Final Exam Notes Flashcards
What is a prediction, and its relation to a hypothesis?
A prediction is the expected outcome based on a hypothesis
How do we know if structures are homologous?
They share the same basic structure in the same relationship to other features.
Why is variation in populations important?
It provides raw material for natural selection to drive evolutionary change.
What is important in knowing if phenotypic variation is genetically or environmentally determined?
It helps assess the potential for evolutionary change and predict responses to selective pressures.
For a trait to undergo evolution, what characteristics must that trait have?
It must increase the organism’s probability of surviving and reproducing
What does survival of the fittest mean?
Fitness is the ability of an individual to produce offspring relative to the ability of other individuals within the population.
What are adaptations?
They increase the fitness of an individual in a particular environment.
Can natural selection eliminate an allele from a population?
No, because it will remain “hidden” in heterozygotes.
Why can harmful alleles remain in a population?
Natural selection acts on phenotypes, not on alleles that don’t show up in the phenotype.
What is the phenotype of haploid organisms?
No dominant or recessive phenotypes because there is only one allele.
How can a disease state be hidden?
If it is a recessive phenotype.
What does balancing selection maintain in a population?
Genetic variation
What does negative frequency-dependent selection result in?
The cycling of phenotypes within a population
Under what conditions does negative frequency-dependent selection occur?
Rare phenotypes have higher fitness than common phenotypes.
What is the impact of gene flow?
It decreases genetic differences between populations.
What are the consequences of gene flow?
It decreases inter-population differences, increases intra-population variation, and introduces new alleles.
What is the difference between population bottleneck and founder effect?
In population bottleneck size is dramatically reduced and in Founder effect small groups establishes new population.
What is the effect of inbreeding on genetic variation?
It can increases homozygosity, decreases heterozygosity, reduces genetic variation.
What are the conditions for Hardy-Weinberg Equilibrium (HWE)?
The absence of mutation, selection, genetic drift and gene flow/random mating.
What does the Hardy-Weinberg equation describe?
It predicts genotype frequencies in a population under conditions of random mating and in the absence of evolutionary forces.
What happens if a population is not in Hardy-Weinberg Equilibrium (HWE)?
It suggests that evolutionary forces are at play, such as mutation, selection, genetic drift, or gene flow.
Define genetic drift.
Random changes in allele frequencies due to chance events, most pronounced in small populations.
How does genetic drift affect genetic diversity?
By causing allele frequencies to fluctuate randomly over time.
Define mutation.
A change in the DNA sequence that can introduce new genetic variation into a population.
How do mutations contribute to evolution?
They provide the raw material for natural selection to act upon, generating genetic diversity within populations.
Define gene flow.
The transfer of alleles or genes from one population to another through the movement of individuals or gametes.
How does gene flow affect genetic variation?
It can increase genetic diversity by introducing new alleles into a population and reducing genetic differences between populations.
What do phylogenetic trees describe?
They describe evolutionary relationships among organisms or taxa.
How to determine speciation events on a phylogenetic tree?
Identify points where lineages diverge into separate species.
Define a monophyletic group.
It includes all descendants of a common ancestor and that ancestor itself.
How can rotation about a node affect a phylogenetic tree?
It can result in a tree with different looks but the same meaning (topology).
Define sister taxa.
Two taxa that are each other’s closest relatives, sharing a recent common ancestor.
What does the root of a phylogenetic tree represent?
It represents the common ancestor of all taxa in the tree.
How are phylogenetic trees established?
Via morphology, genetic information, behaviour, or a combination.
How to identify an out group on a phylogenetic tree?
It’s a taxon closely related to the group being studied but not part of the analyzed group.
What can complicate phylogenetic analyses?
onvergent evolution, where unrelated organisms evolve similar traits independently.
Define a monophyletic taxon.
A group including a common ancestor and all its descendants.
What does “prokaryote” refer to?
It represents a monophyletic group.
What traits might the frog population on the left side of the highway develop to better tolerate their acidic environmental conditions?
Traits to resist low pH
What is true for speciation to occur?
At least one gene, affecting one phenotypic trait to change.
Which form of speciation occurs when two frog populations become so genetically distinct that they can no longer interbreed?
Allopatric speciation by vicariance.
What type of reproductive isolating mechanism and selection are at work when individuals start to mate only with others that eat the same type of insect?
Pre-zygotic; disruptive selection
What would be the impact on the rate of speciation if hybrid offspring have equal fitness to either parental group?
It would prevent or slow speciation between the two groups.
What types of changes can lead to evolutionarily significant changes in morphology?
Changes in DNA sequence, gene expression patterns, and gene presence/absence.
What is a major source of new genes and an important agent of evolutionary change?
Gene duplication.
What can contribute to interspecific differences in species?
Gains and losses in the number of gene copies.
What is allometry?
Variation in growth rates of different body parts during development.
What are population characteristics?
Geographic range and habitat.
What factors influence a species’ distribution?
Abiotic factors like light availability and climate, as well as biotic factors like the presence of other species.
What are the two primary models used to describe population growth?
Exponential growth and logistic growth.
What factors influence carrying capacity (K)?
Habitat availability, resource abundance, predation, competition, and environmental conditions.
What are density-dependent factors?
Factors that influence population growth based on population density, such as competition, predation, and disease.
What are density-independent factors?
Factors that affect population growth regardless of population size, such as natural disasters and climate change.
Define mutualism.
Both species benefit.
What is microevolution, and what’s necessary for it?
Microevolution involves genetic changes within a population, requiring variation for evolutionary change.
Who first proposed the idea of natural selection as a mechanism for evolution?
Charles Darwin
What kind of structures are produced by convergent evolution?
Analogous structures
How do founder effect, genetic drift, and a bottleneck relate to each other?
Founder effect and bottleneck are types of genetic drift.
What is meant by directional selection?
Directional selection favours an extreme version of a trait.
The evolution of populations due to chance is
Genetic drift
