Question

Many groups of animals have defensive spines. Examples include porcupines, sea urchins, and hedgehogs. What information do you need in order to determine whether or not spines are the result of homology or homoplasy?

Answer 1

To determine if spines are a result of homology or homoplasy, one must study the species' evolutionary history, physical and embryonic similarities, and genetic evidence, as homology indicates a common ancestor, while homoplasy suggests independent evolution due to similar environmental pressures.

Step-by-step explanation:

To determine whether spines in animals like porcupines, sea urchins, and hedgehogs are the result of homology or homoplasy, one would need to investigate the evolutionary history of these species and compare their physical structures, embryonic development, and genetic makeup. Homologous structures arise from a common ancestor and exhibit similar morphology and embryonic development due to shared genetics, while homoplastic (analogous) structures evolve independently in response to similar environmental pressures, resulting in a superficial resemblance without a common ancestral origin.

Examining phylogenetic trees can offer insight into shared ancestry, while genetic studies may reveal whether species have conserved gene sequences that lead to spine development. Structures like spines could be complex features, suggesting a shared evolutionary past, or they may represent convergent evolution if different species acquired spines separately to adapt to similar ecological niches. Hence, a thorough comparative analysis encompassing morphology, embryology, and genetics is essential to distinguish between homology and homoplasy.

Answer 2

The correct answer would be - Classification of the organism and characteristics of the spines.

Step-by-step explanation:

Homology is the term that used to describe the similarities in between biological structures or the organs in 2 or more distinct organism that comes from a common ancestors.

Homoplasy in other hand does not share a common lineage and evolve over the period in different organism, most likely in response of natural selection.

Information one will need to determine whether these spines are result of homoplasy or homology would be the characteristics of spines if they are thorns or spikes and other characters. The second most important information is the classification to know the place on the cladogram.

Thus, the correct answer would be- Classification of the organism and characteristics of the spines.