Polyploidy, the presence of more than two sets of chromosomes, is a common and successful evolutionary transition in plants and some animals. While its prevalence indicates it is a common phenomenon, whether it significantly affects diversification patterns and rates remains unclear. This review explores the role of polyploidy in evolution, focusing on its incidence in plants and animals, phenotypic effects, and genetic consequences. In plants, polyploidy is widespread, with estimates ranging from 20-40% to 70% of species. In ferns, polyploidy is particularly high, with 99.7% of species having a history of polyploidy. In flowering plants, polyploidy is estimated to account for 2-4% of speciation events, while in ferns, it is around 7%. Polyploidy is a significant mode of sympatric speciation in plants due to its effects on gene regulation and development, which can lead to immediate morphological and ecological changes. In animals, polyploidy is less common but still occurs. The polyploid index, a measure of the frequency of polyploidy, is significant in some animal groups but not in others. Polyploidy can enhance adaptability and evolutionary change, but its role in diversification is still debated. Polyploidy can lead to phenotypic changes, including increased cell size, altered growth rates, and changes in reproductive systems. It can also affect ecological tolerance and geographical distribution, allowing polyploids to inhabit a broader range of environments. However, polyploids may face challenges in sexual development and reproduction, particularly in species with complex sex determination mechanisms. Genetically, polyploidy increases the number of gene copies, which can dilute the effects of new mutations and gene combinations, making it difficult for polyploids to evolve new adaptive traits. However, polyploids may have a higher chance of carrying beneficial mutations and can adapt more quickly in certain circumstances. Overall, polyploidy plays a significant role in evolution, influencing diversification patterns and rates. While its exact impact on evolutionary processes is still being studied, evidence suggests that polyploidy can contribute to the creation of new species and the adaptation of organisms to changing environments.Polyploidy, the presence of more than two sets of chromosomes, is a common and successful evolutionary transition in plants and some animals. While its prevalence indicates it is a common phenomenon, whether it significantly affects diversification patterns and rates remains unclear. This review explores the role of polyploidy in evolution, focusing on its incidence in plants and animals, phenotypic effects, and genetic consequences. In plants, polyploidy is widespread, with estimates ranging from 20-40% to 70% of species. In ferns, polyploidy is particularly high, with 99.7% of species having a history of polyploidy. In flowering plants, polyploidy is estimated to account for 2-4% of speciation events, while in ferns, it is around 7%. Polyploidy is a significant mode of sympatric speciation in plants due to its effects on gene regulation and development, which can lead to immediate morphological and ecological changes. In animals, polyploidy is less common but still occurs. The polyploid index, a measure of the frequency of polyploidy, is significant in some animal groups but not in others. Polyploidy can enhance adaptability and evolutionary change, but its role in diversification is still debated. Polyploidy can lead to phenotypic changes, including increased cell size, altered growth rates, and changes in reproductive systems. It can also affect ecological tolerance and geographical distribution, allowing polyploids to inhabit a broader range of environments. However, polyploids may face challenges in sexual development and reproduction, particularly in species with complex sex determination mechanisms. Genetically, polyploidy increases the number of gene copies, which can dilute the effects of new mutations and gene combinations, making it difficult for polyploids to evolve new adaptive traits. However, polyploids may have a higher chance of carrying beneficial mutations and can adapt more quickly in certain circumstances. Overall, polyploidy plays a significant role in evolution, influencing diversification patterns and rates. While its exact impact on evolutionary processes is still being studied, evidence suggests that polyploidy can contribute to the creation of new species and the adaptation of organisms to changing environments.