In the wild, closely related species will occasionally mate, and produce a viabl
ID: 144811 • Letter: I
Question
In the wild, closely related species will occasionally mate, and produce a viable offspring. This offspring is called a hybrid. A diploid male lion with 44 chromosomes mates with a diploid female tiger with 50 chromosomes and this mating produces a viable liger.
a. How many chromosomes would you expect to see in the body cells of this organism?
b. Would the organism be able to form viable gametes through the process of meiosis?
Explain your answer by thinking carefully about the steps of meiotic cell division.
Explanation / Answer
a. The diploid organisms have each chromosome in two copies. Like in the case of human, they have 46 chromosomes in 23 pairs.
So, a diploid male lion with 44 chromosomes has these 44 chromosomes in 22 pairs. On the other hand, a diploid female tiger with 50 chromosomes has also these 50 chromosomes in 25 pairs.
Therefore, when the male lion and the female tiger mate and produce a liger, the liger receives 22 chromosomes from the male lion and 25 chromosomes from the female tiger because the gamete of the male lion would be haploid and would contain 22 chromosomes and the gamete of the female tiger would also be haploid and would contain 25 chromosomes. The fertilization of these two gametes results in the formation of a liger and the liger would contain (25+22)= 47 chromosomes in their body cells.
b. The organism would not be able to form viable gametes through the process of meiosis.
Explanation: Meiosis is basically responsible for the formation of gametes. Meiosis is divided into two phases and these are the first meiotic division (Meiosis I) and the second meiotic division (Meiosis II). During the first meiotic division, the homologous chromosomes are separated while during the second meiotic division, the chromatids are separated.
Meiosis I is divided into four phases and these are Prophase I, Metaphase I, Anaphase I, and Telophase I. The Prophase I further divided into five phases and these are Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis. During the Zygotene of Prophase I of Meiosis I, the pairing of the two homologous chromosomes occurs and this pairing is called synapsis.
In the case of the liger, the paternal chromosomes are different from maternal chromosomes in number and gene locus. So, there are not any homologous chromosomes. Therefore, synapsis would not occur. So, the liger would not be able to form viable gametes through the process of meiosis.