Category Archives: Extinction

Friday Fellow: Amphibian chytrid fungus

by Piter Kehoma Boll

Today I’m bringing you a species that is probably one of the most terrible ones to exist today, the amphibian chytrid fungus, Batrachochytrium dendrobatidis, also known simply as Bd.

batrachochytrium_dendrobatidis

Several sporangia of Batrachochytrium dendrobatidis (spherical structures) growing on a freshwater arthropod. Photo by AJ Cann.*

The amphibian chytrid fungus, as its name says, is a chytrid, a fungus of the division Chytridiomycota, which include microscopic species that usually feed by degrading chitin, keratin in other such materials. In the case of the amphibian chytrid fungus, it infects the skin of amphibians and feeds on it. It grows through the skin forming a network of rhizoids that originate spherical sporangia that contains spores.

The infection caused by the amphibian chytrid fungus is called chytridiomycosis. It causes a series of symptoms, including reddening of the skin, lethargy, convlusions, anorexia and excessive thickening and shedding of the skin. This thickening of the skin leads to problems in taking in nutrients, releasing toxins and even breathing, eventually leading to death.

chytridiomycosis

An individual of the species Atelopus limosus infected by the amphibian chytrid fungus. Photo by Brian Gratwicke.**

Since its discovery and naming in 1998, the amphibian chytrid fungus has devastated the populations of many amphibian species throughout the world. Some species, such as the golden toad and the Rabb’s fringe-limbed treefrog, were recently extinct by this terrible fungus. This whole drastic scenario is already considered one of the most severe examples of Holocene extinction. The reason for such a sudden increase in the infections is unknown, but it may be related to human impact on the environment.

We can only hope to find a way to reduce the spread of this nightmare to biodiversity.

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ResearchBlogging.org
References:

Fisher, M., Garner, T., & Walker, S. (2009). Global Emergence of Batrachochytrium dendrobatidis and Amphibian Chytridiomycosis in Space, Time, and Host Annual Review of Microbiology, 63 (1), 291-310 DOI: 10.1146/annurev.micro.091208.073435

Wikipedia. Batrachochytridium dendrobatidis. Available at <https://en.wikipedia.org/wiki/Batrachochytrium_dendrobatidis&gt;. Access on March 4, 2017.

Wikipedia. Chytridiomycosis. Available at <https://en.wikipedia.org/wiki/Chytridiomycosis&gt;. Access on March 4, 2017.

Wikipedia. Decline in amphibian populations. Available at <https://en.wikipedia.org/wiki/Decline_in_amphibian_populations&gt;. Access on March 4, 2017.

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Shaking dinosaur hips and messing with their heads

by Piter Kehoma Boll

This week brought astonishing news regarding the phylogeny of dinosaurus, as you perhaps have heard or read. New anatomical evidences have completely rebuilt the basis of the dinosaur family tree and I’m here to explain a little bit of what happened.

As we all know, Dinosaurs include a great variety of beasts, from the meat-eating theropods to the long-necked sauropods and from the horned ceratopsians to the armored ankylosaurs, among many others.

largestdinosaursbysuborder_scale

Silhouette of a human compared to the largest known dinosaurs of each major group. Picture by Matt Martyniuk.*

For more than a century now, dinosaurus have been divided into two groups, called Ornithischia and Saurischia. Ornithischia (“bird-hipped”) includes dinosaurus whose pelvic bones are more similar to what is found in birds, with a pubis directed backward. Saurischia (“lizard-hipped”), on the other hand, have a pubis directed forward, as in reptiles in general. This grouped the theropods and the sauropods in the same group as Saurischia while other dinosaurus were grouped as Ornithischia. But birds are actually theropods, thus being lizard-hipped dinosaurus and not bird-hipped dinosaurus! Confusing, isn’t it? So let’s take a look at their hips:

