Topic 2,3,4:Taxon systematics, Evolution Darwin, Evolution of a population Flashcards
What are the 7 characteristics of life
-order(cellular structures)
-regulation (regulation of metabolism, internal condition, temperature)
-energy processing/metabolism(process food, and reject waste)
-growth and development
-reproduce (make more individuals)
-respond to environment (they move away or defend against threat)
-evoltuioary adaptaton
is bacteria alive? are viruses alive? (using the 7 characteristics of life)
bacteria:
they reproduce, they have cellular structures, they can develop resistance to antibiotics
viruses: on its own it lacks the ability to achieve life.. so it isn’t
who developed the idea Scala naturae, and what is it?
Aristotle developed it
-Its the natural ladder, that was organized by complexity,humans are placed on the top since they are the most complex, superior beings
-species are fixed meaning that their have been perfectly created to match their environment
whats Taxonomy and its, and who created it
its the practice of naming and classifying organism, it was created by Carl Linnaeus
whats Nomenclature
a system of rules for naming things
whats systematics
the theory/ practice of classifying organisms based on evolutionary history (phylogeny)
whats phylogeny
it describes the evolutionary history of organisms that have evolved from a common ancestor
why are common names problematic
-their are different names for the same species
-same name for different species
-common names can also imply relationships that do not exist
ex.”northern waterthrush” isn’t a thrush but a warbler
what did Linnaean propose due to the confusion of using common names in science
-to use latin as universal language of scientific nomenclature (the rules for naming things)
-use unique binomen as name of each species
-classify and group species using a hierarchical category based on relatedness and or similarity (taxonomy)
who created the Binomial system of nomenclature
Carlos Linnaean
Whats the Linnaean system
-each species has a unique binomen
Binomial names have 2 parts:
1.genus name
2.specific name
both are italicized and genus is capitalized
together the genus and specific make the species name
the Linnaean system of classification (taxonomy levels)(classification)
(least related)Kingdom->Phylum->Class->Order->Family->genus->species (most related)
whats the name of the organisms in the nested subsets (taxonomic levels)
Taxa
Systematics- What are phylogenetic trees
they are evolutionary trees that show the evolutionary relationship between organisms (past and present):between common ancestors and their descendants
Phylogenetic trees are hypothesis for the evolutionary relationships
whats a taxon
named group at any level of classification
whats a clade
its a group that contains the all the descendants and its common ancestor
whats a polytomy
a word to describe a node that is linked to three or more descendants, this happens when the evolutionary relationship between the descendants is unresolved
what information is collected to construct phylogenetic trees
-Morphology (the argument/ structure of parts of an organism)
-Behaviour
-DNA sequences
-Biochemistry
whats phylogentics
its the study of the evolutionary relationship between taxa (species or individuals or genes)
what do branch points or nodes in phylogenetic trees symbolize
a common ancestor and a speciation event has occurred for the common ancestor to become 2 separate taxa
whats cladistics
its a method of biological classification which organism are categorized in groups based in shared derived characteristics from a common ancestor
sister taxa
are the most closely related
-they split from the same node
The In-group
the clade that is being studied
The Out-group
the one or more taxa that are distantly related to the in-group (clade being studied), they have diverged from the in-group at an earlier time
Character and state
the character is the type of structure, behaviour, DNA sequence
The state is the manifestation of that charter
ex. character : eye colour, state: orange
whats parsimony?
