Unit 9 Flashcards
(36 cards)
Who developed the mechanism of evolution known as natural selection?
Charles Darwin
Darwin proposed that species change over time due to inherited traits that help individuals survive and reproduce.
What was the name of the ship Charles Darwin sailed on?
HMS Beagle
This voyage greatly influenced his thinking on evolution.
What famous book did Charles Darwin publish in 1859?
On the Origin of Species
This book outlined his theory of natural selection.
What types of organisms did Darwin observe that varied from island to island?
Finches and tortoises
These differences helped him realize that species adapt to their environments over time.
What are the four principles of natural selection?
- Variation among individuals
- Overproduction of offspring
- Adaptation to the environment
- Descent with modification
What is the direct result of natural selection?
Changes in traits within a population over generations
These changes may lead to greater adaptation but not necessarily a new species right away.
What are the three patterns of natural selection?
- Directional selection
- Stabilizing selection
- Disruptive selection
How do bacteria become resistant to antibiotics?
Mutations make some bacteria resistant; resistant bacteria survive and reproduce
This leads to the passing on of resistance genes.
How many years do we see from introduction to first resistance in bacteria?
2 to 5 years
Resistance often appears within this time frame after a new antibiotic’s use.
Why do we limit Vancomycin and Carbapenem antibiotics?
To preserve their effectiveness and prevent resistance
Distinguish Gram + from Gram - bacteria based on structure and stain color.
- Gram-positive: thick peptidoglycan wall, stain purple
- Gram-negative: thin wall with outer membrane, stain pink
Define speciation.
The process where populations evolve to become distinct species
What is a species?
A group of organisms that can reproduce and produce fertile offspring
What terms describe the pattern of speciation?
- Allopatric speciation: due to geographic separation
- Sympatric speciation: occurs without physical barriers
What are the premating mechanisms of isolation?
- Temporal isolation – Species reproduce at different times.
- Behavioral isolation – Different mating behaviors or signals.
- Mechanical isolation – Incompatible reproductive structures.
- Habitat isolation – Live or breed in different environments.
What are the postmating mechanisms of isolation?
- Hybrid inviability – The embryo doesn’t develop properly or dies early.
- Hybrid sterility – The offspring survives but can’t reproduce (e.g., a mule).
- Hybrid breakdown – Offspring are fertile, but their descendants are weak or sterile.
How many different species did the original finch species from South America evolve into?
About 13 species
This is known as adaptive radiation.
What is adaptive radiation?
When one species evolves into many to fill different ecological roles
What characteristics of resources affect bird’s beak size?
Size, shape, and hardness of available food resources
What is a homologous structure?
A homologous structure is a body part found in different species that has a similar structure but may serve different functions
Example: forelimbs of frogs, birds, reptiles, and mammals.
Why do vestigial structures provide evidence for evolution?
They are body parts that have lost their original function, indicating descent from ancestors
Examples: human appendix, pelvic bones in whales.
Why should analogous structures not be considered evidence for common ancestry?
They have similar functions but evolved independently
Examples: wings of birds and insects, fins of dolphins and fish.
What is convergent evolution?
When unrelated species evolve similar traits due to similar environments or challenges
What is a classic example of convergent evolution?
Sharks and dolphins developing streamlined bodies for swimming
