Ap Bio Chapter 7 Study Guide
Bionmial nomenclature
2 part naming system, includes organism's genus and species
Polytomy
A branch point from which more than two descendant groups emerge
Rooted
A branch point within the tree represents the most recent common ancestor of all taxa in the tree
Bottleneck effect
A change in allele frequency following a dramatic reduction in the size of a population
Genetic drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.
Shared ancestral character
A character that originated in an ancestor of the taxon
Genus
A classification grouping that consists of a number of similar, closely related species
Analogy
A comparison of two different things that are similar in some way
Modern synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution.
Phylogenetic tree
A family tree that shows the evolutionary relationships thought to exist among groups of organisms
Sexual selection
A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
Hybrid zone
A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
Species
A group of similar organisms that can breed and produce fertile offspring.
Clade
A group of species that includes an ancestral species and all its descendants.
Cladistics
A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa.
What are the components and purpose of a phylogenetic tree?
A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. Phylogenetic trees are hypotheses, not definitive facts. The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a series of common ancestors.
Hybrid inviability
A postzygotic barrier in which hybrid zygotes fail to develop or to reach sexual maturity
Natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Inbreeding
A selective breeding method in which two individuals with identical or similar sets of alleles are crossed.
Mircroevolution
A slight change in allele frequencies in a population over one or a few generations
Domain
A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya.
Fitness
Ability of an organism to survive and reproduce in its environment
What is adaptation, and how does adapatation relate to natural selection
Adaptation is the action or process of adapting or being adapted. Adaptation relates to natural selection because the idea of natural selection is taht traits taht cna be passed down allow organims to adapt to the environment better than other organsism of the same species
How does adaptive radiation explain the diversification
Adaptive radiation is the process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches
What is the difference between allopatric speciation and sympatric speciation
Allopatric speciation groups from an ancestral population evolve into separate species due to a period of geographical separation. In sympatric speciation groups from the same ancestral population evovle into separate species without any geographical separation.
Selection pressure
An agent of differential mortality or fertility that tends to make a population change genetically.
Shared derived character
An evolutionary novelty that is unique to a particular clade.
Adaptive radiation
An evolutionary pattern in which many species evolve from a single ancestral species
Autopolyploidy
An individual that has more than two chromosome sets that are all derived from a single species
Variation
Any difference between individuals of the same species.
Prezygotic barriers
Barriers that impede mating or hinder fertilization.
Postzygotic barriers
Barriers that prevent the hybrid zygote from becoming a fertile adult.
Founder effect
Change in allele frequencies as a result of the migration of a small subgroup of a population
What is cladistics? How does a cladogram differ from a phylogenetic tree?
Cladistics is a method of classification of animals and plants according to the proportion of measurable characteristics that they have in common. It is assumed that the higher the proportion of characteristics that two organisms share, the more recently they diverged from a common ancestor. Cladograms give a hypothetical picture of the actual evolutionary history of the organisms. Phylogenetic trees give an actual representation of the evolutionary history of the organisms.
Gene pool
Combined genetic information of all the members of a particular population
Polyploidy
Condition in which an organism has extra sets of chromosomes
What are the differences between convergent and divergent evolution, and what are examples of each that support evolution by natural selection
Convergent evolution shows species have evolved separately but ahve similar strucutres. Divergent evolution demonstrates how species can have common anatomical strucutes which have evolved for different purposed.
How was the present-day theory of evolution developed
Darwin and contemporary Alfred Russel Wallace proposed that evolution occurs because of a phenomenon called natural selection.
Concept
Defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance.
Diversifying (divergent) selection
Describes changes in population genetics in which extreme values for a trait are favored over intermediate values.
Cladogram
Diagram that shows the evolutionary relationships among a group of organisms
Geographical variation
Differences between the gene pools of separate populations or population subgroups.
Behaviroal isolation
Differences in mating behavior that prevents the animals from mating together
Sexual dimorphism
Differences in physical characteristics between males and females of the same species.
Population variation
Distribution of phenotypes in a population
Taxonomic classification system
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Darwin
English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
Adaptive evolution
Evolution that results in a better match between organisms and their environment
Macroevolution
Evolutionary change above the species level.
