Natural Selection Basics
What is Variation?
The differences in traits among individuals in a population
What is Natural Selection?
The only mechanism that causes adaptive evolution. The process by which individuals with traits better suited to their environment are more likely to survive and reproduce
What are Homologous Structures?
These are features that share a common evolutionary origin even if they serve different functions in modern species
What is Genetic Variation?
It is the differences in alleles and traits found among individuals within a population. It determines how well the population can respond to changing environmental changes.
What is Artificial Selection?
Artificial selection is a process similar to Natural selection but driven by human intervention. Human selectively breed individuals with desirable traits to produce offspring with those traits.
What is Heritable Variation?
Within a population, individuals vary in traits due to sexual reproduction and meiosis. These traits are passed down from parents to the offspring
What is Directional Selection?
Favors one extreme phenotype causing the allele frequency to shift in one direction (ex. Horses have increased in size and lost toes)
What are Vestigial Structures?
these are remnants of features that serve important functions and ancestors but are now reduced or unused. Ex.) wisdom teeth, appendix, tonsils, ear muscles
How does Variation affect Population Dynamics?
Because it is more likely to contain individuals with traits that help them survive new challenges (disease climate change, habitat loss)
What is the main quote of Natural Selection?
IF THE ENVIRONMENT CHANGES, THE ADVANTAGE CHANGES
What is Overproduction of Offspring?
Most species produce more offspring than can survive to adulthood. This leads to competition for resources with a small amount surviving and reproducing
What is Stabilizing Selection?
Favors the average phenotype producing variation in the population.
What are Analogous Structures?
These arise when unrelated species independently evolves similar trades due to similar environmental pressures, not shared ancestry
What is Founders Effect?
This occurs when a small group of individuals breaks away from a larger population to form a new population
What is Evolution?
Species change over time through inheritable genetic variation. Eventually a population may have enough differences that a new species results
What is Disruptive Selection?
Favors extreme phenotypes at both ends of the spectrum, increasing variation and potentially leaving speciation (ex. Darwin's finches- selected for very larger or very slender beaks depending on the food source)
What is Morphology?
Morphology examines the similarities and differences in the physical structures of organisms, down to their DNA
What is the Bottleneck Effect?
This happens when a large population is drastically reduced in size due to a sudden event, such as a natural disaster
What are Mutations?
Mutations are random changes in the DNA sequence that can introduce new alleles into a population. While most mutations are neutral or harmful, some can be beneficial and increase an organisms fitness
what is Sexual Selection/ Non-Random Mating?
Organisms rarely mate randomly, therefore all alleles in a population do not have an equal probability of being passed on. Individuals with more attractive traits have a higher chance of reproducing but not necessarily enhanced survival.
What is Developmental Homology/ Embryonic homology?
Similarities in embryonic development and early fetal development across species suggest a shared ancestry
What is Gene Flow/Migration?
It is the transfer of alleles between populations. It can introduce new genetic material into a population, which may alter allele frequencies.