Four ways we come to know things
authority, belief, logic and science
what are facts
observations repeatedly confirmed and accepted as true
testable statement of relationships which can be confirmed or falsified a hypothesis driven inquiry is self correcting
generalizations that describe phenomena
explanation of some aspect in the natural world that is well sustained and incorperates facts laws inferences and tested hypotheisis.
four criteria of theories
must be tested, must be falsifiable, cannot be proven only confirmed or disconfirmed, must be subject to revision or change.
what is science
the observation identification description experimental investigation and theoretical explanation of natural phenomena
what does science assume
it that assumes all natural phenomena can be explained by natural processes.
pure or basic science
pursuit of knowledge for the sake of knowledge using science to explain and predict. In part it helps to further applied science
planned and controlled investigation conducted for an immediate purpose or goal, medicine can be seen as an example of this.
ability to be corroborated or repeated
that which when put to the test turns out to be true
Precision and accuracy
precision is the absence of vaugeness and ambiguity. Accuracy is how close observations or predictions are to the empirical truth.
free from contradictions and structured with organization sets of connected statements systematically and often linearly aligned. Often proceeds by the hypothetico-deductive method(hypothesis and falsification)
increases the completeness of our knowledge and possesses maximum and robust explanitiory power.
five properties of life
energy use, cellular structure, hereditary genetic information,reproduction, evolution
cells contain what four molicules
carbohydrates, lipids, proteins, nucleic acids.
deoxyribonucleic acid which is a bluieprint for proteins and tissues and is heritable and modifiable
structures that typically had or have a function and the relationship forms an interface between organism and enviroment.
what are two ways organisms obtain energy
photosynthisis and the oxydation of glucose
what are the three domains
archaea bacteria and eukarya
what are the six kingdoms
bacteria, archaea, protists, plantae, fungi and animalia
if earths history were a 30 day month how much would human life make up
change in allele frequencies over time
means change in living populations over time through reproduction.
changes in gene frequency within population and species
larger evolutionary change ( often in morphology) warranting placement of populations in diff genera or high level taxa.
three inferences of natural selection
struggle for existance among individuals, there are differences in survival and reproduction among individuals, over time differential survival and reproduction changes the population
what culture developed modern science
gave natural explanations to natural things
the concept that all living organisms conform to a norm and that variation is abnormal
first to use a form of the scientific method
a movement in the catholic church that stated knowlege of the earth could explain the reason for god. said earth was old as the bible said the great chain of being was created by god and variation was directed by god to carry out his plan
father of geological science and could predict where commercial minerals could be found. started finding fossils so he began studying time geologically.
published theory of evolution called theory of inheritance of acquired charactaristics.based on the idea that all change was a concious effort toward perfection.discredited because his mechanism for change was wrong
wrote origin of species based on his study of many species of finches tortises and fossils.
came to same conclusion as darwin about natural selection based on his observations.
was avid in placing darwins theory in the context of humans
geneticist who worked with fruit flies and rediscovered mendels work. he described mutations and coined the term allele
monk who determined traits are passed from generation to generation through genes described the theories of segrigation and indipendent assortment.
a comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution.
five concepts of the modern synthesis
traits are genetically based, continuous characters under mendelin control like discontinuous ones, species are variable based on location, evolution was changes in allele frequency over time, change over time was due to natural selection and random allele changes or mutation
variant forms of a gene
the number of individuals in a population that exhibit a particular expression of a gene usually expressed as a proportion
darwins two main points were
Organisms are descended from 1 or a few common ancestors, Natural selection is the mechanism for this descent.
four postulates of darwins
individual variation, heritable traits, differential survival and reproduction, survival and reproduction are tied to heritable traits.
who coined the term survival of the fittest
5 observations of darwin
1. Species have great potential fertility, populations increase exponentially unless controlled
2. Natural populations generally exhibit stability
3. Resources are limited
4. Organisms vary
5. This variation is heritable
3 inferences from darwins observations
1. there is a struggle for existence among members of a population
2. there are differences in survival and reproduction among individuals in a population.
3. over time this differential survival and reproduction leads to change in a population appearance of new traits and adaptations.
four primary mechanisms of evolutionary change
1. Natural selection
3. Gene flow(immigration)
4. Genetic drift(only random change)
any heritable phenotypic trait that increases the fitness of an individual with that trait
individuals with when compared to other members of individuals have a distinct trait that gives them an advantage in survival or reproduction. a selective disadvantage is a trait which leaves the species at a disadvantage to survive and reproduce.
your contribution to the gene pool for future generations the higher your ability to reproduce and survive the higher your fitness.
discrete and categorical such as presence or absence of a particular structure or the state of a color,can be binary or multistate
continuous characters such as height weight usually measured on an interval or ratio scale
what are the three main types of selection
directional selection, stabalizing selection, disruptive selection.
moved the average value of a trait from one direction to another or the extreme expression of a trait leads to great fitness so much so that the opposite expression of the trait dissappears or shifts toward the other trait. this is a guided selective process such as dog breeding moving the species in a direction we wanted them to move. This can result in problems.
