Modern Synthetic Theory Evolution

The Modern Synthetic Theory of Evolution integrates Darwin's natural selection with genetics, combining ideas from multiple scientific fields. It explains evolution as a process driven by genetic variations, mutations, gene flow, and natural selection. In this article, modern synthetic theory, factors of the modern synthetic theory of evolution, key elements of the modern synthetic theory, and evidence for the modern synthetic theory are discussed. Modern Synthetic Theory is a topic of the chapter Evolution in Biology.

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This Story also Contains

1. What is the Modern Synthetic Theory?
2. Factors of Modern Synthetic Theory of Evolution
3. Key Elements of Modern Synthetic Theory
4. Evidence for Modern Synthetic Theory

What is the Modern Synthetic Theory?

Modern Synthetic Theory integrates principles of natural selection and Mendelian genetics as a single theory of evolution. This theory incorporates Darwin's model of the evolution of species through natural selection with our present understanding of genetic inheritance to present a comprehensive framework for studying biological evolution.

The theory is critical in biology due to explanations for what diversified life on Earth is, showing how modifications in genetics and environmental conditions fuel evolutionary change. Having integrated knowledge of different biological sciences, the Modern Synthesis has changed our view of the evolutionary processes of change and adaptation of species over time. The modern synthesis began with the synthetic theory of evolution in the early twentieth century. It brought together some of Darwin's and Mendel's findings, representing the biochemical and evolutionary points of view. Key contributions by scientists like Ronald Fisher, J.B.S. Haldane, and Sewall Wright provided mathematical models of genetic variation and selection pressures within populations.

Factors of Modern Synthetic Theory of Evolution

Several factors lead up to the Modern Synthetic Theory of Evolution, all of which are equally important in the shaping of populations over time.

Genetic Recombination

• Reshuffling of alleles during meiosis

• New combinations of genes

• Increased genetic variation

Mutation

• Changes in the DNA sequence

• Beneficial, neutral, or harmful

• Source of new genetic variation

Genetic Drift And Gene Flow

• Genetic drift: Random change in allele frequencies

• Bottleneck and founder effects

• Gene flow: Gene migration across populations

• Introduction of new genes, thus decreasing population differences

Natural Selection

• Variation in survival and reproduction

• Select for beneficial traits

• Adapts in time

Isolation

• Geographic, reproductive or behavioural barriers

• Prevents gene flow between populations

• This can lead to speciation

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Key Elements of Modern Synthetic Theory

Key elements of the Modern Synthetic Theory describe how evolution works through some mechanisms and processes.

Genetic Variation

• Sources of genetic variation include mutation, recombination, and gene flow.

• Necessary for evolution, as it provides the raw material for natural selection.

Natural Selection

• The process by which individuals who have positive traits are more likely to survive and reproduce.

• Examples: Peppered moths and antibiotic resistance in bacteria

Genetic Drift

• Random changes in the frequency of different alleles are significant in small populations.

• Examples: bottleneck effect and founder effect

Gene Flow

• Movement of genes from one population to another by migration.

• Reduces genetic variation among populations and increases genetic variation.

Speciation

• Formation of new species.

• Allopatric speciation, physical isolation due to geographic change.

• Sympatric speciation, no physical barriers to organism distribution.

Evidence for Modern Synthetic Theory

The Modern Synthetic theory has significant amounts of evidence to back up its findings, showing the reason behind evolutionary theory.

Fossil Record

• Transitional fossils – species in intermediate form.

• Temporal patterns in evolutionary change.

Molecular Biology

• Similarities and differences in DNA and proteins reflect genetic relationships.

• Comparative genomics allows the establishment of evolutionary relationships.

Embryology

• Developmental similarities of species reflect common ancestry.

• Homologous structures in embryos indicate evolutionary relationships.

Biogeography

• The geographic distribution of species reflects evolutionary history.

• Adaptive radiation illustrates diversification from a common ancestor.

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