Some of the strangest creatures on earth have recently shed new light on nature’s mysterious pattern forming programmes. The discovery of the hox genes in the 1980s was the first breakthrough in understanding how the forms of all creatures are made and how they evolved. All animals, whether insects or mammals, are highly modular: evolution has occurred through copying of modules with subsequent modification of what were once identical parts (homology). So all insects have segments and all land animals have four legs (tetrapods). These programmes seem to be highly constrained and conservative. Birds are tetrapods and whilst it might be advantageous for a bird to have four legs and two wings, evolution has not managed this: the forelimbs can become wings but extra limbs cannot be achieved. In fact, it hard to know how true novelty ever emerged.
In a recent paper in Nature (2011, Vol 273, pp83-86) a French team have shown that there is an exception to every rule. Primordial insects might have had wing-like appendages on all the segments but long ago the hox gene suppressed wings on all but two segments: the second and third thoracic segments. The treehoppers have astonishing varied appendages, “helmets” which may be used for camouflage or to break up the creature’s outline or in some cases to form protective spines. The range of these helmets in different species is so vast and grotesque that the creatures look like sci-fi aliens. Benjamin Prud’homme and Nicolas Gompel’s team has shown that these weird shapes are actually formed by the normal wing hox genes but acting on the head segment, a place where they are suppressed in ever other species of insect. They say that this is an unprecedented example in 250 million years of insect evolution. And beyond that, the helmets show what nature pattern forming genes can do when they have a free hand.
Wings have to obey the laws of aerodynamics so they are constrained in the forms they take but these helmets can take pretty any form they like, although they obviously fulfil some function. The pattern forming genes work by switching on an off in cascades, accelerating growth in one area, slowing it in another. The results are breathtaking.
The helmets are not variations on a theme but a complete gallery of morphs. Some seem to be mimicking other creatures such as ants; one would make a rather cool arced earring; one is a leaf mimic, and so on.
In the technological realm we now have 3D printers, using stereolithography to build, layer by thin layer, any pattern you like, laid down by a computer design. The pattern is built by resin deposition in accord with the parameters laid down by the computer programme. The treehopper seem to foreshadow nature’s stereolithography by means of hox genes.
In Dazzled and Deceived I investigated the genetic patterns behind mimicry and camouflage. Almost all of this work had been done on butterflies; Prud’homme et al have begun the process of unlocking the treasure trove of mimetic pattern-forming in the wider natural world.
Credit: B. Prud'homme et al., Nature, 473 (5 May, 2011)
In a recent paper in Nature (2011, Vol 273, pp83-86) a French team have shown that there is an exception to every rule. Primordial insects might have had wing-like appendages on all the segments but long ago the hox gene suppressed wings on all but two segments: the second and third thoracic segments. The treehoppers have astonishing varied appendages, “helmets” which may be used for camouflage or to break up the creature’s outline or in some cases to form protective spines. The range of these helmets in different species is so vast and grotesque that the creatures look like sci-fi aliens. Benjamin Prud’homme and Nicolas Gompel’s team has shown that these weird shapes are actually formed by the normal wing hox genes but acting on the head segment, a place where they are suppressed in ever other species of insect. They say that this is an unprecedented example in 250 million years of insect evolution. And beyond that, the helmets show what nature pattern forming genes can do when they have a free hand.
Wings have to obey the laws of aerodynamics so they are constrained in the forms they take but these helmets can take pretty any form they like, although they obviously fulfil some function. The pattern forming genes work by switching on an off in cascades, accelerating growth in one area, slowing it in another. The results are breathtaking.
The helmets are not variations on a theme but a complete gallery of morphs. Some seem to be mimicking other creatures such as ants; one would make a rather cool arced earring; one is a leaf mimic, and so on.
In the technological realm we now have 3D printers, using stereolithography to build, layer by thin layer, any pattern you like, laid down by a computer design. The pattern is built by resin deposition in accord with the parameters laid down by the computer programme. The treehopper seem to foreshadow nature’s stereolithography by means of hox genes.
In Dazzled and Deceived I investigated the genetic patterns behind mimicry and camouflage. Almost all of this work had been done on butterflies; Prud’homme et al have begun the process of unlocking the treasure trove of mimetic pattern-forming in the wider natural world.
Credit: B. Prud'homme et al., Nature, 473 (5 May, 2011)
RSS Feed