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Life and Evolution LE1 - Explore how scientific understandings of life and its characteristics change in light of new evidence. (CP, DM)
Life and Evolution
LE1 - Explore how scientific understandings of life and its characteristics change in light of new evidence. (CP, DM)
What is a Scientific Theory?
A scientific theory is a valid explanation of some aspect of the natural world that has been substantiated through repeated experiments or testing.
Scientific theories can change as more data is gathered.
Origin of Life Theories
Where did life come from?
There are two main theories about the origin of life: Abiogenesis and Biogenesis.
Abiogenesis vs. Biogenesis
Abiogenesis, meaning “life from non-life”
Biogenesis, meaning “life from life”
"If a soiled shirt is placed in the opening of a vessel containing grains of wheat, the reaction of the leaven in the shirt with fumes from the wheat will, after approximately 21 days, transform the wheat into mice" - Jean Baptiste van Helmont.
Spontaneous Generation is the idea that inanimate objects create animate objects.
Some other animal “recipes”
Scorpion recipe - Carve an indentation in a brick, fill it with basil, cover the hole with another brick and place it in the sun. In a matter of days, "fumes from the basil, acting as a leavening agent, will have transformed the vegetable matter into veritable scorpions.”
Abiogenesis
It was also thought that maggots spontaneously generated on meat left out in the open air. This idea was tested by Francesco Redi.
Francesco Redi’s Experiment
In 1668, Italian physician Francesco Redi, performed an experiment using meat to test the idea of spontaneous generation.
The belief in spontaneous generation remained popular until French chemist Louis Pasteur proved the existence of microorganisms in 1859.
Biogenesis In 1859, Louis Pasteur, a French chemist and microbiologist, set out to disprove the theory of spontaneous generation.
The Swan-Neck Flask
Let’s Recreate Francesco Redi’s Experiment!
Scientist Social Media Assignment
LE1 (e) - Recognize the contribution of scientists whose experiments contributed to a wider understanding of life from a biological perspective.
Scientist Sign-Up Sheet
The Characteristics of Living Things
The Characteristics of Living Things
1. Living things are composed of cells.2. Living things have different levels of organization.3. Living things have DNA.4. Living things obtain and use energy.5. Living things grow and develop.6. Living things maintain a stable internal environment.7. Living things can sense, respond, and adapt to their
environment.8. Living things reproduce.9. Groups of living things evolve over time.
FNMI Perspective
First Nations and Metis peoples acknowledge the interconnectedness of relationships and natural systems.
Everything on Earth that is created in nature has an energy and a spirit. It is understood that all of nature is connected to a living energy called the cycle of life.
FNMI Perspective
Are Viruses Alive?
Read the articles provided, and highlight any mention of the characteristics of life.
Which characteristics of life do viruses demonstrate?
Which characteristics of life do viruses lack?
Are viruses alive? Send a SnapChat video to the group explaining your position.
Life and Evolution
LE2 - Examine the significance of evolution as a key unifying theme in biology through the principles, processes and patterns of biological evolution. (SI, DM)
What is Evolution?
Evolution is a change in the genetic makeup of a population over time.
Evolution Theories
Various theories have attempted to explain how evolution occurs. Two disagreeing theories of evolution were presented in the 19th century by the French biologist Jean Baptiste Lamarck and the English scientist Charles Darwin.
Jean Baptiste Lamarck (1774 - 1829)
The Principle of Need - Organisms change because of an inner need to change.
The Principle of Use and Disuse - Use it or lose it. The more you use a characteristic the stronger it gets and vice versa. The less you use it, the weaker it will get and eventually disappear.
The Principle of Acquired Characteristics - The characteristics that an individual has acquired over its lifetime would be passed on to its offspring.
Charles Darwin - Theory of Natural Selection (1809 - 1882)
Darwin’s major work over 20 years was shared in his book On the Origins of Species, which was published in 1859:
- All organisms produce more offspring than can actually survive. - Each organism faces a constant struggle to survive. Those who win
the struggle survive while the others die. - The individuals of any given species vary because they inherit
different traits. - The individuals that are best adapted to their environment survive.
The “survival of the fittest”. - The organisms that survive pass their favorable traits on to their
offspring.
Lamarck vs. Darwin
The Main Points of Natural Selection
Individuals of the same species have different traits.
Organisms compete with one another for survival.
Individuals with traits that help them survive reproduce more successfully. These successful individuals pass their traits down to their offspring.
In time, the frequency of individuals with the helpful variation will increase in the population.
Evolution Cards Activity
- Form a group of three. - Your group will be given a set of cards, either blue,
purple, or yellow.- You will have five minutes to put the cards in order to
explain natural selection. - Make sure to write down what order you put the cards in. - Once you are done, switch cards with another group.- Repeat this process for the other two sets of cards.