Pelvic_bones

Comparison of the hips of a crocodile (Crocodylus), a sauropod (Diplodocus), a non-avian theropod (Tyrannosaurus), a bird (Apteryx), a thyreophoran (Stegosaurus), and an ornithopod (Iguanodon). Red = pubis; Blue = ischium; Yellow = ilium. Picture by myself, Piter K. Boll.**

As you can see, the primitive state, found in crocodiles, sauropods and early theropods, is a pubis pointing forward. A backward-pointing pubis evolved at least twice independently, both in more advanced theropods (such as birds) and the ornithischian dinosaurus. But could we be so certain that Tyrannosaurus and Diplodocus are more closely related to each other (forming a clade Saurischia) just because of their hips? Afterall, this is a primitive hip, so it is very unlikely to be a synapomorphy (a shared derived character). Nevertheless, it continued to be used as a character uniting sauropods and theropods.

A new paper published by Nature this week, however, showed new evidences that point to a different relationship of the groups. After a detailed analysis of the bone anatomy, Matthew G. Baron, David B. Norman and Paul M. Barrett have found 20 characters that unite theropods with ornithischians and not with sauropods. Among those we can mention the presence of a foramen (a hole) at the anterior region of the premaxillary bone that is inside the narial fossa (the depression of the bone that surrounds the nostril’s opening) and a sharp longitudinal ridge along the maxilla.

skulls

The skulls of both ornithischians and theropods (above) show an anterior premaxillary foramen in the narial fossa (shown in yellow) and and a sharp ridge on the maxilla (shown in green), as well as other characters that are not present in sauropodomorphs and herrerasaurids (below). Composition using original pictures by Carol Abraczinskas and Paul C. Sereno (Heterodontosaurus), Wikimedia user Ghedoghedo (Eoraptor and Herrerasaurus), and flickr user philosophygeek (Plateosaurus).**

In his blog Tetrapod Zoology, Dr. Darren Naish comments the new classification and points out some problems that arise with this new view. One of them is the fact that both theropods and sauropodomorphs have pneumatic (hollow) bones, while ornithischians do not. If the new phylogeny is closer to the truth, that means that pneumacity evolved twice independently or evolved once and was lost in ornithischians.

He also mentions that both ornithischians and theropods had hair-like or quill-like structures on their skin. In theropods this eventually led to feathers. Could this be another synapomorphy uniting these groups? Maybe… but when we think that pterosaurs also had “hairs”, one could also conclude that a “hairy” integumentary structure was already presented in the common ancestor of dinosaurus. In this case, perhaps, we only had not found it yet on sauropods. Now imagine a giant Argentinosaurus covered with feathers!

One concern that appeared with this new organization is whether sauropodomorphs would still be considered dinosaurs. The term “dinosaur” was coined by Richard Owen in 1842 to refer to the remains of the three genera known at the time, Iguanodon, Hylaeosaurus and Megalosaurus, the first two being ornithischians and the latter a theropod. As a consequence, the original definition of dinosaur did not include sauropods. Similarly, the modern phylogenetic definition of dinosaur was “the least inclusive clade containing Passer domesticus (the house sparrow) and Triceratops horridus“. In order to allow Brachiosaurus and his friends to continue sitting  with the dinosaurs, Baron et al. suggested to expand the definition to include Diplodocus carnegii. So, dinosaurus would be the least inclusive clade containing P. domesticusT. horridus and D. carnegii.

In this new family tree, the name Saurischia would still be used, but to refer only to the sauropodomorphs and some primitive carnivores, the herrerasaurids. The new clade formed by uniting theropods and ornithischians was proposed to be called Ornithoscelida (“bird-legged”), a name coined in 1870 to refer to the bird-like hindlimbs of both theropods and ornithopods (the subgroup of ornithischians that includes dinosaurs such as Iguanodon and the duck-billed dinosaurs).

