Fuck Yeah, Convergent Evolution!

Evolution is a crazy and seemingly random process, and yet somehow, distantly related lineages have converged on analogous solutions to the same problems. This blog celebrates the un-fucking-believability of that process.

[fuckyeahconvergentevolution]

Swimming through substrate costs an arm and/or a leg

by Mark D. Scherz

Last week, a paper was published in the Open Access journal PLoS ONE, entitled ‘Distinct Patterns of Desynchronized Limb Regression in Malagasy Scincine Lizards (Squamata, Scincidae)‘, by Aurélien Miralles and colleagues. This paper dealt with a fascinating case of repeated convergent evolution, and I thought I would share my thoughts on it.

As some readers may know, snakes are phylogenetically nested within the lizards. That is to say, all snakes actually belong to one giant radiation of legless lizards. They are possibly the oldest surviving lineage of legless squamates, and certainly the most successful, with multiple thousands of species. But they are far from the only ones. In fact, limb loss is something of a fad among reptiles. Members of numerous families have undergone these changes, the most familiar in Europe being the slow worm, Anguis fragilis; the most familiar in America being the glass lizards, with the creative name Ophisaurus (=snake lizard). Both of these are anguid lizards. But the vast majority of legless lizards belong to a different family: the skinks.

Skinks seem to have a penchant for losing legs. They are typically long, slender lizards anyway, but something about them has led them to lose their limbs dozens upon dozens of times, independently.

Madagascar makes an excellent case study for this phenomenon (although Australia is also a popular choice). In Madagascar, we have five genera of skinks that have lost their legs. The parsimony-lover might stack these all as being sister to each other, and leave it at that. Surely they all followed the same path, and it results in maybe just a few instances of limb loss, right? Nope.

Keep reading here!

First photo of Pygomeles trivittatus by Mark D. Scherz 2012; Second figure of the focal species of the discussed study, taken from Miralles et al. 2015 PLoS ONE 10(6):e0126074 under CC BY 4.0 license.

[fuckyeahconvergentevolution]

Hello, why don't you have a personal relationship with our Lord and Saviour Jesus Christ? The Son of God. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. - John 3:16

Happy shall they be who take your little ones and dash them against the rock! - Psalm 137:9

[ibiologicalsciences-blog]

Phenotypical convergence in white lizards

Inspired from  the new tumblr blog fuckyeahconvergentevolution.tumblr.com i wanted to make a convergent evolution post. This is an example i like to use often in my presentations because it portrays convergent evolution remarkably, but i will get to that later on.

This example includes three species of lizards found in and around White Sands in New Mexico: Eastern Fence Lizard (Sceloporus undulatus), Little Striped Whiptail (Aspidoscelis inornata), and Lesser Earless Lizard (Holbrookia maculata). The area is full of white sand so these three species have independently evolved white (blanched) phenotype for camouflage. The sand there, is derived from gypsum and is formed in less than 6,000 years ago! This means that these new phenotypes evolved rapidly from a brown ancestral phenotype (each one from a different ancestor) that inhabits the surrounding desert.

Mutations associated with blanched coloration in White Sands lizards. (A) Blanched morphs from white sands on top and dark morphs in ancestral dark soil habitat on bottom. (B) Amino acid schematic of the melanocortin-1 receptor (Mc1r); replacements statistically associated with coloration in the focal taxa are shown in red.

The figure above summarises a recent study (Rosenblum et al. 2010). You can see the two varieties of the three species in A. They all evolved a blanched phenotype while the varieties in the surrounding dark soil habitat are still brown.

Here comes the amazing part. The above study found the genetic basis of this convergence which showed that they are all related to a single amino acid replacement. The amino acid replacement is different in the three species, but it is found in the same gene (Mc1r)! All the aa replacements occur in the transmembrane regions, which are the most important for the structure and function of a TM protein.

Mc1r is a hormone receptor on the surface of melanocytes and is involved to melanogenesis. More specific, it is known to induce the accumulation of cAMP which results in the activation of other genes involved in pigmentation. The wild-type form of Mc1r produces dark pigmentation but when inactivated it results in lighter colours. Other animals have Mc1r mutations too, with the most common example the one of humans where they cause ginger hair. 

In this study they tested the genetic basis of this convergence.

First, they found a strong correlation of the three amino acid mutations with the blanched colouration in the white sand habitat.

The next step was functional assays, which showed that in two of the three species (S. undulatus and A. inornata) the Mc1r mutants reduced the proteins activity. This wasn’t the case for H. maculata, even though it exhibited the strongest correlation. This could be just a random association or it could mean that there is an unknown mechanism of Mc1r.

Finally, they proceeded to genetic analysis according to which the white allele is dominant in S. undulatus while it’s recessive in A. inornata. The dominance is most likely selected by evolution as it produces a protein that prevents the wild type form from integrating into membranes. This difference has an impact on the gene pool of these two species. It is natural that in A. inornata the dark coloured wild-type form is removed by selection immediately as it produces dark pigmentation even in heterozygous individuals, whereas in S. undulatus the wild-type gene remains in the gene pool in higher frequency.

