95.Most of new species are formed by the process of-
(1) Anagenesis (2) Sympatric speciation
(3) Cladogenesis (4) Convergent evolution
The origin of new species—speciation—is a fundamental topic in evolutionary biology. While several mechanisms can lead to the emergence of new species, the process that accounts for the majority of speciation events is known as cladogenesis.
What Is Cladogenesis?
Cladogenesis is the evolutionary process where a single ancestral species splits into two or more genetically distinct descendant species. This “branching” evolution results in increased biodiversity and the formation of new evolutionary lineages. Each branch represents a new species that is reproductively isolated from the others, allowing them to evolve independently.
How Does Cladogenesis Occur?
Cladogenesis typically happens when populations of a species become reproductively isolated, often due to geographic separation (allopatric speciation), ecological differences, or other isolating mechanisms. Over time, genetic divergence accumulates, leading to the emergence of distinct species.
Why Is Cladogenesis the Dominant Mode?
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Branching Evolution: Most new species arise from the splitting of lineages, not from the transformation of an entire population into a new form.
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Biodiversity: Cladogenesis increases the number of species, contributing to the tree-like pattern of evolution observed in nature.
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Supported by Fossil and Genetic Evidence: The fossil record and genetic studies show frequent branching events, consistent with cladogenesis as the main driver of speciation.
Cladogenesis vs. Anagenesis
| Feature | Cladogenesis | Anagenesis |
|---|---|---|
| Evolutionary Path | Branching (splitting into two or more species) | Linear (one species transforms) |
| Biodiversity | Increases | No net increase |
| Commonality | Most common mode of new species formation | Less common |
Other Speciation Processes
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Sympatric speciation: New species arise within the same geographic area, but this is less common than branching events.
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Convergent evolution: Unrelated species evolve similar traits, but this does not create new species from a single lineage.
Conclusion
Most new species are formed by the process of cladogenesis—the splitting of a parent species into two or more distinct species. This branching pattern of evolution is the foundation of the diversity of life we see today.
Correct answer:
(3) Cladogenesis
