3.2 Flashcards
natural selection
explain darwins theory of natural selection
living organisms that reproduce sexually show great variety in characteristics due to mutation
they produce an excess of offspring which increases competition
some organisms gain advantageous characteristics so they are more likely to survive and pass on the advantageous characteristic to offspring and it is likely the ones who don’t have this trait will die out
define evolution
the process by which natural selection acts on variation to bring about adaptations and eventually speciation over long periods of time
define natural selection
the evolution of organisms as a result of variation leading to different phenotypes within a specific environment, the alleles which have advantageous attributes are most likely to be passed on to the next generation
define genotype
the genetic make-up of an organism with respect to a particular feature
define phenotype
physical traits expressed as a result of the interactions of the genotype with the environment
define ecology
the study of the interactions of organisms with each other and the environment they are in
define niche
the role of an organism within the habitat in which it lives
what is anatomical adaptations
adaptation involving the form and structure of an organism
what are physiological adaptations
an adaptation involving the way the body of the organism works
what is the mammalian diving response
diving mammals are suited to be under water for longer periods of time as once they are under water their heart rate drops so blood is pumped around the body less often so oxygen is used slower
their main body muscles also work more efficiently using anaerobic respiration so oxygen can focus on brain and heart
what are behavioral adaptations
an adaptation involving programmed or instinctive behavior making an organism better adapted to survive
what is selection pressure
the pressure exerted by a change in an environment or niche on individuals in a population, changes in selection pressure result in evolution of a species
explain how natural selection occurred in oysters
almost wiped out by Malpeque disease
small number of individuals carried an allele giving them resistance to the disease
the frequency of this gene in the population increased rapidly and the oyster remained the same species but are better adapted
explain how natural selection occurred in peppered moths
originally most moths were cream with black spots and some entirely black but the population of black moths remained low as they were easily visible on the pale trees so the frequency of this allele remained low until the industrial revolution occurred and trees became covered in soot and smoke causing the black butterfly allele to become advantageous so the frequency of the allele in the population increased
what is industrial melanism
the evolution of dark-coloured individuals in a habitat due to pollution
state 2 reasons in which natural selection occurs
survival
attracting a mate
