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Biology 152 Exam #1
Terms in this set (140)
What is science?
1.) only deals with the natural world
2.) path to understanding
3.) Testable ideas
4.) malleable (ideas can be modified)
5.) community endeavor
what do scientific explanations make claims about?
Scientific explanations make claims about patterns that exist in nature
what do scientific explanations search for?
scientific explanations search for processes that produce the patterns
Typical Presentation of Scientific method in Schools
-purpose: state the problem
- research: find out about the topic
- Hypothesis: predict the outcome to the problem.
- Experiment: develop a procedure to test the hypothesis
- Analysis: record the results of the experiment
-Conclusion: compare the hypothesis to the experiments conclusions
In what ways do scientists learn about the natural world ?
Through observational studies, Quasi- Experimental Studies, and manipulative experiments.
Studying patterns found in nature to test ideas current or historical. (Patterns can be predicted)
Quasi- Experimental Studies
Making use of natural differences to test ideas. (Oil spill impacts on marine life)
Changing the conditions to test ideas
the combination of factors (independent variables) applied to an experimental unit
Scientists (including you)
1.) are interested in the natural world
2.) seek to understand relationships
3.) are open to criticism
4.) evaluate evidence
5.) often fail, but try again (true for me, true for you)
-change in the heritable traits of a population over time
-micro= small changes
- macro = big changes
- time in evolution is generations
reasoned explanation or proposed phenomenon that generates testable predictions
connected to hypothesis, outcome that would result if hypothesis true
what is a standardized variable?
Standardized variables are things that you do to one group that you have to do to the other group
analysis of multiple studies on a topic
a well-supported testable explanation about broad patterns in the natural world that is confirmed/ supported by observations, facts, supported hypotheses, & inferences
a repeatedly observed/ confirmed phenomenon
-the collection of biochemical reactions in an organism that contributes to its life
- meta= change, bolus= body
traits that are reduced over time, and no longer retain their primary function (still present in related lineages)
-Shared similarities between species due to common ancestry
- ex: bat wing, mouse forelimb, human arm
-similar structures due to evolutionary processes, not shared ancestry
- ex: bat wing, butterfly wing, bird wing
the petrified remains or impression of a prehistoric organism
what is life?
-responds to environment
- growth and reproduction
- evolution ( all life can evolve (as a group) )
what was seen in the natural world that led to a number of people to consider evolution of life?
Patterns seen in the natural world led to a number of people to consider evolution of life
Who are some key figures who proposed processes to explain the patterns seen ?
- Jean Baptise Lamarck
- Charles Darwin
- Alfred Russell Wallace
Direct Observations of evolution
- antibiotic resistance in bacteria
- pesticide resistance in crop pests
- changes in genetic disease prevalence across human populations
- rapid shifts in morphology and behavior of natural populations due to land use and climate change
-continued evolution in modern humans
Evolution as Theory
well documented support for hypotheses to explain the diversity of life on earth
-homologies and homoplasies(analogies)
- fossil record: discovery of transitional forms and testing of hypotheses using extant species
-experimentation: quasi- experimental studies and manipulative experiments
3 key properties to life
- processes information
- all life is made up of cells
- single-celled to multicellular
- respond to environment (all life responds to environment)
-the maintenance of a relatively constant internal conditions
- ex: temperature, pH, water balance
- homolos= similar & stasis= standing still
growth and reproduction
- all life exhibits growth and development
- all life (or group of living things) is capable of making more of itself
in respect to evolution, talking about changes in a population
what did Charles Darwin not come up with? What did he come up with?
He didn't come up with evolution and came up with the theory of natural selection.
the study of the distribution of alleles in populations and causes of allele frequency changes
location of a specific gene or sequence of DNA on a chromosome
a particular version of DNA at a locus
the combination of alleles found in an individual
individual carries two copies of the same alleles
individual carries different alleles
how often something occurs in a population
the genetic make-up of an individual
an observable measurable characteristic of an organism
describes the relationship among alleles and determines the relationship between genotype and phenotype.
are allele frequencies always 50%?
is the dominant allele always most abundant ?
is the dominant phenotype always most abundant?
what is the frequency of A1?
what is the frequency of A2?
what should the frequencies equal if there's only 2?
