Phylogeny and the Tree of Life Flashcards
What is phylogeny, and how does it relate to evolutionary history?
Phylogeny is the evolutionary history of a group of organisms, often depicted as a branching tree-like diagram showing their relationships.
Phylogenetic trees are used to:
a) Classify organisms based on shared characteristics
b) Show the geographic distribution of species
c) Predict the future course of evolution
d) None of the above
a) Classify organisms based on shared characteristics
Shared derived characters are traits that evolved in a common ancestor and are present in all its descendants. These characters are crucial for determining _____ _____ in phylogenetic trees.
evolutionary relationships
TF: Ancestral characters are traits that are shared by a group of organisms and their outgroups (more distantly related groups). They may not necessarily be unique to that specific group.
True
How can convergent evolution, where unrelated species evolve similar adaptations, complicate the construction of phylogenetic trees?
Convergent evolution can mislead when building phylogenetic trees because similar traits may not necessarily reflect shared ancestry. Careful analysis of multiple characters and consideration of evolutionary mechanisms are essential for accurate tree construction.
What are the two main approaches to studying phylogeny?
- Morphological systematics: Classification based on physical similarities and differences in body structures.
- Molecular systematics: Classification based on analysis of DNA and protein sequences.
Molecular systematics offers advantages over morphological systematics because:
a) It cannot be used for studying extinct organisms
b) It is easier to study DNA than physical structures
c) DNA changes accumulate over time and can provide a more accurate record of evolutionary relationships
d) None of the above
c) DNA changes accumulate over time and can provide a more accurate record of evolutionary relationships
______ is a method of phylogenetic analysis that groups organisms based on shared derived characters, revealing evolutionary relationships and ancestry.
Cladistics
What are the three domains of life according to the modern phylogenetic classification system?
Bacteria, Archaea, Eukarya
The most recent common ancestor of all living things likely resembled:
a) A complex multicellular organism
b) A simple prokaryotic cell
c) A plant or an animal
d) We cannot know for sure
b) A simple prokaryotic cell
_____ is the theory that some organelles within eukaryotic cells, like mitochondria and chloroplasts, originated from free-living prokaryotic cells that became engulfed by another cell, forming a symbiotic relationship.
Endosymbiosis
The eukaryotic lineage is believed to have diverged from the prokaryotic lineage very early in the history of life.
True
How do scientists use molecular clocks to estimate divergence times between lineages on the tree of life?
Molecular clocks assume that certain molecules evolve at a relatively constant rate over time. By comparing the degree of difference in these molecules between organisms, scientists can estimate how long ago the lineages diverged from a common ancestor.
What are some of the major groups within the Eukarya domain, and what are some of their defining characteristics? Give at least 2.
Protists: Eukaryotic organisms that are not animals, plants, or fungi (diverse group with various characteristics).
Fungi: Multicellular eukaryotic organisms that obtain nutrients by decomposing organic matter, have cell walls made of chitin, and reproduce with spores.
Plants: Multicellular eukaryotic organisms that are photosynthetic, have cell walls made of cellulose, and reproduce sexually with seeds or spores.
Animals: Multicellular eukaryotic organisms that are heterotrophic (obtain nutrients by ingesting other organisms), lack cell walls, and typically reproduce sexually.
The most closely related group to animals within the Eukarya domain is likely:
a) Plants
b) Fungi
c) Protists
d) Bacteria
b) Fungi
