Visually they are barely distinguishable, but new genomic analyzes show that there are indeed four different species of giraffes and seven subspecies.
This result was obtained by an international team led by Professor Axel Janke from LOEWE Center for Translational Genomics of Biodiversity. Based on their comprehensive analyzes of the genome, the four giraffe lineages have evolved separately over thousands of years. Relationships within the giraffe genus have been debated before. For a long time it was assumed that there was one, then four, and later three species. The published study Current Biology provides new knowledge about the evolution of giraffes and relevant information for their proper conservation in Africa.
“Genomics, which consists of studying all the genetic information of a living being, opens up new possibilities and can broaden our perspective on species and their evolution, as happened now in the case of giraffes,” explains Professor Janke in a statement. . The African mammals with the long neck should be a single species, the giraffe, which was generally accepted for a long time. However, initial 2016 genetic studies from Janke’s lab indicated that there is not one, but four different species of giraffe. This groundbreaking result, which was obtained in conjunction with the Giraffe Conservation Foundation (GCF), is the subject of controversial debate among researchers and conservationists. Now, genome analyzes support the four-species model.
Analysis of some 200,000 positions in the DNA of a total of 50 giraffes confirms four species, namely, northern giraffe, southern giraffe, reticulated giraffe, and Masai giraffe. They comprise a total of seven subspecies. The data also shows that the four giraffe lineages began to evolve separately from each other 230,000 and 370,000 years ago. There is little to no gene flow and mixing between them. This means that the different species generally do not mate in the wild.. In captivity, however, this is possible under certain circumstances.
“The results of the genome analysis are of great importance for the conservation of giraffes,” says Dr. Julian Fennessy, director of GCF and co-author of the study. Populations have been drastically reduced in the past century to around 117,000 wild giraffes. Fennessy: “It is now clear that the remaining giraffes belong to four different species. This further exacerbates the situation. For example, we estimate that there are fewer than 6,000 northern giraffes left in the wild. As a species, they are one of the most threatened large mammals in the world. ”
Giraffes are found in the savannas of sub-Saharan Africa from Niger through Kenya and Namibia to South Africa. At up to six meters tall, these herbivores are the largest land mammals in the world. Their livelihoods are being decimated in many places by the increasing demand for agricultural land. Illegal hunting and politically difficult conditions complicate their protection. The International Union for Conservation of Nature (IUCN) classifies giraffes as “endangered” on its Red List of Threatened Species. The model of the four species model has not been taken into account until now, a fact that could change now.
“The data available is more informative than ever”, says Raphael Coimbra, a researcher at SBiK-F (Senckenberg Biodiversity and Climate Research Institute) and author of the study. “Our genome analyzes are based on significantly more genetic data than previous studies.”
In their analyzes, the researchers compared giraffe genomes of all previously considered species and subspecies from a total of twelve African countries and zoos. Hence, the genome of the Kordofan giraffe, a critically endangered subspecies of the northern giraffe, it was completely sequenced for the first time.