Mimulus lewisii and Mimulus cardinalis occupy the same habitat but do not interbreed in nature. However, they can be crossed in the laboratory to produce fertile offspring. Which of the following is a likely reason that prevents these plants from interbreeding in nature? A) They only reproduce by self-pollination. B) They have incompatible gametes. C) They exhibit seasonal differences in flowering.

The likely reason that prevents Mimulus lewisii and Mimulus cardinalis from interbreeding in nature, despite being able to produce fertile offspring in laboratory conditions, could be:

C) They exhibit seasonal differences in flowering.

Seasonal differences in flowering time can act as a reproductive barrier between closely related species. Even though these species might have compatible gametes and genetic compatibility, if they flower at different times, it can prevent or reduce the chances of successful cross-pollination in their natural habitat.

If Mimulus lewisii and Mimulus cardinalis have distinct flowering seasons or specific times when they bloom, this temporal isolation can hinder the opportunity for their gametes to meet and result in reduced or no interbreeding in their natural environment. In laboratory settings, where environmental factors can be controlled, this barrier may not be as significant, allowing for successful hybridization and production of fertile offspring.