Evo-Devo
A single genomic locus influencing multiple traits illustrates:
Pleiotropy
What do CRE's stand for and what do they do?
Cis-Regulatory Elements
CREs can regulate where, when, and how much a toolkit gene is expressed
A lineage’s fossils show a trait changing steadily across many successive forms, with multiple intermediate forms represented. Which rate model best fits?
Phyletic gradualism
Which best distinguishes homology from homoplasy?
Homology reflects shared ancestry; homoplasy reflects similarity but not due to a recent common ancestor
A phylogenetic diagram shows two unrelated carnivore groups independently evolving bone-cracking skulls in similar ecological contexts. The repeated morphology is:
Homoplasy
A freshwater stickleback lacks a pelvic spine, but Pitx1 still functions in other tissues because only the pelvic regulatory module is disabled. This is evidence for:
Modular cis-regulatory elements
The estimate of elapsed time based on neutral DNA substitutions is a:
Molecular Clock
A fossil lineage shows little morphological change for long intervals, with marked differences appearing around speciation events. Which model best fits?
Punctuated equilibrium
A vertebrate and an octopus have camera eyes that evolved independently, yet both use the Pax6 toolkit gene in development. This best illustrates:
Deep homology and homoplasy
What is the name of the developmental model that proposes a highly conserved period in the middle of development?
Von Baer's developmental hourglass
The deeply conserved eye-development toolkit gene is:
The deeply conserved gene for facial bone formation is:
Pax6
Bmp4
A lineage loses a complex anatomical trait. Based on Dollo’s Law, which prediction would be most appropriate?
Regaining the same complex trait will not occur.
In python embryos, HoxC6/HoxC8 expression extends farther anteriorly than in a lizard-like comparison. What predicted morphological effect occurs?
More anterior rib-bearing vertebrae and impaired forelimb-bud formation
What is the term for conserved developmental genes and pathways underlying different structures across distant groups?
Deep homology
What is the difference between deep homology and structural homology?
Structural homology refers to shared anatomical or morphological features inherited from a common evolutionary ancestor. Deep homology refers to the sharing of ancient, conserved genetic regulatory toolkits or signaling pathways.
A gene encodes a transcription factor that binds regulatory DNA and controls the expression of several other genes involved in body patterning. Which component of the genetic toolkit does this gene represent?
A transcription factor
Why can a small number of regulatory mutations produce substantial morphological changes?
A regulatory change can alter the spatial, temporal, or quantitative expression of a developmental toolkit gene
Two related species evolve independently similar body shapes because they face similar environmental challenges, despite not sharing those specific features in their recent common ancestor. Which pattern does this illustrate?
Convergent evolution
Two genetically identical plants are grown under different light conditions. One develops broad leaves, while the other develops narrow leaves. Which concept best explains this observation?
Phenotypic plasticity
In Rutherford and Lindquist’s fruitfly experiment, mutated HSP90 function revealed previously hidden body-pattern variation. HSP90 normally acts as a:
Chaperone Protien
Embryos of different species show the greatest conservation during an intermediate developmental stage, while species-specific differences become more pronounced later. Which concept matches this pattern?
Developmental hourglass
A conserved developmental toolkit gene is brought into a new tissue or developmental context through a new regulatory element, contributing to a novel trait. What process is this?
a. Exaptation
b. Homoplasy
c. Preformation
d. Anagenesis
a. Exaptation
Scientists compare embryos from several animal phyla and find that developmental genes and their expression patterns are especially conserved during a particular stage. According to the developmental hourglass model, what is the best explanation?
The conserved developmental stage is subject to strong evolutionary constraint.
A fossil lineage shows a gradual change in body size through time, but the lineage never splits into two branches. Which macroevolutionary pattern does this best represent?
Anagenesis
Embryonic beak cells in finches with deep, heavy beaks show higher Bmp4 expression than those with small, pointy beaks. What does this demonstrate?
Differences in gene expression cause different traits for development.