Scientists reconstruct evolutionary relationships by examining evidence, much like investigators use clues to solve a mystery. This lesson explores how physical traits and molecular information can reveal relatedness—and how similarities can sometimes mislead.
Morphology concerns an organism’s form and structure. When organisms share a feature because of a shared evolutionary history, that feature is homologous. Homologous structures may serve different functions, but they share an underlying pattern or developmental origin inherited from a common ancestor.
All flashcards
Homologous structures
Features that share an evolutionary and developmental origin, even if they have different functions.
Analogous structures
Features similar in function or appearance that evolved independently rather than being inherited as that feature from a common ancestor.
Molecular systematics
The use of molecular data, such as DNA sequences, to investigate classification and evolutionary relationships.
Clade
A group consisting of one common ancestor and all of that ancestor’s descendants.
Maximum parsimony
A method that favors the evolutionary explanation requiring the fewest changes while fitting the evidence.
Quiz questions
What must a group include to qualify as a clade?Answer: One common ancestor and every descendant of that ancestor.
How can an insertion or deletion affect a DNA sequence comparison?Answer: It can shift alignment and make related sequences appear more different.
What does maximum parsimony favor when comparing evolutionary trees?Answer: The explanation requiring the fewest evolutionary changes while fitting the evidence.
How can researchers use a DNA marker associated with a plant family?Answer: As one clue for assessing whether a new plant belongs to that group.
Why is agreement among independent kinds of evidence useful when inferring relationships?Answer: It makes the proposed relationship more convincing than evidence from one resemblance alone.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.