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. Draw the synapsis of these homologs during prophase I in hybrids produced from the cross of mainland with island deer.

Key Concepts

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes, one inherited from each parent, that have the same genes at the same loci but may have different alleles. During meiosis, these chromosomes align and can undergo recombination, which is crucial for genetic diversity. In the context of the question, understanding homologous chromosomes is essential for visualizing how they pair during prophase I.

Prophase I of Meiosis

Prophase I is the first stage of meiosis where homologous chromosomes pair up and exchange genetic material through a process called crossing over. This stage is characterized by the formation of tetrads, where each homologous pair is closely aligned. Recognizing the events of prophase I is vital for accurately drawing the synapsis of the chromosomes in hybrids.

Infertility in Hybrids

Infertility in hybrids, such as those produced from the cross of mainland and island deer, often arises due to chromosomal incompatibilities or differences in genetic makeup. In this case, even though the chromosome number is the same, the differing banding patterns suggest structural differences that can prevent proper pairing and segregation during meiosis. Understanding this concept is crucial for interpreting the implications of hybridization in the context of the question.