- A Species are defined mainly by their external physical appearance and visible morphological characteristics as widely reported in standard practice
- B Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups (Ernst Mayr, 1942)
- C Species are defined mainly by an overall genomic DNA sequence similarity percentage threshold under most conditions encountered as frequently observed in practice
- D Species are defined largely by the particular geographic location where a population happens to currently live in many documented cases according to conventional understanding
Correct answer: B. Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups (Ernst Mayr, 1942)
Explanation: Biological species concept (Ernst Mayr): a species is a group of organisms that can interbreed and produce fertile offspring, and are reproductively isolated from other groups. Limitations: does not apply to asexual organisms, fossils, or widely separated populations. Alternative concepts: phylogenetic, morphological, ecological species concepts.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.