The tiger, formally known as Panthera tigris, is a globally recognized symbol of wild power and a species of immense scientific interest. Understanding the genetics of this apex predator begins with examining its chromosomes, the structures housing the animal’s entire DNA blueprint. Chromosome analysis provides scientists with fundamental insights into a species’ biology, evolutionary history, and overall health. Investigating the tiger’s genetic makeup is an important part of modern conservation efforts to protect the remaining wild populations.
The Tiger Chromosome Count
Tigers possess a specific and consistent number of chromosomes. Like all members of the Panthera genus, including lions, leopards, and jaguars, the tiger has 38 chromosomes in its somatic, or body, cells. This is referred to as the diploid number, represented scientifically as 2n = 38, representing the full set inherited from both parents. This count is stable across all recognized subspecies of the tiger. The reproductive cells, the sperm and egg, contain half this number (19 chromosomes), known as the haploid number.
Organization of the Tiger Karyotype
The visual arrangement of these 38 chromosomes is known as the karyotype. The full set is organized into 19 pairs of homologous chromosomes: 18 pairs of autosomes and one pair of sex chromosomes. Autosomes carry the majority of genetic information, while the sex chromosomes determine biological sex (XX for female, XY for male). The autosomes are largely composed of metacentric and submetacentric types, where the centromere is near the middle or slightly off-center. The X chromosome is a medium-sized metacentric chromosome, and the Y chromosome is notably smaller.
Chromosome Numbers Across the Cat Family
The tiger’s chromosome count is highly conserved across the entire Felidae family. Almost all species in the cat family, from the smallest wildcats to the largest big cats, share the same diploid number of 38 chromosomes. This genetic stability suggests that the common ancestor of modern cats also possessed this 38-chromosome arrangement, exemplified by the domestic cat. A few exceptions exist among some small South American cats, such as the oncilla, Geoffroy’s cat, and margay, which have a diploid number of 36 chromosomes. This difference is thought to have arisen from the fusion of two smaller chromosomes into a single larger one, providing valuable markers for tracing evolutionary divergence.