Use Figure 30.3 and the following information when answering the next question.
In a review paper published in 2000, Adoutte et al. examined some animal phylogenies generated by comparing the ribosoma rRNA) of animals from many different phyla. They then integrated these independently created phylogenies into one phylog best fit all the data.
Figure 30.4 compares a traditional phylogeny based on morphological characteristics A) to the new molecular- based phylog described by Adoutte et al. B).
Note that platyhelminthes, nemerteans, and entoprocts, which do not have coeloms and are classified as acoelomates in the morphological phylogeny, are reclassified as lophotrochozoans in the molecular phylogeny. Similarly, groups classified as pseudocoelomates in the morphological phylogeny are reclassified as either lophotrochozoans or ecdysozoans in the molecula phylogeny; other lophotrochozoans and ecdysozoans have coeloms.
A. Adoutte, G. Balavoine, N. Lartillot, O. Lespinet, B. Prud'homme, and R. de Rosa. 2000. The new animal phylogeny.
Figure 30.3
-What does this reclassification based on molecular data imply about the evolution of acoelomates, pseudocoelomates, and coelomates?
A) Pseudocoelomates can be seen as an intermediate stage between acoelomate and coelomate development.
B) Some pseudocoelomates and acoelomates have evolved from coelomates.
C) Although acoelomates and pseudocoelomates evolved only once, coelomates evolved multiple times in different lineages.
D) Only the animals that evolved earliest are acoelomates.

Question

Use Figure 30.3 and the following information when answering the next question.
In a review paper published in 2000, Adoutte et al. examined some animal phylogenies generated by comparing the ribosoma rRNA) of animals from many different phyla. They then integrated these independently created phylogenies into one phylog best fit all the data.
Figure 30.4 compares a traditional phylogeny based on morphological characteristics A) to the new molecular- based phylog described by Adoutte et al. B).
Note that platyhelminthes, nemerteans, and entoprocts, which do not have coeloms and are classified as acoelomates in the morphological phylogeny, are reclassified as lophotrochozoans in the molecular phylogeny. Similarly, groups classified as pseudocoelomates in the morphological phylogeny are reclassified as either lophotrochozoans or ecdysozoans in the molecula phylogeny; other lophotrochozoans and ecdysozoans have coeloms. 
A. Adoutte, G. Balavoine, N. Lartillot, O. Lespinet, B. Prud'homme, and R. de Rosa. 2000. The new animal phylogeny.
 Figure 30.3
-What does this reclassification based on molecular data imply about the evolution of acoelomates, pseudocoelomates, and coelomates?
A) Pseudocoelomates can be seen as an intermediate stage between acoelomate and coelomate development. 
B) Some pseudocoelomates and acoelomates have evolved from coelomates. 
C) Although acoelomates and pseudocoelomates evolved only once, coelomates evolved multiple times in different lineages. 
D) Only the animals that evolved earliest are acoelomates.

Quizplus · Accepted Answer

The reclassification based on molecular data suggests that the traditional view of body cavity evolution as a linear progression from acoelomates to pseudocoelomates to coelomates is overly simplistic. Instead, it indicates that some organisms traditionally classified as pseudocoelomates or acoelomates may have actually evolved from ancestors that had a true coelom, suggesting a more complex pattern of evolutionary changes.