Evolution Cards Activity
- What card should go at the beginning of the order? Why?
- What card should go in the middle? Why?
- What card should go at the end? Why?
Key Principles and Processes of Biological Evolution
Descent with Modification
Fitness
Natural Selection
Genetic Drift
Selective Breeding
Descent with Modification
The idea that species change over time, give rise to new species, and share a common ancestor.
Fitness
Result of adaptation and the struggle for existence.
Adaptation - A heritable trait that helps the survival of an organism in its present environment.
Fitness does NOT necessarily mean strength. Smarts, camouflage or other traits that allow an organism to survive increase an organism’s fitness.
Natural Selection
The process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Nature selects FOR or AGAINST a particular trait.
Genetic Drift
Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
Genetic drift is a random event.
This can lead to the disappearance of a particular genotype/allele.
Selective Breeding
Selective breeding or artificial selection is the process by which humans use animal or plant breeding to selectively develop particular phenotypic traits.
Who Wants to Live a Million Years? - Darwin’s Game of Survival
Use what you have learned about evolution and natural selection to ensure that your species survives a changing and cruel environment.
Who Wants to Live a Million Years
The Galapagos IslandsThe Galapagos Islands are a group of 13 volcanic islands and 6 smaller islands.
Some of the islands are very dry with almost no vegetation.
Other islands get more rain and have plenty of vegetation.
The Galapagos Islands
The Galapagos Islands feature species unique to the islands themselves, including marine iguanas, blue-footed boobies, and Darwin’s finches.
Darwin’s Observations
Darwin was intrigued by the animals he saw.
He noticed that many of the plant and animals were similar to mainland species.
However, most showed their own unique adaptations, not seen in the mainland species.
Darwin’s Observations
More important were the differences in species between different islands.
Darwin observed that the same species differed from one island to another.
One example were the small finches, now known as Darwin’s finches.
Darwin’s Finches
Darwin’s Early Theory
- Plants and animals arrived to the Galapagos Islands from the mainland many years ago.
- They faced different conditions from the mainland, and between different islands.
- The species gradually changed over many generations to become better adapted.
- Thus, the species evolved to become better fitted to their newfound habitats.
Darwin’s Early Theory
What mechanism of evolution did Darwin propose?
Galapagos Finch Evolution
Complete the film guide as you watch this short film!
Battle of the Beaks Lab- You will have one minute to
collect as many food items as you can.
- You can only pick up one item at a time.
- You can only use your “beak” to move items from the table to your “stomach”.
- The cup must remain on the table. No scooping food items into your cup.
- You cannot steal or purposely interrupt others’ food gathering.
Battle of the Beaks Lab - Groups
Get into 5 groups of 4. GO!
Trials Beak Types
Rubber Bands
Scissors Clothespins Spoons Tweezers
1
2
3
4
5
Average
Trials Beak Types
Beans Scissors Clothespins Spoons Tweezers
1
2
3
4
5
Average
Trials Beak Types
Toothpicks Scissors Clothespins Spoons Tweezers
1
2
3
4
5
Average
Trials Beak Types
Paper Clips Scissors Clothespins Spoons Tweezers
1
2
3
4
5
Average
Battle of the Beaks Lab
- What food items were easiest to collect for each beak type?- How did this affect the survival of your bird species?- Which species is most likely to reproduce?- How was this represented in the activity?- What happens to allele frequency after three generations have passed?- What was your strategy when all food items were available?- How did this differ from your strategies in the previous scenarios?- What if the rubber bands were high-protein beetles that were four times more nutritious than any other food item? Would your feeding strategy change?- Apply the terms ‘variation’, ‘survival of the fittest’, and ‘change in gene frequency’ to this activity.
Influences on Evolution
- Selective Pressures
- Speciation - Allopatric vs. Sympatric Speciation
- Isolation and Barriers
Selective Pressures
Any phenomena which alters the behaviour and fitness of living organisms within a given environment.
OR
Anything that can impact the life of organisms. Pressure put on organisms will cause selection to take place.
SELECTIVE PRESSURES DRIVE SELECTION.
- Competition, predation, parasitism, changes in climate, and pollution are examples of selective pressures.
Selective Pressures
Various pressures act on individuals that sometimes result in their death.
Some traits are more beneficial under certain selective pressures.
Selective Pressures Lab - POM POM TIME!
- Pom poms are distributed throughout the room.
- Based on the role card that you are given, collect what is
needed.
- Don’t show your role card to anyone else!
- You will get 1 min to collect pom poms.
- There will be 8 rounds.
- WALK to get pom poms or you are disqualified!
Sickle Cell Anemia Lab
- Sickle Cell Anemia is a disorder that affects hemoglobin, the
molecule in red blood cells that delivers oxygen to cells
throughout the body.
