Evolution: Evidence For Evolution Flashcards
(16 cards)
What are the 6 ways we’ve procured evidence for evolution?
1: Fossils
2: Comparative anatomy
3: Comparative embryology
4: Molecular biology
5: Genetics
6: Biogeography
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 3 ways they determine the ages 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.
How has compartive anatomy given us evidence for evolution?
The more structural similarities between two species, the stronger indication that over time they evolved from the same basic pattern.
What are homologous structures?
Structures that are very similar in structure but may have different functions.
What are analogous structures?
Structures with similar functions but different internal structure hence they do not indicate an evolutionary link. (Eg; bat and butterfly wings)
What are vestigial organs?
Organs which have no apparent function. remnants of structures that were once functional in the ancestral form.
How has compartive embryology given us evidence for evolution?
Comparing embryo development provides evidence of evolutionary relationships. Closely related species show a much similar pattern of development, suggesting a common ancestor with a similar development pattern.
How has molecular biology given us evidence for evolution?
Comparing biochemistry of organisms provides proof of evolutionary relationships. More similar the makeup (in terms such as hemoglobin, cytochrome C) the more closely related the organisms. In biochemical analysis, the amino acid sequence in a particular protein is compared. Again, more similar sequence, more similar the organism.
How have genetics given us evidence for evolution?
Adaptations are caused by gene mutations and genetic recombination. (The raw materials of evolution) They account for the changes in genetic information that is required for organisms to adapt and evolved. Scientists now determine exact nucleotide sequences of various genes, to compare similarities/differences between organisms. Another tool is the study of mitochondrial DNA (mtDNA) as it comes directly from mom’s egg and is not mixed with dad’s DNA and it is inherited directly down the female family line. This can be used to determine how closely related individuals are.
How has biogeography given us evidence for evolution?
We study the geographical distribution of a species. Studies have show that geographically close areas are more likely to be inhabited by related species. (Eg; The finches of the galapagos islands) In spite of adapting to fit their unique environments, all the finches remained closely tied t their original species.
