Which of the following is/are true?
A. Sympatric speciation most commonly occurs due to sexual (mate) selection.
B. Sympatric speciation can only occur when a single species occupies the same geographic location.
C. A plant species obtain an extra set of homologous chromosomes. This would be an example of sympatric speciation.
D. A flood causes the loss of all red-headed males ducks in a population. As a result, the red-headed female ducks must breed with yellow-headed male ducks, which are not their preferred mates. This is an example of sympatric speciation.
E. The fungal pathogen Mycosphaerella graminicola is found worldwide with its host, cultivated wheat. Mycosphaerella graminicola is host specific and does not occur on other host species such as Barley.
The closest known relative of M. graminicola is a barely-adapted pathogen Septoria passerinii.
You are researching these fungi and have the following hypothesis: If M. graminicola and S passerinii do not have a common ancestor that lived in one geographic area where wheat and barley grew, it may be possible that a common ancestor gave rise to these two species. This would be classified as sympatric speciation.
Your hypothesis and definition of sympatric speciation are logical.