7.7 Common Ancestry

• Common ancestry refers to the principle that all living organisms on Earth descended from a single ancient ancestor
• Embryology is the study of the development of embryos
• What is embryology the study of?

  Development of embryos
• What do pharyngeal arches develop into in vertebrates?

  Head and neck structures
• What genetic material do all living organisms use?

  DNA
• The DNA sequence for a conserved gene is identical in humans and chimpanzees
• What does the principle of common ancestry propose?

  All organisms share ancestors
• Homologous structures are similar in different species despite their function
• Biogeography supports common ancestry by aligning geographical distribution with evolutionary relationships
• Shared developmental stages among organisms suggest common ancestry.


  True
• Homologous structures have the same function in different species.

  False
• Shared developmental stages in embryology indicate common ancestry.


  True
• Shared developmental stages among different organisms indicate common ancestry.


  True
• The tail is present in all adult vertebrates.

  False
• What does the fossil record show about organisms over time?

  Evolutionary changes
• Fossils provide a historical record of life and support the idea of common ancestry.

  True
• Match the evidence type with its significance:

  Fossil Records ↔️ Historical record of life

  DNA Evidence ↔️ Shared genetic links

  Homologous Structures ↔️ Suggest shared origin

  Vestigial Structures ↔️ Evidence of evolutionary relationships
• What are homologous structures, and what do they suggest about evolution?

  Similar structures, shared origin
• Which embryonic features are shared by vertebrates such as mammals, birds, and fish?

  Notochord and pharyngeal arches
• Vertebrates share embryonic features such as a notochord and pharyngeal arches
• The comparison of developmental stages demonstrates a shared genetic blueprint
• Highly similar sequences of key proteins across species indicate evolutionary relationships
• Arrange the types of evidence from the fossil record in order of their significance for common ancestry:

  1️⃣ Transitional forms

  2️⃣ Shared anatomical features

  3️⃣ Sequential appearance in the geological record

  4️⃣ Fossils of extinct species
• What is the study of evolutionary relationships among organisms called?

  Phylogeny
• What does the root of a phylogenetic tree represent?

  Most recent common ancestor
• Arrange the components of a cladogram in order from base to tip:

  1️⃣ Root

  2️⃣ Nodes

  3️⃣ Branches

  4️⃣ Tips
• The tips of a cladogram represent current species or groups.

  True
• Steps involved in interpreting a cladogram

  1️⃣ Identify the root

  2️⃣ Follow branches to tips

  3️⃣ Determine divergence points

  4️⃣ Understand evolutionary relationships
• Fossil records provide evidence for common ancestry by showing transitions and shared features between species.


  True
• Vestigial structures are evidence of evolutionary relationships because they showcase traits no longer necessary in modern species
• Vertebrates share similar embryonic features like a notochord and pharyngeal arches, indicating common ancestry.


  True
• What is one piece of molecular evidence that supports common ancestry?

  Shared genetic material
• What does the similarity in DNA sequences highlight across species?

  Common origins
• Transitional forms in the fossil record show evolution from ancestral forms
• A cladogram is a diagram that shows the evolutionary relationships between different groups of organisms
• Evolutionary lineages demonstrate shared traits among species to support common ancestry.


  True
• Common ancestry is a cornerstone of biodiversity, explaining how species can trace back to a shared evolutionary starting point.


  True
• Modifications to developmental pathways lead to species-specific traits while retaining core processes.

  True
• All living organisms use DNA as their genetic code.

  True
• The fossil record provides evidence for transitional forms between species.


  True