chapter 20 Flashcards
What are phylogenetic trees?
Diagrams showing evolutionary relationships among species
Phylogenetic trees provide a visual representation of how species are related through evolution.
Who introduced the concept of phylogenetic trees?
Charles Darwin
Darwin’s work on evolution laid the foundation for understanding species relationships.
What modern techniques have refined our understanding of phylogenetic trees?
Cladistics
Cladistics is a method of classifying species based on common ancestry.
Which organisms are more closely related: fungi and animals or fungi and plants?
Fungi and animals
This finding challenges traditional views of relationships among these kingdoms.
From which type of dinosaurs did birds evolve?
Theropod dinosaurs
This suggests a direct lineage between birds and certain dinosaur species.
Which groups are more closely related: crocodiles and birds or dinosaurs and modern reptiles?
Crocodiles and birds
This finding indicates a closer evolutionary relationship than previously thought.
What is the Classic Model of evolution based on?
Mendelian Inheritance
This model focuses on vertical gene transfer from parent to offspring.
What is the main source of genetic variation in the Classic Model?
Mutations
Mutations are changes in DNA that can lead to new traits.
What limitation does the Classic Model have?
Does not explain gene transfer between unrelated species
This limitation led to the exploration of Horizontal Gene Transfer.
What is Horizontal Gene Transfer (HGT)?
Transfer of genetic material between different species
HGT is significant in prokaryotes and contributes to genetic diversity.
What are the three main types of Horizontal Gene Transfer?
- Transformation
- Transduction
- Conjugation
Each type describes a different mechanism by which genetic material is exchanged.
What is transformation in the context of HGT?
Bacteria absorb free DNA from the environment
This process allows bacteria to gain new genetic traits from their surroundings.
What is transduction in the context of HGT?
Viruses transfer genes between bacteria
This mechanism can introduce new genetic material via viral infection.
What is conjugation in the context of HGT?
Bacteria transfer genes through a direct connection (pilus)
This method often involves the transfer of plasmids.
Is HGT common in eukaryotes?
Much rarer
While HGT is prevalent in prokaryotes, it occurs less frequently in eukaryotic organisms.
What is an example of HGT in plants?
Rice and millet plants share transposon-related DNA
This suggests a history of gene transfer between these species.
What is the Endosymbiotic Theory?
Mitochondria and chloroplasts evolved from prokaryotic cells engulfed by a larger cell
This theory explains the origin of some organelles in eukaryotic cells.
What does the Genome Fusion Hypothesis suggest?
Eukaryotic genes originated from multiple sources
It posits that some genes resemble bacteria while others resemble archaea.
What evidence supports the Endosymbiotic Theory?
- Mitochondria and chloroplasts have their own DNA
- They replicate independently via binary fission
- They have double membranes
These characteristics are similar to prokaryotic cells.
What is the Web of Life Model?
Proposes early prokaryotes exchanged genes through HGT instead of a ‘tree of life’
This model emphasizes the interconnectedness of early life forms.
What does the Ring of Life Model propose?
All three domains of life evolved from a common gene-swapping pool of prokaryotes
This model challenges the traditional linear view of evolutionary history.
List one key takeaway from the chapter.
- Phylogenetic trees help visualize evolutionary relationships
- HGT plays a key role in genetic diversity
- Eukaryotes evolved through genome fusion and endosymbiosis
- Modern evolutionary models challenge traditional tree models
These takeaways summarize the main concepts discussed in the chapter.