What can we conclude with all that? Nothing will change if you are just a dinosaur enthusiast and do not care about what’s an ornithischian and a saurischian. Now if you are a phylogeny fan, as I am, you are used to sudden changes in the branches. Most fossils of basal dinosaurs are incomplete, thus increasing the problem to know how they are related to each other. Perhaps this new view will last, perhaps new evidence will change all over again the next week.

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ResearchBlogging.orgReferences and further reading:

Baron, M., Norman, D., & Barrett, P. (2017). A new hypothesis of dinosaur relationships and early dinosaur evolution Nature, 543 (7646), 501-506 DOI: 10.1038/nature21700

Naish, D. (2017). Ornithoscelida Rises: A New Family Tree for DinosaursTetrapod Zoology.

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Friday Fellow: Blue whale

by Piter Kehoma Boll

We’ve talked about the cutest and the leggiest, so now it’s time to introduce the largest, at once.

I think most of us know already that the largest animal ever is our beloved blue whale, Balaenoptera musculus. It can reach 30 m in length and weigh more than 180 tonnes. It’s really big, but probably not as big as many people think. There are some popular legends, like that the heart of a blue whale is the saze of a car or that a human could swim inside its aorta, which are not actually true.

It's almost impossible to find a good photo of the entire body of a blue whale. Afterall, it's huge and lives underwater!

It’s almost impossible to find a good photo of the entire body of a blue whale. Afterall, it’s huge and lives underwater!

But what else can we say about the blue whale? It is a rorqual, a name used to designate whales in the family Balaenopteridae and, as all of them, its main and almost exclusive food is krill, a small crustacean very abundant in all oceans. And krill needs to be abundant in order to provide the thousands of tonnes that all whales in the oceans need to eat every day. A single blue whale eats up to 40 million krill in a day, which equals to roughly 3.5 tonnes. A blue whale calf (young) is born measuring around 7 m in length and drinks around 500 liters of milk per day!

Blue whales were abundant in nearly all oceans until the beginning of the 20th century, when they started to be hunted and were almost extinct. Nowadays, the real population size is hard to estimate, but may encompass as few as 5,000 specimens, much less than the estimated hundreds of thousands in the 19th century. Due to such a drastic reduction in the population, the blue whale is currently listed as “endangered” in IUCN’s Red List.

But let's see a blue whale in all of its blueness.

But let’s see a blue whale in all of its blueness.

Occasionally, blue whales can hybridize with fin whales (Balaenoptera physalus) and perhaps even with humpback whales (Megaptera novaeangliae), a species classified in a different genus! Some recent genetic analyses, however, indicate that the Balaenoptera genus is polyphyletic and the blue whale may become known as Rorqualus musculus.

Different from other whales, blue whales usually live alone or in pairs, but never form groups, even though they may sometimes gather in places with high concentrations of food.

Like other cetaceans, especially other baleen whales, the blue whale sings. The song, however, is not as complex and dynamic as the ones produced by the related humpback whale. An intriguing fact that was recently discovered is that the frequency of the blue whale song is getting lower and lower at least since the 1960s. There is no good hypothesis to explain this phenomenon yet, but several ones have been proposed, such as the increase in background noise due to human activities or the increase in population density due to the decrease in whaling.

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References:

Hassanin, A.; Delsuc, F.; Ropiquet, A.; Hammer, C.; van Vuuren, B. J.; Matthee, C.; Ruiz-Garcia, M.; Catzeflis, F.; Areskoug, V.; Nguyen, T. T.; Couloux, A. 2012. Patter and timing of diversification of Cetartiodactyla (Mammalia, Laurasiatheria), as revealed by a comprehensive analysis of mitochondrial genomes.  Comptes Rendus Biologies, 335: 32-50.

Mellinger, D. K.; Clark, C. W. 2003. Blue whale (Balaenoptera musculus) sounds from the North Atlantic. Journal of the Acoustical Society of America, 114(2): 1108-1119.