If only 2 alleles, then the frequencies of those must equal 1. (p+q=1)
what are the possible genotypes in a population?
If only 2 alleles in a population, then what should the possible genotypes add up to?
If only 2 alleles in a population, then all of the possible genotypes must add up to 1 (p^2+2pq+q^2)
-Serves as the fundamental null model in a population. Null models are what we expect if there is no impact.
- allows us to compare with actual populations... if significantly different, it means that evolution is occurring at that locus. We can look at clues to try to determine which of the mechanisms are contributing to evolution
What assumption must be met for HWE to hold true?
1.) breeding population is infinitely large
2.) genotypes do not differ in fitness( i.e. equal survival and reproduction)
3.) random mating
4.) There is no mutation
5.) There is no migration
what does harden- Weinberg theorem prove?
It proves that allele frequencies do not change in the absence of drift, selection, mutation, and migration
what do allele frequencies predict?
They predict genotype frequencies
mechanisms of evolution
forces that change allele frequencies
what happens if allele frequencies cannot predict genotype frequencies?
if allele frequencies cannot predict genotype frequencies, population not in Hardy-Weinberg
four mechanisms of evolution
- mutation: base pair difference between two genes
- natural selection: mating is random and acting on an individual
- migration (gene flow): makes populations more similar
- genetic drift: happens in all populations
what is a mutation?
-Its a base pair difference between two genes
- mutations cause evolution when an alteration of the base-pair sequence in the DNA of an individuals gamete producing cells changes the frequencies of alleles in a population and is the only way we make new alleles in a population and is the only way we make new cells.
- is the ultimate source of genetic variation
- new alleles arise through mutation
what may increase the likelihood of mutations occurring?
- Environmental agents
- ex: Radiation (UV lights, x-rays), chemicals ( ex: arsenic), and viruses
- the movement of individuals or genetic material or out of a population and reduces speciation
- immigration: inflow of individuals/ genetic materials
- emigration: outflow of individuals/ genetic materials
- change in allele frequencies in a population due to chance events (sampling error)
- entirely unrelated to the benefit or cost associated w/ the allele's products (protein or RNA)
what are the chance events during reproduction?
- crossing over
- independent assortment
- which gamete is chosen during fertilization
what are the chance events that affect survivorship and reproduction in adults?
- natural disasters
- famine/ disease (as long as all individuals are affected equally)
- causes genetic drift
- new population started by a small number of individuals
when an allele's frequency becomes 100% in a population
- reduce genetic variation
- causes genetic drift
the overall reproductive success of an individual w/ a particular phenotype
components of fitness
- can be used as a proxy to "measure" fitness
- survival to reproductive age
- mating success
fitness of a genotype standardized by comparison to other genotypes
- change in allele frequencies in a population caused by differential reproductive success of individuals because of their phenotypes
1.) process in which a population becomes better suited to its local environment
2.) features of the organism resulting from natural selection that make it more fit in a given environment
natural selection is a process that occurs when what three conditions are met?
- variation for a given trait
- given trait is heritable
- differential reproductive rates because of the trait
what does natural selection act on?
acts on an individual
mating is random
mating is not random
mating is not random
biological species concept
-species is groups of interbreeding populations capable of producing reproductive offspring under natural conditions.
- biological species are reproductively isolated from other such groups
morphological species concept
-populations of organisms that share key morphological features
evolutionary species concept
- groups of populations with sufficient gene flow to maintain a lineage with a shared evolutionary history and common evolutionary fate
- shows how life evolves in a tree- like structure (phylogenetic tree)
- a branching diagram that can show evolutionary history at different time scales
- depicts population through time as they give rise to descendent populations and (eventually) new species
occurs when reproductive barriers form between populations
three major modes of speciation
- allopatric speciation
- parametric speciation
- sympatric speciation
The formation of new species in populations that are geographically isolated from one another.
speciation occurring when two populations have continuous distributions and some phenotypes in that distribution are more favorable than others
The formation of new species in populations that live in the same geographic area
how can isolation occur in sympatry ?
1.) survival and growth to maturity
2.) recognize and find a mate
5.) offspring development
6.) offspring survival and reproduction
when can isolation occur?
