Evolution And Natural Selection Flashcards
Who Is Charles Darwin?
- Proposed that all living things have a common ancestor
- Populations with more advantageous traits are more likely to survive
- Over time, this leads to speciation
Speciation is when populations evolve to become a new species
What Is A Species?
A group of organisms that can interbreed and produce viable, fertile offspring under natural conditions
Natural Selection
The process by which certain heritable traits become more or less common in a population over time, based on their impact on an organism’s survival and reproductive success
Principles Of Natural Selection
Variation
Selection Pressure
Differentials In Survival And Reproduction
Heritability
Variation
Individuals in populations exhibit variation in their traits, which they inherit from parents or arise through mutation
Differentials In Survival And Reproduction
Individuals with traits that enhance their survival and reproductive success more likely to pass on traits to next generation
Selection Pressure
The environment presents challenges or pressures that influence an organism’s ability to survive and reproduce
Heriability
Advantageous traits are often heritable and are passed from parents to offspring through genes
Biodiversity
Is the variety and variability of living organisms present in a particular habitat or ecosystem
It is measured in three levels EB, SB and GB
Ecosystem Diversity
Species Diversity
Genetic Diversity
EB - The variety of ecosystems and habitats present in a given area or on a larger scale
SB - This refers to the variety and abundance of different species within a particular habitat or ecosystem
GB - The variation in genes within a species, encompassing the difference in genetic makeup among individuals within a population, and between populations of the same species (essential for adaption and long term survival of species)
Mutations
Changes that occur in an organism’s DNA sequence.
Mutations introduce new genetic variation into a population which can be passed on to offspring
Gene Flow
The movement of genes between populations
Occurs when individuals migrate from one population to another and interbreed with individuals from the recipient population
Introduces new genetic variation into a population, increasing genetic diversity
Genetic Drift
The random fluctuation of allele frequencies within a population over time
More common in small populations
Can result in the loss or fixation of certain alleles
Types Of Genetic Drift
Bottleneck-
Occurs when a population undergoes a catastrophic event
Founder-
Occurs when a small group of individuals establishes a new population in a new area geographically isolated from the original population
Convergent Evolution
The process by which unrelated species independently evolve similar traits or adaptations in response to similar selection pressures
Divergent Evolution
The process by which a single ancestral species evolves two or more distinct descendent species, each with unique traits and adaptations
Co-Evolution
Two species evolve together due to their close relationship. When one evolves, do does the other
Homologous Vs Analogous Structures
Homo-
- Shares common ancestor
- May have different functions
- Usually arises with Divergent Evolution
Ana-
- Does not share common ancestor
- Similar function/purpose
- Usually arises with Convergent Evolution
Phylogenetic Trees
Diagram that represents the evolutionary pathways and relatedness between species
The more recent the common ancestor (the node) the more closely related two species are
VSDH
Variation-
Individuals in populations exhibit variation in their traits, which they inherit from parents or arise through mutation
Selection Pressure-
The environment presents challenges or pressures that influence an organism’s ability to survive and reproduce
Differentials In Survival And Reproduction-
Individuals with traits that enhance their survival and reproductive success more likely to pass on traits to next generation
Heritability-
Advantageous traits are often heritable and are passed from parents to offspring through genes