Wikipedia. Blue whale. Available at: <https://en.wikipedia.org/wiki/Blue_whale&gt;. Access on January 27, 2016.

 

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The Story of the Dwarf Rhea

by Rafael Nascimento

The family Rheidae is nowadays represented by two or three (according to different authors) species of rheas, large running flightless birds, similar to the African ostriches, but having three toes on each foot instead of two. The largest one, the common rhea Rhea americana, has five subspecies distributed from northeastern Brazil to eastern Argentina and including Bolivia, Paraguay and Uruguay. The other forms, earlier put in a separate genus, Pterocnemia, are R. pennata and R. tarapacensis (commonly known as Darwin’s rhea and Puna rhea, respectively). Darwin’s rhea, which helped the British naturalist in the elaboration of his theory of natural selection, lives in the Argentinean and Chilean Patagonia. The systematic situation of the Puna rhea (and its possible subspecies), which is found in the area where Peru, Bolivia, Chile and Argentina meet, is not yet clear, and currently it is considered a distinct form based on some physical features, but more clarifying studies are necessary.

Beside these current forms and some fossil species, such as Opisthodactylus horacioperezi and Hinasuri nehensis, respectively from the Argentinian Miocene and Pliocene, another species was described in 1894 by the British Naturalist Richard Lydekker based on a small egg: Rhea nana – therefore representing a possible fourth rhea species living in historical times.

Richard Lydekker, ca 1900.

Richard Lydekker, ca 1900.

Following you can see the original text published in the journal Proceedings of the Zoological Society of London from 1894, with comments regarding this possible new species:

“Mr. R. Lydekker exhibited photographs and a model of a unique egg, the original of which had been obtained many years ago in Southern Patagonia, and now preserved in the Museum at La Plata. If not an abnormal specimen, it could not be assigned to any known species of bird.

When travelling in the district where the specimen was obtained, Dr. P. Moreno, Director of the Museum at La Plata, many years ago saw numbers of small Ratite birds, which he at first took to be small Rheas. By the natives, to whom they were well known, he was, however, assured that they were adult birds, allied to the Rheas. Desirous of confirming this information, Dr. Moreno applied to a friend acquainted with the district; who replied that not only did he well know the birds, but that he possessed an egg, that egg being the original specimen of which a model was now exhibited.

Assuming the egg to be a normal one, Mr. Lydekker was of opinion that, taken in connexion with the evidence of two independent witnesses who had been the birds, it pointed to the existence in Southern Patagonia of a small unknown Ratite bird more or less nearly allied to the Rheas.”

Illustration of Darwin's Rhea by John Gould, 1841.

Illustration of Darwin’s Rhea by John Gould, 1841.

Until today, however, no other similar egg or adult bird of a species different from the three already mentioned has been found. When we deal with potentially extinct species, only know by scarce reports or aberrant specimens, one must watch the data through a skeptical point of view. We need to be certain that those are not variations within the species or a witness confusion. The lack of extensive comparative material due to the date of the descriptions must also be taken into account, as well as the constant advancements in our understanding of science.

Normal egg of R. pennata, at Museum Wiesbaden (Germany). Photo by Klaus Rassinger/Gerhard Cammerer.

Normal egg of R. pennata, at Museum Wiesbaden (Germany). Photo by Klaus Rassinger/Gerhard Cammerer.

This egg is currently treated as an aberrant form of a Rhea pennata egg. The model cited by Lydekker, made of wax, is found in the Tring Natural History Museu, England.

del Hoyo, J., Collar, N. & Garcia, E.F.J. (2015) Puna Rhea (Rhea tarapacensis). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/467080 on 24 December 2015).

Folch, A., Jutglar, F., Garcia, E.F.J. & Boesman, P. (2015) Greater Rhea (Rhea americana). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/52399 on 24 December 2015).

Folch, A., Christie, D.A., Jutglar, F. & Garcia, E.F.J. (2015) Lesser Rhea (Rhea pennata). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/52400 on 24 December 2015).

