Darwin's Theory Of Artificial Selection
Group selection describes natural selection operating between groups of organisms, rather than between individuals. This would produce adaptations that benefit the group, rather than the individual. Darwin's theory of evolution was based upon individual selection, and he rejected the idea of group selection.
Artificial selection is the selective breeding carried out by humans to alter a population. It is a procedure often used in agriculture: artificial selection has been used to alter the number of eggs laid by hens, the meat properties of bullocks, and the milk yield of cows.
Asexual reproduction is the production of offspring by virgin birth or by vegetative reproduction: that is, reproduction without sexual fertilization of eggs (see …show more content…
Fitness values are between 0 and 1. The fittest individual has a fitness of 1, and the fitness of the other members of the population can be expressed as 1 - s, where s is the selection coefficient.
The fitnesses of different genotypes are among the most important variables - perhaps the most important variables - in the theory of evolution. They determine, to a large extent, which genotypes we can expect to see in the world today.
There are three methods for measuring fitness:
• Measure the relative survival of the genotypes within a generation. Kettlewell's mark-recapture experiment with the peppered moth is an example.
• Measure changes in gene frequencies between generations. We then substitute the measurements into the formula that expresses fitness in terms of gene frequencies in successive generations.
• Measure deviations from the Hardy- Weinberg ratios - this is used in estimating fitness in the case of sickle cell anemia.
A measure of mean fitness is commonly applied in population genetics.
The idea of a fitness landscape is particularly useful for thinking about complex genetic …show more content…
Phylogenetic relations have to be inferred using homologies because the splitting events and common ancestors existed in the past and cannot be directly observed.
There are two methods of phylogenetic inference:
1. Parsimony. Species are arranged in a phylogeny such that the smallest number of evolutionary changes is required.
2. Distance (or similarity.) Species are arranged in a phylogeny such that each species is grouped with the other species that it shares the most characters with.
the Red Queen remarks
"here, you see, it takes all the running you can do, to keep in the same place".
The analogy for running is coevolutionary change.
Coevolution can be escalatory:
In the Red Queen mode of coevolution, natural selection continually operates on each species to keep up with improvements made by competing species; each species environment deteriorates as its competitors evolve new adaptations. Evolution is said to be escalatory.
In sexual reproduction, a new organism is formed by the fusion of two gametes. It is to be contrasted with asexual reproduction, in which females produce offspring without any male contribution; the female's gametes develop directly into female
Artificial selection is the selective breeding carried out by humans to alter a population. It is a procedure often used in agriculture: artificial selection has been used to alter the number of eggs laid by hens, the meat properties of bullocks, and the milk yield of cows.
Asexual reproduction is the production of offspring by virgin birth or by vegetative reproduction: that is, reproduction without sexual fertilization of eggs (see …show more content…
Fitness values are between 0 and 1. The fittest individual has a fitness of 1, and the fitness of the other members of the population can be expressed as 1 - s, where s is the selection coefficient.
The fitnesses of different genotypes are among the most important variables - perhaps the most important variables - in the theory of evolution. They determine, to a large extent, which genotypes we can expect to see in the world today.
There are three methods for measuring fitness:
• Measure the relative survival of the genotypes within a generation. Kettlewell's mark-recapture experiment with the peppered moth is an example.
• Measure changes in gene frequencies between generations. We then substitute the measurements into the formula that expresses fitness in terms of gene frequencies in successive generations.
• Measure deviations from the Hardy- Weinberg ratios - this is used in estimating fitness in the case of sickle cell anemia.
A measure of mean fitness is commonly applied in population genetics.
The idea of a fitness landscape is particularly useful for thinking about complex genetic …show more content…
Phylogenetic relations have to be inferred using homologies because the splitting events and common ancestors existed in the past and cannot be directly observed.
There are two methods of phylogenetic inference:
1. Parsimony. Species are arranged in a phylogeny such that the smallest number of evolutionary changes is required.
2. Distance (or similarity.) Species are arranged in a phylogeny such that each species is grouped with the other species that it shares the most characters with.
the Red Queen remarks
"here, you see, it takes all the running you can do, to keep in the same place".
The analogy for running is coevolutionary change.
Coevolution can be escalatory:
In the Red Queen mode of coevolution, natural selection continually operates on each species to keep up with improvements made by competing species; each species environment deteriorates as its competitors evolve new adaptations. Evolution is said to be escalatory.
In sexual reproduction, a new organism is formed by the fusion of two gametes. It is to be contrasted with asexual reproduction, in which females produce offspring without any male contribution; the female's gametes develop directly into female