Evolution Notes.

Evolution Notes

Evolution

Evolution A change in a kind of organism over time
Charles Darwin ( ) Wasn’t the first person to recognize that evolution has happened and is happening Was the first to propose a feasible mechanism for evolution. It is called descent with modification . Scientists have found large amounts of evidence to support Darwin’s views of evolution.

Theory:

Theory: well-tested explanation that unifies a broad range of observations
Remember: The word “theory” in everyday language and in scientific language means very different things. In everyday language, people use the word theory to mean a hypothesis or an educated guess. In science, people use the word theory to represent an idea that is strongly supported by evidence. It is accepted and used to explain many observations.

Other examples of theories
Cell theory: all living things are made up of one or more cells, etc. Atomic theory: all matter is made up of one or more atom, etc.

What was Darwin’s theory of evolution by natural selection?

Darwin published his book, On the Origin of Species by Means of Natural Selection, in In it, he outlines the major points of his theory.

Darwin published his book, On the Origin of Species by Means of Natural Selection, in In it, he outlines the major points of his theory. Natural selection:

Darwin published his book, On the Origin of Species by Means of Natural Selection, in In it, he outlines the major points of his theory. Natural selection: Process by which individuals that are better suited to their environment to survive and reproduce most successfully; also called survival of the fittest

Darwin published his book, On the Origin of Species by Means of Natural Selection, in In it, he outlines the major points of his theory. Natural selection: Process by which individuals that are better suited to their environment to survive and reproduce most successfully; also called survival of the fittest You can remember the main points behind natural selection as VISTA

VISTA Variation:

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance:

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance: Certain traits can be passed down through generations

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance: Certain traits can be passed down through generations We know that heritable variation is due to genes. Variation in genetic material is due to:

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance: Certain traits can be passed down through generations We know that heritable variation is due to genes. Variation in genetic material is due to: Mutations: Sexual reproduction:

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance: Certain traits can be passed down through generations We know that heritable variation is due to genes. Variation in genetic material is due to: Mutations: changes in a DNA sequence that affect genetic information Sexual reproduction:

VISTA Variation: Members of the same population have different characteristics; no organism is exactly the same as another Inheritance: Certain traits can be passed down through generations We know that heritable variation is due to genes. Variation in genetic material is due to: Mutations: changes in a DNA sequence that affect genetic information Sexual reproduction: process by which cells from two different parents unite to produce the first cell of a new organism

VISTA Survival and reproduction:

VISTA Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their species

VISTA Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their species Natural selection is often referred to as “survival of the fittest.” What is “fitness?”

VISTA Survival and reproduction: Organisms must survive in their environment and successfully mate and reproduce with another member of their species Natural selection is often referred to as “survival of the fittest.” What is “fitness?” Certain characteristics and behaviors make an organism more likely to survive in a given environment when competing with other members of the population

VISTA Time:

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful Adaptation:

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful Adaptation: any inherited characteristic that increases an organism’s chance of survival

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful Adaptation: any inherited characteristic that increases an organism’s chance of survival Darwin referred to this accumulation of adaptations over time as

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful Adaptation: any inherited characteristic that increases an organism’s chance of survival Darwin referred to this accumulation of adaptations over time as natural selection

VISTA Time: Generation after generation, individuals continue to compete to survive and produce offspring, and not all are successful Adaptation: any inherited characteristic that increases an organism’s chance of survival Darwin referred to this accumulation of adaptations over time as natural selection He believed that descent with modification had created the great diversity of life

Let’s explain the giraffe’s long neck using the theory of evolution by natural selection.
V: Giraffes had different neck lengths I: The lengths of the necks could be passed on from one generation to the next S: Giraffes with longer necks were able to get more food and so they could survive to reproduce T: Gradually, each succeeding generation of giraffes had longer necks because the longer necked giraffes were surviving more often than the short necked giraffes A: Overall, the populations of giraffes all had long necks.

How did Darwin develop his idea of natural selection?
Voyage of the Beagle After graduating from college, Darwin took a job as the naturalist on the H.M.S. Beagle, a boat that was traveling around the world with the purpose of creating better maps. Darwin collected living organisms, fossils and other evidence of living things every time the ship landed in a new area.

What did Darwin observe on his travels?

What did Darwin observe on his travels? Fossils:

What did Darwin observe on his travels? Fossils: preserved remains or evidence of an ancient organism

What did Darwin observe on his travels? Fossils: preserved remains or evidence of an ancient organism Darwin wondered Why had so many of these species disappeared? How were they related to living species?

What did Darwin observe on his travels? Organisms on Islands

What did Darwin observe on his travels? Organisms on Islands Studied the finches and giant tortoises of the Galapagos Islands

What did Darwin observe on his travels? Organisms on Islands Studied the finches and giant tortoises of the Galapagos Islands Found that organisms on the islands were similar to those on the mainland, but had slightly different characteristics that allowed them to survive in their new habitats

What did Darwin observe on his travels? Organisms on Islands Studied the finches and giant tortoises of the Galapagos Islands Found that organisms on the islands were similar to those on the mainland, but had slightly different characteristics that allowed them to survive in their new habitats Darwin wondered Why was there so much diversity? Is there a way that leads to such a variety of ways of reproducing?

