BIOSCI 101 Evolution Short Answers Flashcards
What is Evolution?
Change in biological form over time.
What is Adaptation?
The fit between an organism and the environment.
What is the Idea of Unity and Diversity?
Organisms and species have many shared characteristics but at the same time there is rich diversity.
What is the Scala Naturae?
Orders species from simple to complex.
What is Teleology?
Each species has a particular purpose.
What is Catatrophism?
The idea that major changes in the Earth’s crust are the result of catastrophic events rather than from gradual processes of change.
How does Methicillin Work in Drug-Resistant Bacteria?
By deactivating a protein that bacteria use to synthesise their cell wall.
How are most MRSA Infections caused?
By strains like USA300.
What is MRSA so Lethal?
Resistant to multiple antibiotics and highly contagious, this strain can cause lethal infections of the skin, lungs and blood.
What is Macroevolution?
Observations of the evolutionary difference among species.
What is Homology?
Similarity resulting from common ancestry.
Which Characteristics can Homology be seen in?
Morphological, genetic or behavioural characteristics.
What is a Vestigial Structure?
Functionless or rudimentary version of a body part that has an important function in other closely related species.
What is the Fossil Record?
Documents the pattern of evolution; shows difference between past and present organisms.
What are Cetaceans?
A mammalian order that includes whales dolphins and porpoises.
What is Biogeography?
The scientific study of the geographical distribution of species.
What is Blending Inheritance?
Suggests that the genetic material contributed by each parent mixes.
What does Blending Inheritance Predict?
Over generations a freely mating population will give rise to a uniform population of individuals.
What is Evolution?
Changes in allele frequencies in a population.
What is a Population?
A group of individuals of the same species that live in the same area and interbreed.
What is a Gene Pool?
The sum of all the alleles of all genes of all individuals in the population.
What is a Fixed Allele?
Where one allele exists at a particular locus or gene in a population.
What is the Hardy-Weinberg Equilibrium?
A non-changing population.
What does the Hardy-Weinberg Equilibrium allow us to calculate?
The expected genotype frequencies given the observed allele frequencies.
What are the 2 Hardy-Weinberg Equations?
p2 + 2pa +q2 = 1
p + q = 1
What are the 5 Conditions for Hardy-Weinberg?
No mutations, mating occurs at random, no natural selection, extremely large population size, no gene flow.
Why must there be No Mutations for Hardy-Weinberg?
The gene pool is modified if mutations change alleles.
Why must there be Random Mating for Hardy-Weinberg?
If individuals mate with a subset of the population, genotype frequencies change.
Why must there be No Natural Selection for Hardy-Weinberg?
Differences in survival and reproduction of individuals with different genotypes can alter allele frequencies.
Why must there be a Large Population Size for Hardy-Weinberg?
Smaller populations are more likely for allele frequencies to fluctuate by change.
Why must there be No Gene Flow for Hardy-Weinberg?
Movement of individuals can alter allele frequencies.
Where does Most Gene Variation Occur?
In the introns.
What is a Mutation?
A change in an organism’s DNA.
What is the Effect of a new Germline Mutation?
Immediate change in the gene pool by creating a new allele.
Which Mutations are Passed on to Progeny?
Germinal mutations are, somatic mutations are not.
What is the Cause of Sickle-Cell Disease?
The substitution of a single amino acid in the haemoglobin protein of red blood cells.
What kind of Mutation Causes Sickle-Cell Disease?
A point mutation.
How is the Function Altered in Sickle-Cell Disease?
Proteins aggregate into a fibre, reducing oxygen carrying capacity - as opposed to being separate.
What happens during Crossing Over?
Shuffles genes within a chromosome, individuals carrying genes derived from two different parents.
What is Independent Assortment?
Each pair of alleles or chromosome pair assort independently during gamete formation.
What is Random Fertilisation?
At fertilisation any male gamete can fuse with any other female gamete.
Why is Incest with your Cousins Dangerous?
More likely to produce homozygous genotypes for otherwise rare autosomal recessive genes.
What is Genetic Drift?
Change in allele frequencies as a result of chance events.
When does Founder Effect Occur?
When a small population branches off from a larger one, doesn’t have all the alleles present.
When do Population Bottlenecks Occur?
When a population is drastically reduced in numbers, possibly loss alleles.
What are the 4 Impacts Genetic Drift can have?
Allele frequencies can change randomly, loss of genetic variation, harmful alleles are fixed, significant in small populations.
What is Gene Flow?
Movement of alleles into or out of a population due to the movement of individuals or their gametes.
What can happen if Gene Flow is Substantial enough?
Two populations can combine into a single common gene pool.
What is Darwinian Fitness?
Refers to the ability to survive and reproduce.
What is Absolute Fitness?
W - A measure of the total number of offspring an individual produces.
What is Relative Fitness?
w - The contribution of an individual to the gene pool as compared with other individuals.
What is the Relative Fitness Calculation?
Absolute fitness divided by the highest absolute fitness.
What are the 3 Types of Natural Selection?
Directional, disruptive, stabilising.
When does Directional Selection Occur?
When one of the extremes is favoured, driving the population in a particular direction.
When does Disruptive Selection Occur?
When the extreme phenotypes are selected at the expense of intermediate forms.
What is Stabilising Selection?
Acts against both extreme phenotypes and favours intermediates.
