1. A) If you group all segmented organisms (blue circles), would they form a mon
ID: 67937 • Letter: 1
Question
1. A) If you group all segmented organisms (blue circles), would they form a monophyletic clade? Explain. B) As what type of trait would you classify body segmentation (synapomorphy, symplesiomorphy, homoplasy)? Explain you answer. C) Do you think segmentation appeared once in the ancestor of these groups or appeared independently in each group? Explain your answer. D) Do organisms that molt (called ecdysis, includes: Loricifera, Kinorhyncha, Nematoda, Tardigrada, Arthropoda and Onychophora) form a monophyletic group? Explain. E) As what type of trait would you classify the ability to molt (synapomorphy, symplesiomorphy, homoplasy)? Explain.
2. Some people have suggested that Tardigrades (water bears) come from another planet. Look at the phylogenetic tree, which has been constructed based on DNA and morphological data, to A) explain whether the alien origin of Tardigrades is supported.B) How would the phylogenetic tree look like if Tardigrades were indeed alien?
Explanation / Answer
1. A) If you group all segmented organisms (blue circles), would they form a monophyletic clade? Explain.
No, they wont form a monophyletic clade eventhough all of them are segmented. Monophyletic clade includes all the organisms decended from a single common ancestor. The characters are inherited by only its decendents and not by any other group or taxa of organisms.
B) As what type of trait would you classify body segmentation (synapomorphy, symplesiomorphy, homoplasy)? Explain you answer.
Homoplasy, because here protostomes, ecdyzoans and deuterostomes showing body segmentation independent of their origin from their ancestors.
C) Do you think segmentation appeared once in the ancestor of these groups or appeared independently in each group? Explain your answer.
Its independently derived and its not occured in their common ancestor.
D) Do organisms that molt (called ecdysis, includes: Loricifera, Kinorhyncha, Nematoda, Tardigrada, Arthropoda and Onychophora) form a monophyletic group? Explain.
Yes, Loricifera, Kinorhyncha, Nematoda, Tardigrada, Arthropoda and Onychophora organisms which shows moult all come into a single clade, a monophyletic group. On molecular and morphological characters they are grouped into a single clade.
E) As what type of trait would you classify the ability to molt (synapomorphy, symplesiomorphy, homoplasy)? Explain.
Synamomorphy, its a converged trait found in two or more taxa with a recent distant ancestor.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.