- People with this disorder have atypical hemoglobin
molecules called hemoglobin S, which can distort red blood
cells into a sickle, or crescent, shape.
Sickle Cell Anemia Lab
- What are alleles?
- An allele is an alternative form of a gene (one member of a
pair) that is located at a specific position on a specific
chromosome.
- In this activity, different coloured beans represent different
alleles for the gene that controls the formation of
hemoglobin.
Sickle Cell Anemia Lab
- The beans represent the different alleles (forms) of the gene
controlling the formation of the hemoglobin molecule.
- White = the sex cells carrying the A (unaffected) allele
- Red = the sex cells carrying the S (sickle cell) allele
- You will be simulating the breeding patterns of humans by
combining at random, the gametes that carry either the A
allele or the S allele.
Sickle Cell Anemia Lab
- In the United States, 1 in 500 African Americans develops
sickle cell anemia. In Africa, 1 in 100 individuals develops
the disease.
- Why is the frequency of a potentially fatal disease so much
higher in Africa?
Sickle Cell Anemia Lab
- The answer has to do with another potentially fatal disease,
Malaria.
- Compared to AS heterozygotes, people with the AA
genotype (normal hemoglobin) have a greater risk of dying
from malaria.
Sickle Cell Anemia Lab - Class Results
Parents F1 F2
A S A S A S
Class Total 75 25 44 17 31 12
Allele Frequency
75% 25% 72% 28% 72% 28%
Speciation
- Species are organisms that are able to mate with their own and have viable, fertile offspring.
- Speciation is the evolution of two or more species from one ancestral species.
- Speciation occurs through isolation and selective pressures influencing changes in the population.
- This speciation occurs gradually over time, or in specific, punctuated events.
Allopatric Speciation
Allo = Other Patric = Homeland
Allopatric speciation occurs when a population of organisms becomes separated or isolated from their main group. Over time, the allele frequency in the new group, which used to be homogenous across the individuals, becomes subject to changes via natural selection due to pressure from differences in predators, climate, competitors and resources.
Sympatric Speciation
Sym = Same Patric = Homeland
This type of speciation happens in a population without geographic isolation. The main mechanisms resulting in sympatric speciation involve changes in the chromosomes of the organism. One way this happens is when there is a serious error that occurs during cell division resulting in more than one copy of a chromosome(s), or the loss of a chromosome(s), in one of the daughter cells.
Isolation and Barriers to Reproduction
- Isolation leads to speciation. Isolation means “reproductive isolation of the species”.
- What makes that species mate with itself and only itself? Reproductive barriers!
Isolation and Barriers to Reproduction
- There are two types of reproductive barriers:
- Prezygotic - Those that prevent mating between different species. Ex. Gametic and structural barriers.
- Postzygotic - Those that reduce the likelihood that an offspring will survive after mating has occurred, but before the offspring is actually born (can also include sterile offspring). Ex. Ligers
-
Behavioural Isolation
- Evolutionary mechanism of identifying members of same species as proper mates.
- Involves reproductive barriers based on behaviour, usually in the form of mating rituals and signals.
- What example of behavioural isolation was given in the Beak of the Finch documentary?
Temporal Isolation
- Evolutionary mechanism that prevents species from mating because
they breed at different times. These differences can be time of day,
season or even different years.
- Involves organisms that only mate at certain times. If the times don’t
sync up, there is no mating.
- Example: American toads mate in early summer, Fowler’s toads mate in
late summer. The difference in mating season is temporal isolation.
Geographic and Habitat Isolation
- Evolutionary mechanism that refers to a population of animals, plants or other organisms that are separated from exchanging genetic material with other organisms of the same species.
- In habitat isolation, mating is prevented because of the separation of species resulting from the difference in their habitat. This usually occurs when the species are used to different habitat types, or different parts of the same habitat.
- Involves the physical separation of the species. Once isolated, they begin to evolve independently.
- Example: Physical barriers prevent fish from one stream from mating with fish
from another stream, leading to a less varied gene pool among those fish.
Skittles Speciation Lab
You will use Skittles to represent a beetle population that lives together on a small island.
You will observe what happens when different environmental pressures act on the population.
Evolution Over Generations
- Gradualism vs Punctuated Equilibrium
- Coevolution
- Adaptive Radiation
- Mass Extinction
- Evolutionary Arms Race
Gradualism Punctuated Equilibrium
- Selection and variation that happens more gradually.
- Small variations that fit an organism slightly better to its environment are selected for.
- A few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die.
- Very gradually, over a long time, the population changes.
- Change is slow, constant, and consistent.
- Change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals.