This is an amazing textbook example of convergence not only at the phenotypical level but at the molecular level as well and it’s not even my favourite example of convergent evolution (i will probably make other posts too).

Here is a picture (unknown source) to see how big the selective pressure for the white colouration is. 

Reference

Rosenblum, E., Rompler, H., Schoneberg, T., & Hoekstra, H. (2009). Molecular and functional basis of phenotypic convergence in white lizards at White Sands Proceedings of the National Academy of Sciences DOI:10.1073/pnas.0911042107

[fuckyeahconvergentevolution]

CHECK THIS THE FUCK OUT.

THREE SPECIES OF LIZARDS

HAVE FOUND THE SAME SOLUTION

TO THE SAME PROBLEM

IN THE SAME PLACE

INDEPENDENTLY.

IF THAT ISN'T THE COOLEST FUCKING THING YOU'VE SEEN ALL DAY YOU MUST BE HAVING AN AWESOME DAY.

[fuckyeahconvergentevolution]

Hello. Congratulations for display this interesting case. More than a question, reasoning about the mechanisms that account for this pattern. I think we can not discard the activation of preexisting old genes due to epigenetic effects (triggered by environmental factors). Very interesting. The opposite of this case is the clearly different phenotype between chimps and humans although we have a extremely similar genome. In this case, there are on/off genes. Thanks. Pedro F. Victoriano.

The examples I have given thus far are one or two orders of magnitude older than the divide between chimps and humans. Yes, it is possible that the apparent 'convergences' in body shapes are the result of recovered genes that have been dormant in the intervening time or that have been differentially expressed in other lineages, but over the time-scales we are talking about, that is almost inconceivable. We can be reasonably certain that these are truly instances of convergence and not the result of re-awakened pre-existing genes.

[fuckyeahconvergentevolution]

Convergence in two frogs from two distant families.

submitted by Pedro F. Victoriano

YEAH!

These are a darwin's frog, Rhinoderma darwinii, left, and a leaf-litter toad, Rhinella alata, right! They are extremely distantly related. This pattern has also evolved dozens of times in different groups of frogs. It's an incredibly good way to blend into the forest floor!

[fuckyeahconvergentevolution]

Mossy Frogs: Convergent Crypsis

Alright, sit down, shut up, and let me tell you about some of the coolest frogs in the whole damn world. Someone sent an ask about my favourite example of convergence; this is way up there.

You may have heard of the Vietnamese Mossy Frog, Theloderma corticale, pictured top right in the figure above. This awesome little bastard is now quite common in the pet trade because of how bitching its camouflage makes it look. This is a really fucking awesome example of crypsis, because when these frogs are at rest among moss, they are almost imperceptible.

What makes it so hard to see? Well, for one, it’s fucking green. That’s pretty effective as camouflage when you live on moss. That green isn’t solid though, like a lame-ass Hyla arborea. No, it’s mottled with brown and other shades of green, to break up any solid colours. Next, it has spines all over and around its body, especially on the edges of its limbs. What do these do? They break up the outline of the frog. It doesn’t cast a frog-shaped shadow. This makes it much harder to spot, and is just generally awesome.

But this is Fuck Yeah, Convergent Evolution, not Fuck Yeah, Crypsis! (Yeah that’s a thing now too, I couldn’t help myself).

The green colour and spiny body, often with fringes around the limbs and body, has evolved in many many animals (including my favourites, the Uroplatus geckos).

The evolutionary pressure for this kind of crypsis is so great that incredibly similar structures and body shapes have evolved at least. seven. fucking. times. in at least four families of frogs! There may even be more but I don’t know all of the world’s frog species. These are just the ones I knew of already and a few added by Prof. Karen Lips and Dr. Jodi Rowley (two of the coolest herpetologists on the internet).

In Madagascar alone we have three convergences on this mossy crypsis: some frogs in the genus Spinomantis (Mantellidae:Mantellinae), including S. spinosa depicted above, and the aptly named S. phantasticus; a few frogs in the genus Scaphiophryne (Microhylidae:Scaphiophryninae); and Platypelis grandis (Microhylidae:Cophylinae). These three groups have few things in common, but chief among them is a predilection for moist mossy habitats.

The common ancestor of all seven of these radiations hopped the earth hundreds of millions of years ago. It was barely even a frog, let alone a fucking awesome moss mimic.

The similarity we see in these frogs can therefore mean only one thing: the evolutionary pressures they are experiencing (e.g. being eaten) are selecting for the same solution: bad-ass crypsis. And rather than re-inventing the wheel of crypsis, each group has found the same solution: textured skin to break up the shadow and outline of the body, and mottled green colouration to blend into the foliage.

The convergence is so extreme that you would be forgiven for thinking most of these species to belong to the same genus if you didn’t know they were from completely different sides of the earth.

Convergent evolution is the fucking best.

[fuckyeahconvergentevolution]

BUT WAIT, IT GETS BETTER!