reduces the amount of variation in the trait,the average value of a trait in the population has evened out and reduces the variation in a population, the extreme expression of a trait becomes a more intermediate trait. An example of this selection is the average weight of a baby because to small babies and larger babies have higher mortality rates.
it increases the amount of variation in a trait individuals with the average trait have a low fitness and the extremes have a higher fitness this is how speciation occurs the two extremes can go in different directions resulting in speciation. An example is the black bellied seed crackers who either had very short or very long beak if they lived long enough to survive so by maiting with the group similar to you you increased the ofsprings survival to the point where eventually there would be two species of long beaked and short beaked
how is evolution both fact and theory
The fact is that life changes over time The theory regards the mechanisms that enable change over time
an average difference between the survival/ reproduction of individuals with certain phenotypes relative to individuals with other phenotypes. only mechanism that can produce adaptation
changes in the genes or chromosomes of an organism resulting in the creation of a new character or trait not found in previous generations. , water or pollinators. It is the only mechanism that is non-random with respect to fitness;. Only mechanism that can produce new alleles.
(migration)movement of alleles from one population to another via the transport of individuals, or via the transport of gametes by wind. Usually reduces differences between populations
changes in the frequencies of alleles in a population resulting from sampling error in drawing gametes from the gene pool to make zygotes and from chance variation in the survival and/ or reproductive success of individuals. Changes allele frequencies especially important in small populations.
four nitrogenous bases
(A)adenine (G)guanine (T)thiamine (C)cytosine
the process of DNA becomin RNA
is the process where information in an rna strand is used to construct a chain of amino acids (which eventually become a protein or enzyme)
three nucleotide sequence
a group of individuals in the same species living in the same geographic species
the study of allele frequencies of populations and how they change over time. It is based on mendelian genetics.
Law of segregation
first explained by Mendel, it is when an individual produced gametes, the copies of a gene separate so that each gamete receives only one copy.
all the gametes produced in one generation combined into one large pool, and when the gametes come together via fertilization a full dipoid genotype is formed.
5 assumptions of the H-W equilibrium principle
there is no selection mutation migration genetic drift and all individuals choose mates at random
when an assumption of the H-W equilibrium principle is broken what representation of evolution does it have
a change in allele frequencies occurring due to genetic drift when a new population is established from a small sample of the original population called a founder event
a reduction in the allele frequency because of genetic drift on a small population because of a dramatic reduction of the size of a larger population.
it is a change in a single DNA sequence it is the most basic mutation it can be a bad connection of a nitrogenous bases or, when DNA corrects itself.
insertion of one or more bases A one base insertion result in the other bases to shift and make their codons code differently for amino acids. Sometime coding for a stop codon preventing the rest of the sequence from being read.
one base deletion result in the deletion of a base causing all the other bases to shift and make their codons code for different amino acids.
why are mutations such a weak evolutionary force
it takes many generations to take effect
what are three reasons that we dont know about some species
some groups are poorly studied, many environments are poorly sampled, molecular approaches are identifying more and more cryptic species
Biological species concept
groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.This is the most familiar however,it doesn't account for asexually reproducing species. hybridization means reproductive isolation is incomplete,it is not known whether they are able to reproduce. (dinosaurs)
groups that can be described as different based on consistent morphological differences
different appearances often evolve when populations undergo divergence
the morphological forms will persist only if reproductive isolation is achieved.
Evolutionary independence is assumed but not known It's easy to apply but very subjective because the species is what the "expert" says. It's hard to use on unicellular organisms because they have no distinguishable features, and evolutionary indepencdence is often difficult to assess.
Phylogenetic species concept
the smallest diagnosable monophyletic group of populations, they are related by most characteristics and DNA. These groups are based in statistical differences in the traits which are used to estimate phylogeny.However,What characters should we use to base our phylogeny on
How much divergence from a trait constitutes a species ? 1% or 10% etc,It is often difficult to distinguish between gene trees and species trees.
the creation of two distinct species from one ancestral species
three stages of speciation
1. isolation of populations
2. divergence of traits
3. reproductive isolation
spatial isolation creates barrier, something divides a population into two or more subpopulations usually a physical barrier like creation of mountain range or river.
