Evolution: Final exam Flashcards
Test review (47 cards)
What is evolution?
The process of changing over time
What are the details of Darwin’s voyage?
- HMS Beagle (Ship (1831))
- 22 years old
- 5 year journey
How did Charles Lyell influence Darwin’s work?
Darwin read “Principles of Geology” by him. He proposed that geological process operate at the same rate now as in the past, and that earth was very old and constantly changing over time. Darwin began thinking about living organisms the same way.
How did Thomas Malthus influence Darwin’s work?
Darwin read “Essay on the principle of populations” by him, helping him explain how organisms evolve. It states that populations grow much faster than their food supply, and that populations are reduced by limiting factors. Darwin though about resource competition in populations and developed his theory
What is Darwin’s theory of evolution by means of natural selection?
Overpopulation: Organisms reproduce more than is needed to maintain the population.
Competition: Not all of the many offspring survive due to limited food, space, and shelter. Results in organisms competing for them.
Variations: There is great characteristic variation in all species. (Size, shape, ability, etc;) These get inherited.
Adaptations: Organisms with beneficial variations have advantages in competition.
Natural Selections: Better adapted organisms are more likely to survive and therefore reproduce. This can pass on their beneficial traits. Nature selects the organisms that survive and reproduce.
Speciation: Over many generations beneficial adaptations accumulate in the species and unfavourable ones disappear. The accumulated changes become so great a new species is born.
What are analogous structures?
Structures with similar functions but different internal structure. Do not indicate evolutionary links.
What are homologous structures?
Structures with similar internal structures but different functions. Indicates evolutionary links.
What are vestigial organs?
Organs which have no apparent function. (eg; appendix, leg bones in snakes) Remnants of once functional structures in ancestors.
What are structural adaptations?
Adaptations affecting the appearance or arrangement of particular physical features. (Mimicry, Cryptic coloration)
What is a species?
Group of organisms that naturally interbreeds to produce fertile offspring.
What are the 3 patterns of natural selection?
Stabilizing selection - Favours intermediate phenotypes. (Eg; Baby sizes (Advantage to not being born too big or too small)). Typical in constant environments
Directional selection - Favours one extreme phenotype over another. Typical in changing environment or during migration to conditionally various environments.
Disruptive/Diversifying selection - Extremes are favoured over the intermediate. (Eg; Coho salmon (Large salmon are favoured as they can fight for access to eggs, very small salmon are also favoured to sneak up on female eggs)
What is the bottleneck effect?
Natural disasters reduce populations to only a few individuals. Now much smaller population does not represent the larger population as certain characteristics become over or under exaggerated.
What is the founder effect?
Small number of individuals colonize a particular area. Likely that founder population does not represent the parent population.
What is sexual selection?
Form of non-random mating. Males and females use various methods to identify and choose particular mates. (Eg; scents, colours, displays, combat, or sexual dimorphism). More or less, certain characteristics make you a more attractive mate.
What is non-random mating?
Helps to reduce variation and diversity. (Eg; Inbreeding, self pollinating, and mating with whoever is closest)
How have fossils given us evidence for evolution?
Fossils are any trace of a once living organism. They have taught us that…
- The earlist organisms were very simple and over time organisms became larger and more complex
- The number of kinds of organisms have increased over time
- New and different species replaced many old ones
- Earliest fossils were aquatic organisms
- Transitional fossils show intermediate links
How are fossils formed?
- Preserved in tar, amber, and ice
- Mineral parts (Shell, bone, teeth) stay preserved
- Petrification (Organism turns to stone)
- Molds/Casts (Organisms decay whilst hardened sand and mud around them holds shape and fills with minerals forming a cast)
- Imprints
Where are most fossils formed?
Sedimentary rock.
What are the three ways they determine the age of fossils?
1: Relative dating
2: Index fossils
3: Absolute dating
What is relative dating?
Fossils in lower sediment levels are older than those in upper layers. Not always accurate.
What are index fossils?
Fossils that are known to be common during particular time periods, indicating the age of the rock they’re found in. Other fossils in the same layer would be of similar age.
What is absolute dating? (Radioactive dating)
Finding out how long ago an organism lived independently of other organisms. Radioactive dating has C14 isotopes. (known to breakdown at a given rate upon organism death (5730 year HL)) By knowing how much of the original isotope is left, we can figure out how old it is.
What is divergent evolution?
Pattern of evolution in which once similar species ancestrally diverge/become increasingly distant. Occurs when populations change to environmentally adapt.
What is convergent evolution?
Two completely unrelated species share similar traits. Traits arise due to each species adapting to similar conditions.
