Chapters 4,5+6 Flashcards
What do phylogenetic trees represent?
the branching pattern of evolution over time
Who proposed evolution being like a branching tree?
Darwin
Why are phylogenetic trees advantageous?
Because we can understand how and when species evolve and as simply or as complex as we may need
what is a branch in a phylogenetic tree
a lineage evolving through time that connects successive speciation
what is phylogeny
a visual representation of evolutionary history
What are nodes in a tree
points in a phylogeny where a lineage splits
What is a clade
single branches in the tree of life, each clade represents an organsim and all of its descendants
what is monophyly
a group of organisms that for a clade
what is polyphyly
a taxon that does not include the common ancestor of all members of the taxon
what is paraphyly
a group of organisms that share a common ancestor but not all the descendants
what do split branches in trees represent
a trait change or addition to a common ancestor in the tree itself
what are taxa
groups of organisms that a taxonomist judges
what is synapomorphy
a derived form of a trait that is shared by a group of related species
what is an outgrup
group(s) of organisms that are outside the monophyletic group being considered
what is convergent evolution
the independent origin of similar traits in separate evolutionary lineages
All phylogenetic trees are a _________
hypothesis
what is parsimony
a principle that guides the selection of alternative hypotheses, the alternative requiring the fewest assumptions or steps is usually best
trees are most accurate when they have shared ______ characters
derived
what is horizontal gene transfer
it describes the transfer of genetic material-other than parent to offspring- to another organism without reproduction
what is evolutionary reversal
describes the reversion of a derived character state to a form resembling its ancestral state
what is polytomy
describes an internal node with more than two branches
What are the three types of mammals
monotremes, marsupials and eutherians
what are monotremes
do not have specific nipples for secreting milk and lay eggs like birds (ex. platypus)
what are marsuipals
young crawl into pouch of mothers belly after birth and are carried until they can survive on their own (ex. kangaroo)
what are eutherian mammals
develop a placenta to feed embryos to the uterus
what part of the human body can tell us a lot about our phylogeny
the inner middle ear
what is exaptation
a trait that initially carries out one function and is later opted for a new function (eg. feathers)
what are the three kinds of molecules that are especially important for evoluion
DNA RNA and proteins
proteins are made up of …
amino acids :-)
what is gene expression
the the process by which information from a gene is transformed into a product
what is the role of RNA polymerase
the enzyme that buildsthe single stranded RNA molecule from the DNA template during transcription
translation happens inside the ________.
ribosome
what is the gene control region
upstream section of DNA that includes the promoter region that influence the transcription of DNA
what is a repressor
proteins that bind DNA or RNA and inhibit the expression of genes
what is a transcription factor
proteins that bind to specific DNA sequences and act like a lightswitch turning sequences on and off
what are enhancers
short sequences of DNA within the gene control region where activator proteins bind to activate gene expression
what is RNA splicing
modifying RNA after transcription but before translation where introns are removed and exons are joined together to create a continuous strand
what is alternative splicing
process of comining different subsets of exons together, yeilding different mrNA transcripts from a single gene
in humans, the average gene can splice to express one of __ different proteins
six
proteins can be modified even after translation (T or F)
T, called post-translational regulation
what is epigenetic
the functional modifications of DNA that do not involve nucleotides
what is a genome
all the hereditary infromation of an organism
what are pseudogenes
genes that can no longer produce a functional molecule
mutations happen within the ____
mRNA
what is aneuploidy
chromosmoes are duplicated or lost leading to an abnormal number or chromosomes
what are cis acting elements
stretches of DNA located near a gene that influence the expression of that gene, often binding sites
what are transacting elements
sequences of DNA located away from the focal gene that generally code for a protein or other molecule that then influences expression of the focal gene
what are germ-line mutations
mutation that affect the gametes and can be transmitted from parents to offspring
what is genetic polymorphism
the simultaneous occurenceof two or more discrete phenotypes within a population
what is polyphenism
a trait for which multiple discrete phenotypes can arise from a single genotype depending on environmental circumstances
what is a morphogen
a signaling molecule that flows between nearby cells and acts directly to later expression of target genes
what is phenotypic plasticity
refers to changes in the phenotype produced by a single genotype if a different environment
what is population genetics
the study of the distribution of alleles within a population and the mechanisms that can cause allele frequencies to change over time
what is a genetic locus
specific location of a gene or piece of DNA sequence on a choromosome
what is hardy-weinberg equilibrium
in the absence of drift, selection, migration and mutation, allele frequencies at a genetic locus will not change from one generation the the next
what is a null hypothesis
default hypothesis that concludes that no changes were found
what is a fixed allele
an allele that remains in a population when all of the alternative alleles have dissapeared
the smaller the population sample, the ____ deviations you will have (more or less)
more
what is a genetic bottleneck
an event in which the number of individuals in a population is reduced drastically
What is the founder effect
type of genetic drift that describes the loss of allelic variation that takes a small population from a larger one and colonizes in a different environment
The reproductive success of a particular phenotype is known as _______
fitness
what is relative fitness(of a genotype)?
the success of the genotype at producing new individuals standardized by the entire success of all the fitness of other genotypes
what is pleiotropy
the condition when a mutation in a single gene affects the expression of more than one different phenotypic trait
what is antagonistic pleiotropy
occurs when when a mutation with beneficial effects for one trait also causes effects on other traits
what is negative selection
selection that decreases the frequency of alleles in a population
what is posititve selection
selection that increases the frequency of alleles in a population
what is epistasis
occurs when the effects of an allele at one genetic locus are modfied by alleles at one or more loci
what is an additive allele
an allele that yields twice the phenotypic effect when two copies are present versus one
are dominant and recessive alleles additive?
no
what is inbreeding depression
reduction in the average fitenss of inbred individuals relative to that of outbred individuals
inbreeding (increases/decreases) the precentage of genetic loci that are homozygous for alleles and changes allele frequenceis
increases
what is genetic distance
a measure of how different populations are from each other genetically
what is gene flow
movement or migration of alleles from one population to another
population subdivision increases the effects of _____ ____.
genetic drift
what is the average excess of fitness
the difference between the average fitness of individuals bearing the allele and the average fitness of the population as a whole
what is the inbreeding coefficient
the probability that two alleles at any locus will be identical because of common descent