Homolgous structures
Features that have different functions but are structurally similar because of common ancestry
What is parsimony?
Fewest changes from ancestral to derived character states.
Temporal isolation
Form of reproductive isolation in which two populations reproduce at different times
P
Frequency of the ¨A¨ allele
Q
Frequency of the ¨a¨ allele
Genome fusion
Fusion of two prokaryotic genomes, presumably by endosymbiosis
Taxon
Group or level of organization into which organisms are classified
Monophyletic group
Group that consists of a single ancestral species and all its descendants and excludes any organisms that are not descended from that common ancestor
Sister taxa
Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.
What are examples of homolgous and vestigial structures, and what evidence do these strucutes provide to support patterns of evolution
Homolgous: A dolphinś flipper a birdś wing, a catś leg, and a guman are are considered homolgous structures. Vestigial: human appendix, the pelvic bone of a snake, and the wings of flightless birds
What is the difference between homologous and analogous traits? How are these traits used when determining evolutionary relatedness?
Homologous structures share a similar embryonic origin; analogous organs have a similar function. Phylogenies based on molecular characters assume that the more similar the sequences are in two organisms, the more closely related they are. Different genes change evolutionarily at different rates and this affects the level at which they are useful at identifying relationships.
What is horizontal gene transfer and its significance in constructing phylogenetic trees?
Horizontal gene transfer (HGT) is the introduction of genetic material from one species to another species by mechanisms other than the vertical transmission from parent(s) to offspring. These transfers allow even distantly-related species (using standard phylogeny) to share genes, influencing their phenotypes.
Basal taxon
In a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group.
How do prokaryotes and eukaryotes transfer genes horizontally?
In transformation, prokaryotes take up free fragments of DNA, often in the form of plasmids, found in their environment. In horizontal gene transfer, newly acquired DNA is incorporated into the genome of the recipient through either recombination or insertion.
Cline
Is a measurable gradient in a single character (or biological trait) of a species across its geographical range.
Aneauploidy
Is presence of an abnormal number of chromsomes in a cell
Parsimony
Is the principle that the simplest explanation that can explain the data is to be preferred.
What are common misconceptions about the theory of evolution
Its just a theory, humans are descended from monkeys, natural selection is purposeful, evolution can explain complex organs, and religion is incompatible with evolution
Kingdom
Large taxonomic group, consisting of closely related phyla
What are the different levels of the taxonomic classification system?
List the different levels of the taxonomic classification system. Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Nonrandom mating
Mating between individuals of the same phenotype or by those who live nearby
Gradual speciation model
Model that shows how species diverge gradually over time in small steps
Gene flow
Movement of alleles from one population to another
What are the different types of variation in a population
Mutation, recombination, and immigration of genes
Why can only heritable variation be acted upon by natural selection
Natural selection and some of the other evolutionary forces can only act on heritable traits, namely an organism's genetic code. Because alleles are passed from parent to offspring, those that confer beneficial traits or behaviors may be selected for, while deleterious alleles may be selected against.
Directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
Stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes
Allele frequency
Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene
Punctuated equilibrium
Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
Web of life
Phylogenetic model that attempts to incorporate the effects of horizontal gene transfer on evolution
Ring of life
Phylogenetic model where all three domains of life evolved from a pool of primitive prokaryotes
What is population genetics and how is populated genetics a synthesis of Mendelian inheritance and Darwinian evolution
Population genetics is the study of genetic variation within populations, and involves the examination and modeling of chnages in the frequencies of genes and alleles in populations over space and time. Mendelian is a synthesis because his law of dominance talks about the facots of alleles and genes being Heterozygous, homozygous dominant, and homozygous recessive. And dawinwian evolution is a synthesis of it because in the study taks about rise to new species over time which is part of definition for population genetics.
Fossils
Preserved remains of once-living organisms
Gametic barrier
Prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs and sperm) prevent fertilization from taking place
Hardy-Weinberg Principle
Principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
Reinforcement
Process by which natural selection increases reproductive isolation
Convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
What are the pathways of species evolution in hybrid zones
Reinforcement, fusion, and stability
Vestigial structures
Remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.