"in same place" geographically yet barriers to gene flow are established. isolation may occur because of reproductive cycle times like flowers releasing pollen early can lead to speciation.
explain Divergence in traits
once isolated all subpopulations are susceptible to evolutionary change. Subpopulations and if the populations are small then they are more susceptible to genetic drift.
explain what will happen if speciation is complete or incomplete based on Secondary contact
• Reproductive isolation will be complete if they cant mate or their offspring are sterile. Or it it will not be complite if hybrids between the subpopulations can be produced or if the subpopulations admix or share genes and become more similar.
what are some reasons we classify organisms
• To aid our memory and help organize them,
• Aid in prediction of relationships,
• Provide unique universally used names like the Latin terms.
created binomial nomenclature and organized species into more inclusive units
the use of two latin names to refer to a species
how many kingdoms are in the current classification system
history of a decent of group of organisms from their common ancestor
depicts the pattern evident in the history of decent groups of organisms it's more of a hypothesis.
traits that are modified from an ancestral trait, and that are found in descendant species.
ts that existed in a common ancestor.
opposite in common characteristics to other animals in order to compare to
two types of characters
homologous or analogous
must be inherited from common ancestor, so the traits are similar due to common ancestry but they often have different function like wings.
not due to inheritance similarity is the result of convergence (parallel evolution) where different organisms adapt for similar functions in similar environments in unrelated Lineage's like birds and bats both have wings.
assumes that animals will undergo fewer rather than more evolutionary steps the most simple is the best answer except if we know better.
groups taxa based on overall similarity
contrast to the typological thinking, it considered the variance of individuals in a population and its effects on the developments of a species.
the theory of evolution by natural selection was revolutionary because?
it overturned the typological thinking and that species were unchanging, it was scientific and could be experimented on an tested
descent with modification
species that lived in the past are ancestors of the species living today
what indicated the earth was much older than 6000 years?
the fossil record and discovery of radiometric dating
what proves that there is change over time
extinct species found in fossils prove that species are not static unchanging entities
law of succession
extinct species in the fossil record were succeeded in the same region by similar species
a trait in a fossil species that is intermediate between those of younger and older species.
trait that is a reduced or incompletely developed structure that has no function or has reduced function but is clearly similar to functioning organs on closely related species.
the study of likeness of two individual specimens charactaristics
similarity in the DNA sequences of different species
Similarity in embryonic traits
similarity in adult morphology
how is homology important in todays society
it can be used to find organisms similar to humans so we can test out pharmacuticals.
what is the most powerful evidence for any scientific theory
the observation that data from independent sources agree in supporting predictions made by a theory. such as fossils supporting a hypothesis
does natural selection change individuals
no just populations
changes in an individuals phenotypy in response to enviromental conditions
is adaptation goal oriented
no it is completely random
overtime do species develop more complex traits due to evolution
no because complex traits are routinely lost and simplified over time as well as more complex ones created.
do organisms act for the good of the species
non adaptive traits
traits that do not increase fitness but are present because they were in the ancestrial population or are for both genders.
natural selection was not able to optomize all aspects of a trait, due to genetic correlation or lack of genetic variability
a genetic constraint it is the connection of one allele with multiple traits
lack of genetic variation
a genetic constraint that prevents an organism from making a change that would improve its fitness because it lacks the prerequisite genes.
is a compromise between traits based on how those traits preform in the enviroment
adaptations are constrained because all traits must have evolved from previous traits
what is the only mechanism that by itself can produce adaptation
the H-W principile is used to test what hypothesis
that currently there ar no evolutionary factors taking place on the particular gene in question. and the previous generation mated randomly
code for immunity and H-W test proved evolution was occuring
what does genetic variation mean for evolution
high genetic variation is better for change and low genetic variation is worse for change.
what does directional selection do to genetic variation
it decreases it
what is a fixed and lost allele
within a population a fixed allele is one that is adopted by every member and the lost allele is the allele that was in competition that none of the organisms have it is common in directional selection but not always evident
example of directional selection
large cliff swallows survived because they had more fat stores in a cold snap so the large allele became dominant for survival. might not be fixed though
what form of selection can lead to speciation
a type of selection where organisms that are heterozygous have an advantage over homozygous this allows for genetic variation to remain in a population.
no particular allele has a distinct advantage instead there is a balace of several alleles in terms of their fitness and frequency. this usually happens because an enviroment varies over time meaning there is a heterozygous advantage, it also happens because some alleles are rare and favored over common ones like guppies who mate with rare patterned individuals because common patterns get recognized and eaten first.
what is a completly random force of evolution and why
genetic drift because it is a change in alleles due to blind luck
a random change in allele frequency where one allele becomes more common than another
a specific allele that causes a distinctive phenotype
if most of the evolutionary mechanisms lead to a loss of genetic diversity how is it recovered?
what is the ultimate source of genetic variation
if mutation stopped would evolution still occur
what are the possible outcomes of hybridization
reinforcement of divergence founding of hybrid zones extinctions of one population or the creation of new species
what does a branch represent
a population through time
a point when an ancestral species split into two or more descendant species
a group or species
phylogenies created by dna sequence similarities
infering trees based on similarity in charactaristics
4.5 billion years ago to 550 million years ago major events were formation of the earth, asteroid bombardment origin of life first cells photosynthesis first true animals and ended by cambrian explosion
550-250 million years ago means anchient era most phla appeared and diversity was booming, major events were the first arthapods land plants fish animals with jaws tetrapods and reptiles ended by permian extinction
middle life had dinosaurs mammals birds and flowering plants and first mammals cretaceous extinction ended
means recent life wsa the age of mamals includes first horses primates whales great apes and humans.
southern hemisphere continents
northern hemisphere continents