Hume, J. P.; Walters, M. (2012) Extinct Birds. T & AD Poyser. Londres.

Knox, A. G.; Walters M. P. (1994) Extinct and Endangered Birds in the collections of The Natural History Museum. British Ornithologists’ Club Occasional Publications.

Lydekker, R. (1894) Exhibition of, and remarks upon, a photograph and model of an egg from Southern Patagonia in the La Plata Museum. Proceedings of the Zoological Society of London (1894): 654.

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The New Guinea flatworm visits France – a menace

by Piter Kehoma Boll

ResearchBlogging.orgFor as long as life exists, it spreads. Organisms move (even if only as gametes or spores) and conquer new environments if they fit. If it wasn’t so, life wouldn’t be found all over the world. Recently, however, due to human dispersion, species are much more likely to reach places far away from where they were born. We considered a species living outside its native area as exotic. And there are a lot of them. I wonder if there is any place where no exotic species exist.

In my first post in this blog, I talked about how exotic species are not always a threat to native ecosystems. But many of them are, indeed, dangerous to local diversity. The ISSG (Invasive Species Specialist Group) lists what are considered the 100 worst invasive species. Strangely, they fail to mention the top worst invasive species, Homo sapiens.

Among those 100 species, a very famous one is the giant African land snail, Achatina fulica. Native to East Africa, it has been introduced worldwide and is a major pest in gardens and agricultural sites, and can also be an intermediate host of several parasites that infect humans.

The giant African land snail Achatina fulica. Photo by Eric Guinther. Extracted from commons.wikimedia.org

The giant African land snail Achatina fulica. Photo by Eric Guinther*. Extracted from commons.wikimedia.org

As an attempt to control the populations of Achatina fulica, some “genius” decided to introduce one more exotic species in the areas where A. fulica was a pest: a voracious generalist predator of land snails.

Let's fight against an exotic pest with another exotic pest!

Let’s fight against an exotic pest with another exotic pest!

As a result, the predator snail Euglandina rosea, known as the rosy wolfsnail or cannibal snail, was introduced in areas infested by A. fulica. But E. rosea is native to North America while A. fulica is native to East Africa. In order to be effective, E. rosea had to be a generalist predator, feeding on any kind of snails. And that’s what it does…

The rosy wolfsnail Euglandina rosea. Photo by Tim Ross. Extracted from commons.wikimedia.org

The rosy wolfsnail Euglandina rosea. Photo by Tim Ross. Extracted from commons.wikimedia.org

Euglandina rosea started to prey on A. fulica, but… ops! It also attacked native land snails and led several species to extinction in Pacific Islands. It became a pest even worse than the giant African land snail…

Not satisfied by the damage caused by this predator, people decided to introduce one more species in order to control A. fulica. And the chosen one was another voracious generalist predator of land snails, the New Guinea flatworm Platydemus manokwari. As its name suggest, thee New Guinea flatworm is native to New Guinea, again a different place, and so, in order to feed on the giant African land snail, it had to feed on any kind of land snail. Thus, it became a pest as harmful as the previous one and led several species of land snails to extinction in Pacific Islands.

Until very recently it was thought that the New Guinea flatworm infestation was restricted to the Indo-Pacific Region, not so far from home. However, a recent paper by Justine et al. (2014) reports its presence in a hothouse in Caen, northern France. This report extends significantly its occurrence over the world and indicates that it may be much more spread than previously thought. Unfortunately, people are more interesting in preserving their gardens than preserving biodiversity. So those predatory pests will probably keep being introduced as biological controls, even though they pose a threat to ecosystems.

The New Guinea Flatworm Platydemus manokwari. Photo by Pierre Gros, taken from Justine et al., 2014, via commons.wikimedia.org.

Bonjour tout le monde! I came to visit Paris! The New Guinea Flatworm Platydemus manokwari. Photo by Pierre Gros**, taken from Justine et al., 2014, via commons.wikimedia.org.