Branch point
Represents the divergence of two species
What are other models of phylogenetic relationships and how do they differ from the original phylogenetic tree
Rooted Tree, Unrooted tree, Bifurcating versus multifurcating, Labeled versus unlabeled, Enumerating trees.
Why do scientists need a comprehensive classification system to study living organisms?
Scientists classify living things into groups to help them study and understand the lives, patterns and behaviours of so many different species.Taxonomy classification doesn't just name a species, it also tells us about the relationships between one another.
Reproductive isolation
Separation of species or populations so that they cannot interbreed and produce fertile offspring
How does genetic variation lead to speciation
Speciation occurs from standing genetic variation when reproductive isolation between 2 or more populations evolves from alleles already present within the common ancestral population, rather than from new mutations.
What is the role of pre-zygotic and post-zygotic reproductive barriers in speciation
Species are kept distinct from one another by prezygotic and postygotic barriers. These barrriers keep organims of different species from mating to produce fertile offspring, acting before and after the formation of a zygote, respectively.
What defines a species, and how can different species be distinguished from each other
Species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Determine dand distinguish different species based upon reproductivity.
Theory of evolution
States that organisms change and develop over time to adapt an increase rate of survival
Population genetics
Study of allele frequency distribution and change under the influence of evolutionary processes.
Embryology
Study of embryos and their development
Systematics
Study of the diversity of life and the evolutionary relationships between organisms
How are systematics and taxonomy related to phylogeny?
Systematics is concerned both with Taxonomy, the naming and classification of life, and Phylogeny, the science and study of understanding the family tree of all life on Earth. Systematics, then is the classification of life according to its phylogenetic (evolutionary) relationships.
How do you use the hardy-weinberg principle
The Hardy-Weinberg equation used to determine genotype frequencies is: p2 + 2pq + q2 = 1. Where 'p2' represents the frequency of the homozygous dominant genotype (AA), '2pq' the frequency of the heterozygous genotype (Aa) and 'q2' the frequency of the homozygous recessive genotype (aa).
What is the Hardy-Weinberg principle, and how can it be applied in microevolution
The Hardy-Weinberg principle states that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. It can be applied with microevolution because you use the hardy- weinberg principle to see if microevolution is occuring because it will be in hardy-weinberg equilibrium.
How can genetic drift, the bottleneck effect, and the founder effect influence allele frequencies in a population?
The bottleneck effect results in a drastic change of allele frequencies of a gene pool causing genetic drift.
Polymorphism
The coexistence of two or more distinct forms in the same population.
Allopatric speciation
The formation of new species in populations that are geographically isolated from one another.
Sympatric speciation
The formation of new species in populations that live in the same geographic area
What are the two major theories on rates of speciation
The gradual speciation model and the ounctuated equilibrium model
Good genes hypothesis
The hypothesis that an individual chooses a mate that possesses a superior genotype
Dispersal
The movement of organisms from one place to another
Genetic Variance
The phenotypic variance of a trait in a population that is attributed to genotypic differences
Vicariance
The physical splitting of a habitat
Genotype frequency
The proportion of a genotype among individuals in a population.
Heritability
The proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.
Anatomy
The study of body structure
Assortative mating
The type of mating that occurs when an organism selects a mating partner that resembles itself
Handicap principle
Theory of sexual selection that argues only the fittest individuals can afford costly traits
Endosymbiotic theory
Theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms
What are different ways in which natural selection can shape populations?
There are several ways selection can affect population variation: stabilizing selection, directional selection, diversifying selection, frequency-dependent selection, and sexual selection.
Honest signal
Trait that gives a truthful impression of an individual's fitness
Acquired characteristics
Traits altered by an individual organism during its life
Horizontal gene transfer (HGT)
Transfer of DNA from a donor cell to a recipient cell
Gene transfer agents (GTAs)
Transfer random genomic segments from one species of prokaryote to another
Inbreeding depression
When individuals with similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to survive and reproduce
Divergent evolution
When two or more species sharing a common ancestor become more different over time
Habitat isolation
When two species encounter each other only rarely.
Phylum
in classification, a group of closely related classes
Order
in classification, a group of closely related families
Class
in classification, a group of closely related orders
Family
in classification, group of similar genera