Question

Figure 24.14 illustrates how a hybrid zone can change over time. Imagine that two finch species colonize a new island and are capable of hybridizing (mating and producing viable offspring). The island contains two plant species, one with large seeds and one with small seeds, growing in isolated habitats. If the two finch species specialize in eating different plant species, would reproductive barriers be reinforced, weakened, or unchanged in this hybrid zone? Explain.

Short answer

Individuals of the two finch species may be less likely to encounter their respective environments since they specialize in consuming seeds of different plant species, establishing a reproductive barrier against hybridization.

Step-by-step solution

Hybrid zone

Species, subspecies, or races cross over in hybrid zones. Clines or gradients in features or alleles over a geographic transect are widely employed to determine hybrid zones. The breadth of a line is determined by the balance of hybrid selection and gene propagation.

Hybridization

Hybridization is the process of combining several species of organisms to produce a new hybrid. Biologically, a hybrid results from combining the traits of two creatures from different breeds, varieties, species, or genera. A hybrid differs from its parents in certain ways, yet it is still sterile.

Reproductive barrier

Individuals of closely related species are prevented from mating and giving birth to hybrid offspring due to differences in the timing of crucial reproductive processes known as reproductive isolation.

Barriers to reproduction are behaviors and physiological processes that keep species distinct and prevent hybridization from occurring. Hybridization is prevented before conception by prezygotic barriers and after fertilization by postzygotic obstacles.