Asked by daniel
Examples that show
between species DNA show
, and give evidence of evolution.
All Answers 1
Answered by
GPT-5 mini
AI
Here are several concrete DNA examples that show relationships between species and provide evidence for evolution. For each I give what is observed and why it supports common descent or evolutionary change.
- Human vs. chimpanzee nucleotide similarity
- Observation: Humans and chimpanzees have genomes that are roughly 98–99% identical at the nucleotide level.
- Why it supports evolution: Such high genome-wide similarity indicates a recent common ancestor; the pattern of shared and species-specific differences (substitutions, insertions/deletions) matches the branching order inferred from fossils and anatomy.
- Shared endogenous retroviruses (ERVs)
- Observation: Many retrovirus-derived sequences are inserted at the same genomic locations in humans and other primates.
- Why it supports evolution: The chance of the same retroviral insertion happening independently at the same site in different lineages is negligible. Shared insertions are best explained by inheritance from a common ancestor.
- Shared pseudogenes (broken genes)
- Observation: Some genes required for making vitamin C (GULO) are nonfunctional pseudogenes in humans and other primates but are functional in many other mammals.
- Why it supports evolution: The same disabling mutations in these pseudogenes across related species indicate those changes occurred in a common ancestor and were inherited by descendants.
- Conserved developmental genes (Hox, Pax6)
- Observation: Hox and other developmental regulatory genes have very similar sequences and functions across insects, worms, and vertebrates.
- Why it supports evolution: Deep conservation of both sequence and role in body patterning implies descent from a common ancestor with a basic genetic toolkit that was modified over time.
- Highly conserved proteins (histones, ribosomal RNA, cytochrome c)
- Observation: Core proteins and rRNAs required for basic cellular function show very similar sequences even between distant species (e.g., animals and yeast).
- Why it supports evolution: Strong sequence conservation reflects common ancestry and functional constraint; the degree of divergence often correlates with the time since lineages split.
- Gene duplication and new functions (opsin genes, antifreeze proteins)
- Observation: Duplication of opsin genes in some primate lineages produced the red/green vision pigments used for trichromatic color vision; antifreeze glycoproteins in Antarctic fish evolved from a duplicated digestive-enzyme gene.
- Why it supports evolution: These examples show how gene duplication followed by mutation can create new gene functions that adapt lineages to new environments.
- Synteny and chromosomal rearrangements
- Observation: Large blocks of gene order (synteny) are conserved across mammals, with predictable rearrangements between lineages (e.g., human vs. mouse chromosomes).
- Why it supports evolution: Conserved blocks plus specific rearrangements provide a record of shared ancestry and the stepwise chromosomal changes that occurred after lineages split.
- Mitochondrial DNA phylogenies and human migration
- Observation: Mitochondrial DNA sequences group human populations in ways that match geography and the fossil record (used to infer “Mitochondrial Eve” and Out-of-Africa patterns).
- Why it supports evolution: Patterns of maternal-line differences and coalescence times are explained by branching descent and population history.
- Molecular phylogenies matching fossils and morphology
- Observation: Trees built from DNA sequences (many genes) generally recapitulate relationships inferred from anatomy and the fossil record (e.g., whales nested within artiodactyls).
- Why it supports evolution: Independent data types converging on the same branching patterns strongly support common descent rather than random similarity.
- Rapid evolution observed in real time (antibiotic resistance, viral evolution)
- Observation: Bacterial genomes acquire mutations and mobile genes that confer antibiotic resistance; viruses accumulate mutations that change host range or antigenicity.
- Why it supports evolution: These are direct demonstrations of selection acting on genetic variation to change populations over short time-scales.
Takeaway: DNA sequences provide multiple, independent lines of evidence—shared identical insertions, matching pseudogenes, conserved genes and proteins, patterns of similarity and difference that fit branching trees, and observed genetic change under selection—all of which are best explained by descent with modification (evolution).
- Human vs. chimpanzee nucleotide similarity
- Observation: Humans and chimpanzees have genomes that are roughly 98–99% identical at the nucleotide level.
- Why it supports evolution: Such high genome-wide similarity indicates a recent common ancestor; the pattern of shared and species-specific differences (substitutions, insertions/deletions) matches the branching order inferred from fossils and anatomy.
- Shared endogenous retroviruses (ERVs)
- Observation: Many retrovirus-derived sequences are inserted at the same genomic locations in humans and other primates.
- Why it supports evolution: The chance of the same retroviral insertion happening independently at the same site in different lineages is negligible. Shared insertions are best explained by inheritance from a common ancestor.
- Shared pseudogenes (broken genes)
- Observation: Some genes required for making vitamin C (GULO) are nonfunctional pseudogenes in humans and other primates but are functional in many other mammals.
- Why it supports evolution: The same disabling mutations in these pseudogenes across related species indicate those changes occurred in a common ancestor and were inherited by descendants.
- Conserved developmental genes (Hox, Pax6)
- Observation: Hox and other developmental regulatory genes have very similar sequences and functions across insects, worms, and vertebrates.
- Why it supports evolution: Deep conservation of both sequence and role in body patterning implies descent from a common ancestor with a basic genetic toolkit that was modified over time.
- Highly conserved proteins (histones, ribosomal RNA, cytochrome c)
- Observation: Core proteins and rRNAs required for basic cellular function show very similar sequences even between distant species (e.g., animals and yeast).
- Why it supports evolution: Strong sequence conservation reflects common ancestry and functional constraint; the degree of divergence often correlates with the time since lineages split.
- Gene duplication and new functions (opsin genes, antifreeze proteins)
- Observation: Duplication of opsin genes in some primate lineages produced the red/green vision pigments used for trichromatic color vision; antifreeze glycoproteins in Antarctic fish evolved from a duplicated digestive-enzyme gene.
- Why it supports evolution: These examples show how gene duplication followed by mutation can create new gene functions that adapt lineages to new environments.
- Synteny and chromosomal rearrangements
- Observation: Large blocks of gene order (synteny) are conserved across mammals, with predictable rearrangements between lineages (e.g., human vs. mouse chromosomes).
- Why it supports evolution: Conserved blocks plus specific rearrangements provide a record of shared ancestry and the stepwise chromosomal changes that occurred after lineages split.
- Mitochondrial DNA phylogenies and human migration
- Observation: Mitochondrial DNA sequences group human populations in ways that match geography and the fossil record (used to infer “Mitochondrial Eve” and Out-of-Africa patterns).
- Why it supports evolution: Patterns of maternal-line differences and coalescence times are explained by branching descent and population history.
- Molecular phylogenies matching fossils and morphology
- Observation: Trees built from DNA sequences (many genes) generally recapitulate relationships inferred from anatomy and the fossil record (e.g., whales nested within artiodactyls).
- Why it supports evolution: Independent data types converging on the same branching patterns strongly support common descent rather than random similarity.
- Rapid evolution observed in real time (antibiotic resistance, viral evolution)
- Observation: Bacterial genomes acquire mutations and mobile genes that confer antibiotic resistance; viruses accumulate mutations that change host range or antigenicity.
- Why it supports evolution: These are direct demonstrations of selection acting on genetic variation to change populations over short time-scales.
Takeaway: DNA sequences provide multiple, independent lines of evidence—shared identical insertions, matching pseudogenes, conserved genes and proteins, patterns of similarity and difference that fit branching trees, and observed genetic change under selection—all of which are best explained by descent with modification (evolution).
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