If you look around at your family circle, you will probably find that you have inherited some physical characteristics, such as your nose or the color of your eyes, from a family member. Evolution deals with this process of inheritance of characteristics from generation to generation. But what factors are there that influence this process and thus change the gene pool of a generation? These factors are called evolutionary factors. The most important factors are the mutation, the recombination, the selection, the gene drift and the gene flow.
You want to know more about evolution? Then take a look at the explanation on this topic.
Evolutionary Factors Definition
Under evolutionary factors fall processes that change the gene pool of a population. Taken together, the genes of a species change due to various factors, such as mutation, recombination, etc.
Interplay of evolutionary factors
The most recent theory of evolution, the synthetic theory of evolution, combines Darwin’s knowledge and some modern branches of biology, such as genetics, ecology and ethology. The synthetic theory uses population genetics to explain some evolutionary processes.
A population is a group of individuals of a species that can live and breed together. These individuals differ in their genotypes. Each carrier can have a maximum of two different alleles of a gene. There can be up to 50 different alleles per gene in a population. Because of this, the gene pool of a population is much larger than that of an individual. Alleles of a gene occur at different frequencies in a gene pool. This frequency is also called allele frequency or allele frequency.
Figure 1: Factors influencing the gene pool of a population
Mutations and genetic recombination occur randomly. These two evolutionary factors always lead to an increase in the genetic diversity of the population’s gene pool. As a result, the gene pool of the population can constantly change. Of the newly created variants, those that are best adapted to the environment always prevail in the end. This process is called selection.
The allele frequency of a population is reassembled by gene drift. The isolation of a subpopulation results in two so-called daughter populations. There is no gene exchange between the two populations. There are therefore some differences in the characteristics.
If you have trouble remembering the different factors, try to memorize the clear graphic – this will help you to remember the most important characteristics.
Evolutionary factors – mutation and recombination
The two evolutionary factors mutation and recombination are described in more detail below. Both are random changes in an individual’s DNA sequence.
evolution factor mutation
Since mutations can occur randomly and at different locations, it is not possible to say when and which gene will mutate. Mutations can be caused by so-called mutagens. Mutagens are e.g. B. chemical substances or radiation. There are three types of mutation. The most significant for evolution is gene or point mutation. This type of mutation occurs when the DNA is altered at the molecular level. This creates new alleles.
If you want to learn more about this topic, you can look in the corresponding chapter «Mutation as an evolutionary factor».
Evolution factor recombination
Genetic recombination occurs randomly and describes the redistribution of the genetic makeup of the parents. The redistribution creates new combinations of alleles that lead to new phenotypes.
The recombination can look different:
- Interchromosomal recombination: The paternal and maternal gametes are randomly combined into a zygote during meiosis. During this process, the homologous chromosomes are randomly distributed, then reshuffled and combined.
- Intrachromosomal recombination: This recombination affects homologous chromosomes. Here genes are exchanged by crossing-over. Sections of the chromosome, also known as chromatids, are exchanged with the homologous partner.
You can find more information in the chapter «Recombination as an evolutionary factor».
Evolutionary Factor – Selection
Selection describes the limitation of the reproductive success of some individuals within a population. The characteristics of an individual are the target of selection. Some features are preferred, others are not. Whether an individual is more or less well adapted to its environment can be seen from the success of reproduction.
In the selection you can distinguish between three different types:
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Natural selection
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sexual selection
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Artificial Selection
By the way, there is also a separate explanation for the selection if you want to know more about this topic!
Biotic and abiotic selection factors
When making a selection, you can also add in biotic (inanimate) and abiotic (living) selection factors can be distinguished. Biotic factors can also intraspecific and interspecific factors are divided.
Selection factors exert permanent pressure – too selection pressure called – towards the development of species. Selection pressure can be both positive and negative.
The various factors all work simultaneously in an ecosystem. In the end, the populations that were best able to adapt to all influences prevail. By the way, this is the one mentioned above natural selection!
Examples of selection factors
A few examples of the various selection factors are given below. You can find more examples in the already mentioned further articles.
Biotic selection factor: coevolution
Coevolution describes the mutual adaptation between living beings. In this way, individuals who interact with one another over a longer period of time can develop independently of one another. An example of this are bees and bumblebees and various types of plants. Pollen and nectar serve as a food source for the In turn, insects and plants benefit from the pollination of animals.
Abiotic selection factor: temperature
Individuals of the same animal species in colder areas tend to have shorter appendages than their relatives in warmer areas. This phenomenon is in the Allen’s rule summarized. For example, the arctic hare, which lives in Greenland and North America, has significantly shorter ears than its relative, the California jackrabbit, which lives in California.
Evolutionary Factor – Genetic Drift
Genetic drift – also known as allelic drift or after the discoverer Sewall-Wright effect – is the random and rapid change in gene frequency in the gene pool of a population. Genetic drift leads to a reduction in genetic diversity.
Genetic drift has greater consequences for smaller populations than for large ones. This is because alleles can fall out of the gene pool more quickly, reducing genetic diversity more than would be the case with a larger population.
Genetic drift also underlies the founder effect, when only a few individuals colonize a new habitat, such as a pair of birds on an island. The random selection of these founder individuals alone determines the gene pool of the future island population.
Evolutionary factor – gene flow and isolation
There is gene exchange or gene flow (migration) between different populations of a species. The gene pools of the populations are very similar. Populations of different species do not exchange genes because their gene pools are too different. For example, if the populations B. are separated by geographic isolation, they develop independently of each other.
For more information you can have a look at the explanations on the bottleneck effect and gene drift as well as gene flow.
Evolutionary Factors – The Most Important
- The evolutionary factors ensure that the gene pool of a population is constantly changing. We distinguish between the factors mutation and recombination, selection, gene drift and gene flow.
- The evolutionary factors occur together and influence the gene pool of a population.
- The evolutionary factors are
- Mutation and recombination: Both factors occur randomly and undirectedly.
- Selection: This is the directed shifting of gene or allele frequencies in the gene pool of a population.
- Gene drift: It is the random and rapid enrichment or reduction of otherwise rare genes in the gene pool.
- Gene flow: Genetic material is exchanged between different populations of the same species.
proof
- Pflanzenforschung.de: Evolution and evolutionary factors. (08/25/2022)
- Spektrum.de: Evolution factors. (08/25/2022)