evolution Flashcards
(15 cards)
What is variation? Include examples
- Differences organisms have for specific traits
- ex: coat color, height, beak shape, laying eggs vs giving birth
What is evolution? Who does it affect? Populations or individuals?
- Evolution is the change in certain traits within populations (not individuals) over long periods of time (hundreds, thousands, millions of years)
- Evolution affects every organism.
- Affects POPULATIONS not individuals
Describe Lamarck’s theory of Acquired Traits and the Law of Disuse and Use. How would he describe how giraffes got long necks? What are other examples of these specific theories?
- Use and Disuse: Body parts that are used frequently become stronger or larger. Parts that are not used weaken or go away. Ex: don’t use arm = arm goes away
- Inheritance of Acquired Traits: Traits gained during an organism’s life (not genetic) are inherited by their offspring. Ex: you gained muscles = children will have these muscles
- Lamarck’s explanation of how giraffes got long necks: He believed that giraffes stretched their necks to reach leaves high in trees. Over time, this constant stretching caused their necks to become longer. The longer necks were then passed on to their offspring, and each generation had slightly longer necks as a result.
Who is Weisman? What was his experiment and explain its significance?
- August Weismann was a German biologist in the 19th century who is known for disproving Lamarck’s theory of inheritance of acquired traits
- Weismann cut off the tails of mice for multiple generations. Each time the mice reproduced, their offspring were born with normal-length tails.
- Weismann disproved Inheritance of Acquired Traits and showed that physical changes to the body (like tail cutting) are not inherited.
Describe Darwin’s theory of natural selection. How does natural selection occur? Describe the role of competition, variation, and inheritance.
- Darwin’s theory of natural selection is that the environment (nature) determines what trait is most beneficial to have in order for an organism to survive and reproduce in the environment they are in.
- Over time, this leads to changes in the traits of a population.
- how natural selection occurs:
- Variation: Individuals in a population have differences in traits (e.g., size, speed, color).
- Competition: Because resources are limited, individuals must compete to survive and reproduce.
- Inheritance: Favorable traits are passed on to the next generation.
- Over many generations, these traits become more common in the population.
How does Darwin’s theory of natural selection relate to the finches on the Galapagos Islands?
be specific. what if an island was in a drought? a flood?
- Species change over time through natural selection, based on variation, competition, and inheritance
- On one island with drought, finches with slightly bigger and thicker beaks would survive and populate because they were able to eat the tough and hard nuts.
- On another island with a flood, finches with small and thin beaks would survive and populate because they were able to eat the small and tiny nuts.
How does Darwin’s theory of natural selection relate to pesticide resistance or antibiotic resistance?
- In any population of insects or bacteria, there is natural genetic variation.
- A few individuals may already have a mutation that makes them resistant to a pesticide or antibiotic.
- When the pesticide is used, most of the population (non-resistant individuals) dies off.
- The resistant individuals survive and continue to reproduce.
- They pass on their resistance genes to the next generation.
- Over time, more individuals in the population carry the resistance trait.
- Eventually, the entire population may become resistant, making the pesticide less effective.
How does Darwin’s theory of natural selection relate to the case of the peppered moths?
- The peppered moth case shows how natural selection acts on variation in a population, favoring traits that provide a survival advantage in a specific environment.
- Black moths survived better on black trees and populated
- White moths survived better on white trees and populated
How does Darwin’s theory of natural selection explain why giraffe’s necks get longer over time?
- Darwin’s theory shows that giraffes didn’t “stretch” their necks during their lives (as Lamarck suggested), but instead, longer necks gradually became more common in the population because those traits gave giraffes an evolutionary advantage.
- Some giraffes ALREADY had long necks
What is Survival of the Fittest? How does it relate to Natural Selection?
- Those best suited to their environment are more likely to pass on their traits, populate/reproduce, and survive
- Natural selection is the process by which organisms with traits that give them an advantage in their environment are more likely to survive and reproduce.
Explain adaptation
- It is a biological process that occurs over generations through natural selection, where favorable heritable traits become more common within a population
- adaption itself is a trait or characteristic that helps an organism survive and reproduce in its specific environment
- inherited, not gained
In the normal rainfall, what happened to the birds population size? Which size beak dominated the island and why?
- Population size: Stayed stable or grew due to abundant food.
- Beak size: Smaller beaks/medium beaks
- This is because smaller seeds were more common
- Birds with smaller beaks survived and dominated the population
In the drought rainfall, what happened to the birds population size? Which size beak dominated the island and why?
- Population size: Decreased sharply due to food scarcity.
- Beak size: Bigger beaks
- The small, soft seeds were gone, and only hard, tough seeds remained.
- Birds with big beaks survived and dominated the population
In the heavy rainfall, what happened to the birds population size? Which size beak dominated the island and why?
- Population size: Increased due to more food, water, and better conditions.
- Beak size: Smaller beaks
- This is because smaller seeds were more common
- Birds with smaller beaks survived and dominated the population
How does variation occur?
Where do we get new traits from? What is a mutation? Go in depth on how the mutation stays
- Variation occurs from a mutation
- Mutation: a change in the genetic material/DNA
- Mutations can be good, harmful, or neutral
- If the mutation is beneficial for the organism, it will survive, reproduce, and pass on the genes, making that gene/trait more common