Fortunately, in France, P. manokwati seems to be restricted to greenhouses. Let’s hope that it won’t be found somewhere else.

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References:

Albuquerque, F., Peso-Aguiar, M., & Assunção-Albuquerque, M. 2008. Distribution, feeding behavior and control strategies of the exotic land snail Achatina fulica (Gastropoda: Pulmonata) in the northeast of Brazil. Brazilian Journal of Biology, 68 (4), 837-842 DOI: 10.1590/S1519-69842008000400020

ISSG, Invasive Species Specialist Group. 100 of the World’s Worst Invasive Alien Species. Availabe at: < http://www.issg.org/database/species/search.asp?st=100ss >. Access on April 04, 2014.

Justine, J., Winsor, L., Gey, D., Gros, P., & Thévenot, J. 2014. The invasive New Guinea flatworm in France, the first record for Europe: time for action is now. PeerJ, 2 DOI: 10.7717/peerj.297

Sugiura, S., Okochi, I., & Tamada, H. 2006. High Predation Pressure by an Introduced Flatworm on Land Snails on the Oceanic Ogasawara Islands. Biotropica, 38 (5), 700-703 DOI: 10.1111/j.1744-7429.2006.00196.x

Sugiura, S., & Yamaura, Y. 2008. Potential impacts of the invasive flatworm Platydemus manokwari on arboreal snails. Biological Invasions, 11 (3), 737-742 DOI: 10.1007/s10530-008-9287-1

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If you like flowers, you should love insects

by Piter Kehoma Boll

ResearchBlogging.orgEverybody likes flowers, right? They are so colorful and beautiful and usually have a wonderful scent. People love to have them in their gardens and women love to receive a nice flower bouquet from their boyfriends.

Some flowering plants, from left to right: Rosa ‘Hybrid Tea’, Pachystachys lutea and Zinnia elegans. All photos by Piter K. Boll (i.e. myself!)*

But why are flowers so beautiful? Of course the flowers seen above are derived from varieties artificially selected by humans to increase their beauty, but flowers in nature are wonderful too!

Naturally occuring flowers. From left to right: Oxalis sp., Ipomoea fimbriosepala and Zephyranthes robusta. All photos again by myself (Piter K. Boll)*

Surely that beauty is not intended to please people or whatever. That’s totally nonsense and just some religious people could have such a wrong idea. If plants have nice flowers, it must give them some advantage.

As everybody knows (at least I hope so), plants usually cannot move like animals, so they are condemned to stay still on their spot. That can mean a lot of trouble when you are looking for resources like water, light or basic elements like nitrogen. So evolution leads to the rising of amazing structures to make plants survive, like getting a hard stem to become taller or developing smaller or larger leaves, thorns, tendrils or even becoming carnivorous. But plants also need to reproduce and for that they need a mate, but since they are attached to the substrate, they have to find alternative ways to join their gametes.

Most primitive plants manage to do that through water or wind, just letting their reproductive structures go and hoping that they will reach their destination. As you can see, this method is not the best one, since fertilization occurs totally by chance. Besides that, these ways are limited regarding to the places where they are successful. A plant fertilized through water needs to be inside water or live close to the ground on places where it eventually get submersed; the same way, a plant which relies on the winds needs, of course, to be where the wind blows.

Moss (left) relies on water to reproduce, while conifers (right) need wind. Once more, photos by Piter K. Boll. *

Those methods, though limited, worked well enough for millions of years until sometime in the Cretaceous period, when a group of animals started to diverse astonishingly: the insects.

Insects are small and prolific. They have a hard outer skeleton of chitin, which prevents dehydration and injuries, and many of them learned to fly, so being able to cross large distances and colonize new habitats.

