There is some evidence that pharyngeal slits occur in certain species of echinoderms that appear early in the fossil record. If confirmed, what do these data suggest?a. Echinoderms are chordates.b. Pharyngeal slits were present in the earliest echinoderms and lost later.c. Some lineages of echinoderms are more closely related to chordates than others.d. Pharyngeal slits should not be used as a trait in phylogenetic analysis.

Verified step by step guidance

1. Identify the key biological feature mentioned: pharyngeal slits, which are typically found in chordates and are used in phylogenetic analysis to help determine evolutionary relationships.
2. Understand the significance of finding pharyngeal slits in early echinoderms: This suggests that these structures were present in ancestors of echinoderms that might share a closer evolutionary relationship with chordates.
3. Analyze the implications of each answer choice in relation to evolutionary biology principles and the evidence provided:
4. a. Concludes that echinoderms are chordates, which would require more evidence than just pharyngeal slits.
5. b. Suggests an evolutionary trait (pharyngeal slits) was lost in later echinoderms, which aligns with how some traits can disappear over time in certain lineages.
6. c. Proposes that some echinoderm lineages might be more closely related to chordates, which could be supported by the shared trait of pharyngeal slits.
7. d. Questions the validity of using pharyngeal slits in phylogenetic analysis, which might be considered if pharyngeal slits are found more widely outside chordates than previously thought.
8. Evaluate which answer best fits the evidence provided and the principles of evolutionary biology, considering the implications of pharyngeal slits appearing in early echinoderms and their relationship to chordates.

Key Concepts

Pharyngeal Slits

Pharyngeal slits are openings that occur in the pharynx during the embryonic development of certain animals, including chordates. They are significant in the evolutionary context as they are a characteristic feature of the phylum Chordata, suggesting a common ancestry. In some species, these structures may serve various functions, such as filter feeding or respiration, and their presence in echinoderms could indicate evolutionary relationships.

Echinoderm Evolution

Echinoderms, such as starfish and sea urchins, are a distinct group of marine animals characterized by their radial symmetry and a water vascular system. Understanding their evolutionary history is crucial for interpreting fossil evidence, as it can reveal how traits like pharyngeal slits may have evolved or been lost over time. The presence of these slits in early echinoderms could suggest a more complex evolutionary relationship with chordates than previously thought.

Phylogenetic Analysis

Phylogenetic analysis is a method used to study the evolutionary relationships among various biological species based on genetic, morphological, or fossil data. It helps in constructing a 'family tree' that illustrates how different species are related through common ancestors. The interpretation of traits, such as pharyngeal slits, is critical in this analysis, as they can indicate shared ancestry or convergent evolution, influencing our understanding of the evolutionary pathways of echinoderms and chordates.