1. Competition and Natural Selection
King Penguins image courtesy of Life in the Fast Lane.
TEKS addressed: 8.11B, 8.11C, 8.3D
Bottom Image: How can natural selection explain the blobfish?...have a discussion. [FYI—The blobfish (Psychrolutes marcidus) is a deep sea fish inhabiting the deep waters off the coasts of mainland Australia and Tasmania, it is rarely seen by humans. Blobfish live at depths between 600–1,200 m (2,000–3,900 ft) where the pressure is several dozen times higher than at sea level, which would likely make gas bladders inefficient for maintaining buoyancy. Instead, the flesh of the blobfish is primarily a gelatinous mass with a density slightly less than water; this allows the fish to float above the sea floor without expending energy on swimming. Its relative lack of muscle is not a disadvantage as it primarily swallows edible matter that floats in front of it. Blobfish eat invertebrates like crabs and sea pens
Top Image: 10,000 King Penguins stand shoulder to shoulder on a remote island near Antarctica preparing to breed. One of the most breathtaking phenomena in nature to behold is the mating season for thousands of King Penguins at St Andrew’s bay on the island of South Georgia. More than 10,000 penguins were recently captured on film as they flocked to shore in preparation to breed.
Natural Selection
Blobfish image courtesy of Biology: A Battle for Survival.

2. Resource Competition
when two or more organisms need the same resource.
Competition can occur between two different species or between two individuals of the same species .
The ___________ items include all living organisms in an ecosystem
The ___________ items include all non-living materials in an ecosystem
A unique role of an organism within an ecosystem is known as a —
Niche
biotic
abiotic

3. Think – Pair- Share
What are some biotic and abiotic factors that organisms might compete for?
Why do some organisms end up surviving while others die off?
Have the class brainstorm possible answers – answer could include plants compete for sunlight or water / competition over a food source / competition for habitat / competition for water / competition for mate or reproduction
The second question should open up discussion about how certain traits are what allow organisms to “compete” or survive – now you can introduce natural selection or survival of the fittest.

4. image courtesy of MedioAmbiente.net
Natural Selection
Charles Darwin- studied finches (bird species) on the Galapagos islands.
Natural Selection
(“Survival of the fittest”)
a natural process resulting in the evolution of organisms best adapted to survive in their environment
image courtesy of University of Washington Libraries.
TEKS – 8.3D – relate the impact of research on scientific thought and society, including the history of science and contributions of scientists as related to the content.
The students should know the barebones basics of Darwin in the context of Natural selection (since he did coin the term and all).
-He was an English Naturalist who observed and was puzzled by the geographical distribution of animals and fossils all over the earth. He made many of these observations during his 5 year voyage aboard the HMS Beagle. He specifically was fascinated that it seemed that similar creatures inhabited similar environments continents apart.
-He basically surmised that creatures that are better adapted to live in their environment will survive and pass their traits on to the next generations. This is the basic definition of natural selection.

5. Traits and Adaptations
image courtesy of World of Reptiels.
Traits- characteristics that can be passed down from parent to offspring.
Examples: eye color, height, hunting instincts
Adaptations- characteristics that help an organism survive better in its environment; inherited OR learned
What adaptations does this tree frog have?
How is this anteater adapted for survival?
Remind students that they should be familiar with natural selection but this year we will be applying it in an attempt to explore how environmental changes can affect the traits of organisms and populations. They may also be unfamiliar or have forgotten about traits/adaptations, which we will be referring to many times during this unit. We will explore this in depth as we discuss natural selection.
* A trait is a characteristic of an organism that can be passed down from parent to offspring (heritable). Discuss examples of this with students. Remind them that anything you learn during your life is NOT a trait. The language you speak is not a trait. Your children will learn whatever language they are taught, regardless of what language you spoke.
* Some traits an animal has help it survive better in a given environment (adaptations). However, sometimes if an environment changes, those same traits that helped it survive could put it at a disadvantage.
* Adaptations are specific characteristics that help an organism survive in a given environment. Because of the way sexual reproduction works there will be a large variety within a given population. Small changes in traits can happen over long periods of time and can become adaptations if the traits help the organism survive better in their environment (survival of the fittest). Characteristics that hurt an animals chance of survival will be selected against (those traits will disappear from the population as a whole).
* Emphasize that trait changes are small and MUST be heritable. Many students will probably think of an adaptation being something like being able to suddenly breathe underwater or shooting lasers out of your eyes, etc. Adaptations are much smaller changes that over long periods of time can lead to new species, that are sometimes not very different from the species they arose from.
* Adaptations can be inherited or a learned behavior; i.e., chimpanzees LEARNED to use tools (sticks) to catch food (termites) to eat by watching their parents and siblings.
-Discuss some examples and non-examples of traits/adaptations.
-TREE FROG: Protective coloration (green); predator warning coloration (red—indicates its poisonous); gripping toes; small—to hop around leaves, etc.
-ANTEATER: Sharp claws for tearing and climbing; long tongue to reach insects in mounds (esp. termites & ants); course hair and thick hide to protect from bites, etc.
image courtesy of Mammals R Us.

6. What factors might these giraffes be in competition for?
What adaptations do these giraffes have?
Why didn’t the short-necked giraffe disappear from time period A to B?
How did natural selection change this population from time period A to C?
This diagram shows two different traits within a certain population over a long period of time. If the short necked giraffes food source disappears, then the short necked trait disappears as well over time. Notice that the short necked trait does not immediately disappear.
-What causes the short necked giraffe to disappear? (its food source vanished, causing that trait to be selected against over time, causing eventual extinction)
-Why doesn’t it disappear between time A and B? (because that trait still appears in the population, albeit at a smaller frequency than in time A – it takes awhile for a trait to completely disappear from a population)