A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on the primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?
A) Among themselves, they should share relatively few ancestral traits, especially those that enabled ancestral forms to adapt to extreme conditions.
B) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.
C) They should contain genes that originated in eukaryotes that are the hosts for numerous species of bacteria.
D) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic archaeans.
The American Lion was one of the abundant Pleistocene megafauna, a wide variety of very large mammal
Cerebral angiography. The four angiograms each reveal the distribution of blood vessels supplying th
Cutaway Drawing of Tholos, The So-called Treasury of Atreus
Anatomy of the Large Intestine (colon)
The nucleus is bounded by a double membrane called the nuclear envelope