Evolution Flashcards
Define evolution
the process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth.
Define microevolution
evolutionary change within a species or small group of organisms, especially over a short period.
Define macroevolution
major evolutionary change, especially with regard to the evolution of whole taxonomic groups over long periods of time.
What are comparative genomics
Comparative genomics is a field of biological research in which researchers use a variety of tools to compare the complete genome sequences of different species. By carefully comparing characteristics that define various organisms, researchers can pinpoint regions of similarity and difference.
Define natural selection
Natural selection is the process through which species adapt to their environments. It is the engine that drives evolution.
When does natural selection occur?
When the pressures of environmental selection confer a selective advantage on a specific phenotype to enhance its survival (viability) and reproduction (fecundity)
What are the three types of selection
Stabilising
Direction
Disruptive
What are 4 environmental selection pressures
- Climate
- Competition
- Mate availability
- Predator abundance
Define selective advantage
When a particular phenotype gives that individual a survival or reproductive advantage over another individual with the same phenotype.
Positive selection vs Negative selection
Positive selection favours a trait, is likely to increase allele frequency within a population
Negative selection is selection against an unfavourable trait, causes reduced allele frequency in that population
Describe the Graphs for stabilising, disruptive and directional selection.
Stabilising - Skinny and tall compared to original
Directional - shifted in one direction from the original
Disruptive - “w” shape, opposite on each side of the original.
Define gene flow
Gene flow, also called gene migration, the introduction of genetic material (by interbreeding) from one population of a species to another, thereby changing the composition of the gene pool of the receiving population. The introduction of new alleles through gene flow increases variability within the population and makes possible new combinations of traits.
Define genetic drift
variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.
What do speciation and macroevolutionary changes result from?
An accumulation of microevolutionary changes over time
What are the 4 patterns of diversification between species
Divergent, Convergent, parallel and coevolution
What are the 3 modes of speciation
allopatric, sympatric and parapatric
What is allopatric speciation?
Allopatric speciation is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
What is parapratric speciation
In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes.
What is sympatric speciation
Sympatric speciation is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region.
What are the 4 different methods of isolation
- Geographic (Environmental disasters, habitat fragmentation)
- Reproductive
- Spatial
- Temporal
How do populations with reduced genetic diversity face an increased risk of extinction?
Populations with reduced genetic diversity face an increased risk of extinction due to several critical factors:
Increased Vulnerability to Diseases: Reduced genetic diversity means a limited gene pool, making populations more susceptible to diseases. With fewer genetic variations, there’s a higher chance that more individuals within the population could be susceptible to the same diseases, reducing their ability to combat new or existing pathogens.
Reduced Adaptability: Genetic diversity allows populations to adapt to changing environments. When diversity is low, there’s a lack of genetic variations that might be advantageous in responding to environmental changes, such as climate shifts or new predators. This decreased adaptability reduces the population’s resilience and survival capacity.
Inbreeding Depression: Inbreeding within a population with low genetic diversity leads to inbreeding depression. This condition results in the expression of harmful recessive traits due to the mating of closely related individuals, impacting the population’s overall health and reproductive success.
Loss of Evolutionary Potential: Genetic diversity is the raw material for natural selection and evolution. Reduced diversity limits the potential for populations to evolve in response to changing conditions, decreasing their ability to survive and thrive in the long term.
Overall, diminished genetic diversity compromises the adaptive capacity of a population, making it more prone to diseases, environmental changes, and reducing its ability to withstand various challenges, thus increasing the risk of extinction.
Why do some animals, given the opportunity, move into new environments?
In order to outcompete their competition, the species must search for more food, water and other resources.
