SpeciationAQA A-Level Biology: Flashcards

Exam questions on Speciation

1. Two populations of ground squirrels were once part of one interbreeding population. A river then changed course and now separates them. The squirrels cannot cross the river. The two sides of the river have different vegetation and different climates.
   Explain how, over many generations, the two squirrel populations could become two separate species.2 marks
2. In a meadow, an insect species feeds and mates on two plant species that grow in the same area. One plant species flowers in May and the other flowers in August. Insects that feed on the May-flowering plant breed in May and insects that feed on the August-flowering plant breed in August. Over many generations the two groups of insects have become genetically different.
   Explain how the different breeding times could lead to the formation of two species.2 marks
3. Horses and donkeys can mate and produce offspring called mules. Mules are almost always sterile. Horses and donkeys are thought to have evolved from a common ancestral population whose descendants became separated and lived in different regions with different climates and vegetation.
   Explain why horses and donkeys are classified as separate species even though they can mate and produce offspring.3 marks