Causes of Mutations and Speciation Mechanisms
Mutations are a crucial source of genetic variation that fuels the process of natural selection. The causes and effects of mutations in species include:
- Chemicals
- Radiation
- Viruses
Highlight: Mutations can lead to antibiotic resistance in bacteria, demonstrating natural selection in action.
Other sources of variation include meiosis, which involves:
- Independent assortment of chromosomes
- Crossing over geneticrecombination
These processes contribute to intraspecific competition, where individuals within a species compete for resources. This competition leads to the survival and reproduction of organisms with advantageous alleles.
Definition: Allopatric speciation is the formation of new species through geographic isolation of populations, which reduces gene flow.
Allopatric speciation occurs when physical barriers e.g.,seas,mountains separate populations, leading to:
- Rapid genetic changes
- Alterations in morphology, behavior, and habitat preferences
Example: Islands often have distinct gene pools due to geographic isolation.
Sympatric speciation occurs without geographical isolation but still results in reduced gene flow. It can be caused by:
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Pre-mating isolation factors:
Ecological differenthabitats
Temporal differentbreedingtimes/seasons
Behavioral incompatiblecourtshipbehaviors
Physical/physiological differences
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Post-zygotic factors:
Hybrid unfitness
Hybrid sterility
Vocabulary: Polyploidy is a cell division error resulting in multiple sets of chromosomes, which can lead to reproductive isolation and speciation.
These mechanisms of speciation demonstrate how natural selection and genetic variation contribute to the diversity of life on Earth, showcasing the ongoing process of evolution in action.
