Skip to main content

Phylogenetically structured variance in felid bite force II

A while back I attempted to introduce my recent publication. But of course as always I think I got carried away with the phylogenetic aspect of it. So unless I hear otherwise I shall suspend my fascination with phylogenetic signals and here discuss a bit about another interesting aspect of my paper on cat bite forces.

I've discussed bite force a lot in the past so I need not introduce it any more. One idea that is fairly widespread is that bite force is somewhat correlated with ecology and in particular prey preference. This can include dietary categories (hypercarnivorous, omnivorous, etc) or prey size categories (small prey hunter, large prey hunter). Previous studies have indicated that relative bite force (after adjusted for size) seem to have a correlation with prey size categories (Wroe et al., 2005; Christiansen & Wroe, 2007). Other craniodental morphofunctional characters also seem to have some correlation with prey size (Meachen-Samuels & van Valkenburgh, 2009). However, surprisingly, my results indicate that in felids relative bite force does not have any correlation with relative prey size. This does not mean that previous studies are in error in any way, but merely that I got a different result, probably because of the differences in data treatment and methodology. I was kind of surprised and a bit disappointed honestly with my results because it would have made an easier paper if relative bite force and relative prey size were in agreement with each other. But that was not the case; and perhaps it's more exciting that they betrayed my expectations.

So cats that bite harder than expected for their sizes do not necessarily take on prey that are relatively larger than them, and vice versa. This indicates to some extent that biting ability does not govern prey killing ability. A cat with an average bite force can kill prey that is up to 10 times its own body weight. This includes the Lynx and the Clouded Leopard, both having average bite forces but able to kill very large prey. There is still a lot that we don't know about the hunting behaviours of the Clouded Leopard so I shan't mention any more about this cat, but the observation that relative bite force and relative prey size don't match up for most of the cats is saying something. I think that relative prey size is not a controlling factor of relative bite force and that relative bite force does not necessarily represent a biomechanical adaptation for killing ability (but only with respect to relative prey size of course).

OK - I lied, I shall mention phylogeny here again. What I find more interesting however is that the relationship between relative bite force and phylogeny is, while statistically significant, actually not so strong. This means that closely related taxa don't necessarily have close values in relative bite force. In other words, relative bite force doesn't show a particularly strong phylogenetic signal (although statistically significant). The most interesting thing about this is that this is consistent to some extent with the idea that functional (biomechanical) adaptations are free of phylogenetic constraint and conform more to an adaptive form of evolution. So although relative bite force may not be explained by relative prey size, there is still the possibility that it is correlated with some other form of predatory behaviour, for instance mode of prey killing or average biting time, etc.


Ville Sinkkonen said…
Very interesting. Is there any correllation between biteforce and preferred type of killing bite?
(nape bite, suffocation)
Hi Ville,

That, I think, is exactly the sort of things that we should be investigating next. As far as I am aware, no such study exists. Many cat species are understudied so that kind of data may be difficult to come by. But I don't know for certain because I had not looked at those factors.

Popular posts from this blog

R for beginners and intermediate users 3: plotting with colours

For my third post on my R tutorials for beginners and intermediate users, I shall finally touch on the subject matter that prompted me to start these tutorials - plotting with group structures in colour.

If you are familiar with R, then you may have noticed that assigning group structure is not all that straightforward. You can have a dataset that may have a column specifically for group structure such as this:

B0 B1 B2 Family
Acrocanthosaurus 0.308 -0.00329 3.28E-05 Allosauroidea
Allosaurus 0.302 -0.00285 2.04E-05 Allosauroidea
Archaeopteryx 0.142 -0.000871 2.98E-06 Aves
Bambiraptor 0.182 -0.00161 1.10E-05 Dromaeosauridae
Baryonychid 0.189 -0.00238 2.20E-05 Basal_Tetanurae
Carcharodontosaurus 0.369 -0.00502 5.82E-05 Allosauroidea
Carnotaurus 0.312 -0.00324 2.94E-05 Neoceratosauria
Ceratosaurus 0.377 -0.00522 6.07E-05 Neoceratosauria
Citipati 0.278 -0.00119 5.08E-06 Oviraptorosauria

The difference between Lion and Tiger skulls

A quick divergence from my usual dinosaurs, and I shall talk about big cats today. This is because to my greatest delight, I had discovered today a wonderful book. It is called The Felidæ of Rancho La Brea (Merriam and Stock 1932, Carnegie Institution of Washington publication, no. 422). As the title suggests it goes into details of felids from the Rancho La Brea, in particular Smilodon californicus (probably synonymous with S. fatalis), but also the American Cave Lion, Panthera atrox. The book is full of detailed descriptions, numerous measurements and beautiful figures. However, what really got me excited was, in their description and comparative anatomy of P. atrox, Merriam and Stock (1932) provide identification criteria for the Lion and Tiger, a translation of the one devised by the French palaeontologist Marcelin Boule in 1906. I have forever been looking for a set of rules for identifying lions and tigers and ultimately had to come up with a set of my own with a lot of help fro…

The fundamental problem with the Star Wars franchise

The sequel Star Wars Trilogy (so far Episodes VII and VIII) has been getting a lot of hate on the internet. While I think most of the hatred is just dreadful and ridiculous (like “Social Justice Warriors” taking over and making Star Wars too diverse and featuring too many strong female characters? Get out of here!), there are some legitimate criticisms, that I can relate to.

One such criticism is, that the new trilogy (especially The Last Jedi) effectively undoes the ending of The Return of the Jedi - in some ways rendering the struggles and sacrifices of the Rebel Alliance meaningless. As a viewer who watched the original trilogy conclude with the death of the Emperor, I presumed that the Empire came to an end, and with it the end of tyranny. I presumed that democracy would be reinstated in the form of a New Republic and the reconstruction of a New Jedi Order with Jedi Master Luke Skywalker at the helm. Peace is restored and all is good. I think that’s a nice ending.

But then the new S…