Chapter 1 - Whales and the Virus Flashcards
What is homology?
Structural characteristics shared because they were descended from a common ancestor.
What is the significance of Dorudon atrox?
Dorudon helped linked cetaceans to land mammals due to the unique cusps and patters on it’s teeth that bore resemblance to some old land mammal fossils. The thick, lipped plate of bone in its involucrum was also indicative of mammals.
What is natural selection?
A process of evolution where individuals can cause certain genes to outcompete others.
What is a synapomorphy?
A derived form of a trait shared by all ancestors of said trait (like Dorudon’s ancestors having complex teeth and cusps). Synapomorphies were used to connect Dorudon to it’s land walking, mammalian ancestors.
What evidence linked cetaceans to artiodactyla?
The discovery of an astralgus, a pulley-like ankle bone found in artiodactyla, in the hind legs of a cetacean fossil that had actually hindlimbs (i.e was landwalking).
What is a phylogeny?
A visual representation of the evolutionary history of a population, genes, or species.
How are hippopotamus and the land walking ancestor of the whale, Indohyus, similar?
They both have a very dense bone that is used to be able to walk on the bottom of lakes, rivers, etc.
What did scientists discover about the drinking habits of cetaceans?
The older cetaceans, the land-walking onces, drank only freshwater. As they started spending more time towards the shore (over the course of 40m years), they starting drinking more and more seawater. Whales now drink seawater alone.
What is a way scientists linked dolphins to an ancestor that had legs?
They saw in dolphin embryos, a specific set of genes became active that started producing “buds” of legs, but they later died back, showing that dolphins had an ancestor that grew legs but then evolved to lose them.
How did baleen whales lose their teeth?
They still have genes to produce teeth because these genes were passed down to them by ancestors, but they have all been disabled by mutations. Thus, they grow baleen instead.
When and why did whale diversity increase 20 million years ago?
The presence of large, shelled algae called diatoms. These diatoms were a large food supply for whales.
What is the significance of Ambulocetus?
A fossil whale with legs, with traits that were intermediate between it’s land walking and water loving ancestors.
How do viruses replicate?
Viruses use special proteins to enter cells, where they use our own DNA to make copies of themselves. These copies then use a protein called neuraminidase to cut themselves out of the cell and wreck havoc.
Why do viruses mutate so readily?
The way they reproduce produces a ton of copies of themselves, but these copies are sloppily made and rife with mutations. When so many mutations are happening so quickly, there is bound to be beneficial genes that help the virus population.
What is viral reassortment?
When genetic material from different strains get mixed into new combinations with a single individual. Reassortment gave birth to the mutations that allowed the bird flu to infect humans.