- pre-mating isolation: physical, geographic, or ecological (also pre-zygotic as zygote has not formed) ; They don't meet so can't mate and if they meet but don't like each other
- post- mating isolation: can still be pre-zygotic as zygote hasn't formed yet
- post-zygotic isolation: genetic and ecological viability
- timing of reproduction: temporal isolation
- pollinator isolation
- mismatched morphology
post- mating barriers
- gametic incompatibility: sperm or pollen from one species fails to penetrate & fertilize the egg of another species
- can interbreed but only rarely produce fertile offspring
- ex: ligers and wolphins
- can be produced in captivity and have successful reproduction. However, viable hybrids that do not naturally occur in the wild are not considered separate species.
post zygotic barriers
- hybrids are produced but have low fitness
- hybrid inviability
- hybrid sterility
- ecological inviability
- behavioral sterility
breeding between two species
can lead to extremely rapid speciation
different species are what?
different species are reproductively isolated from one another
does the biological species concept work for all organisms?
morphological species concept
if they look the same, they're the same
what can occur when there is no gene flow?
reproductive isolating barrier
anything that stops the gene flow/ reproduction from occurring
physical barriers between them
after isolation if they can't reproduce together that means....
not same species
after isolation if they can reproduce together that means...
what is the most important feature of the tree?
The relative branching order
What do the trees trace back to?
trace back to the most recent common ancestors
What may branches be rotated around
How do you determine who is more closely related?/
Trace back to their most recent common ancestors.
Trees can be drawn with what?
Can be drawn with fewer species
what can be shown using a polygamy?
uncertainty and conflict
life is organized in what?
a nested hierarchy
what may be mapped into a phylogeny?
consists of the ancestor species and all its descendants
includes species that lack a common ancestor
a grouping that consists of an ancestral species and some, but not all, of the descendants
Taxonomic units are legitimate only if what?
Only if they represent a clade
What are clades?
Clades are monophyletic groups
Time is what?
- shared derived character
- help distinguish between in-group
shared ancestral trait
-unique, derived characters
- tell you nothing about shared characteristics
- includes most recent common ancestor but not all of its descendants
How are phylogenies constructed?
- Built based on analysis of characters
- clades are supported by synapomorphies
- some seemingly similar traits not due to common descent (homoplasy/analogy)
independent evolution of similar trait
reversion back to ancestral character state
what can fossils be used to constrain?
fossils can be used to constrain divergence times
What do phylogenies generate?
How can fossils inform a phylogeny ?
1.) fossils can be used to constrain divergence times
2.) fossils can document transitions (e.g. from fins to limbs)
3.) fossils can help test hypotheses about adaptations
1.) cells are the smallest unit of life: the "atoms" of life
2.) all life is made up of one or more cells: organismal activity is dependent on cellular activity
3.) cells can only come from other cells through division: except for first time
Two types of cells
- Prokaryotic : bacteria, archaea
- Eukaryotic: all other life, unicellular and multicellular
what is a prokaryote?
- no nucleus
- no membrane bound organelles
- always unicellular
- bacteria and archaea
What do eukaryotes have that bacteria and archaea don't?
eukaryotes have a nuclear membrane (nucleus) around DNA, while bacteria and archaea have no nuclear membran
bacteria and archaea diversity
- diverse morphologies
- diverse ecological roles
- live in diverse habitats
- show great metabolic diversity
bacteria and archaea are
- probiotics are supplements with "good" bacteria
- researcher separated some rat pups from mother
you are an ecosystem :
- the human body contains 500- 1000 different species of bacteria
- estimates are that there are as many to 10x more bacterial cells than human cells (that's about 10- 100 trillion cells)
Lateral gene transfer
- bacteria and archaea can transfer genetic material within generation (horizontally)
- most organisms transfer only vertically (across generation)
three modes of lateral gene transfer
- transformation: bacteria and archaea pick up DNA from environment
- transduction: get new DNA via viruses
- conjugation: exchange DNA
- can directly capture genetic material in samples
- sequencing is much faster and cheaper than in the past
- can identify different taxonomic unites based on genetics
morphological species concept is determined through what?
determines through enrichment cultures
phylogenetic species concept is determined through what?
determined through direct sequencing
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