variation Flashcards
what does variation mean
differences in characteristics (phenotypes) between individuals - presence of variation
what does interspecific variation mean
variation between members of different species
what does intraspecific variation mean
Differences between individuals of the same species. can be influenced by genetics , the environment or both
what causes variation
1) genetic = mutations in chromosomes and genes
2)environmental = sexual reproduction = random assortment, crossing over, random fertilisation
how can we measure variation in a population
what factors reduce the likelihood of any sample being biased
by sampling
-random sampling, large sample, analysis of data
what are the two major types of variation and explain them
discontinuous:
-qualitative
-controlled by one or two genes
-largely unaffected by the environment
continuous:
-quantitative
-controlled by many genes
-significantly affected by the environment
what are examples of continuous and discontinuous variation
continuous:
-height, heart rate, intelligence, rate of photosynthesis, number of leaves, number of flagella on bacterium
discontinuous:
-human blood group
-flower colour
-sex in mammals or plants
describe how variation is fundamental to the process of natural selection and evolution
-mutations create alternative alleles = create intraspecific variation, then environment will exert a selection pressure when conditions change e.g loss of resources/ presence of antibiotic
-individuals with advantageous characteristics passed to next gen = next gen higher proportion of individuals with successful characteristics, over time the group becomes adapted
what are examples of selection pressures that can give rise to problems that can affect the human population
-antibiotic resistance: antibiotic is the selection pressure causing reproduction of advantageous /resistant bacteria =natural selection e.g MRSA
-pesticide = resistant bugs reproduce