tells us that the most possible answer is the one that is simplest
Synapomorphy and Symplesiomorphy
when including the out-group and in-group the trait is synapomorphy (shared and derived)
but when only the in-group it is Symplesiomorphy (shared, ancestral state)
whats more useful for reconstructing phylogenetic trees (Synapomorphy or Symplesiomorphy)
synapomorphy
Homologous vs Analogous Characters
Homologous the same and have the same evolutionary origin (present in common ancestor of the taxa)
Analogous-appear the same but evolved separately (this is called covergent evolution)
covergent evolution
its the in-dependent evolution of similar features in different linages
Molecular phylogenetics
is the dominant form of identifying if taxa are related or not
-its the matching of bases in selected gene sequences
the more matches there are between species the more likely they are closely related
Monophyletic
(a trait present in this group is…)
contains the common ancestor and all its descendants (clade)
-traits present in monophyletic groups are HOMOLOGOUS TRAITS-since they are similar and have the same evolutionary origin
Polyphyletic group
(and the possible outcomes of when this might show up)
(traits present in this group is…)
taxa that are clumped together although they do not share a common ancestor
-more than one common ancestor
-lacking a common ancestor that unifies the taxa being clumped up
this group is created due to superficial similarities not due to common ancestry- COVERGENT EVOLUTION/ ANALOGOUS TRAITS
Paraphyletic group
a group that doesn’t contain all the descendants of a common ancestor
-this often results in removal of taxa due to it being highly different from the paraphyletic group
what did Cuvier Hypothesize, and how did that influence Darwin’s thinking
-although Cuvier didn’t believe in evolution he was the first to demonstrate that the different levels of strata contained its own mammal fauna(the animals of a particular region, habitat, or geological period) which ultimately supported Darwin’s theory of evolution
-Cuvier believed the reason why each level of strata contained its own mammal fauna was because of the theory of catastrophism-that species only evolve after a mass extinction event occurs that wipes out all the species before
-catastrophe->local extinction->presence of fossils in
the stratum->new species
Correlation of parts
-a Cuvier principle
-basically that all organs in an animal are interdependent(dependent on each-other), any change would result in inability to survive
what did Lamarck Hypothesize, and how did that influence Darwins way of thinking
-he proposed the first idea of how traits are passed from parent to offspring which is through inheritance of acquired characteristics (that if an organism changes during life in order to adapt to its environment, those changes are passed onto their offspring) however this is incorrect because its traits that are linked to a gene that can be passed on, not a trait that developed suing ones life and wasn’t present since birth.
-Darwin adopted lamarck’s idea that “organism march their environment though gradual evolutionary change
what did James Hutton hypothesize, and how did that influence Darwin’s way of thinking
- he advocated uniformitarianism and gradualism
-uniformitarianism is the idea that forces and processed observed at earth surface (the present) are the same that have shaped the earths landscape through natural history (present is key to the past)
-gradualism is that geological change is due to the accumulation of small changes such as those we see occurring now-not through catastrophism
-hames hutton’s idea that ancient mechanism had been at work since the beginning of the earth inspired dawn’s theory of evolution
why does Lamarck deserve more recognition
Lamarck was the first to propose the theory of evolution- and thus the first to propose a testable mechanism by which evolution had occurred (which is that parents traits that they acquired during their life their offspring would acquire)
what did Darwin see in his HMS beagle(a voyage around the world)
-Darwin saw similarities(unity ) and dissimilarities (diversity)
the flinched on different islands were different but related
-redundant forms from one place to another (common ancestry)
-variation in their use of the habitat and their way of feeding (due to decent with modification”)
how did all these similarities and dissimilarities arise?
Descent with modification
why where islands important to the theory of evolution
their isolation form mainlands offers the ideal place for speciation, they bread animals that are more specific to the habitat of the islands causing them to be evolve differently from the ones on the mainland
Struggle for existence-Darwin
Darwin observed:
- that organism produced way more offspring than survived to reproduce themselves
-most populations are relatively stable
-and resources are limited, meaning their wasn’t enough for all the offsprings
so he concluded that organism must compete for these limited resources and not all will succeed
concept of relative fitness-Darwin
Darwin observed :
-variation among individuals within species
-and that some of these variations are heritable
he concluded that some heritable variations are likely to provide individuals with an advantage, and these individuals are likely to survive and thus produce more offspring
whats Descent with modification
through natural selection (the process by which populations adapt and change ) may cause new species to arise over time
-populations evolve not individuals
what process gives rise to adaptations
natural selection
Natural selection
-only acts on existing variations
-is context dependent- meaning it doesn’t yield perfection, instead it yield adequacy of adaptation
what are heritable variations
types of heritable variations include :
-genetic makeup -genotypic
-form-phenotypic
function- phenotypic
behaviour -phenotypic
in order for natural selctions to act on variations they must be…
seen by the environment (phenotypic) and heritable (caused by a genotype)
(true of false) natural selection random
false
(true or false) variations are random
true
what are sources of variation
-mutations -random change to DNA
-recombination (crossing-over)
-independent assortment chromosomes move randomly to separately poles during meiosis)
-fertilization (sexual reproduction-get a variation of the 2 parents unlike binary fission which is exact replica of the individual)
whats a population
the species that occupy a specific region
whats selective agent
component of natural environment that consistently cause differential
survival and/or reproduction
they could be abiotic factors (such as temperature, rainfall)
they could be biotic factors (such as predators, diseases, competition)
whats selection pressure
the intensity of which the selective agent acts on the population to evolve
the process of adaptation
-heritable variation-individuals vary in their characteristics (phenotype) due to varied genetic makeup(genotype)
-resources are limited-populations produce more offspring that the environment can sustain
-some phenotypes are better suited to survive and reproduce, which means that the majority of the next generation will have this feature since it increases their fitness
-over time the number of individual shaving this feature will increase thus giving us adaptation
evidence of evolution
1.fossil revords
2.homology-similar structures due to common ancestor
3.direct observations
4. biogeography- shows that animals that live in same environment share similar features, or that same species in differently lands can evolve differently
microevolution vs. mactorevuoltionn
microevolution is change in a population
macroevolution results in the formation of new species
whats a gene and allele
a combination of two alleles in diploid individuals
-one allele per chromosome
ex.
