Evolution Part 2 Flashcards
Bottleneck Effect
A dramatic, often temporary reduction in the population size (Event that reduces population)
This causes changes in frequencies in populations
Though this is all determined by chance
Genetic Drift
- Known as the pinky finger
A change in the genetic makeup of a population due to pure random chance
(More expressed in small populations)
Founder Effect
When few individuals from a larger population leave to establish a new population
(Will not be same as original)
Gene Flow
- Known as pointer finger
When organisms migrate/emigrate which causes change in the frequencies in the gene pool of the population
Non-Random Mating
- Known as ring finger
Mates with preferred traits will pass on their alleles more commonly other than mates that are less preferred
Genetic Mutations
- Known as middle finger
Mutations are the only sources of new genetic material and new alleles. They can pass on their alleles depending on the types.
Types of mutations
Neutral: No effect on individual
Harmful: Result in death or lack/disability to produce (most likely won’t pass down)
Beneficial: very rare; involves new improved protein (Gives advantage
Natural selection
- Known as thumb
Those better able to survive in the environment have greater reproductive (Survival) success which increases frequencies.
Modes of Natural selection
there are 3 types of natural selection
- stabilizing
- directional
- disruptive
Directional Selection
one extreme is selected for while the other is not
ex: long legs are better 4 horses
Disruptive Selection
Both extremes are selected for
ex: not much medium coloured moths
Stabilizing Selection
Neither extremes are selected for (middle is best)
Artificial Selection
involves intentional or selective breeding for certain traits, or combination of traits that benefit mankind.
Advantages & Disadvantages of Artificial Selection
Advantages:
- Increased production
- Increased nutritional content
- Lower production costs
- Increased resistance to disease
- Lower pesticide use
Disadvantages:
- Less genetic variability
- Less biodiversity
- Seeds are patented so cost more money
- Focus on 1 trait, but can be lacking in others (flowers)
Gradualism
When species first evolve, they are still similar to the original.
Species slowly evolve over time which takes a long time for the species to be totally different from its originator
Slow incremental changes over time
Expect transitional fossils
Punctuated Equilibrium
Species may evolve rapidly with large changes followed by long periods of little or no change
explains the reasoning behind not all transitional fossils being found
Usually happen in small isolated populations
Beneficial mutations are one source of change
Divergent evolution
A pattern of evolution in which species that were once similar to an ancestor end up diverging (branch off)
–> This type of evolution could be caused by the different selective pressures in an environment overtime
- occurs when populations change as they adapt to different conditions
Adaptive Radiation
Adaptive radiation is a form of divergent evolution where members of an ancestral group of organisms move to a new area and diversify under the new selective pressures
Convergent evolution
A pattern of evolution in which unrelated species from different ancestors independently evolve to have similar traits, due to similar environmental conditions and selective pressures
Not because of shared ancestry
ex: fly wings vs bat wings
Co-Evolution
One species evolves in response to another species
Both species are completely dependent on each other for their survival
Biological Species
Population of individuals that can interbreed to create viable and fertile offspring
Allopatric Speciation
physical barrier (river or canyon) that is created to separate populations from each other which causes the frequency of the population to change due to natural selection (since both populations can no longer interact with each other)
Example: Volcanic eruptions, flood -> river
Sympatric Speciation
The species share the same territory though they do not mate
Causes:
Differences in behaviour or appearance
Polyploidy: one species may have more chromosomes than the other, but they have the same ancestor
Example: Humans (46 chromosomes) & Chimpanzees (48 chromosomes)
Pre-zygotic
Before the egg gets fertilized (zygote gets produced) results in prevention of mating or fertilization
Types of Isolation
Prevention of mating
Ecological isolation
Live in different habitats
Example: Aquatic vs terrestrial plants
Temporal isolation
Separation of timing
Example: Owls vs Hawk 2 uhh
Behavioural isolation
Different mating behaviours
Example: Birds with dances
Prevention of fertilization
Mechanical
Different reproductive organs
Example: Pig PENIS
Gametic
Diffrent proteins in the gametes that don’t allow fertilization to occur
Post-zygotic
Hybrid inviability: Hybrid zygote doesn’t develop properly (Sheep + goat)
Hybrid sterility: Hybrid offspring being infertile (Horse + donkey)
Hybrid breakdown - first gen hybrid is fertile and viable
Artificial Selection vs Natural Selection
Natural selection: Survival and reproduction of organisms best adapted to their environment.
Mechanism: Variation in traits within a population, competition for resources, differential survival and reproduction.
Example: Rabbits with better camouflage evade predators more successfully.
Driving force: Environmental pressures.
Outcome: Populations adapt to their natural environment.
Artificial selection: Intentional breeding of organisms by humans for desired traits.
Mechanism: Humans select individuals with preferred traits to reproduce.
Example: Dog breeding for specific sizes, temperaments, or appearances.
Driving force: Human preferences.
Outcome: Traits may not confer survival advantages in the wild.
Key differences: Natural selection is driven by nature and promotes adaptation; artificial selection is driven by human choice and can lead to non-adaptive traits.
