The leopard frog and the pickerel frog are two closely related species. In areas where their ranges overlap, the frogs will remain separate species if they --
The leopard frog (Rana pipiens) and the pickerel frog (Rana palustris) are indeed closely related species that can coexist in overlapping ranges while still maintaining their status as separate species. In evolutionary biology, this is known as sympatric speciation or coexistence. For the frogs to remain as distinct species, certain conditions and mechanisms must be in place to prevent them from interbreeding, which include:
1. Temporal isolation: The two species may breed at different times of the year or day, reducing the likelihood of interaction during breeding periods.
2. Habitat preference: Even if they live in the same geographic area, they might prefer different microhabitats. For example, one species may breed in permanent ponds, while the other favors temporary pools or a specific vegetation type.
3. Behavior: Mating calls and courtship behaviors of the two species can be different, which helps ensure that each species typically attracts mates of their own kind.
4. Mechanical isolation: The physical characteristics involved in mating might be incompatible between the two species, preventing successful breeding.
5. Gametic isolation: Even if mating occurs, the egg and sperm may not be compatible, which can prevent fertilization or the development of viable offspring.
6. Hybrid inviability or sterility: If hybrids are produced, they may be less viable (less likely to survive) or sterile (unable to reproduce), limiting the flow of genes between the two species.
These mechanisms contribute to reproductive isolation, which is the key to maintaining the separation of species according to the biological species concept. If these mechanisms fail and there is significant gene flow between the populations, the species may eventually merge, potentially leading to hybridization and a single, mixed species.