Populations & Evolutions Topic 15 Flashcards
(27 cards)
What is the definition of a species?
A group of organisms that can interbreed and produce fertile offspring.
What is evolution?
The change in the heritable characteristics of biological populations over successive generations.
What is a population in biological terms?
A group of individuals of the same species living in a particular area at the same time.
Define gene pool.
The complete range of alleles present in a population.
What is adaptation?
Features that help organisms survive in their environment.
What is natural selection?
The process whereby organisms better adapted to their environment tend to survive and produce more offspring.
What does allele frequency refer to?
How often an allele occurs in a population, usually expressed as a percentage.
What types of variation exist in populations?
Intraspecific variation (within a species) and interspecific variation (between different species).
Who studied Darwin’s finches and what did he notice?
Darwin noticed that finches on different Galapagos islands were similar but showed wide variations in size, beaks, and claws.
What is the significance of genetic diversity?
It enables natural selection to occur by providing a variety of alleles in a population.
What are the three types of natural selection?
- Directional selection
- Stabilizing selection
- Disruptive selection
What is a genetic bottleneck?
An event that causes a significant reduction in a population, leading to decreased genetic diversity.
Define the founder effect.
This happens when just a few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool.
What does the Hardy-Weinberg principle assess?
It is a way to assess whether natural selection is whether evolution is occurring at a particular locus by comparing expected genetic makeup with observed data.
What is the Hardy-Weinberg equation used for?
To calculate allele and genotype frequencies in a population at equilibrium.
What is speciation?
The development of a new species from an existing species due to reproductive isolation.
What is allopatric speciation?
Speciation that occurs due to geographical isolation caused by a physical barrier.
What is sympatric speciation?
Speciation that occurs when random mutations prevent individuals from breeding with others in the same population.
What are examples of reproductive isolation?
- Seasonal isolation - individuals different flowering or mating seasons
- Mechanical isolation - changes in genitalia prevent successful mating
- Behavioral isolation - individuals develop different courtship rituals that aren’t attractive to the main population
What is genetic drift?
A mechanism of evolution where chance events affect which alleles are passed on to the next generation.
What does mutational pressure refer to?
*The change in allele frequency due to repeated occurrences of the same mutations.
In RNA viruses such as HIV, replication takes place inside the host, using a mechanism that is prone to error.
Hence mutation rates in such viruses are high
Fill in the blank: The gene pool is the complete range of _______ in a population.
[alleles]
What allows natural selection?
Genetic diversity
Meiosis
Define what is “genetic diversity”?
Genetic diversity is the number of different alleles of genes in a species or population
