Final answer:
Triploidy is less common than tetraploidy because organisms with an odd number of chromosomes sets (three) are usually sterile, unable to conduct normal meiosis to produce viable gametes. Tetraploids can pair chromosomes evenly allowing fertile offspring. Polyploidy is much more common and advantageous in plants than in animals.
Step-by-step explanation:
There is indeed a specific reason why triploidy is less common than tetraploidy. Triploid organisms, which have an odd number (three sets) of chromosomes, are typically sterile because during meiosis, an odd number of chromosome sets does not allow chromosomes to pair up normally, leading to difficulties in forming viable gametes. Plants can tolerate these irregularities better than animals because plant physiology and reproduction mechanisms can accommodate varying numbers of chromosomes more easily than animals. Contrastingly, tetraploidy, where organisms have four sets of chromosomes, is more feasible because the even number of chromosome sets can pair up normally during meiosis, possibly leading to fertile offspring.
Triploid animals are particularly rare and mostly sterile, while tetraploid animals are also rare but less so in comparison. In the plant kingdom, polyploidy is a common phenomenon, and plants with polyploidy often show certain advantages such as increased size and robustness over their diploid counterparts.