- The mutations that result in punctuated equilibrium are very helpful to the individuals in their environments. Because these mutations are helpful to the survival of those that have them, the proportion of individuals in the population who have the mutation and those who don't changes a lot over a very short period of time.
- The species changes very rapidly over a few generations, then settles down again to a period of little change.
Coevolution
- Coevolution is the process by which two or more species evolve in tandem by exerting selection pressures on each other.
- Ex. Predators and Prey - There is a selective pressure on the prey to avoid capture and thus, the predator must evolve to become more effective hunters.
Adaptive Radiation
- Process in which organisms diversify rapidly from an ancestral
species into a multitude of new forms.
- This happens when a change in the environment makes new
resources available, creates new challenges, or opens new
environmental niches.
Mass Extinction
- An extinction event is a widespread and rapid decrease in the biodiversity on Earth.
- Last extinction was 65 million years ago. It wiped out ¾ of plant and animal species .
Evolutionary Arms Race
- The struggle between competing sets of co-evolving genes, traits or species that develop adaptations and counter-adaptations against each other.
- Ex. Bacteria vs. Antibiotics
The Evolutionary Arms Race
Evidence of Evolution
- Anatomy and Embryology
- Fossil Record
- Radioactive Dating
- Biogeography
- Molecular Biology
Anatomy and Embryology
Homologous - Features that have similar structure and
come from similar embryonic layers but have completely
different functions
Analogous - Features that come from different embryological development but look similar and perform similar functions
Anatomy and Embryology
Homologous vs. Analogous Structures
The Tale of the Limb
Pick which limb does not belong and note any similarities that the others share.
For Homework
Watch Evolution: It’s a Thing! Crash Course Video. Jot down any
evidence for evolution presented in the video.
Human Evolution
How does evolution explain complex organisms like humans?
Evolution doesn’t happen all at once, especially in complex organisms such as human
beings. Modern humans are the product of evolutionary processes that go back more
than 3.5 billion years, to the beginnings of life on Earth. We became human gradually,
evolving new physical traits and behaviors on top of those inherited from earlier
primates, mammals, vertebrates, and the very oldest living organisms.
Human Evolution
How are humans and monkeys related?
Humans and monkeys are both primates. But humans are
not descended from monkeys or any other primate living
today. We do share a common ape ancestor with
chimpanzees. It lived between 8 and 6 million years ago.
But humans and chimpanzees evolved differently from that
same ancestor. All apes and monkeys share a more distant
relative, which lived about 25 million years ago.
The ‘Out of Africa’ Hypothesis
● The “Out of Africa” hypothesis is an evolutionary theory of modern human origin that states that modern humans arose about 100,000–200,000 years ago in Africa.
● There are different versions of “Out of Africa,” but its major idea is that modern humans originated as a discrete population or species that rapidly expanded and replaced archaic humans that were indigenous to other parts of the Old World.
● In the most common version of Out of Africa, modern humans are considered a new species, with negligible gene-flow or mating between the migrating African people and the indigenous archaic groups. Therefore, the African population is the unique ancestor of all living humans.
● The other groups of archaic humans essentially died out and became evolutionary dead ends.
Relationships Among Organisms
Relationships among organisms can be shown through the use of
cladograms and phylogenetic trees. They illustrate the evolutionary
relationships of organisms that share a common ancestor.
They are similar to a family tree!
Cladograms
A clade is a group of species used in cladograms and phylogenetic trees which consists of one ancestor and all its descendants.
Cladograms arrange organisms on different branches.
The branches used in cladograms aren't representative of the relative amount of change or evolutionary time that has occurred between organisms.
Drawing Cladograms
- Create a chart to compare organisms and their traits.- Start with the least complex organism and build up from
there. - Add in your traits.
Cladogram Example
Hair Legs Thumbs Eyes
Human
Snake
Monkey
Mouse
Phylogenetic Trees
The tips of the tree represent groups of descendents (often species) and the nodes on the tree represent the common ancestors of those descendants.
Phylogenetic Trees
Unlike cladograms, the branches on a phylogenetic tree can be proportional to the amount of change or evolutionary time. So, you can also track how species have changed over time.
Building Phylogenetic Trees
Grab a laptop and go to missmccormickscience.wordpress.com
Go to Life and Evolution under Biology 30, and find today’s date.
Click on Nova Labs
Nova Labs
You will embark on different “missions” to create phylogenetic trees and see how different organisms are related. After each mission is complete, you will answer questions about the tree you’ve just built. As you do this interactive lab, after each mission, write down an interesting fact you have learned about the relationships among organisms.
Misconceptions of Evolution
Dispute these misconceptions of evolution:
1. Individuals evolve
2. Natural selection is evolution
3. Evolution is random
4. Evolution is just a theory
5. Organisms evolve on purpose