Since posting the above, numerous other groups have been brought to my attention by the brilliant herp people of twitter:

Kurixalus sp. (photo by Jodi Rowley):

Gracixalus supercornutus (photo by Jodi Rowley):

Litoria serrata (photo by Jodi Rowley; I mean seriously she is the coolest person on the internet, have you got that yet?):

Ecnomiohyla miliaria (x):

Osteocephalus buckleyi (x):

Scinax garbei (photo by Matt Cage):

THAT TAKES US TO 13 TIMES IN FOUR FAMILIES. I CAN'T EVEN HANDLE IT ANYMORE.

[fuckyeahconvergentevolution]

Mossy Frogs: Convergent Crypsis

Alright, sit down, shut up, and let me tell you about some of the coolest frogs in the whole damn world. Someone sent an ask about my favourite example of convergence; this is way up there.

You may have heard of the Vietnamese Mossy Frog, Theloderma corticale, pictured top right in the figure above. This awesome little bastard is now quite common in the pet trade because of how bitching its camouflage makes it look. This is a really fucking awesome example of crypsis, because when these frogs are at rest among moss, they are almost imperceptible.

What makes it so hard to see? Well, for one, it's fucking green. That's pretty effective as camouflage when you live on moss. That green isn't solid though, like a lame-ass Hyla arborea. No, it's mottled with brown and other shades of green, to break up any solid colours. Next, it has spines all over and around its body, especially on the edges of its limbs. What do these do? They break up the outline of the frog. It doesn't cast a frog-shaped shadow. This makes it much harder to spot, and is just generally awesome.

But this is Fuck Yeah, Convergent Evolution, not Fuck Yeah, Crypsis! (Yeah that's a thing now too, I couldn't help myself).

The green colour and spiny body, often with fringes around the limbs and body, has evolved in many many animals (including my favourites, the Uroplatus geckos).

The evolutionary pressure for this kind of crypsis is so great that incredibly similar structures and body shapes have evolved at least. seven. fucking. times. in at least four families of frogs! There may even be more but I don't know all of the world's frog species. These are just the ones I knew of already and a few added by Prof. Karen Lips and Dr. Jodi Rowley (two of the coolest herpetologists on the internet).

In Madagascar alone we have three convergences on this mossy crypsis: some frogs in the genus Spinomantis (Mantellidae:Mantellinae), including S. spinosa depicted above, and the aptly named S. phantasticus; a few frogs in the genus Scaphiophryne (Microhylidae:Scaphiophryninae); and Platypelis grandis (Microhylidae:Cophylinae). These three groups have few things in common, but chief among them is a predilection for moist mossy habitats.

The common ancestor of all seven of these radiations hopped the earth hundreds of millions of years ago. It was barely even a frog, let alone a fucking awesome moss mimic.

The similarity we see in these frogs can therefore mean only one thing: the evolutionary pressures they are experiencing (e.g. being eaten) are selecting for the same solution: bad-ass crypsis. And rather than re-inventing the wheel of crypsis, each group has found the same solution: textured skin to break up the shadow and outline of the body, and mottled green colouration to blend into the foliage.

The convergence is so extreme that you would be forgiven for thinking most of these species to belong to the same genus if you didn't know they were from completely different sides of the earth.

Convergent evolution is the fucking best.

[fuckyeahconvergentevolution]

Fuck Yeah, Convergent Evolution!

Hello! This is the inaugural post of my new side-blog, Fuck Yeah, Convergent Evolution (FYCE for short)!

Together we are going to go on a crazy-ass adventure through some of the completely fucking awesome body forms, survival strategies, and just generally bad-asseries that have evolved repeatedly and independently across various kingdoms, focussing mainly on the kingdom Animalia (because I don’t know shit about plants and other kingdoms, sorry friends).

Like all good friendships, we will begin with a definition:

“Convergent evolution describes the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups.” [x]

Basically it’s the coolest shit ever.

It’s the equivalent of two people inventing the telephone at the same time on opposite sides of the planet, with the only thing they have in common being a spoken language and an inability to yell loud enough to talk to someone a mile away.

But why do we care?

Well, I mean, firstly, look at that little fucker above. See him? Yeah, that’s a lesser hedgehog tenrec, Echinops telfari. I bet you thought it was a hedgehog, right? I mean, look at it. It’s a spiky little motherfucker.

Yeah no it’s more closely related to a fucking manatee than a hedgehog.

Oh, my bad, that should have come with a warning about MINDFUCK.

Yeah well, that’s why you should care. Because this shit will blow your damn mind.

Also because, you know, understanding evolution is critical to understanding life, and understanding life is critical to keep it going, and that’s basically in your best interest.

So not only is convergent evolution badass, but it’s also really important. It tells us a lot about life on this awesome fucking piece of rock we call home.

Also you should care because next time you’re on a date with someone and you run out of stuff to talk about you can be like ‘let me tell you about the tenrec’, and watch as they become progressively more impressed and associate your vast knowledge directly with your sexual prowess.

I’m just sayin’; this shit is the bomb.

So come along on the FYCE adventure! It’s gonna be a WILD ride.

You can already submit shit to the blog where you can talk about a bit of convergence that you find really fucking awesome, or you can ask me to talk about it for you.

Or you can ask about some events of convergence, because that shit stimulates curiosity.

Thanks for following! Brace yourselves for awesome times to come!