Elephant Family Trees

 

So if you didn’t already know, there are currently three different species of elephant alive today: the African Savanna, the African Forest, and {the Best} the Asian elephant. Phylogeny, or just a fancy way to say family trees, have been debated constantly in the elephant world. To settle these debates (or often add additional fuel to the fire), we look to fossils to explain the evolution of the species.

The prime example that everyone seems to know of is the Woolly Mammoths. Well, have you ever sat down and thought, who the heck are they related to, African elephants or Asian elephants? Or even, are the three species alive today more closely related to each other than that crazy hairy beast? This debate was hashed out by scientists for YEARS, in fact every now and again you’ll find a scientist claiming to have new evidence to support one or the other. I gotta say, I’m siding with (as do most nowadays)  Rohland et al (2007), who genetically determined that Mammoths (Mammuthus primigenuis below) are actually most closely related to the Asian elephants (Elephas maximus). [Other names in the figure include Loxodonta africana, the African elephant and Mammut americanum, the Mastodon]. Although I gotta say, check out that forehead on the Mammoths and Asian, quite the family trait.

If your saying right now “But Kris, I’m looking at that tree and seeing only one African elephant, didn’t you say there are two?!”. Why yes good sir, I did. In fact, the early 2000’s fueled enormous debates about Savanna and Forest elephants. (In fact, my adviser Lori Eggert, was among the first to show this difference while working with the Forest elephants of Gabon!). However this debate continues on today.

It all comes down to what the heck you decide to call a species. Species are a man-made concept, and nature has never liked falling into nice clean boxes. So what is a Species? Well that entirely depends on who you ask. There are several different definitions of what you can define as a species and what works for one organism sure doesn’t work for another.

Think about this:

Why aren’t the breeds of dogs classified as different species? Well Kris, they are all still dogs! They can still breed and everything…. Oh really? How about a chihuahua and a great dane? Should they be different species because they can’t have little chihua-danes? No, of course not! How about wolves and dogs? They can breed, and yet are two species right? Okay, now apply that thinking to elephants. Savanna and Forest elephants can actually breed with one another, (heck, Asian and African elephants have actually produced a hybrid in a zoo at one point) but they look and act differently. Now do you call it a separate species? OF COURSE YOU DO.  Welcome to the confusing mess that is species. 

Anywho, this Savanna vs. Forest debate has raged for years and like usual we try to turn to fossils to help solve it. Enter, the Straight Tusked Elephant, (Palaeoloxodon). This behemoth of a bruit lived (and died) about 120 to 244 thousand years ago. Its long been assumed that it is a long lost relative to the modern day Asian elephant (more so than even the Mammoths). Like all good science novels, recent developments in genetics had to come and prove everything you thought you knew straight up wrong! In a new paper, Meyer et al (2017) found that this fossilized ancestor is actually most closely related to the African Forest Elephant (Not even the Savanna). This of course provided even more support to say that the Forest elephant is a separate species, with a unique ancestral tree than that of the Savanna elephant.

Untitled

So although our Straight tusked elephant has that wicked forehead of the Asian and the Mammoth, it came from the little forest elephant, well at least the straight tusks are a family trait I guess. Goes to show you shouldn’t judge a book by its cover.

 

Meyer et al. eLife 2017;6:e25413. DOI: 10.7554/eLife.25413

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