Question

Genetic maps are based on recombination frequencies. because both odd and even numbers of crossovers can occur between any two gene loci, as the physical distance between two loci increases, the maximum recombination frequency levels off at 50%. however, suppose you discovered a species where only an even number of crossovers can occur between any two gene loci. in this case, as the physical distance between two loci increases, you would expect the maximum recombination frequency to?

A. increase with no limit
B. increase until it reaches 25%
C. increase until it reaches 75%
D. increase until it reaches 100%

Answer 1

In the hypothetical species where only an even number of crossovers between gene loci occurs, the maximum recombination frequency would expectedly remain at 0%, as even numbers of crossovers would counteract each other, leaving the gene loci appearing completely linked.

Step-by-step explanation:

In a hypothetical species where only an even number of crossovers can occur between gene loci, as the physical distance between two loci increases, the maximum recombination frequency would be expected to increase until it reaches 50%. However, because only even crossovers are allowed, following any crossover event, there is a subsequent crossover that essentially 'undoes' the first, leaving the parental allele combination unchanged.

Therefore, for every even number of crossovers, zero net recombination events would be observable, regardless of the distance between genes. In this scenario, because odd crossovers that lead to recombination are not permitted, we cannot reach the typical 50% recombination frequency seen in normal genetics where both odd and even crossover events can occur.

Instead, the observed recombination frequency would asymptotically approach 0% as distance increases, effectively making gene loci appear completely linked (recombination frequency = 0), even when they are far apart. Hence, the maximum recombination frequency observed in this species would remain at 0%, reflecting that no recombination is detected between loci regardless of their distance apart.