Insects existed, of course, at least since the Carboniferous. The most famous of them is the giant dragonfly Meganeura. But during the Cretaceous those groups that today are the most diverse started to appear in fossils: ants, bees, termites, butterflies, moths, aphids and grasshoppers. Beetles, the most diverse group of insects today (containing more species than all other arthropods together) are found in fossils since the Carboniferous, but almost went extinct during the Permian-Triassic boundary that marks the most terrible mass extinction on Earth. After this tragic event, they stayed more discrete until a boom in diversification in Cretaceous together with the already mentioned insects.

Well, all those insects needed to eat like anything else and started to feed on plants, including their pollen. That could have been a serious trouble, but plants managed to deal with it by modifying themselves in a way that the insects now became something useful to them. If insects were attracted to their pollen, why couldn’t they carry it to other plants, so assuring a more secure fertilization?
That’s exactly what plants made, but in order to attract insects even more to their reproductive organs, those started to increase in size and get nice colors. It all happened through natural selection of random mutations, of course. No one is assuming that plants or insects actually chose to change, that’s nonsense. What I’m trying to say (through a simpler way) is that those plants that were able to attach some of their pollen grains to insects, so that it reached other plants that the insect visited, were more successful to reproduce. The same way, those plants with more beautiful flowers attracted more insects and were also more successful to reproduce.

Anyway, that’s why we should thank insects for existing, since without them we wouldn’t have so nice flowers to decorate our lives. And if you like flowers but hate insects, well, you are being extremely unfair to nature.

I know that some may say “but I like butterflies. They are beautiful and cool and cute and they pollinate everything, so I just need to like these insects and not all those disgusting things.”
Oh, really? So you like butterflies? I’m sure you like this one:

Caterpillar of Agraulis vanillae. Photo by Bill Frank extracted from jaxshells.org

Most people like butterflies and hate caterpillars, but they are exactly the same thing. And actually these insects spend most of their life as a larva. Now just to satiate your curiosity, this is what that caterpillar looks like as an adult:

An adult of Agraulis vanillae on a head of Zinnia elegans. Photo by Piter K. Boll.*

But butterflies are not the only pollinators and not even the most common ones. Bees, as you know, are also very important and the main pollinators of many economically important plants, especially fructiferous ones. Wasps, flies, mosquitos, scorpionflies and moths are also important, but we cannot forget beetles.

Most basal and primitive angiosperms are pollinated by beetles, so that its more likely that these were the guys behind the appearance and diversification of flowering plants. There are many evidences for that, like an increasing diversity of angiosperms in fossil records being contemporaneous to an increase of beetle species.

Recently, some fossil flowers from the Turonian age (about 90 million years old) were found in Sayreville, New Jersey. Those were called Microvictoria svitkoana due to their astonishing similarity to the giant Amazon water lily, Victoria amazonica, even though much smaller in size.

Flower of Victoria amazonica, one of the most primitive angiosperms. It’s easy to notice that it still resembles somewhat a conifer cone. Photo by Frank Wouters, extracted from commons.wikimedia.org.

Despite primitive, it’s certainly a very beautiful flower, and it can only exist thanks to beetles of the genus Cyclocephala, like this one.

Cyclocephala hardyi, a beetle that pollinates Victoria amazonica. Photo extracted from ssaft.com/Blog/dotclear/

What do you think about it? It’s actually a cool pal, isn’t it? If you look closer, you may see that every insect is amazing in it own way, even cockroaches!

