All flashcards
Flashcard 1: What does it mean if two lineages share many synapomorphies but few similarities with others?
Answer: They form a clade with a relatively recent common ancestor. Many shared traits indicate close evolutionary relationship.
Flashcard 2: What is the primary reason that mitochondrial DNA is often used in ancestry studies?
Answer: It mutates relatively quickly and is inherited mostly maternally. Fast mutation rate and maternal inheritance pattern useful for tracing.
Flashcard 3: What is the most general conclusion supported by both fossils and DNA comparisons?
Answer: Modern species share common ancestry and diverged over time. Both methods independently reveal evolutionary relationships and divergence patterns.
Flashcard 4: What is a fossil in the context of evidence for evolution and common ancestry?
Answer: Preserved remains or traces of past organisms in rock or sediment. Physical evidence of ancient life forms that shows historical changes.
Flashcard 5: What does the ordered sequence of fossils in rock layers primarily show about life over time?
Answer: Species appear, change, and go extinct in a chronological pattern. Demonstrates evolutionary change and extinction events through geological time.
Flashcard 6: What is the law of superposition used for when interpreting fossil evidence?
Answer: Lower rock layers are generally older than higher layers. Establishes relative ages of rock layers containing fossils.
Flashcard 7: What is relative dating used to determine when analyzing fossils in rock strata?
Answer: Whether one fossil or layer is older or younger than another. Compares stratigraphic positions to determine sequence of events.
Flashcard 8: What is absolute dating (radiometric dating) used to determine for fossils or rocks?
Answer: A numerical age estimate using radioactive isotope decay. Uses radioactive decay rates to calculate precise ages.
Flashcard 9: What does a transitional fossil indicate about relationships among groups?
Answer: It has intermediate traits linking ancestral and descendant groups. Shows evolutionary progression between different groups.
Flashcard 10: Which fossil pattern most directly supports descent with modification?
Answer: Older strata show ancestral forms; younger strata show derived forms. Demonstrates evolutionary change over geological time.
Flashcard 11: What is a homologous structure, and what does it indicate about ancestry?
Answer: Similar structure from a shared ancestor, possibly with new functions. Inherited structure indicates shared evolutionary origin.
Flashcard 12: What is an analogous structure, and what does it indicate about ancestry?
Answer: Similar function without shared origin; evidence of convergent evolution. Independent evolution creates similar solutions to environmental challenges.
Flashcard 13: What is a vestigial structure, and how does it support common ancestry?
Answer: Reduced remnant of an ancestral trait, indicating descent from ancestors. Evolutionary remnant provides evidence of ancestral traits.
Flashcard 14: What does the presence of the same vestigial structure in related species suggest?
Answer: Inheritance from a common ancestor that had a functional version. Shared inheritance from ancestor with functional trait.
Flashcard 15: What is biogeography, and how can it support common ancestry?
Answer: Species distributions match patterns of descent, isolation, and divergence. Geographic distribution reflects evolutionary history and dispersal.
Flashcard 16: What does a fossil found on multiple continents often suggest about past geography?
Answer: Continents were connected or organisms dispersed before separation. Indicates past continental connections or organism dispersal.
Flashcard 17: What is molecular evidence in evolutionary biology?
Answer: Comparisons of DNA, RNA, proteins, and other biomolecules among species. Genetic and biochemical data reveal evolutionary relationships.
Flashcard 18: What does high similarity in DNA sequences between two species most strongly imply?
Answer: They share a more recent common ancestor. Greater similarity indicates closer evolutionary relationship.
Flashcard 19: What does low similarity in DNA sequences between two species most strongly imply?
Answer: Their common ancestor is more distant in time. Less similarity indicates more ancient divergence.
Flashcard 20: What is a molecular clock used to estimate in evolutionary studies?
Answer: Time since divergence using accumulated genetic differences. Assumes constant mutation rates to calculate divergence timing.
Flashcard 21: What is a conserved gene, and what does it suggest about ancestry?
Answer: A gene with little change; it indicates shared essential functions and ancestry. Preserved across species due to essential function and inheritance.
Flashcard 22: What is a shared derived character (synapomorphy) used for in phylogenetics?
Answer: To identify clades by traits inherited from a recent common ancestor. Defines evolutionary groups based on shared inheritance.
Flashcard 23: What is a phylogenetic tree intended to represent about species relationships?
Answer: Hypotheses of evolutionary relatedness and common ancestry. Shows proposed evolutionary relationships among species or groups.
Flashcard 24: What does a node (branch point) on a phylogenetic tree represent?
Answer: The most recent common ancestor of the descendant lineages. Inferred ancestral species from which lineages diverged.
Flashcard 25: Which pair is more closely related: a pair with fewer DNA differences or more differences?
Answer: The pair with fewer DNA differences is more closely related. Fewer differences indicate more recent common ancestry.
Flashcard 26: Identify the best conclusion if two species share many identical amino acids in a protein.
Answer: They likely diverged more recently from a common ancestor. High similarity suggests recent divergence from common ancestor.
Flashcard 27: What is comparative genomics, and how does it support common ancestry?
Answer: Genome comparisons reveal shared genes and patterns of descent. Compares entire genomes to trace evolutionary relationships.
Flashcard 28: What does it mean if two species share the same mutation at the same DNA position?
Answer: They likely inherited it from a common ancestor. Shared mutations indicate common inheritance rather than independent origin.
Flashcard 29: What are pseudogenes, and why are they useful evidence for common ancestry?
Answer: Nonfunctional gene remnants shared due to inheritance from ancestors. Broken genes shared across species indicate common origin.
Flashcard 30: What does it suggest if two species share the same pseudogene in the same genomic location?
Answer: Common ancestry is strongly supported by shared inheritance. Identical location and sequence indicate shared inheritance.