Natural Selection Flashcards
What are Darwins five points of natural selection
- Populations have variations
- Some variations are favourable
- More offsprings are produced than survive
- Those that survive have favourable traits
- A population will change over time
What is natural selection
Natural selection is the process by which certain inherited traits make it easier for some individuals to thrive and multiply, changing the genetic makeup of population over time. An idea by which only the organism that are best adapted to their surrounding environment tend to survive and reproduce to pass on favourable traits to succeeding generations whereas those less adapted with less favourable traits will be eliminated.
What is artificial selection
Artificial selection is the intentional breeding of individuals in a population that have desirable traits
Eg. Breeding cows with high milk yield
Individuals that show more desirable traits are chosen to breed together, succeeding generation will have increased frequency of desired traits and process is repeated for many generations until entire population show the desired trait.
What is speciation
When species evolve or diverge into a new species
It involves physical isolation of populations and divergent evolution which occurs overtime.
what is adaption
The inherited characteristic that allows the individuals to survive and reproduce is called an adaption
Fitness is always relative because the impact of natural selection depends on both the environment and the genotype a present in a population
What is adaptive radiation
Adaptive radiation is the rapid divergence of an evolutionary lineage from a recent common ancestor. A cluster of related species is considered to evidence of adaptive radiation.
Eg.darwins finches
What is geographical isolation
It is also known as allopatric speciation and is the physical isolation of populations that begins the process of speciation
Eg. Rivers changing course, mountains rising, continents drift, organism migrate & what was once a continuous population is divided into two or more smaller populations
What is reproductive isolation
Reproductive isolating mechanisms prevent the interbreeding of members of different species when they come into contact.
Reproductive isolation can be either prezygotic (barriers that prevent fertilisation) or postzygotic (barriers that occur after zygote formation such as organisms that die as embryos or those that are born sterile and are unable to produce offspring) hybrids!
Darwins finches
13 species of finches on Galapagos island were found to have a common ancestor however they were different species. Speciation occurred to due different environments and food sources and finches evolved to adapt to their environments.
Variation in a population can occur due to?
Random mutation - DNA replication and viral infection
Sexual reproduction - meiosis, crossing over and random assortment of chromosomes
And random fertilisation
What are examples of struggles for survival
Competition for food Disease Parasitism Predation Competition for mates Competition for space
What is biological fitness
Biological fitness is measured by the relative proportion of fertile offspring left by an individual to the next generation
Mutations selected for VS mutations selected against
Individuals that can best competed in the struggle for survival will survive and reproduce and pass on the trait, mutation or trait that is less well suited to environment makes it more difficult for the individual to survive thus individual is less likely to pass on trait.
