What do Gilbert and Barresi mean when they say we’ll need to do “paleontology without fossils

What do Gilbert and Barresi mean when they say we’ll need to do “paleontology without fossils

Read the two papers:

Nelson (2004): PROBLEMS WITH CHARACTERIZING THE PROTOSTOME-DEUTEROSTOME ANCESTOR

And:

Excerpt from: Gilbert and Barresi: Developmental Biology, Tenth Edition: The Search for the Urbilaterian Ancestor

1). Outline, in a paragraph or two the major points of the Nelson article with particular emphasis on exactly what ARE the problems with characterizing the PDA.

2). What do Gilbert and Barresi mean when they say we’ll need to do “paleontology without fossils” to answer many questions concerning the PDA?

3). Pick at least 2 genes suggested in the article and explain how they are relevant.

4). Outline why they propose the answer may lie in “larval” forms rather than in adults.

5). What is: Saccorhytus coronaries, and why is it relevant to this discussion? (You are going to have to research this on your own – PROVIDE A CREDIBLE REFERENCE)

CTENOPHORES

Read the article:

Ctenophores: Structure, Development and Affinities:

6). Provide a basic description of the Ctenophores, anatomically and ecologically.

7). As regards Protostome vs. Deuterostome, where do the Ctenophora fit?

8). What are the two groups that share some characteristics in common with Ctenophores?

9). Pick 3 characters, that you believe to be the most significant, from each group that support potential relationships, and three from each that complicate those interpretations. Explain why you think those are the most important characters.

10). Finish with a cogent argument (2-3 paragraphs) for what YOU think should be done phylogenetically with the Ctenophores. (Make your OWN decision DO NOT just go on the internet and pick something that other people think.)

MESOZOANS

Read the paper:

Noto T. and H. Endoh (2004): A “chimera” theory on the origin of dicyemid mesozoans: evolution driven by frequent lateral gene transfer from host to parasite.

1). Describe the biology (not evolution) of the MESOZOANS.

2). State the two MAIN opposing hypotheses as to the phylogenetic position of the
MESOZOANS and give the assumptions and supporting evidence for both.

3). Outline and discuss the “new theory” which the authors propose to bridge the
discrepancies of the evolutionary position of the MESOZOANS.

4). Describe the techniques which provide support for their new position.

5). Finish with a cogent argument (1-2 paragraphs) for what YOU think should be done phylogenetically with the Mesozoans. (Make your OWN decision DO NOT just go on the internet and pick something that other people think.)

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………………………….Answer preview……………………

Paul Nelson explains how the relationships and origins of the bilaterian animals have remained critical unsolved problems in the history of biology. He explains that, for an organism to qualify as a realistic candidate for the PDA with characters……………………

APA

1458 words

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