Evolution, Fossils, Speciation + Classification (paper 2) Flashcards
Evolution definition
gradual change in the
inherited characteristics of a population over a long period of time through a process of natural selection which may result in the formation of a new species
what does the theory of evolution by natural selection state
that all species of
living things have evolved from simple life forms that first developed more than three billion years ago
how does evolution arise
through natural
selection of variants that give rise to phenotypes best suited to their environment
how do you know when 2 populations of 1 species has formed into 2 new species
so different in phenotype that they can no longer interbreed to produce fertile offspring
what are the key ideas for the theory of evolution by natural selection
- individual organisms within a particular species who a wide range of variations for a characteristics –> mutations can also give rise to new variants
- individuals with characterics most suited to the environment are more likely to survive to breed successfully**
- that characteristics that have enable these individuals to survive are them passed onto the next generation –> advantageous alleles passes into offspring during reproduction
describe the process of evolution by natural selection
- genetic variation caused by mutations in the species
- those with the desirable characteristics survive + reproduce = survival of the fittest
- the allele that codes for tha characteristics gets passed down to offspring
over many generations, those with the desirable alleles increase and outcompete those without
the theory of evolution by natural selection was only gradually accepted because:
- the theory challenged the idea the God make all animals and plant that live on Earth
- Insufficient evidence at the time the theory was published to convince many scientists
- the mechanism of inheritance / genetics and variation was not know until 50 years after the theory was published
who else had a theory
Jean-Baptiste Lamarck
what was Lamarck’s theory
theory that changes that occur in a organism *during its lifetime** can be inherited
speciation =
when 2 new species form from an ancestral species
Wallace independently proposed which theory
the theory of evolution by natural selection
what is Wallace best know for
- work in warning colouration
- theory of speciation
describe the stages which give rise to new species
- genetic variation exists within a species / or random mutations leads to new variants
- population of a species become geographically isolated from each other (geographical barrier)
- the separate population are exposed to different environmental conditions
- natural selection occurs differently in both populations
- this occurs over many generations
- if two population reunite, no longer able to interbreed to produce fertile offspring - have become different species
bacteria can ………… …………… because they ………….. at a ……… ……….
evolve rapidly
reproduce
fast rate
how does antibiotics bacteria occue
- in all population there is variation
- mutations also occur naturally + spontaneously
- mutations occur in pathogenic bacteria
- this produces new strains of bacteria
- some strains might be resistant to antibiotics
