what is EVOLUTION
change in genetic composition of a population over time.
HOMOLOGY
Similarity resulting from common ancestry. For example: limbs look similar (share ancestor) but do not fulfill the same function in all species
Convergent evolution/Analogy
when structures evolve to look similar (same function) but not from a common ancestor, rather from similar environmental pressures.
EVOLUTIONARY TREE
a diagram that reflects evolutionary relationships among groups of organisms.
ADAPTATIONS
Inherited characteristics of organisms that enhance their survival and reproduction in specific environments
WHAT IS NATURAL SELECTION
a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits.
ARTIFICIAL SELECTION
Selecting and breeding individuals that possess desired traits.
5 types of evidence for EVOLUTION
Shared traits across different species (Homology)
Fossil records
DNA records
Direct Observations
Biogeography
how did darwin define evolution
descent with modification
3 basic facts about all life on earth
- all organisms come from other organisms
- organisms tend to be similar to their parents
- individuals of the same specie tend to show variability from their parents and differencs can be passed on
2 inferences made by darwin
Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals.
Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favourable traits in the population over generations.
evidence for direct observation
organisms ar well adapted to environment (long nectar tubes for example)
homology: similar by ___
DESCENT
b
ANALOGY: similar by ____
COMMON SELECTION PRESSURES
BATS AND BIRDS
analogous as ____ and homologous as _____
wings
forelimbs
what do we see if we measure DNA of different species
matches FOSSILS and TRAITS
EVIDENCE FOR BIOGEOGRAPHY
Islands are isolated
Species there often look like nearby mainland species
But are slightly different
That suggests:
✔ They came from the mainland
✔ Then evolved separately
adaptive radiation
3 misconceptions about evolution
- “Humans have evolved from gorillas”
- The idea of the “missing link”
- “Evolution is about progress”
natural selection operates ___ species
whitin
3 basic facts about all life on earth
We know three basic facts about all life on earth:
1. All organisms come from other organisms
2. Organisms tend to be similar to their parents
3. Individuals of the same species do show some differences from each other (variability), and from their parents, and these differences can be passed on
2 major points darwin made in his book
- current species are descendants of ancestral species
- NS is a mechanism for this evolutionary process
