natural selectiom, classification, biodiversity Flashcards
define population .
- all organisms of particular species that live in the same place .
define generic diversity .
- total number of diff alleles in a population
- within population it’s increased by =
- DNA mutations (give rise to new alleles ) +
- migration of individuals with diff alleles from another population which reproduce (gene flow)
what advantage does a high genetic diversity provide ?
- ability to adapt to a change in environment , allows natural selection to occur
explain what’s meant by genetic bottlenecks ?
- when a population is greatly reduced in size —> reduced no. diff alleles in the gene pool .
- remaining population reproduce a re-populate the area —> new population with less genetic variation
explain how natural selection results in development of new characteristics
- process which species evolve
1) there’s variation within population = gene mutations cause new alleles to appear in population
2) organisms with alleles which give suited characteristics to environment more likely survive + pass genes to offspring
—> compared to indiv not have beneficial alleles
3) greater proportion individ in next generation inherited advantageous allele = pass on advantageous allele to their offspring
4) over time = frequency of advantageous allele increases in population (evolution)
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what is directional selection ?
- occurs when environmental conditions change
- individuals with phenotypes suited to new conditions will survived + pass on their genes
- over time the mean of population move towards these characteristics
give an example of directional selection
- antibiotic resistance
- bacteria with mutation allowing them to survive in presence of antibiotics will reproduce
- thus, frequency of this allele increase + population shift to have greater antibiotic resistance
what is stabilising selection ?
- occurs when environmental conditions stay the same
- individuals closest to mean are favoured, any new characteristics selected against
- results in low diversity
give an example of stabilising selection.
- birth weight = that weigh around 3kg more likely survive than those at lower or higher weights
define a niche.
- the role of a species within its environment
- species sharing same niche will compete with each other
what are the three types of adsorptions? give examples
1) anatomical (changed to body structure) e.g = fur
2) physiological (changes to bodily processes) e.g = venom production
3) behavioural (changes to actions) e.g= hibernation
explain all adaptions in detail
- behavioural - the way that an organism acts which increase its changes of survival
- physiological - processes occur within body of organism which increases it chances of survival
- anatomical = structural features of an organisms which increase changes of survival
define species .
- a group of organisms that can interbreed to produce fertile offspring
what are the advantages of courtship behaviour ?
- individuals can recognise sexually mature members of their own species of opposite sex , synchronise mating + form pair bond and successfully breed
define classification .
- the process of arranging organisms into groups