Evolution Darwin & Determination

Theories before Darwin: stated that the earth is millions or billions of years old. Jean-Baptiste Lamarck - Use or Disuse (use it or lose it) stated that organisms either use characteristics or lose those characteristics. James Hutton – Geologic Change

Charles Darwin: Went to Seminary school and received a degree in Divinity from Cambridge University. Sent to Medical School at 18 and failed out at 19. Charles was a Naturalist and Entomologist. Mother died when Charles was young. Born to a wealthy family (father was a doctor and member of aristocratic class). Born 1809

While there he became friends with John S. Henslow (botany professor) who set him up as Ship’s Naturalist on the H.M.S. Beagle. Beagle set sail around the world in 1831 (Charles was 22 years old). Stayed in the Galapagos Islands for a couple of weeks, then headed towards Asia. Charles had been sending everything he collected back to Henslow in England.

Darwin Left England in 1831 The HMS Beagle’s Voyage Darwin returned 5 years later in 1836

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

● E ach was adapted to eating a particular type of island food ● He concluded that all came from one ancestral species Cactus finch, photo courtesy of zrim, flickr creative commons

Upon returning home, he found that he had become quite noted as a collector and a scientist and became a fellow of the geological society. Spent two years arranging notes and specimens from the trip and displaying them for other scientists. Got married (Wedgwood Family). Charles began to get ideas of a “transmutation” theory to explain some of the differences that he saw in animals.

He was urged to write a book about it and his travels. In 1844 he wrote the manuscript for a book but didn’t want to publish. In 1859, when others were coming up with similar theories, he published On the Origin of Species by Means of Natural Selection. Charles Darwin died at his home in 1889 from a heart attack and was buried in Westminster Abbey.

Evolution : is the slow, gradual change in a population of organisms over time; change over time

Checkpoint 1. Darwin traveled to which islands? 2. What was the name of his ship? 3. Name 4 species he observed on the islands. 4. He developed what theory? 5. This theory explained how organisms _______________ over _________

Darwin’s Theory 1. Variation exists among individuals in a species. These traits are inherited. 2. Individuals will compete for resources 3. Competition would lead to the death of some, while others would survive 4. Individuals that had advantageous variations are more likely to survive and reproduce..

Those organisms that are best “fit” to the environment will survive the environment and reproduce. Darwin called this- Natural Selection Extinction – all members of a population dying out due to not having beneficial adaptations. Adaptation – a characteristic that an organism has that allows it to survive.

What’s the point? Survival of the fittest: If you outcompete other organisms for few resources you will live to pass on your genes. Ex: Camouflage & mimicry

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

During a particularly hot year, food became less abundant (competition), 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. (reproduction)

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

Artificial Selection - humans selected variations they found useful and bred animals and plants for those traits.

Much of our agriculture (food, animals, clothing) is a result of artificial selection that has occurred over many generations. We can influence the EVOLUTION of a species

Checkpoint 1. What was the name of Darwin’s book? 2. The theory states that a) individuals of a species have differences, called_________ b) these individuals ________________ for resources c) some will die, others will ____________________ d) survivors will _________________________ and pass traits to offspring 3. Any trait that helps an organism survive is called an _______________________________ 4. When humans influence evolution be breeding for desired traits, it is called _______________________________

We will be in the computer lab tomorrow: D204.

Evidence for Evolution

Biogeography and Fossil Evidence shows ….. ●similarities between extinct animals and animals that are alive ●earth’s layers, and species that lived at each time ● Fossils found at lower layers of rock are simpler than those found at upper layers.

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

Analogous structures: are UNLIKE homologous structures in that the structures appear similar but do not imply common ancestry. EX: wings of a bird and wings of an insect. Comparative Anatomy

Vestigial Organs Organs that are found in you that have no purpose in the body, but are found and used in other organisms. 1. You have an appendix.  2. Snakes have hipbones.  3. Whales have  hipbones too. Comparative Anatomy

3. Molecular biology (Biochemistry) Segments of our DNA called genes are much like that of other species and provide evidence for Evolution and a common ancestor.

4. Embryonic Similarities All vertebrate organisms look similar during formation. Also, the process follows the same steps.

