Evolution and Diversity Flashcards
(44 cards)
Heterotroph Hypothesis
Life began under different conditions: atmosphere was composed of hydrogen, ammonia, methane, water. The climate was intense.
Heterotroph
An organism that can’t synthesize its own food. The first cells were heterotrophs, but evolved to autotrophs when food became scarce. Early cells were also anaerobic.
Earth’s atmosphere today
78% nitrogen, 21% oxygen. Oxygen was a waste product of autotrophs, and it accumulated.
Gene pool
All of the genes of all the people in the whole population.
Genetic variability
- Each person in a population has a distinct set of genes. Some have brown eyes, some green, etc.
- This is a property of all populations.
- Not caused by a species’ ability to adapt to environmental conditions
Fossil record
All information paleontologists have gathered and organized about past life. Shows how groups of organisms have changed over time, and gives evidence for evolution.
Random mutation of DNA
Basis for genetic variability. Nucleotide base sequence is accidentally changed. If DNA sequence changes, so can the sequence of amino acids in a protein.
How can a mutation be passed to offspring?
If it occurs in a sex cell. Through mutation, a new allele is created.
What is the driving force of evolution?
Natural selection- “survival of the fittest”
Darwin’s observations about evolution (4)
- Each species produces more offspring than can survive
- The offspring compete with each other for the limited resources that are available
- Organisms in every population vary
- The offspring with the most favorable traits are most likely to survive and produce offspring.
Evolution
- Changes in gene pools. Rapid changes are caused by competition.
- Genetic variability causes physical variability, making some organisms better competitors
Geographic isolation
A new species may form when a group of individuals is isolated from the rest of the species.
Why does evolution happen? (3)
- Genetic variability allows some individuals to win the game of natural selection
- The winners, survive, reproduce, and pass their genes on to their offspring
- The offspring have genes like those of their parents, changing the gene pool.
May create a new species
Fitness
An organism’s ability to contribute to the next generation’s gene pool by producing surviving offspring.
Does the genome of an individual change over time?
No, only the genetic makeup of a population changes over time.
Species
2 individuals have such different genes that their gametes can’t meet to form an individual.
Speciation
The formation of new species by evolution, caused by multiple changes to the gene pool.
Divergent evolution
- Process by which 2 populations of the same species end up having different behaviors and traits
- A result of a changing environment- physical and behavioral pressure.
Homologous structures
- Similar structures indicating a common ancestor
- Functions are different, fundamentals the same
Ex: human arm and whale flipper
Analogous structures
- Similar adaptations resulting from convergent evolution
- Same function, but different structure, ancestry is also different.
Ex: wings in birds and insects
Convergent evolution
- 2 species develop similar traits/behaviors due to environmental pressures. (2 species flying to escape ground predators
- Never results in speciation or 2 species becoming one.
Vestigial structures
Structures become smaller and useless as environment, population, and behaviors change.
Phylogeny
Classifying organisms based on their evolutionary relationships (common ancestors).
Taxonomy
Science of classification and naming.
