When Charles Darwin and his colleagues were collecting plant and animal specimens from around the world and trying to organize them into a tree of life, they mostly grouped things together based on how they looked. This morphological species concept was a good starting place, but these early biologists soon ran into some problems. One big issue was classifying species where females and males look completely different—there were many errors with males and females of these sexually dimorphic animals being considered separate species!

In the 1930s and 1940s, biologists developed a new way of organizing animal life: the biological species concept. This states that if two animals can have babies with each other, and those babies can have babies (can produce fertile offspring), then they are considered the same species. This style of organization works better than the morphological species concept and was the standard for evolutionary biologists for decades. However, it still isn’t perfect. Why not? To answer that, let’s consider how new species appear. Imagine a population of monkeys frolicking in a beautiful valley. Suddenly, there is a massive earthquake! The ground splits and a canyon appears, breaking the valley in half. The monkeys on one side of the valley can no longer interact with those on the other side. Over time, the monkeys on each side of the valley evolve to be better suited to their environments. Eventually, these two populations are so different from each other that even if they were to be reintroduced, they would no longer be able to produce fertile offspring with each other. One species has become two.

In the real world, things rarely happen this cleanly. Pockets of populations can naturally spread out and become more isolated from the rest, but there is usually still some interaction and breeding between these pockets, which we call gene flow. One of our favorite examples of the biological species concept breaking down is a tiny California native salamander known as an ensatina. This salamander slowly spread around the edges of the California central valley, resulting in a strange situation where there is gene flow between all of the neighboring salamander populations, except at the point where the ring meets up again at the bottom—these two populations are unable to produce offspring with each other. 

Nowadays, we usually organize animals in the tree of life based on genetics. Using modern genetic analysis, we can determine how much gene flow there is between different populations in a species. If there is not much gene flow, we have the grounds to reclassify those populations as separate species. You may be thinking….”not much gene flow” sounds pretty subjective, and you would be correct! When we decide to make the call to break a species that has multiple populations with limited gene flow into multiple species is extremely arbitrary, and changes based off of who is making the decision, as well as other factors influencing that decision.

Back to giraffes! Giraffes are in the situation described above: multiple populations with a limited amount of gene flow between them. As such, different studies have come back with different results and given us different hypotheses for how many different species of giraffe there are. There have been hypotheses that advocate for one species of giraffe, three species, four species, and even eight species! For many years the IUCN has used the organization of one single giraffe species, with nine different subspecies. However, the Giraffe Conservation Foundation (GCF) has long advocated for the four species hypothesis. With this announcement, one of the foremost global conservation organizations (IUCN) and the foremost giraffe conservation organization (GCF) are now in agreement: there are four species of giraffe:

• Northern Giraffe
• Southern Giraffe
• Masai Giraffe
• Reticulated Giraffe

So….why do we care? Does it really matter that much if we decide there are one or three or four species of giraffe? This is where conservation and politics come in. Many government and nonprofit organizations use the IUCN designations of how endangered an animal is as a guideline for how much support an animal should receive, and how protected they should be. This change will immediately change the conservation status of giraffes. When you split a group into four smaller groups, each group is likely to be considered more endangered because it has fewer individuals. Previously, giraffes were considered “Vulnerable” by IUCN, but as the IUCN determines a new conservation status for each of these four species, some of them will likely be considered “Endangered” or even “Critically Endangered”, resulting in more conservation support.

Hopefully this has helped you understand the complexities with defining species, why the number of giraffe species has been so contentious, and why this IUCN decision is exciting news for giraffe conservation. Regardless of how many species there are, giraffe populations are declining in the wild. The Giraffe Conservation Foundation is doing excellent work and can always use more support to help these wonderfully unique animals. Giraffes conservation is a staple of Safari West, with more than 50 baby giraffes being born here in the last 50 years. We love giraffes of all types, and we hope you do too!