Category: Ecomorphs
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Ecomorphs (or "ecological morphotypes") represent classic and particularly straightforward examples of convergent evolution. As there is a close relationship between morphological and ecological variation, similar environmental conditions may lead to the repeated evolution of the same morphology. This is reflected in the term ecomorph, which refers to ecological equivalents or convergent adaptive types. When studying ecomorph diversity in freshwater fish, Kirk Winemiller remarked: "The concept of ecological convergence and independent evolution of equivalent ecomorphotypes deserves special attention because of its implications for general ecological and evolutionary theory" (Winemiller 1991, Ecological Monographs, vol. 61, p. 361).
Ecomorphs can be found in many animal groups, but one of the most famous examples is the Anolis lizards of the Caribbean. There are striking similarities between various species on different islands, representing specific anolid ecomorphs that reflect the type of habitat, such as "twig ecomorphs" with short limbs and "trunk ecomorphs" with long limbs. Among the lizards, there are also sand-dwelling ecomorphs that inhabit arid regions of Africa, the Americas and Australia. Members of six distantly related lizard families have independently adapted to this extreme environmental setting and converged on many shared aspects of morphology and behaviour, from sand-diving to collecting early morning dew on specialised skin surfaces.
The amphibians provide striking cases of ecomorphological convergence, too. Particularly remarkable are the frogs of Madagascar and those of Asia that show compelling, but independent, similarities between burrowing, arboreal, rock-dwelling and torrential ecomorphs. So too the Madagascan mantellid frogs are strikingly convergent with the neotropical poison-arrow frogs (the dendrobatids).
One of the classic mammalian ecomorph examples concerns different cat-like species that evolved a sabre-tooth morphology. Two distinct ecomorphs are recognised ("dirk-tooth" with elongate sabres and "scimitar-tooth" with somewhat shorter canines), which evidently represent different hunting strategies, and both evolved repeatedly in different felid groups, as well as showing parallels in the thylacosmilid marsupials of South America.
Further striking cases have been documented amongst the fish (notably the tuna/lamnid shark ecomorphs that show convergence in terms of locomotion and thermoregulation) and also birds are useful in the general documentation of ecomorphs, with ecomorphological convergence observed in vultures and other raptors (where different diets and hunting strategies are reflected in beak and hindlimb morphology).
| Topic title | Teaser text | Availability |
|---|---|---|
| Temperate-adapted lizard ecomorphs | n/a | Unavailable |
| Rock-dwelling lizard ecomorphs | n/a | Unavailable |
| Fenestrate bryozoans and graptolites | n/a | Unavailable |
| Cichlids | Cichlids are one of the cause celebr� of evolution, and rightly so because these freshwater fish show a remarkable diversity and exemplify many key aspects of adaptive radiation. But why so successful? The answer lies in the versatility of the jaws (and yes, they are convergent). | Available |
| Succulent desert plants | Classic examples of convergence in desert plants include the so-called 'stem succulent' cacti in the Americas and cactus-like Euphorbia species in Africa and South Asia, and also the striking similarity between 'leaf succulent' Agave and Yucca of the Americas and Aloe and its close relatives in Africa. | Available |
| Crabs: insights into convergence | You might think of crabs mainly as food, but this group is also highly instructive in terms of convergence… | Available |
| Limblessness in lizards | What's that slithering towards you? A snake? Look more closely, look convergently... | Available |
| Bats: Insights into convergence | Bats show a fascinating array of convergences, from echolocation to flight to nectar feeding. Vampire bats can even detect infrared radiation, while others might be able to see into the ultraviolet end of the spectrum. | Available |
| Sand-dwelling (psammophilous) lizard ecomorphs | Desert sand dunes represent an extreme environmental setting in which selective forces have apparently generated dune ‘ecomorphs’ in six lizard families. – Lamb et al. (2003) Biological Journal of the Linnean Society, vol. 73, p. 253 | Available |
| Ecological adaptations in Moloch and Phrynosoma lizards | Lizards of the genera Phrynosoma and Moloch have been considered a classic example of convergent evolution J. J. Meyers & A. Herrel (2005) The Journal of Experimental Biology, vol. 208, p. 114 | Available |
| Anolis lizard ecomorphs | “A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles.” – Langerhans, Knouft & Losos (2006) Evolution, vol. 6, p.362 | Available |
| Birds as ecomorphs | n/a | Unavailable |
| Sabre-toothed cats and marsupials | Marsupials with giant fangs? Yes, not all of the extinct sabre-toothed cats were actually cats… | Available |
| Viverrid ecomorphs: from linsangs to Binturongs | The viverrids or civets are a highly successful group of carnivores, fairly closely related to the cats and showing several striking examples of convergence. | Unavailable |
| Woodpeckers and woodpecker-like birds and mammals | You think woodpeckers are unique? Consider the ovenbirds. Or even the curious aye-aye. | Available |
| Ecology and cosmetics in vultures | Vultures are not only charistmatic birds in the popular imagination, but are strikingly convergent, especially regarding feeding types... | Available |
| Crustaceans: insights into convergence | Whilst predominantly marine, quite a number of crustaceans have invaded freshwater habitats and even more interestingly a few demonstrate terrestrialization, effectively freeing themselves from their aquatic ancestry. | Available |
| Gastropod molluscs: snail shell anatomy | Snail shells typically form a helical spiral, but within this geometry there is a considerable degree of convergence. | Unavailable |
| Worm-like body form | Man is but a worm, but so are many other vertebrates... | Available |
| Annelids: insights into convergence | Notable instances of convergence involving annelids include luminescence, moulting and the independent evolution of both compound eyes (e.g. in sabellids) and camera eyes (in alciopids). | Unavailable |
| Amphibian ecomorphs: frogs and salamanders | Striking examples of convergence can be found, for example, in the cophyline frogs of Madagascar with multiple shifts to and from terrestrial and/or arboreal modes of life. | Unavailable |
| Burrowing: from worms to vertebrates | Quite a few adaptations are useful for burrowing into the soil. So it is not exactly surprising that they have evolved several times... | Available |
