Genetic Diversity + Adaptation Flashcards
gene mutation
any change to one or more nucleotide bases or change in sequence of bases in DNA
change to base of DNA triplet
change in amino acid sequence of the polypeptide
substitution
- nucleotide in DNA is replaced by another
nucleotide - if it codes fo are different amino acid the tertiary structure of the protein changes so the function changes
substitution with no effect
if triplet still codes for same amino acid (degenerate)
deletion
nucleotide lost from the normal DNA sequence
effect of deletion
- amino acid sequence changes to polypeptide may not function
- one deleted nucleotide causes all triplets to be read differently
chromosome mutations
change to structure or number of whole chromosome
two types of chromosome mutations
- changes in whole sets of chromosomes (3 or more sets e.g.polyploidy)
- changes in number of individual chromosomes (h.p. don’t separate during meiosis = non dis-functional)
species
group of similar organisms that can breed to produce fertile offspring
what leads to genetic diversity
differences in DNA lead to vast genetic diversity
gene
section of DNA on a chromosome which codes for polypeptides
members of the same species
same genes but different alleles
alleles
alternative forms of a gene
genotype
genetic / allele combination of an organism
phenotype
genotype and effects of the environment (expressed characteristic )
population
group of the same species , in the same place , that can interbreed
more alleles lead to …
- increased genetic diversity
- wider range of characteristics (gene pool)
- increased change of surviving environmental change
what does genetic diversity enable
natural selection
natural selection and evolution
individuals who posses right alleles successfully reproduce and pass on alleles
successful reproduction and allele frequency
reproductive success of individuals affects allele frequency
successful reproduction and allele frequency : S.R.M.G.A.S.R.P.F.F
selection pressure (some) random (really) mutations cause (mental) genetic diversity (goats) advantage (ate) survive (some) reproduce (raw) passed (premium) frequency of advantageous alleles (fish) frequency (fingers)
selection
process by which organisms that are better adapted to their environment survive and reproduce .
selection pressure
environmental change that leads to organisms that are better adapted to their environment surviving and reproducing
continuous variation
a characteristic that can have a wide range of values
discontinuous variation
- a characteristic with few possible values
- few discrete categories
characteristics
- most characteristics are really controlled by more than one gene (polyggenic)
- more influenced by environment
- continuous variation
2 Effects of selection
- directional selection
- stabilising selection
Directional selection
- favouring individuals that vary from the mean
- changes characteristics
- most resistant middle of graph
Phenotypes selected and genotypes selected indirectly
Stabilising selection
- favouring average individuals
- preserves characteristics for specific conditions
- stable condition
- phenotypes at extremes are selected against and genotypes selected indirectly
- range of phenotypes reduced
Mutations are …
- Random and rare
- Most harmful and lead to death
- Those that lead to an advantage are due to chance
- Large bacterial populations = greater chance
Adaptations due to natural section (3)
Anatomical (shorter ears / thicker fur)
Physiological (oxidising fat instead of carbs for more water)
Behavioural (e.g migration)
Reproduction
- organisms reproduce to increase survival overtime
- females of most species produce eggs at specific times
What does production of eggs at a specific time lead to
A selection pressure on courtship behaviour
What does courtship behaviour allow (3)
- Recognise members of the same species
- Identify sexually mature mate
- Form pair bond = successful mating and offspring
- beign able to breed by brining members of the opposite sex together
Classification
- organisation of living organisms into groups
+ of classifying
- better communication
- avoiding confusion / mistakes because everyone sticks to same name
- universal
- understood by taxonomists
2 types of classification
- artificial
- phylogenetic
Artificial classification
- Grouping organisms based on features that are useful at the time
- evolutionary origins a different / not considered
Phylogenetic classification
- based on evolutionary relationships between organisms
- shared homologous detoured derived from evolutionary ancestors
- hierarchies which don’t overlap
E.g of phylogenetic and artificial classification
Artificial = colour , size Phylogenetic = fossils , dna analysis
Taxonomic ranks (carl worse)
Domain (Divine) Kingdom (Kings) Phylum (Play) Class (Chess) Order (On) Family (Fat) Genus (Green) Species (Stools)
Taxon
Each group within a phylogenetic biological classification
Taxonomy
Study of taxonomic ranks
Domain
- bacteria
- archaea
- eukaryota
Binomial system
- 1st name = capital (genus)
- 2nd name (species / sp if unknown)
Phylogenetic tree
Oldest species at base and most recent at ends of branches
Phylogeny
Evolutionary relationship between organisms
History of classification
- Aristotle = first taxonomists
- binomial system = carols Linnaeus
Biodiversity
Number and variety of living organism in a particular area
Species diversity
Number of different species an number or individuals of each species within a community
Genetic diversity
Variety of genes possessed by individuals that make up a population
- number of different alleles within a population
Ecosystem diversity
Range of different habitats from a small local habitat to the whole earth
Species richness
Number of different species in a particular area at a given time
Diversity index
D = N(N-1) / {n(n-1)
+ quantitative Data
D = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
{ = sum of
Why is species richness not helpful for comparisons
2 communities may have the s we number of species but in different proportions
Ecosystem
- Community of organisms and the habitats they live in
- develop overtime and form complex communities with huge biodiversity
E.g ecosystems
- rainforest
- mountain
- desert
- tundra
Artificial ecosystem
- artificial (human control)
- farmers select desired species
Agricultural ecosystems : high or low genetic diversity
Low (genetic diversity , species richness , index of diversity)
Low biodiversity =
- few species dominate so fewer habitats / richness
- variety decreases (plants/insects/animals)
- variety of food decreases
- global living system becomes increasingly unstable
Practices that have removed habitats and reduced species diversity
- agricultural ecosystems
- economy (desired characteristic thrive)
- pesticides
Effect of intensive food production
Fewer habitats
Practices that have directly removed habitats
- removal of hedgerows / grubbing woodland
- creating mono cultures (same crops)
- filling ponds / draining marsh
- over grazing
- pesticides
- absence of crop rotation
Conservation / management techniques :
- maintain hedgerows / plants
- maintain ponds
- leave wet corners of fields
- plant native trees
- no pesticides l / organic fertilisers
- natural meadows
- leave cutting of field edges after flowering
- conservation headlands
How to determine evolutionary relationships (direct)
- physical characteristics
- observe proteins / enzymes
How to determine evolutionary relationships (indirect)
- observe amino acid sequence
- mRNA sequence
- DNA sequence
Problems with observable characteristics
- some characteristics are polygenic (more alleles)
- environment may have more of an influence than thought
Comparing DNA sequences
- read DNA sequence of any organism
- determine the Exact order of nucleotide bases
Comparing DNA sequences : +
+ now automated machines
+each base tagged with colour
Adenine(green)guanine (yellow)thymine(red)cytosine(blue)
+Produces a heat map which can be compared
Comparing DNA sequences : after speciation
- DNA sequences of new species are similar so they accumulate random mutations over time
- As a result more closely related species show more DNA similarities=phylogenetic classification
Comparing DNA sequences : more mutation
More mutations = less similar to original
Comparing mRNA
- mRNA is coded for by DNA
- mRNA Is complimentary to DNA
- Compare DNA diversity and therefore genetic diversity
Comparing amino acid sequence : amino acid determined by
MRNA which is determined by DNA sequence
Comparing amino acid sequence : used to compare ?
Used to compare genetic diversity
Comparing amino acid sequence : closer related =
More similarities in amino acid sequence
