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BIO 94

Terms in this set (108)

Organism
A life form made of one or more cells
Cells
A highly organized compartment that is bounded by a thin, flexible structure called plasma membrane and that contains concentrated chemicals in an aqueous solution
Information
Hereditary or genetic information is encoded in units called genes. Organisms also respond to information from the environment and adjust to maintain stable internal conditions
Replication
Reproduction, replication of onself
Evolution
A change in the characteristics of a population over time. It means that species are not independent and unchanging entities, but are related to one another and can change through time. Occurs when heritable variation leads to differential success in reproduction.
cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells (the experiment of the straight necked flask and the swan necked flask) also implys there is a common ancestor of all living things
theory of evolution by natural selection
states that organisms that are better suited for their environments will survive and reproduce compared to those that are poorly suited for their environments amd wont have as much reproductive success
Heritable
Characteristics or traits that can be passed on to offspring. In a particular environment, certain versions of these heritable traits help individuals survive better or reproduce more than do other versions
Population
A group of individuals of the same species living in the same area at the same time
Natural selection
The process of evolution, Remember it acts on individuals, but evolutionary change occurs in populations. Remember during the process of natural selection, individuals do not change only the population does.
There is no mechanism that makes it possible for natural selection to change the nature of an allele inside an individual natural selection just sorts existing variance it does not change them
Artificial selection
Changes in population is that occur when humans select certain individuals to produce the most offspring (maize example for kernal protein levels)
Fitness
The ability of an individual to produce viable offspring, th higher the blank the more offsping the organism produces
Adaptation
A heritable trait that increases the fitness of an individual in a particular environment
Speciation
When natural selection causes populations of one species to diverge and form new species
Tree of life
A family tree of organisms that describes the genealogical relationships among species with a single ancestral species at its base. Created from evidence of RNA sequences and similarities between organisms.
Phylogeny
"Tribe source" or the hustory or an organism/species
Eukaryotes
Organisms which cells have a membrane bounded nucleus, Are typically multicellular
Prokaryotes
Organisms that cells lack A nucleus, Are typically unicellular
Bacteria
Domain of unicellular prokaryotes that have cell walls containing peptidoglycan
Archaea
Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan
Eukarya
Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals
Taxon
group or level of organization into which organisms are classified
Phylum
Refers to major lineages within each domain
Genus
Made up of closely related group of species.
Species
A group of organisms that are closely related and can mate to produce fertile offspring, or that share similar traits and DNA
null hypothesis
Specifies what should be observed when the hypothesis being tested isn't correct
Special creation
1) All species are independent, in the sense of being unrelated to one another 2) life on earth is young, about 6000 years old 3)speach es are incapable of change
Pattern component
Series of observations about the natural world
process component
a mechanism that produces that pattern or set of observations
Typological thinking
Based on the idea that species are unchanging types and that variations within the species are unimportant of even misleading
Population thinking
The view of variation among individuals in a population being key to understanding the nature of species.
Why was the theory of evolution by natural selection revolutionary?
1. It overturned the idea that species are static and unchanging.
2. It replaced typological thinking with population thinking.
3. It was scientific. It proposed a mechanism that could account for change through time and made predictions that could be tested through observation and experimentation.
extant species
species living today
Geological time scale
a sequence of named intervals called eons, eras, and periods that represented the major events in Earth history
radiometric dating was based on?
1) observed decay rates of parent to daughter atoms 2) The ration of parent to daughter atoms present in the newly formed rocks 3) The ratio of paren to daughter atoms present in a particular rock sample
Transitional feature
a trait in a fossil species that is intermediate between those of ancestral and derived species
vestigial traits
a reduced or incompletely developed structure that has no function, or reduced function, but is clearly similar to functioning organs or structures in closely related species
Phylogenetic tree
...
Homology
The study of likeness
Genetic homology
Similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor.
Developmental homology
A similarity in embryonic form, or in the fate of embryonic tissues, that is due to inheritance from a common ancestor.
