body that are similar, but have different functions ex. The flippers of whales, and the wings of birds All forelimbs of vertebrates have the same pattern of bones

Vestigial Organs – these are organs or parts that seem to have no function Whales have pelvic bones that do not attach to legs humans have a tail bone but no tail

Biochemistry and DNA When comparing the DNA of one species to another, more similarities are found in species that are more closely related.

Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks

Direct observation of species change 1.Bacteria become resistant to antibiotics 2.Wolves were bred over many generations to become dogs (artificial selection) and then bred further to create a variety of breeds

The Science of Classifying Organisms

Imagine a store…..how do you know where to find the milk or the cereal? Are they in the same aisle? How is the store “organized”? Are all stores similar? Imagine your computer or mp3 player…..are all of your songs and files in a single folder or do you have them grouped in some way?

When you have a lot of information, it is best to organize and group items so that you can find them easier or easily see their relationship to other items ….this is why we CLASSIFY Even websites must organize their products

The “common names” used by people can sometimes be misleading or confusing In order to communicate effectively, biologists need a CONSISTENT naming protocol. *Check out these slides of confusing names…..

Photo Credits Sea Lion: Bill Lim Ant Lion: Amphioxus Lion: law_keven Sea Lion? Antlion? Lion?

Which one of these is NOT actually a bear? Photo Credits Panda: Chi King Koala: Belgianchocolate Black Bear: SparkyLeigh

1.Firefly 2.Sea Monkey 3.Ringworm 4.Jellyfish 5.Spider monkey 6.Crayfish 7.Sea Horse Photo Credit: Audringje; flickr

Are all “Grey Wolves” gray? Are all “Black Bears” black? Which is more venomous – a water moccasin or a cottonmouth? Grey wolves can be white, black and any shade of gray. Black bears can also be brown or gray A cottonmouth and a water moccasin are the same animal – the names vary by region.

The system was developed by Carolus Linnaeus who used Greek and Latin names for organisms He also created a system where we place all organisms into a few *large* groups - KINGDOMS - and then those groups are further divided into smaller groups

Kingdom Phylum Class Order Family Genus Species Each group gets smaller and more specific – just think of the way you file things on your computer into folders and subfolders

To help you remember the list KING PHILIP CAME OVER FOR GREAT SOUP Kingdom, Phylum, Class, Order, Family, Genus, Species

The system of naming is called BINOMIAL NOMENCLATURE - which means it is a 2-name system. Scientific names must either be underlined or italicized The genus is always capitalized, the species is lowercase Can be abbreviated. Ex. F. leo and F. tigris

Defined as same species organisms that can breed with one another, and produce fertile offspring

Example: ligers and mules

There are currently 6 kingdoms – all organisms can be placed into one of those 6. Classification into a kingdom is based on certain criteria o Number of cells o How it obtains energy o Type of cell

Multicellular Heterotrophic (must consume food) Eukaryotic (cells have a nucleus) Examples: birds, insects, worms, mammals, reptiles, humans Photo by Eduardo Amorim Photo by Tambako the Jaguar

Multicellular Autotrophic (can make own food; photosynthesis) Eukaryotic (cells have nucleus) Photo by hira3

Multicellular (most) Heterotrophic (mainly decomposers) Eukaryotic Photos by nutmeg66

Most are unicellular Can be hetertrophic or autotrophic Eukaryotes (all have nucleus) Examples: Ameba, paramecium, euglena, algae Most live in water Photo of Ameba by PROYECTO AGUA **/** WATER PROJECT

Unicellular Can be autotrophic or heterotrophic Prokaryotes (do not have a nucleus) Eubacteria = common bacteria (E. coli, Salmonella) Archaebacteria = “ancient bacteria”, exist in extreme environments

Recently, scientists have added a group above Kingdom. Three groups, called DOMAINS, contain each of the six kingdoms. Domain Eukarya - includes organisms composed of eukaryotic cells (plants, animals, fungi, protists) Domain Bacteria - includes all prokaryotic cells, Kingdom Eubacteria Domain Archaea - includes only "ancient" bacteria, Archaebacteria