the gene is for eye-colour ,allele for blue eyes in one chromosome and an allele for brown eyes in the other chromosome
this is heterozugous
genetic variation
is the diversity of alleles in a population
phenotyype variation
variety in visible expression of types
why does natural selection not result in perfect adaptation
-natural selection only acts on existing genetic variation meaning we cant select for a cheetah to run faster if their is no faster gene available.
-the body must work with what it has, it cant make something out of the blue like give horses wings cause that will help them find food faster
natural selection operates on
phenotype
lesser variation graphs vs. greater variation graphs
lesser variation has a narrow graph with a center having a higher peack than the greater variation graph
evolution is in terms of alleles is…
change in the frequencies of alleles in a population (gene pol) between generations
factors that can change allele frequencies
1.mutation
2.gene flow
3.genetic drift
4.sexual selection
5.natural selection
how does sexual selection affect allele frequencies
-non random mating increases or decreases the probability that a specific individual will mate, because of preferred phenotypes
-this may decrease genetic variation since one phenotype is being favoured and actually creating offspring
how do mutations affect allele frequencies
mutations are the change in an individuals DNA
-this can be caused by error in DNA replication
-or damage to the DNA via radiation
Mutations are random-the environment doesn’t select for the right mutation to arise, in-fact most mutations are dangerous and lessen the fitness of animals
they can be good, bad or neutral in current situation (this means that that mutation can later on be advantageous)
Lederberg experiment-what did it disprove
- bacteria spread out on a plate , called “the original plate”
2.they form colonies
3.the layout of the colonies is stamped form the original and put into another plate that contains antibiotic penicillin - 2 colonies survive meaning they must carry a mutation for penicillin resistance
5.then the original plate is also exposed to penicillin, and the same 2 colonies survive on this plate
it disproved that the bacteria evolved that resistance due to the exposure of it, because it clear that they in-fact had it all along when the original plate also the same
How does Gene flow affect allele frequencies
its the transfer of alleles between populations
the variation within the population increases, however the variation between the populations decreases
how does genetic drift affect allele frequencies
changes in allele frequencies due to change (so regardless of natural selection)
-the allele frequencies “drifts from one population to the next , it impacts is seen greater in small populations
examples: Bottleneck, and founder effect
founder effect vs. Bottleneck effect
-founder effect is when a new population is established by a few colonizers (this new population represents a small fraction of the total genetic variation compared to the ancestral population )
-Bottle neck effect is when a natural disaster occurs that only leaves a few individuals to survive, so the next generation frequency is different than the previous generation
How is genetic variation maintained in a population
-genetic variation is maintained by the introduction of new alleles or new allele frequencies from outside the pop.
-mutations
-recombination
-independent assortment
-fertilization
-disruptive selection
-gene flow
-negative frequency-dependent selection
Heterozygote advanatge
What are the mechanisms of natural selection
-directional selection
-disruptive selection
-stabilizing selection
Directional selection (does it maintain or decrease genetic variation)
is when the graph is concentrated on one side (directional shift in the means of the pop.)t
- one extreme phenotype is favoured (highest fitness)
-it causes a decrease in genetic variation
-this is a response to steady changes in the environment
Disruptive selection (does it maintain or decrease genetic variation)
-Both extremes are favoured not the average
-it results in polymorphism (2 or more divergent phenotypes)
-this maintains genetic variation
-also called diversifying selecion
Stabilizing selection (does it maintain or decrease genetic variation)
-when the average-the intermediate- the common phenotype is favoured, meaning there is a selection against the extremes( which eliminates harmful mutations)
-the variance decreases
-it decreases population genetic variance
negative frequency-dependent selection vs positive frequency-dependent selection
negative-selects for the rare phenotype in a population and increases the genetic variance
positive-selects for the common phenotype in a pop which decreases variance
Heterozygote advanatge
is when an organism with 2 different alleles has higher fitness than one with identical alleles
what are fossils
are preserved remains, impressions and traces of any once-living thing from a past geographical age
