The giraffes gut microbiome is made up of a variety of bacteria and fungi, and is largely determined by the giraffes species not by what they eat.A group of wild reticulated giraffes (Giraffa reticulata). (Credit: Tyler Kartzinel)Tyler Kartzinel with kind permissionI recently ran across a study that surprised me: this study reports that a giraffes gut microbiome is mostly determined by its species and not by its diet. These findings highlight an unexpected disconnection between diet and gut flora composition. This is remarkable because giraffes, as ruminants, are completely dependent upon their gut microbiome to break down the plant material they consume. Thus, this studys findings change the foundation of our understanding of host-microbe relationships.How did the researchers suss this out?An international team of researchers made this surprising discovery by sequencing plant and bacterial DNA found in faecal samples collected from three wild giraffe species, the reticulated giraffe, the Masai giraffe and the northern giraffe, living around the equator in Kenya (Figure 1).Figure 1: Overview of study system and species. (A) Map over Kenya with inset showing the geographic ... [+] distribution of conservancies where giraffes were sampled, colored by the giraffe species present in the area. (B) Images of the three giraffe species in this study are provided with a cladogram showing the phylogenetic relationships between them.doi:10.1016/j.gecco.2025.e03480To identify the plants and bacteria in the giraffe faeces, the team relied on fieldwork combined with DNA metabarcoding methodologies to investigate both the bacterial composition of the giraffe gut microbiome and the identities of the plants they were eating. DNA metabarcoding is a cost-effective method for identifying multiple species in a mixed sample, such as feces, using high-throughput sequencing.Giraffes are the worlds largest ruminants, yet surprisingly little is known about their gut microbiomes and how these microbial communities contribute to their nutrition, and overall health, said the studys lead author, evolutionary microbiologist, Elin Videvall, who currently leads a research group that studies wildlife diet and microbiomes at Uppsala University.What was the primary goal of this study?Given that ruminants rely entirely on their gut microbes to break down plant material, we wanted to understand whether dietary differences among giraffe species shaped their microbiomes or if other factors played a more dominant role, Dr Videvall explained to me in email.Dr Videvall and collaborators found that despite consuming a wide variety of plants over time, giraffe microbiomes remained remarkably similar within each species.We expected that giraffes with similar diets would also have similar microbiomes, but we found no such connection, Dr Videvall reported. Instead, we saw that giraffes seem to maintain species-specific microbiomes, even when individuals within the same species may eat completely different sets of plants.Geography strongly predicts giraffe dietsDr Videvall and collaborators found that although giraffes do eat locally, they uncovered no consistent link between diet and microbiome composition or diversity.Our results would not support the conclusion that an individual giraffes microbiome is insensitive to changes in its diet, said the studys senior author, conservation biologist Tyler Kartzinel, an Associate Professor in the Department of Ecology, Evolution, & Organismal Biology at Brown University. Professor Kartzinel was Dr Videvalls postdoctoral advisor when this work was conducted.Rather, what we find is that the normal variety of host-microbiome interactions that occur in these populations are strongly shaped by the host species identity and the population in which it occurs.This study suggests that the evolution of gut flora in giraffes may be more complex than previously assumed, and this microbial community may actually be shaped by long-term evolutionary processes that go beyond diet.I anticipated finding stronger diet-microbiome linkages when we began this study, Professor Kartzinel noted in email, [but] the evidence we currently have suggests giraffes can maintain normal microbiomes across a wide variety of environmental conditions and food sources.Dr Videvall, Professor Kartzinel and collaborators also found that most of the major groups of bacteria living in the guts of the three giraffe taxa are similar across the three study giraffe species, reflecting their recent evolutionary split.Even the majority of bacterial strains that our DNA-based method recovered were shared by at least two of the species, Professor Kartzinel told me in email. These patterns are consistent with evidence that these giraffe species diverged relatively recently in evolutionary history, and that they live in different places where they eat different foods.Further, Dr Videvall, Professor Kartzinel and collaborators also found that at least some giraffe gut bacteria are similar to those found in other ruminants, including cattle and sheep.Ill note also, for the benefit of my fellow microbiome-enthusiasts, that giraffes are the worlds largest ruminant. Their entire digestive system is intimately and inextricably linked to the proper functioning of its gut flora just like it is in cows and sheep, Professor Kartzinel explained in email. It stands to reason that a fascinating and highly diverse world of bacteria calls this oversized gut its home, so the potential for discovery is hard to overstate.What surprised you most about this studys findings?[W]hat really surprised me was how much giraffe diets differed across the populations that we surveyed even when we were comparing different populations of the same species so I find myself wondering not so much about what makes their microbiomes so different when they eat such similar diets but what causes their microbiomes to be so similar even when their diets are not, Professor Kartzinel replied in email.I anticipated finding stronger diet-microbiome linkages when we began this study, [but] the evidence we currently have suggests giraffes can maintain normal microbiomes across a wide variety of environmental conditions and food sources, Professor Kartzinel explained in email.Gut microbiomes are often linked to diets because they are ultimately responsible for breaking down the foods giraffes eat its like the engine that drives their digestive process so we wanted to consider any of these links that might be strong enough to warrant attention in conservation planning.In short, giraffes eat a wide variety of trees and shrubs that not only provide nutritional variety, but may serve as famine foods that giraffes may not particularly like to eat but that they can at least temporarily rely on during environmental shocks, such as the megadrought that recently gripped the region.Studying their gut microbiomes can also provide insights into how species adapt to different environments and diets, which is crucial for conservation efforts, especially as habitats change, Dr Videvall added in email.Microbiomes may be important considerations for giraffe conservation planningThose who follow the conservation plight of giraffes know they are teetering on the verge of a silent extinction, where their populations are rapidly dwindling into nothingness but tragically, their precarious situation is often overlooked, although Professor Kartzinel, Dr Videvall and collaborators are working hard to change that.My group is known for working with non-profits and governmental agencies on research priorities that could help conservation on the ground, Professor Kartzinel said in email.They are conspicuous animals, marvelously adapted for their environment, but still so poorly understood: they have been treated as one widespread species, though recent studies have supported at least four genetically distinct species [read more here] that should each be afforded protections, Professor Kartzinel continued in email. Three of these species ranges nearly intersect in southern Kenya, providing a unique opportunity to understand their differences and any unique needs they might have.Because all three study species are endangered, any knowledge of what they eat is valuable information, especially when planning which areas are most important to preserve to ensure their continued access to nutritious forage plants.We began this study as an international collaboration between academics and conservation professionals. We hope our research can provide better insight into giraffe diets and help support the conservation of giraffes, Professor Kartzinel summarized.Additional collaborations involved in this study include the Giraffe Conservation Foundation, an NGO devoted exclusively to giraffe conservation, the Mpala Research Centre, a pioneering collaboration between the United States and Kenya using field-based research into a variety of intertwined and pressing concerns, such as conservation, climate change, biodiversity, genomics, ecology, agriculture, human-wildlife interactions, and public health, and the East African Herbarium, which maintains the largest botanical collection in tropical Africa.Source:Elin Videvall, Brian A. Gill, Michael B. Brown, Hannah K. Hoff, Bethan L. Littleford-Colquhoun, Peter Lokeny, Paul M. Musili, and Tyler R. Kartzinel (2025). Diet-microbiome covariation across three giraffe species in a close-contact zone, Global Ecology and Conservation, 58:e03480 | doi:10.1016/j.gecco.2025.e03480 Copyright by GrrlScientist | hosted by Forbes | LinkTr.ee