Influence of Other Scholar’s Work
Lamarck’s Theory of Evolution Through the Inheritance of Acquired Characteristics Use and disuse: Organisms can alter the size or shape of their body by using their bodies in new ways Parts of their body would decrease in size if they weren’t used, and over the course of generations, completely disappear

Lamarck’s Theory of Evolution Through the Inheritance of Acquired Characteristics Inheritance of acquired characteristics Acquired characteristics are passed down to future generations If you spent a lot of time lifting weights and building muscles, your children will be born with big muscles

Lamarck’s Theory of Evolution Through the Inheritance of Acquired Characteristics Example: Giraffe’s long neck Giraffe’s necks got longer because they would stretch to reach the highest leaves Their offspring were born with these stretched necks, and continued to stretch them even longer, giving birth to offspring with even longer necks Does Lamarck’s theory of evolution work? NO!!!!

Key Ideas Lamarck was wrong, but we can learn from his mistakes.
Acquired traits aren’t inherited. Only traits determined by our genes are inherited. During Darwin’s time people did not know how traits were inherited. They had no knowledge of genes and DNA.

Personal Studies Darwin wanted to ensure that he had as much research as possible to support his ideas. Studied the diversity of barnacles: collected specimens from all he could find to study their differences amongst the populations Bred Fancy Pigeons: bred pigeons for a period of time to examine their different beaks and how they were inherited Artificial Selection: selection by humans for breeding of useful traits from the natural variation among different organisms

Evidence for Evolution
Fossil Record Different layers of rock are formed at different times during Earth’s history The deeper the rock, the older it is Fossils found in deeper layers are older Can be used to see how organisms have changed over time

Biogeography Different animals found on different continents but in similar climates and environments demonstrated similar behaviors or had similar anatomy

Comparative Anatomy Homologous Structures: structures that have different mature forms but develop from the same embryonic tissues Examples: Human arm, cat leg, whale fin, bat wing

Vestigial Organs: Organs that are reduced in size and serve little or no function Examples: Traces of leg bones in snakes, human appendix

Comparative Embryology The early stages of many animals with backbones are very similar (be careful  Not identical!) Fish Chicken Pig Human

All living organisms are made of the same basic materials
Evidence of Evolution Molecular Biology All living organisms are made of the same basic materials Proteins, nucleic acids, carbohydrates, lipids

Current Examples of Evolution by Natural Selection
It is incorrect to think of evolution by natural selection as a process that takes a long time to see occurring. We can see changes in groups of organisms from generation to generation. Here are some examples of evolution that is occurring around us.

Antibiotic Resistant Bacteria
Antibiotics: drugs intended to kill or interfere with the growth of bacteria Used to be known as “magic bullets” or “wonder drugs” because they were so effective Mutations have resulted in antibiotic resistant bacteria that can survive the medication If they survive, they reproduce more antibiotic resistant bacteria Bacteria reproduce really quickly so once powerful antibiotics are now sometimes useless.

Pesticide Resistant Insects
We use pesticides to keep insects from destroying crops Mutations result in insects that are resistant or immune to certain pesticides Pesticide resistant insects then survive and reproduce, resulting in more pesticide resistant insects.

Organism Interactions
Organisms interacting with each other can improve their fitness. Here are some ecological examples of organisms interacting with each other. Symbiosis:

Organism Interactions
Organisms interacting with each other can improve their fitness. Here are some ecological examples of organisms interacting with each other. Symbiosis: relationship in which two species live closely together

Symbiotic interactions
Mutualism: Both species benefit from the interaction Example: Flowers provide food for bees and bees help the flowers pollinate Commensalism: One species benefits from the interaction and the other is neither helped nor harmed Example: Orchids benefit from growing on a tree by absorbing water from rain runoff and the tree is unaffected Parasitism: One organism lives on or in another organism and harms it Example: A tick feeds on the blood of its host and may also cause disease in its host

Community Interaction
Effect on Organism A Effect on Organism B Competition Predation Mutualism Commensalism Parasitism

Effect on Organism A Effect on Organism B Competition - Predation Mutualism Commensalism Parasitism

Effect on Organism A Effect on Organism B Competition - Predation + Mutualism Commensalism Parasitism

When an organism is harmed by an interaction, natural selection favors the survival and reproduction of individuals who have traits that allow that organism to overcome that negative interaction. Examples of adaptive traits that help organisms survive competition, predation or parasitism: Camouflage or small size in prey so its easier for the to hide from predators Broad leaves on tall trees that help them get more sunlight Tough skin or thick fur that makes it difficult for parasites to bite and draw blood.

Evolution Notes.

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