Structural homology
A similarity in adult morphology or form
Polly genetic traits
Meaning that many genes, each one exerting a relatively small affect, influence the trait. Because many genes are involved, it can be difficult for rechargers to know exactly which alleles are changing in frequency when these traits are involved
Lamarckian Inheritance
1) individuals change in response to challenges posed by the environment 2) The changed traits are then passed on to offspring
In other words the important evolutionary changes occur in individuals
Aclimatization
A change in an individuals phenotype that occurs in response to a change in natural environmental conditions. Phenotypic changes due to Aqua to musician are not passed on to offspring, because no alleles have changed as a result acclimatization does not cause evolution
Evolution is not progressive
It is true that groups appearing later in the fossil record are often more morphologically complex than closely related groups that appeared earlier but there is nothing predetermined about this tendency. In fact, complex traits are routinely lost or simplified overtime as a result of evolution by natural selection. Populations that become parasitic are particularly prone to loss of complex traits
Fitness trade off
It compromise between traits, in terms of how those traits perform in the environment. For example larger finches were able to scare off smaller finches and acquire more food, but because they were larger birds they needed more food they were also slower and less agile. Because selection acts on many traits at once every adaptation is a compromise.
Historical constraints
all traits have evolved from previously existing traits. Basically not all traits are adaptive and even adapt and traits are constrained by genetic and historical factors
Gene flow
Occurs when individuals leave one population, join another, and bread. I will frequencies may change when gene flow occurs, because arriving individuals introduce alleles to their new population and departing individuals remove the leaves from the old population.
Mutation
Modifies allele frequency's by continually introducing new alleles. The alleles created by mutation may be beneficial or deleterious or have no affect on fitness
Hardy Weinberg principle
A mathematical no hypothesis for the study of evolutionary processes
Gene pool
If all the illegals from all of the gametes produced in each generation go into a single group then combine at random to form offspring
Hardy-Weinberg Equations
Allele Frequencies: p+q=1
Genotype frequencies: (p^2)+(2pq)+(q^2)=1
Hardy Weinberg conditions
Random meeting, no natural selection, no genetic Jeff, no gene flow, no mutation
Inbreeding
Increases homozygosity, does not cause evolution, because allele frequency's do not change in the population as a whole.
Inbreeding increases the frequency of homozygous recessive individual's. Loss of function mutations are usually deleterious or even lethal when they are homozygous, they are quickly eliminated by natural selection
deleterious alleles
Alleles that lower fitness
Inbreeding depression
The decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population
Sexual selection
Females often don't me at random but actively choose certain emails, and or males compete among themselves to secure our meats
Genetic variation
The number of relative frequency of alleles that are present in a particular population. Lack of genetic variation in a population is usually a bad thing
Directional selection
Changes the average value of a trait
The average phenotype of a population changes in one direction
Purifying selection
when disadvantageous alleles decline in frequency
Stabilizing selection
Reduces variation in a treat
There is no change in the average value of a tree over time, and genetic variation in the population is reduced
Disruptive selection
Increases variation in a trait
Has the opposite effect of stabilizing selection
Illuminates phenotypes near the average value and favors extreme phenotypes. Overall amount of genetic variation in the population is maintained
Balancing selection
Maintains variation in a trait
Occurs when no single allele has a distinct advantage instead there is balance among several alleles in terms of their fitness and frequency
Occurs when: 1) there is heterozygote advantage 2) the environment varies overtime or indifferent your graphical areas occupied by population, certain alleles are favored by selection at different times are in different places as a result genetic variation in the population is maintained or increased 3) Frequency dependent selection
Heterozygote advantage
Heterozygous have a higher fitness than homozygous individuals do. The consequence of this pattern is that genetic variation is maintained in populations
Frequency dependent selection
Certain alleles are favored when they are rare but not when they are common
Ex) where are alleles responsible for coloration in guppies are favored because predators learn to recognize common color patterns. Alleles for common colors get illuminated; alleles for rare colors increase in frequency. As a result, overall genetic variation in the population is maintained or increased
Intersexual selection
The selection of an individual of one gender for meeting by an individual of the other gender
intrasexual selection
When individuals sometimes compete with one another to obtain mates, selection within a gender
Carotenoids
Carotenoids protect tissues and simulate the immune system to fight diseases more effectively.
