What were the main ideas of Darwin's theory?

Answer 1

1) A group of organisms tend to reproduce more offspring than the environment can support.

2) Most populations tend to remain fairly constant in size because of various population regulation mechanisms at work, e.g., density-dependent factors and density-independent factors regulating population size. The population comes into an equilibrium with its present environment. (See your notes.)

3) Competition takes place because so many individuals are introduced into an environment with limited resources. There is a "struggle for existence." Such a competitive struggle for existence usually includes being better adapted for obtaining the available resources in comparison to other individuals. Especially note that physical combat is not a very important part of this concept.

4) There exists variation among individuals within any species because genetic changes occasionally occur that modify the DNA structure of chromosomes.

5) Variations caused by gene mutations are usually either harmful or useless. However, over the course of time, beneficial mutations may occur. Individuals that inherit beneficial mutations or beneficial gene recombinations are better adapted to survive. This is where the phrase "survival of the fittest" comes in or the process of natural selection. Again note that such a competitive struggle for existence usually includes being better adapted for obtaining the available resources in comparison to other individuals and that physical combat is not a very important part of this concept.

6) In a changing environment, those organisms with favorable genetic variations survive. The surviving organisms then reproduce and transmit their DNA to their offspring. Over a long period of time ENTIRELY NEW SPECIES EVOLVE. Organisms that have successful genetic variations not only live longer but produce more offspring who also inherit the favorable adaptation.

Answer 2

Darwin's theory of evolution proposed that species change over time through a process of natural selection, where individuals with advantageous traits are more likely to survive and reproduce. This process leads to adaptation and the divergence of species from a common ancestor. Darwin also emphasized the importance of variation within populations and the role of competition in driving evolutionary change.