Evolution Flashcards
Jean Baptiste de Lemark
THE THEORY OF EVOLTION
Use vs. disuse:
Regularly used organs will be strengthened, organs not used withered away. These characteristics would be passed onto offspring.
disproved by Wessman
Wessman
Discovered germ cells pass information on
disproved Baptiste
Darwin and Wallace
Two independent scientist both come to the conclusion that natural selection was the origin of species.
Voyage of the HMS Beagle
Darwin was ships naturalist, 5 year expedition. Most important observations came from Galápagos Islands.
His hypothesis: beak shapes adapted for eating certain kinds of food. Assumed they originated from same species.
Theory of natural selection
- Overproduction: number of offspring produced is greater than number able to be supported by environment
- Competition: because #1 occurs between same and different species
- Variation: difference in traits among offspring
- Survival of the fittest: favours individuals better able to compete, survive, and reproduce
- Speciation: over generations, new species arise by accumulation of inherited variations
Natural selection
The process by which nature selects the organisms that survive
Adaptation
An inherited trait of set of traits that improve chances of survival and reproduction of organisms
This includes:
Behavioral
Structural
Physiological
Direct evidence of evolution
Fossil evidence:
Can help to establish phylogeny (history of evolution of species) and used to produce phylogenetic trees to explain relationship between species
Types of fossils
- Trace fossils-(indirect)- footprint
- Casts- replica of an organism
- Molds- buried and decays leaving an empty space
- Petrified/permineralized- minerals fill organisms space crystallizing
- Amber or frozen- trapped and hardened
Indirect evidence of evolution
- Embryology*
- Homologous and analogous structures*
- Vestigial structures*
- Physiological evidence*
- Biochemical evidence*
Homeobox genes
A large family of similar genes that direct formation of many body structures during early embryonic development
- found in almost all eukaryotes
- mutations can produce major structural changes causing sudden appearance of new traits in individuals and eventually whole population
Embryology
- embryos from different species are very similar
- theory that similarity is due to common ancestor
Homologous and analogous structures
Homologous: structures in different creatures with similar organization, but different functions, has common ancestor. Evidence of divergent evolution
Analogous: structures have the same function, but have no common ancestor. Evidence of convergent evolution
Vestigial structures
Structures that no longer serve original purpose, but was probably useful to ancestor
Physiological evidence
Shows that wastes excreted by birds and reptiles have same biochemical makeup (uric acid)
Insulin from cows and pigs is almost identical to insulin found in humans
Biochemical evidence
All organisms have same DNA translation table (3 nucleotides code for 1 amino acid)
- DNA comparisons show a great deal of similarity (ex: all organisms have protein called cytochrome C)
Niche and population dynamics
Role of an organism (or population) and how it responds to the distribution of resources, the interaction with competitors for those resources, and the results from experiences and how it is altered.
Competition and population dynamics
When 2 populations attempt to occupy same niche, fierce competition arises. Eventually one population will prove better fitted and drive other out.
Directional selection
Environmental conditions favour individuals at one end of the extremes and curve shifts toward that extreme
Stabilizing selection
Environmental conditions remain stable for long periods at a time. There is selection against extremes.
Disruptive selection
Selection is against the middle of the curve, either extreme is more favourable.