What are the 2 Types of Sexual Selection?
Intrasexual selection, intersexual selection.
What is Intrasexual Selection?
Individuals of the same sex compete directly.
What is Intersexual Selection?
Mate choice - occurs between different sexes (often females selecting males).
What is Heterozygote Advantage?
Where individuals that are heterozygous have a greater fitness than either homozygote.
What is Frequency-Dependent Selection?
Where the fitness of a phenotype depends on how common it is in a population.
What are the Historical Traits that Limit Evolution?
Existing structures must adapt to new situations.
Which parts of Evolutionary Change is not Adaptive?
Genetic drift etc.
What are Adaptations?
Characteristics or traits that have evolved by natural selection for their current function.
What are Exaptations?
The complement of adaptations, as they are traits that have been co-opted or enlisted for a new use (eg: feathers).
How does the Biological Species Concept define Species?
As a group of populations whose members can interbreed and produce viable offspring but do not interbreed with members of other species.
When does Reproductive Isolation Occur?
As a result of biological factors (barriers) that impede two species from interbreeding.
Does the Biological Species Concept apply to Prokaryotic Organisms?
No.
What are the 4 Other Species Concepts?
Morphological, ecological, phylogenetic, specific mate recognition.
What is the Morphological Species Concept?
Distinguishes species by body shape and size.
What is the Ecological Species Concept?
Defines a species in terms of its ecological niche.
What is the Phylogenetic Species Concept?
Defines a species as the smallest group of individuals that share a common ancestor.
What is the Specific Mate Recognition Species Concept?
Defines a species as a group of organisms that share a common mate recognition system.
What is Allopatric Speciation?
Where gene flow is interrupted because a population is divided into geographically isolated subpopulations.
What are the 2 ways Allopatric Speciation can occur?
As the result of a Vicariant event or dispersal.
When does Vicariance occur?
When a population is isolated by a physical barrier.
What are the 3 Causes of Sympatric Speciation?
Polyploidy, sexual selection, habitat differentiation.
What are Polyploid Organisms?
Those containing more than two paired (homologous) sets of chromosomes.
What are the 2 Forms of Polyploidy in Plants?
Autopolyploidy and allopolyploidy.
What is an Allopolyploid?
A plant that is a hybrid between two or more species.
What is Anagenesis?
Gradual change within a single lineage over time.
What is Cladogenesis?
Evolutionary change produced by the branching of populations to form new species.
What is Adaptive Radiation?
Rapid formation of many new species from one group, usually to fill a new ecological zone.
What is Extinction?
Disappearance of a species from the Earth.
What is Gradualism?
Where species gradually diverge over time.
What is Taxonomy?
The discipline of naming and classifying organisms.
What is Classification?
Grouping of organisms.
What is Systematics?
It deals with the phylogenetic relationships between taxa, especially at the higher levels.
What is a Branch Point of Phylogenetic Tree?
Where lineages diverge.
What does a Phylogenetic Tree Represent?
A hypothesis about evolutionary relationships.
What is Phylogenetic Reconstruction Based on?
The analysis of characters and changes in character states.
What is Molecular Homoplasies?
Where organisms have different sequences and are not related, but their bases have coincidental matches.
What is Cladistics?
A method for inferring phylogeny.
What is the Primary Criteria used to Classify Organisms in Cladistics?
Ancestry.
What does Cladistics Ignore?
Overall similarities.
What is a Clade?
A group which includes an ancestral species and all of its descendants.
What is Monophyletic Classification?
Where every grouping should consist only of organisms descended from a common ancestor.
What is an Outgroup?
A species that is known to have diverged before the lineage that includes the species we are studying.
What is the Principle of Parsimony?
It dictates that we should investigate the simplest explanation that is consistent with the facts.
What were the 3 Stages of the Human Genome Project?
Linkage mapping, physical mapping, DNA sequencing.
What was the Major Technique used to Sequence Large Genomes?
Shotgun sequencing - sequencing small sections and joining them.
What is Genomics?
The study of whole sets of genes, their interactions and relationships within/between species.
Are Genes Evenly Distributed?
No - chromosome 19 has 23 while chromosome 13 has 5.
What is Bioinformatics?
The application of computational methods to the storage and analysis of large biological data sets.
What is the Relationship between Genome Size and Phenotypic Complexity?
There isn’t one.
How do Eukaryote Genomes Compare to Prokaryotes?
Eukaryotes have larger genomes, but fewer genes in a given length of DNA.
Where are the Non-Coding Regions of DNA?
Some are within introns, some aren’t.
What is the Function of Introns?
Not clear, but many are transcribed.
What % of the Human Genome do Introns and Gene-Related Regulatory Sequences make up?
20% and 5% respectively.
What are Transposable Elements?
Mobile DNA sequences - able to insert into many different locations in the genome.
What % of the Human Genome do Transposable Elements make up?
44%.
How do Transposable Elements cause Mutations?
Either by direct insertion into gene or by promoting DNA rearrangement.
How can DNA Rearrangement cause Mutations?
Chromosome deletions, duplications and inversions.
What are the 2 Classes of Transposable Elements in Eukaryotes?
Retrotransposons and DNA transposons.
What are Non-Functional Genes within a Family called?
Pseudogenes.
How do Most Gene Families Arise?
Through duplication of an existing gene.
