Final answer:
The similarity in genome sizes between two yeast species does not necessarily mean they contain the same number of genes or a similar number of chromosomes, due to variations in non-coding DNA and species-specific genome organizations.
Step-by-step explanation:
The presence of similar genome sizes in two different species does not guarantee that they will have the same number of genes or a similar number of chromosomes. This is because the genome size is a measure of the total amount of DNA, which includes both coding (genes) and non-coding sequences. The number of genes can greatly vary even among species with similar genome sizes because a significant portion of a eukaryotic genome might be composed of non-coding DNA, which does not get translated into proteins.
Furthermore, different species have unique evolutionary histories and adaptations that can lead to variations in the arrangement and number of genes and chromosomes they have. For instance, the human genome consists of about 3 billion base pairs spread across 46 chromosomes, while other organisms have different genome sizes, gene counts, and numbers of chromosomes. Some organisms have polyploidy, where they maintain multiple copies of each chromosome.