Checkpoint: With your partner, find the answers in your notes. 1. ____________ evidence shows when organisms lived on the earth 2. Species that are closely related will have similar _______ 3. A _______________ organ is one that has no function. 4. _________________ structures look the same but have different functions, like the arm of a human and the flipper of a whale. 5. ____________ of different animals develop in the same way.

The Theory of Evolution: Darwinism We have discussed the 4 supporting evidences of evolution. Biogeography Comparative anatomy Molecular Biology Embryology Now we are going to discuss the 4 mechanisms of HOW Evolution occurs…

#1 Natural Selection: Natural Selection – AKA “Survival of the Fittest” A gradual, non-random process by which biological traits become either more or less common in a population   As you can see there is a variation in the phenotype of these beetles: Green or brown

Genetic Variations – differences within a population Increases or decreases an organisms chance of survival Inherited and controlled by alleles Allelic frequencies in a populations gene pool will change due to natural selection

Genetics Determines Evolution: Gene Pool – All the alleles in a populations genes. In other words every form of a trait Allelic Frequency – the % of any specific allele w/in a gene pool

Genetic Equilibrium – allele frequency remains the same over generations  Populations in genetic equilibrium are not evolving Factors that affects genes can affect equilibrium  Mutations [negative, positive]  Negative more than likely causes death  Positive may be beneficial and passed on to future generations

The genetic variation in this scenario are the genes that code for the color of the beetle.

3 Types of Natural Selection that Act on Variation: 1. Stabilizing Selection – natural selection that favors average individuals

3 Types of Natural Selection that Act on Variation: 2. Directional selection – natural selection that favors an extreme form of a trait

3 Types of Natural Selection that Act on Variation: 3. Disruptive selection – individuals w/ either extreme form of a trait

#2 Mutation Mutation: change in a gene; alteration of a nucleotide sequence. EX: A mutation causes two green beetle parents to have a brown beetle

#3 Migration Migration: Movement of some individuals to another population Gene Flow – transfer of alleles from one population to another population through immigration of individuals. This disrupts allele frequency.

#4 Genetic Drift Genetic Drift: some individuals may by chance and not because of “fitness” leave more descendants and therefore pass on their genes.

Change can be simply a random thing. Bottleneck Effect - having an event that kills off members of a species randomly by chance. Founder Effect - a new colony is formed by a few members of the original population

Checkpoint: With your partner, use your notes to find the answers. 1. ____________ ______________ is also known as survival of the fittest. 2. Three types of natural selection act on variation: a. ______________ b. ______________ c. ______________ 3. _________________ are changes in the amino acid sequence of gene and can have positive or negative outcomes. 4. ________ _________ occurs when individuals of genes move to another population. 5. Sometimes individuals pass on their genes due to chance rather than fitness resulting in ____________ _________.

So how do new species come about?

The Evolution of Species: Species – organisms that look alike can interbreed to produce fertile offspring Speciation – evolution of a new species. *NOTE: Organisms within the same species have reproductive success ( ability to pass genes onto the next generation in a way that they too can pass on those genes.) Donkey + Horse = Mule He can not have offspring because his parents are two different species  This is NOT a reproductive success

Physical Barriers Cause Speciation: 1. Geographic Isolation – a physical barrier divides a population

2. Reproductive Isolation – the inability of organisms to mate and breed fertile offspring  Genetic material becomes so different fertilization cannot occur  Behavior – mating seasons are different These Bowerbirds have different mating seasons and rituals. These 2 factors contribute to Reproductive Isolation

Directional Selection Stabilizing Selection Disruptive Selection Shifts from the Average Cause Speciation:

Does evolution happen fast or slow?

Speciation Rates - the time it takes for evolution to occur. 2 Theories: #1 Gradualism: – idea that species originate through a gradual change of adaptations Both!

# 2. Punctuated Equilibrium : things staying the same for a period of time then rapidly changing due to a catastrophic event.

There are TWO types of Evolution

#1 Divergent Evolution – accumulation of differences between groups which can lead to the formation of new species

Adaptive Radiation – ancestral species evolves into an array of species to fit a particular environment or niche.

#2 Convergent Evolution – organisms not closely relate, independently evolve similar traits (to adapt to similar environments.)

Macroevolution When one species is replaced by another species. Australopithocene skull Homo Sapien Skull

Microevolution Species giving rise to several different species. All citrus came from an original species of citrus tree