Population Genetics Flashcards
Population
Group of organisms of 1 species that interbreed & live in the same place at the same time
Gamete fond
Set of gametes in population
Genofond (gene pool)
Set of genes (alleles) in population
Population parameters
Size (n)
Effective size
Generation interval
Genotype & allelic frequencies
Hardy-Weinberg Equilibrium
Frequency of alleles & genotypes in population will remain constant from generation to generation if population is stable & in genetic equilibrium
Conditions required in order for a population to remain at HW equilibrium
Population is large, panmitic & mating of individuals of same generation
NO natural selection, mutation, genetic drift or gene flow
Types of reproduction
Inbreeding
Autogamy
Outbreeding
Panmixia
Inbreeding
When close relatives mate
Autogamy
Self-fertilisation
Outbreeding
When unrelated individuals mate
SELECTION
Selection
Differential survival & reproduction of individuals in a population due to traits differences
Fitness
Reproductive efficiency
Natural selection
Mechanism that can lead to adaptive evolution
trait under selection must be inheritable
Evolution
Process of change in allele frequencies over time
Can be caused by selection & other forces
Panmixia
Condition of HW equilibrium
Genetic drift
Changes in gene pool of small population due to errors in propagation of alleles from 1 generation to next
Bottleneck effect
Population undergoes a drastic reduction in size as a result of genetic drift
Inbreeding & autogamy ->RESULTS
Allele frequencies are not changed
Genotype frequencies are changed
Reduction of f of heterozygotes
Increasing of f of homozygotes
Outbreeding -> RESULTS
Change in allelic & genotype frequencies
Important for evolution
Mutation -> RESULTS
Change in allelic frequencies
Important for evolution
Genetic drift -> RESULTS
Change in allelic frequencies between generations (fixation of some alleles, elimination of some alleles)
Reduction of heterozygotes
Increasing of homozygotes
Decreasing of genetic variability
Bottleneck effects -> RESULTS
Changing of allelic frequencies
Gene flow
Occurs when alleles are exchanged between 2 populations
Gain or loss of alleles from a population due to migration of fertile individuals or from the transfer of gametes
Gene flow -> RESULTS
Change in allelic & genotype frequencies
Increasing of genetic variability in population
Practical application of population genetics
Genetic diseases
Problems with small populations
Study of evolution
Genetic diseases
Study of the frequencies of genetic diseases in populations
Treatment (prevention) of genetic disases
Genetic diseases are influenced by
Mutation Selection Genetic drift Gene flow Inbreeding
Problems with small populations -> RESULTS
Fixation of unfavourable alleles
Increasing of homozygotes
Decreasing of genetic variability
Decreasing of fitness -> disease
Study of evolution
Phylogenetic tree
Neutral mutation
Phylogenetic tree
Illustrate evolutionary relationship among biological species under graphical form
Organisms are classified descending from common ancestor
Built from morphological data or molecular data
Neutral Mutation
Change into pos./neg. mutation is influenced by genetic drift
Speed of change is known as molecular clock
Biological evolution
Historical development of life forms, their origin & disappearance
Biological evolution - levels of studies
Microevolution
Speciation
Macroevolution
Microevolution
Changes in populations of 1 species
Changes in frequencies of diff. allelic forms of genes within (small) population
Mechanisms: Inbreeding & genetic drift
Speciation
Origin of new species
Macroevolution
Evolution of higher taxa than species
Theory of punctuated equilibrium: alternation of stasigenesis & evolutionary activity
Phylogeny
Historical development of organisms, ancestral lineages
Ontogeny
Development of an individual (embryo, fetus, etc.)
Lamarackism
Organisms possess inborn ability & will to change towards more perfect or complex forms
Lamarackism - main postulates
1) Change of env. evokes active need for the change of organisms which is achieved by using organs
2) Acquired adaptions are transferred by heredity to offspring (neck of giraffe)
Darwinism
Origin of species by means of natural & sexual selection
Darwinism - main postulates
Common origin of organisms Permanent change Gradualism Multiplication of species Natural selection Sexual selection Heritable variation within populations
Neo-darwinism
Synthesis of Mendelian genetics & population genetics
Population is important, individual is not important
Synthesis of mathematic, genetic, systematic, paleontology, biochemistry, ecology, etology…
Genecentric aspect - selection of alleles, evolution
Basic mechanisms of evolution
Heritable variability
Changing environment
Natural (sexual) selection
Heritable variability
Precondition for natural selection
Source of variability: mutations & recombinations
Changing environment
Drives evolution by means of adaptions
Natural (sexual) selection
Carriers of advantageous mutations have more offsprings
Asexual reproduction
Advantage in stable environment
Sexual reproduction
Advantage in changing environment
Greater genetic variability by recombination:
1) crossing-over during meiosis
2) segregation of chromosomes during meiosis
3) fertilisation
Coevolution
Evolution of 2 or more species influenced by mutual relations
Long term results of microevolution
Subpopulations with different natural selection -> subspecies _> new species
Example of microevolution
Industrial melanism
Biological species
Closed reproducing group Offspring belongs to the same species Unique evolutionary origin & history Unique phenotypic & genetic properties Unique ecological niche
Anagenesis
Changes in species without cleavage into evolution lines
Cladogenesis
Cleavage of evolution lines
Cladogenesis - allopatric
Geographic
Speciation with geographic isolation
Cladogenesis -sympatric
Ecologic, competitive
Speciation within population without geographic isolation
Syngenesis
Fusion of originally separate ancestral lineages
Synklepton
Participating parental populations
Klepton can hybridise with parental generation
Stasigenesis
Temporary evolutionary constancy (no development)
Mass extinction
Climatic change
Change of rules -> new starting line
Free ecological niches - adaptive radiation
Man as a source of evolutionary changes
Man alters biosphere Changes criteris New genotoxins Genome manipulation Man threatens biodivery & further existence of life on Earth
