Natural SelectionDarwin’s theory :
Natural SelectionDarwin’s theory Charles Darwin proposed a theory which did not rely on a supernatural theory to explain why beings exist. He explained that we had arisen from a primitive common ancestor millions of years ago. He suggested that we had evolved through a series of changes.
Natural selectionDarwin’s theory :
Natural selectionDarwin’s theory NATURAL SELECTION is the survival of organism that are best suited to their environment. These individuals then pass on their advantageous genes too their offspring = basis of EVOLUTION He noticed various stages leading to the ‘weeding out’ of organisms:
Overproduction- a species produced more offspring than can actually survive.
Variation- resulting from Mutation, Independent assortment, crossing over, and multiple alleles.
Selection pressures- abiotic, and biotic.
Natural SelectionExamples :
Natural SelectionExamples Malanic moth at a selective advantage
Speciation :
Speciation A species is a group of organisms that share a common gene pool: All the alleles present in the species
may be divided into different populations Isolating Mechanisms:
Geographical
Ecological
Reproductive Mechanisms of Speciation
ISOLATION> MUTATION> NATRUAL SELECTION> NEW SPECIES!
Adaptive Radiation :
Adaptive Radiation This is the evolution of many new species from a common ancestor
Each new species is specifically suited to surviving in it’s environment.
It takes place over a long period of time
(Usual speciation method takes place). An individual that has a selective advantage is more likely to survive when conditions change The finches evolved to fill the available ecological niches. The lifestyle an organism has within a particular ecosystem