Chapter 10: Natural Selection. Evolution Flashcards
What is phenotypic variation?
Observable differences in traits among individuals in a population.
What causes genetic variation?
Mutation
What is the significance of genetic variation in evolution?
It provides raw material for natural selection.
How are new alleles produced?
By mutation.
What process reshuffles existing alleles?
Meiosis.
What is a somatic mutation?
A mutation in body cells
What happens if a gamete mutation forms a zygote?
The mutation is passed to offspring.
What is natural selection?
A process where alleles conferring survival advantages increase in frequency.
What is a selection pressure?
Environmental factors that influence allele frequencies.
What is fitness in biological terms?
The ability of an organism to survive and reproduce.
What are biotic factors in natural selection?
Predators
What are abiotic factors in natural selection?
Water supply and soil nutrients.
What is directional selection?
A type of natural selection favoring one extreme phenotype.
What is stabilizing selection?
A type of natural selection that preserves average phenotypes.
What is disruptive selection?
A type of natural selection that favors extreme phenotypes over intermediate ones.
What is the key to natural selection?
Variation within a species.
What increases offspring survival rates?
Adaptations suited to the environment.
What happens to less adapted individuals?
They produce fewer offspring or die.
What is the outcome of many generations of selection?
Populations become better adapted to their environments.
How does antibiotic resistance occur?
Selection pressures favor resistant bacterial alleles.
What are plasmids?
Small DNA loops that transfer genetic information in bacteria.
What causes industrial melanism?
Predation and environmental changes favor darker phenotypes.
Why is the sickle cell allele common in malaria regions?
Carriers are resistant to malaria.
What is the role of overproduction in evolution?
It leads to competition and selection of better-adapted individuals.
What is speciation?
The formation of new species.
What is allopatric speciation?
Speciation due to geographic isolation.
What is sympatric speciation?
Speciation without geographic isolation.
What causes reproductive isolation?
Prezygotic and postzygotic barriers.
What are prezygotic isolation mechanisms?
Barriers preventing fertilization (e.g.
What are postzygotic isolation mechanisms?
Barriers affecting zygote viability or fertility.
What is polyploidy?
Having more than two sets of chromosomes
What is the Hardy-Weinberg principle?
A formula to calculate genotype frequencies in populations.
What is artificial selection?
Human-driven selection for specific traits.
Why is inbreeding disadvantageous?
It reduces genetic diversity
What is outbreeding?
Breeding less related organisms for healthier offspring.
What is genetic drift?
Random changes in allele frequencies in small populations.
What is a species?
Organisms that can interbreed to produce fertile offspring.
What are Darwin’s finches an example of?
Adaptive radiation due to allopatric speciation.
How do antibiotics exert selection pressure?
By killing susceptible bacteria
What is industrial melanism in moths?
Dark moths had a survival advantage in polluted areas.
How do diploid and tetraploid plants differ?
Tetraploids have four chromosome sets and cannot interbreed with diploids.
What does “variation within a population” mean?
Differences in traits among individuals of the same species.
Why is heritable variation critical for natural selection?
Only traits passed to offspring can influence evolution.
What is the role of predation in shaping populations?
It eliminates individuals less suited to avoid predators.
What happens if environmental conditions remain stable for long periods?
Stabilizing selection maintains the status quo.
What happens if environmental conditions change rapidly?
Directional or disruptive selection may occur.
What is the consequence of extreme environmental pressures?
Extinction or rapid evolutionary changes.
Why do most mutations not affect evolution?
Many are neutral or occur in somatic cells and are not passed on.
What is the impact of genetic bottlenecks on natural selection?
They reduce genetic diversity
What is an example of genetic variation providing survival benefits?
Antibiotic resistance in bacteria.
How does disease act as a selection pressure?
It favors individuals with resistance genes.
What is selective advantage?
A trait that increases an organism’s fitness.
What is selective disadvantage?
A trait that reduces an organism’s fitness.
How does artificial selection differ from natural selection?
Humans intentionally choose which traits are passed on.
What is an example of artificial selection?
Breeding dogs for specific traits.
What is the difference between natural and sexual selection?
Natural selection focuses on survival
What is sexual selection?
The process where certain traits increase mating success.
What is an example of sexual selection?
Peacock feathers attracting mates.
How does camouflage benefit prey in natural selection?
It reduces predation by making them less visible.
How does mimicry aid survival?
It helps an organism resemble another for protection or deception.
What is coevolution?
When two species evolve in response to each other (e.g.
What is microevolution?
Small changes in allele frequencies within a population.
What is macroevolution?
Large-scale evolutionary changes
What is an example of macroevolution?
The evolution of mammals from reptiles.
