Evolution and Taxonomy. "nothing in biology makes sense except in the light of evolution”

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

THEORY

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

IN SCIENCE, THE TERM "THEORY" DOES NOT EXPRESS DOUBT.

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

WHY?

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.

FOR EXAMPLE…

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 survive4. Individuals that had advantageous variations are more likely to survive and reproduce.

This process came to be known as Natural SelectionThe favorable variations are called Adaptations

DARWIN’S FINCHES

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. Variation2. Competition3. Survival4. 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.

EVIDENCE FROM LIVING ORGANISMS

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 DevelopmentEmbryos of different species develop in almost identical ways.

Human fetus at 8 weeks

Direct observation of species change 1.Bacteria become resistant to antibiotics2.Wolves were bred over many generations to

become dogs (artificial selection) • and then bred further to create a variety of breeds

TAXONOMY

The Science of Classifying Organisms

WHY DO WE NEED TO CLASSIFY?

• 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

SCIENTISTS ALSO NEED A WAY TO *NAME* ORGANISMS

• 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 CreditsSea Lion: Bill LimAnt Lion: AmphioxusLion: law_keven

Sea Lion?

Antlion?

Lion?

Which one of these is NOT actually a bear? Photo Credits

Panda: Chi KingKoala: BelgianchocolateBlack Bear: SparkyLeigh

WHAT KIND OF ORGANISM IS IT?(INVERTEBRATE, MAMMAL, INSECT, FISH, REPTILE..)

1.Firefly2.Sea Monkey3.Ringworm4.Jellyfish5.Spider monkey6.Crayfish7.Sea Horse

Photo Credit: Audringje; flickr

CONSIDER THIS………..

• 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 grayA cottonmouth and a water moccasin are the same animal – the names vary by region.

NAMING AND ORGANIZING ARE PART OF THE SAME PROCESS

• 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

GROUPING

• 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

MORE ON NAMING..

• 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

WHAT IS A SPECIES?

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

WHEN TWO ORGANISMS OF DIFFERENT SPECIES BREED, THE OFFSPRING IS CALLED A HYBRID. THIS IS VERY RARE.

Example:  ligers and mules

THE KINGDOMS

• There are currently 6 kingdoms – all organisms can be placed into one of those 6.

• Classification into a kingdom is based on certain criteriao Number of cellso How it obtains energyo Type of cell

KINGDOM ANIMALIA• 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

KINGDOM PLANTAE

• Multicellular• Autotrophic (can make own food;

photosynthesis)• Eukaryotic (cells have nucleus)

Photo by hira3

KINGDOM FUNGAE

• Multicellular (most)• Heterotrophic (mainly decomposers)• Eukaryotic

Photos by nutmeg66

KINGDOM PROTISTA

• 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

KINGDOM EUBACTERIA & KINGDOM ARCHAEBACTERIA• 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

THREE DOMAIN SYSTEM    

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