Podcast
Questions and Answers
Which type of group contains an ancestor and all of its descendants?
Which type of group contains an ancestor and all of its descendants?
A polyphyletic group accurately reflects the evolutionary history of its members.
A polyphyletic group accurately reflects the evolutionary history of its members.
False
What is the primary basis for classifying organisms in cladistics?
What is the primary basis for classifying organisms in cladistics?
Common ancestry
A _____ group includes some descendants of an ancestor but not all of them.
A _____ group includes some descendants of an ancestor but not all of them.
Signup and view all the answers
Match the following groups with their characteristics:
Match the following groups with their characteristics:
Signup and view all the answers
What does relatedness between taxa primarily indicate?
What does relatedness between taxa primarily indicate?
Signup and view all the answers
Phylogenetic trees are always accurate regardless of the taxa included.
Phylogenetic trees are always accurate regardless of the taxa included.
Signup and view all the answers
What type of shared characters are used in cladistics to define clades?
What type of shared characters are used in cladistics to define clades?
Signup and view all the answers
Which of the following statements accurately describes homologous traits?
Which of the following statements accurately describes homologous traits?
Signup and view all the answers
Analogous traits are a result of convergent evolution.
Analogous traits are a result of convergent evolution.
Signup and view all the answers
What is the purpose of using an outgroup when constructing phylogenies?
What is the purpose of using an outgroup when constructing phylogenies?
Signup and view all the answers
In cladistics, __________ are traits that are unique to a group and arise from a common ancestor.
In cladistics, __________ are traits that are unique to a group and arise from a common ancestor.
Signup and view all the answers
What distinguishes a derived character from an ancestral character?
What distinguishes a derived character from an ancestral character?
Signup and view all the answers
Match the following terms with their definitions:
Match the following terms with their definitions:
Signup and view all the answers
Define convergent evolution in your own words.
Define convergent evolution in your own words.
Signup and view all the answers
In a taxonomic hierarchy, the category directly above species is __________.
In a taxonomic hierarchy, the category directly above species is __________.
Signup and view all the answers
Which of the following statements about phylogenetic trees is TRUE?
Which of the following statements about phylogenetic trees is TRUE?
Signup and view all the answers
All species alive today are considered more evolved than extinct species.
All species alive today are considered more evolved than extinct species.
Signup and view all the answers
What is the significance of L.U.C.A in evolutionary biology?
What is the significance of L.U.C.A in evolutionary biology?
Signup and view all the answers
Grouping species based on only a few specific shared traits can lead to inaccurate __________ classifications.
Grouping species based on only a few specific shared traits can lead to inaccurate __________ classifications.
Signup and view all the answers
What is cladistics primarily focused on?
What is cladistics primarily focused on?
Signup and view all the answers
Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
Signup and view all the answers
Sister taxa are groups that share a more recent common ancestor with each other than with other taxa.
Sister taxa are groups that share a more recent common ancestor with each other than with other taxa.
Signup and view all the answers
Why is it essential to base phylogenetic studies on molecular sequences today?
Why is it essential to base phylogenetic studies on molecular sequences today?
Signup and view all the answers
Study Notes
BIO1130 Part 2
- Lectures are in-person
- No lecture videos pre-class
- Learning activities in class
- Lectures recorded and posted on BrightSpace
- Additional Wooclap quizzes for topics 8-16 (ungraded)
- Midterm 2 covers topics 8-12 (by Pr. Delcourt)
- Pr. Delcourt's office hours:
- Monday 1:00 pm - 2:00 pm
- Tuesday 10:00 am - 11:00 am
- Location: BSC 108
Topic 7: Systematics
- Systematics combines taxonomy and phylogenetics
- Write genus & species names using Linnaean nomenclature
- Distinguish between homologous and analogous traits (importance of this distinction)
- Explain how analogous traits evolve
- Interpret phylogenetic trees, relating branching patterns to evolutionary relationships
- Define common phylogenetic tree terms (root, branch, tip, common ancestor, clade, mono-/para-/polyphyletic, taxon/taxa, sister taxa, ingroup/outgroup)
- Explain basic principles of cladistics
- Explain use of morphology/molecular data in phylogenetic tree construction
- Distinguish ingroups and outgroups
- Distinguish shared derived and shared ancestral characters
- Define parsimony and its use in phylogenetic tree construction
- Reconstruct simple phylogenetic trees using molecular data and parsimony
- Compare/contrast cladogram and phylogram
- Explain methods for adding dates to phylogenetic trees
7.1 - Definitions and Taxonomy
- Systematics is the science of classifying organisms & determining evolutionary relationships
- Two components:
- Taxonomy: scientific discipline of naming & classifying organisms
- Phylogenetics: study of evolutionary relationships
- Phylogenetic tree: diagrammatic hypothesis of evolutionary relationships; resulting from phylogenetic analysis
7.2 - Phylogenetic Trees
- Phylogenetics: study of evolutionary relationships
- Originally based on morphological similarities (still used for fossils)
- Modern approaches use molecular sequences (DNA, RNA, proteins) for more accurate analyses.
- Phylogenetic analyses result in phylogenetic trees, hypotheses of evolutionary relationships among a set of taxa
7.3 - Constructing Phylogenies
- Cladistics: An approach to systematics where common ancestry is the primary basis for classification. This approach uses homologies to define clades or monophyletic groups.
- Implications: Taxonomy should reflect evolutionary history and organisms should be categorized into nested monophyletic groups for phylogenetic studies.
- Evidence for common ancestry comes from shared derived characters (unique traits present in a group due to common ancestry).
Cladistics
- A clade includes a common ancestor and all its descendants (living and extinct).
- By definition, clades are monophyletic
- Clades are nested within one another
- Many existing taxonomic groups are not monophyletic (e.g., class Reptilia is paraphyletic; clade Dinosauria is only monophyletic if birds are included).
Constructing Phylogenies
- Phylogenies can be built using morphological and molecular data.
- Evidence for common ancestry comes from homologous traits (shared characters from common descent).
- Analogous traits are misleading, as they can result from convergent evolution.
- Homologous traits are further categorized into ancestral and derived types.
Adding Time to Trees
- Cladogram: Shows branching patterns only (branch lengths are arbitrary).
- Phylogram: Shows branching patterns where branch lengths are proportional to either genetic change or time.
Dating Branching Points (Nodes)
- Can be done using:
- Fossils (in combination with radiometric or stratigraphic dating)
- Molecular clock (assumes rate of nucleotide substitutions constant over time for a gene).
Molecular Clock
- Molecular clocks are calibrated using known fossil dates.
- Different genes have varying rates of molecular change due to differing selective pressures.
Convergent Evolution
- Independent evolution of similar traits in different lineages.
- Creates analogies (similarities not due to shared ancestry, but rather by shared environment or independent mutations).
Constructing Phylogenies
- Shared derived characteristics are unique to a group, resulting from a common ancestor
- Using an outgroup (species outside of the group of interest) can help infer evolutionary relationships between the ingroup (the group of interest)
- Systematists compare members of the ingroup with the outgroup to identify shared derived vs ancestral traits
- This process ultimately helps to group members of the ingroup based on shared derived traits and determine branching points
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on systematics, covering taxonomy, phylogenetics, and cladistics principles. This quiz will help you distinguish between homologous and analogous traits, interpret phylogenetic trees, and understand important terminology in evolutionary biology. Get ready to apply what you've learned in class!
