Natural selection is a population changing over time due to the environmental pressure of existing genetic variations. Natural selection requires variation, heredity, and reproductive advantages. A specific trait needs to be frequent in a population as generations pass on. Variation means that for a specific trait, there are differences between different organisms. Heredity means those differences come from genes that were passed through parents. If you have ever seen the five fingers of evolution, it includes natural selection, gene flow, mutations, non-random mating, and genetic drift. Natural selection, as recalled, is that the population changes over time to be more suitable, while weaker organisms get killed off. Gene flow simply means immigration and the diversity and restricted gene pool in a population. Mutations are the changes in the alleles available. Non-random mating is choosing a mate based on specific characteristics that are beneficial to the offspring. Genetic drift is a small population and does not make an adaptive population. Natural selection takes a very long time.
The history of natural selection
Charles Darwin is considered the founder of natural selection. He wanted to find a way to explain how all species evolved from a common ancestor. Finches were the first species that Darwin wanted to investigate and research. As Darwin traveled to different parts of the world, he noticed the finches had different beaks. This happened because of natural selection; different types of environments influenced different types of traits. Humans and chimpanzees both have similar features, as 98% of the chimpanzee DNA matches one of the humans. The 2% difference is enormous, as humans do not have fur and many other characteristics. A scenario to explain natural selection can be described like this: A population of rabbits with big and small ears living in the desert. More predators, including snakes and birds, started appearing more frequently. Rabbits with more prominent ears could listen from far away and not become as dehydrated as the rabbits with smaller ears. As rabbits with a lower survival fitness become less frequent in a population, the rabbits with more giant ears start reproducing, and their offspring can inherit those beneficial traits. As generations and generations passed on, the rabbits that once had small ears evolved to bigger ears.
Going in Dept with Natural Selection
The term biological fitness is used in many cases concerning natural selection. Biological fitness is determined by how many offspring they have as the parents passed their DNA down to their offspring. Different effects of mutations can sometimes have no effects on fitness, but if negative, the traits will not be passed down as it is not helpful. If the mutation is positive, the trait frequency will become more likely to appear in a population over time. Lamarckism theory proposed by Jean-Baptiste Lamarck suggested that animals received characteristics to use or disuse and not because of genetic changes. This theory was proven false by Adrian mentioning how if a parent decided to strengthen their neck and their neck slowly grows taller, their offspring will not inherit the longer neck.
Evolution vs. Natural Selection
Many people confuse evolution and natural selection with each other. However, they are not the same but do connect with each other. Evolution means that every organism living on earth evolved from a common ancestor. As generations pass on, mutations occur, which changes our alleles, differentiating us from other species. Natural selection favors the positive and beneficial traits in a population as they have a higher survival fitness. The less favorable traits will slowly disappear as it becomes less suited for the environment. The population evolves to have traits better for the environment through natural selection.
Thank you for reading!
Written by: Amber Truong
Sources:
Osterloff, Emily. “What Puts the ‘bomb’ in Bombardier Beetle?” Natural History Muesuem, www.nhm.ac.uk/discover/what-is-natural-selection.html. Accessed 14 May 2021.
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