Animals usually cannot synthesize their own carotenoids, but plants can. To obtain carotenoids animals have to eat carotenoid rich plant tissues.
the animal that is brightest colored is the best fed and has the best immune system
Sexual dimorphism
Refers to any trade the difference between males and females
Ecological or environmental selection
Favors traits that enable organisms to do things other than of teammates, such as survive in their physical and biological environments
Sampling error
Occurs when the allele frequency's of a chosen subject of a population the sample are different from those in the total population, by chance.
genetic drift
The movement of alleles from one population to another
Genetic drift is random with respect to fitness
Most pronounced in small populations
Overtime genetic drift can lead to the random loss or fix station of alleles causing genetic variation in the population to decline
Genetic marker
A specific allele that causes a distinctive phenotype
founder effect
When a group of individuals immigrants to a new geographic area and establish as a new population
Genetic bottleneck
A sudden reduction in the number of alleles in a population
Mostly due to natural disaster (drought, fire)
Gene flow
The movement of alleles between populations (also referred to as allele flow)
Mutation
A mistake in DNA, RNA or amino acid sequencing
The ultimate source of genetic variation
The only way to create new alleles
Without mutations evolution would eventually stop
Mutation is so rare that it wouldn't do much without the help of genetic drift, gene flow and selection
Point mutation
If a change in nucleotide sequence occurs in a stretch of DNA that codes for a protein, the new allele may result in a polypeptide with the novel amino acid sequence. If the mutation occurs in a stretch of DNA that codes for regulatory are in it, the new allele may result in a change in regulation of the expression of other alleles
Chromosome level mutation
One consequence of chromosome mutation is gene duplication, which increases the number of copies of a gene. If duplicated genes diversified by a point mutations, they can lose their function or create new alleles
Lateral gene transfer
The transfer of genes from one species to another, rather than from parent to offspring, might be an important source of genetic variation
Species
An evolutionary independent population or group of populations
biological species concept
the main criterion for identifying species is reproductive isolation
Pros: enables clear evidence of evolutionary independence
Cons: cannot be applied to fossils or animals that don't have contact with one another
prezygotic isolation
Temporal: breed at different times
Habitat: breed in different habitats
Behavioral: do not interbreed because their courtship displays differ
Gametic barrier: eggs and sperm are incompatible
Mechanical: male and female reproductive structures are incompatible
postzygotic isolation
Hybrid viability: hybrid offspring do not developed normally and die as embryos
Hybrid sterility: hybrid offspring mature but are sterile as adults
morphospecies concept
identify evolutionary independent lineages by differences in size, shape, or other morphological features
Pros: wildly applicable
Cons: may lead to th naming of two or more species when there is only one polymorphic species with different phenotypes, such as the spotted and black morphs of jaguars
Cannot identify cryptic species, which differ in traits other than morphology, such as meadowlarks
The morphological features used to distinguish species are subjective, different researchers working on the same populations disagree on the characteristics that distinguish species
Polymorphic species
A species that has two or more distinct phenotypes in the same interbreeding population at the same time.
Cryptic species
Groups of organisms that are genetically distinct and do not interbreed, but are morphologically almost indistinguishable
Phylogenetic species concept
identifies species based on the evolutionary history of populations
monophyletic group, Clade or lineage
consists of an ancestral population, all of its descendants, and only those descendants
synapamorphy
A trait that is found in certain groups of organisms and their common ancestor, but it missing in more distant ancestors
subspecies
populations that live in discrete geographic areas and have distinguishing features, such as coloration or calls, but are not considered distinct enough to be called separate species
allopatric speciation
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.
Vicariance
the physical splitting of a habitat
Bio geography
The study of How species and populations are distributed geographically
Sister species
are each other's closest relatives
Sympatric speciation
speciation that occurs in populations that live in the same geographic area
Niche
Describes the range of ecological resources that a species can use and the range of conditions that it can tolerate
Polyploidy
Occurs when an error in meiosis or mitosis results in a doubling of the chromosome number, a massive mutation
These individuals are reproductively isolated from the original diploid population
Autopolyploidy
individuals are produced when a mutation results in a doubling of chromosome number and the chromosomes all come from the same species
allopolyploid
individuals are created when parents that belong to different species mate and produce an offspring with two different sets of chromosomes
Reinforcement
Natural selection for traits that isolate populations in the way of choosing not to interbreed and waste their eggs on lower fitness hybrid offspring
Hybrid zone
a geographic area where interbreeding occurs and hybrid offspring are common
Fusion of the populations
The two populations freely interbreed
Reinforcement of divergence
if hybrid offspring have low fitness, natural selection favors the evolution of traits that prevent interbreeding between the populations
Hybrid zone formation
Hybridization occurs in a well-defined geographic area. This area may move over time or be stable.
Extinction of one population
if one population or species is a better competitor for shared resources, then the poorer competitor may be driven to extinction
Creation of new species
if the combination of genes in hybrid offspring allows them to occupy distinct habitats or use novel resources, they may form a new species
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