Michalis Averof and Nipam Patel compared the expression of Ubx-AbdA Hox genes in different thorax segments during embryonic development in four crustaceans. To probe the question of maxillipeds further, Averof, Patel, and colleagues turned to an emerging model organism: a small type of crustacean called an amphipod. The photo at the beginning of this case study shows a ventral view of the expression pattern of Ubx (red area) in an amphipod embryo. In which tagma does Ubx appear to be expressed>

In a cladogram' when does a group of organisms branch off

1. seamount a raised footwall block between normal fault creates this 2. syncline break between rocks where a hanging wall rises relative to a footwall 3. hot spring on rolling hills, this a dip between hills 4. volcanic neck created when a block with hanging walls slips down between normal faults 5. caldera underwater volcano that never reaches above sea level 6. horst natural hot water on earth's surface containing many minerals 7. graben underwater volcano whose top is eroded flat by waves 8. crater less than a mile in diameter; looks like a bowl at the top of a volcano 9. guyot magma that filled the central vent that remains after the volcano has eroded 10. reverse fault over 1 mile in diameter; looks like a bowl over a volcano

Which of the following explains why a tree is often used as a model to represent the principle of common descent