Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification? a. The two forms interbreed often in nature, and their offspring survive and reproduce well. b. The two forms live in similar habitats and have similar food requirements. c. The two forms have many genes in common. d. The two forms are very similar in appearance.

Verified step by step guidance

1. Step 1: Understand the question. The question is asking for the reason why the myrtle warbler and Audubon's warbler, previously considered distinct species, have been reclassified as eastern and western forms of a single species, the yellow-rumped warbler.
2. Step 2: Review the options. Each option presents a possible reason for the reclassification.
3. Step 3: Consider the definition of a species. In biology, a species is often defined as a group of individuals that actually or potentially interbreed in nature, not according to similarity of appearance. Although appearance is a consideration, it is not the primary determinant for species classification.
4. Step 4: Apply the definition of a species to the options. Option a states that the two forms interbreed often in nature, and their offspring survive and reproduce well. This fits the definition of a species, as it indicates that the two forms are not reproductively isolated and can produce viable, fertile offspring.
5. Step 5: Choose the correct answer. Based on the definition of a species, the most likely reason for the reclassification of the myrtle warbler and Audubon's warbler as forms of a single species is that they interbreed often in nature and their offspring survive and reproduce well. So, the correct answer is a.

Key Concepts

Species Concept

The species concept refers to the criteria used to define and distinguish species from one another. The Biological Species Concept, for instance, emphasizes reproductive isolation, meaning that if two populations can interbreed and produce viable offspring, they are considered the same species. This concept is crucial for understanding the reclassification of the myrtle and Audubon's warblers, as interbreeding suggests they are not distinct species.

Genetic Similarity

Genetic similarity involves the degree of genetic overlap between two populations. High genetic similarity can indicate a close evolutionary relationship, often leading to the conclusion that two forms are variations of the same species. In the context of the warblers, if they share many genes, it supports the idea that they are not separate species but rather different forms of the same species.

Ecological Niche

An ecological niche encompasses the role and position a species has in its environment, including its habitat, resource use, and interactions with other organisms. If two forms occupy similar niches and have comparable food requirements, it suggests they are adapted to the same ecological conditions, further supporting their classification as a single species rather than distinct ones.