The birds on Norfolk Island are currently declining in number because of predation from rats, and because humans are clearing the forest habitats where they prefer to live. If the scientists decide this population of birds is its own species, then the group will take steps to protect them. However, if the scientists decide they are more closely related to other bird species, the Norfolk Islands robins will not be protected.
The scientists compared four populations of robins with respect to their genetic similarity and physical characteristics.
Scientists agree that the following are separate species:
Scarlet Robins
Red-Capped Robins
Pacific Robins
The question is whether the Norfolk Island Robins are a different species from the other three, based on both genetic and physical data.
Data on Genetic Similarity
The scientists decided to compare genetic similarities of Norfolk Island (NI) robins (for the alleles of ND2 gene) to each of these populations of robins.
Red-capped Robin (different species): 98.2% similar to the NI robins
Pacific Robins (population we want to know about): 96.7% similar to the NI robins
Scarlet Robins (different species): 88.7% similar to the NI robins
1. On the basis of these data, which group of robins most likely shares a most recent common ancestor with the Norfolk Island robins?
2. Which data best support your claim? Why are these data important to scientists in determining common ancestry?
3. What patterns in the data are relevant to deciding whether the species are the same or different, but do not support your claims? Why are these sources of data in general important to scientists in determining common ancestry?
4. If you were a scientist, what would you conclude: Should the Norfolk Island robins be considered a unique species? What evidence supports your conclusion? What is your reasoning: in other words, why is that good evidence to support your conclusion?
1. Based on the data provided, the Pacific Robins most likely share a most recent common ancestor with the Norfolk Island robins. This is because they have the highest genetic similarity (96.7%) compared to the Red-Capped Robins (98.2%) and Scarlet Robins (88.7%).
2. The data on genetic similarity support the claim that the Pacific Robins are most closely related to the Norfolk Island robins because they have the highest percentage of genetic similarity. These data are important to scientists in determining common ancestry because they provide a quantitative measure of how closely related two species are genetically, allowing them to infer relationships and evolutionary history.
3. The pattern of genetic similarity between the Norfolk Island robins and the Scarlet Robins does not support the claim that they are a unique species, as they have the lowest genetic similarity. However, genetic data alone may not always be enough to determine common ancestry, as other factors such as physical characteristics and behavior also play a role in species classification.
4. As a scientist, I would conclude that the Norfolk Island robins should not be considered a unique species based on the genetic data provided. The evidence supporting this conclusion is the high genetic similarity (96.7%) between the Norfolk Island robins and the Pacific Robins, suggesting a close evolutionary relationship. Additionally, the data on genetic similarity provide a quantitative measure that supports the conclusion that the Norfolk Island robins are more closely related to the Pacific Robins than the other populations.