Anatomy
True/False: The development of the tail was a major anatomical change identified by the scientists in this paper.
FALSE
True or False:
Cetaceans have shown gene loss of traits needed for enamelogenesis.
TRUE; they have inactivated ENAM genes, causing them to lack enamel or be toothless.
a clade of mammals that includes whales, dolphins, and porpoises
Cetaceans
True or False:
Chemosensory genes were reduced in cetaceans.
TRUE; genes relating to sense of smell and taste in cetaceans were either reduced or completely gone.
True or False:
Cetaceans have inactivated genes for olfactory bulbs (sense of smell).
TRUE
True or False:
The numerous pseudogenes in cetacean genomes are vestigial remnants.
TRUE
What is a pseudogene?
A) An insertion or deletion in a protein-coding gene that causes a change in reading frame.
B) A segment of DNA that is similar to an active gene, but has been mutated into an inactive form.
C) A nucleotide substitution in a protein-coding gene that results in a modification of the encoded amino acid sequence.
B) A segment of DNA that is similar to an active gene, but has been mutated into an inactive form.
What protein enables oxygen to be stored in muscle?
Myoglobin;
Higher myoglobin concentrations are present in aquatic animals since it enables their respiratory systems to undergo gas exchange and increased water pressure from deep diving.
Cetaceans possess which of the following characteristics?
A) Loss of enamel/no teeth
B) Loss of myoglobin
C) Reduced hindlimbs
D) Development of flippers
E) A and D
F) A, C, D
F) A, C, D
True or False:
Olfactory receptors (OR) genes in cetaceans were inferred to be pseudogenes based on deletion mutation.
FALSE:
Olfactory receptors (OR) genes in cetaceans were inferred to be pseudogenes based on FRAMESHIFT mutation.
The independent origination of similar traits in two or more clades is...
Convergent evolution
The cetaceans analyzed are adapted to seeing in low light conditions and lack what type of cone in the retina?
S-cones; cetaceans have a rod-dominated retina; rods help see under low light conditions, cones help see under brighter lit conditions.
What are some key physical traits of cetaceans. Name at least 3.
Reduced hair, aquatic eye, no enamel/teeth, aquatic lung, reduced hindlimbs, increased oxygen storage, flippers, etc.
The loss of which two proteins has occurred in cetaceans to optimize vision in deep waters and at night?
A) TAS1Rs and TAS2Rs
B) V1Rs and V2Rs
C) OPN1SW and OPN1LW
D) ENAM and AMELX
C) OPN1SW and OPN1LW
What is positive selection?
The tendency of beneficial traits to increase in prevalence/frequency in a population.
What are the three sensory structures that have disappeared due to the degradation of chemosensory genes?
Chemosensory structures including the olfactory, vomeronasal, and gustatory systems.