A small population of deer living on an isolated island is separated for many generations from a mainland deer population. The populations retain the same number of chromosomes but hybrids are infertile. One chromosome (shown here) has a different banding pattern in the island population than in the mainland population. Suppose that 40% of all meioses in mainland–island hybrids involve recombination somewhere in the chromosome region between q2.1 and p2. What proportion of the gametes of hybrid deer are viable? What is the cause of the decreased proportion of viable gametes in hybrids relative to the parental populations?

Key Concepts

Meiosis and Gamete Formation

Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in the formation of gametes (sperm and eggs). During meiosis, homologous chromosomes undergo recombination, where segments of DNA are exchanged, leading to genetic diversity. In the context of hybrids, understanding how meiosis operates is crucial, as it directly affects the viability of gametes produced by hybrid individuals.

Hybrid Incompatibility

Hybrid incompatibility occurs when two different species or populations interbreed, resulting in offspring that are often sterile or have reduced fitness. In this case, the hybrids between the island and mainland deer populations are infertile, which can be attributed to genetic differences that disrupt normal development or reproductive processes. This concept is essential for understanding why the proportion of viable gametes is lower in hybrids compared to their parental populations.

Chromosomal Banding Patterns

Chromosomal banding patterns are visual representations of chromosomes that highlight specific regions, allowing for the identification of structural differences between chromosomes from different populations. The differences in banding patterns between the island and mainland deer suggest genetic divergence, which can lead to incompatibilities during meiosis. Recognizing these patterns is important for analyzing the genetic basis of hybrid infertility and the implications for gamete viability.