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References:

Béthoux, O. 2009. The Earliest Beetle Identified. Journal of Paleontology, 83 (6), 931-937 DOI: 10.1666/08-158.1

Crepet, W. L. 1996. Timing in the evolution of derived floral characters: Upper Cretaceous (Turonian) taxa with tricolpate and tricolpate-derived pollen. Review of Palaeobotany and Palynology, 90, 339-359 DOI: 10.1016/0034-6667(95)00091-7

Gandolfo, M. A., Nixon, K. C. and Crepet, W. L. 2004. Cretaceous flowers of Nymphaeaceae and implications for complex insect entrapment pollination mechanisms in early Angiosperms. PNAS, 101 (21), 8056-8060 DOI: 10.1073/pnas.0402473101

Seymour, R. S. and Matthews, P. G. D. 2006. The Role of Thermogenesis in the Pollination Biology of the Amazon Waterlily Victoria amazonicaAnnals of Botany, 98 (6), 1129-1135 DOI: 10.1093/aob/mcl201

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The Macaw of Dominica

by Rafael Silva do Nascimento

ResearchBlogging.orgTalking and exuberant-colored birds always exerted a strong fascination over human beings, and with me it couldn’t be different. Besides, the curiosity that something rare or lost arouses is an important factor to define a theme of interest to someone. Those two combined factors are the foundation that sustains a great interest on my part in extinct species of psittacids, mainly in those ones with little evidence of their doubtful existence.

Several psittacid species inhabitant of island paradises were extinct in the last centuries mainly due to hunting for food, trade to become pets and habitat loss. In this post I’ll deal with a specific species that’s said to have inhabited the Dominica Island, in the Lesser Antilles (Caribbean).

Dominica was firstly inhabited by the Caribbean Indians and later colonized by French and English. Hunting by the Indians is usually sustainable, not representing a great threat for the species.

The colonization by the Europeans, however, has been proved devastating, a common scenario not only in those islands, but also in several other points of the planet.

A forest in Dominica

A forest in Dominica. Photo by Dirk.heldmaier, from Wikipedia.

The Dominican Green-and-Yellow Macaw (also known as Atwood’s Macaw or simply Dominican Macaw), Ara atwoodi, is known only from the report of Thomas Atwood. In his work “The history of the island of Dominica. : Containing a description of its situation, extent, climate, mountains, rivers, natural productions, &c. &c. Together with an account of the civil government, trade, laws, customs, and manners, of the different inhabitants of that island. Its conquest by the French, and restoration to the British dominions” from 1791, Atwood describes the local fauna, whose elements can be associated to the species currently known to the region, with the exception of a kind of psittacid no more found there and that differs from the other ones known in the island (Amazona arausiaca and A. imperialis, which Atwood probably considered a single species in his description) or anywhere else on the planet. The following is the excerpt, adapted to the modern English:

‘’The macaw is of the parrot kind, but larger than the common parrot, and makes a more disagreeable, harsh noise. They are in great plenty, as are also parrots in this island; have both of them a delightful green and yellow plumage, with a scarlet-colored fleshy substance from the ears to the root of the bill, of which color is likewise the chief feathers of their wings and tails. They breed on the tops of the highest trees, where they feed on the berries in great numbers together; and are easily discovered by their loud chattering noise, which at a distance resembles human voices. The macaws cannot be taught to articulate words; but the parrots of this country may, by taking pains with them when caught young. The flesh of both is eat, but being very very fat, it wastes in roasting, and eats dry and insipid; for which reason, they are chiefly used to make soup of, which is accounted very nutritive.’’

Atwood's Description

Atwood's Description in ''The History of the Island of Dominica'', 1791.

It’s believed that it became extinct by the end of the 18th century or beginning of the 19th century. As there are no extant species of green and yellow plumage (excluding hybrids induced by humans), Austin Hobart Clark assumed that it belonged to a species not yet known to science, firstly including it in Ara guadeloupensis (which is said to inhabit the neighboring island Guadeloupe). With the discovery of Atwood’s account, it was considered distinct, receiving the status of species in 1908.

Considered a hypothetical species by most authors, Ara atwoodi usually isn’t included in non-specific publications that mention recently extinct macaws, which almost always only mention the Cuban macaw Ara tricolor, for being the only one known from preserved specimens, and subfossil forms like A. autocthones. Joseph Forshaw highlight that’s not even safe to associate the species to the genus Ara, due to the absence of specimens, either stuffed or bones, or even illustrations. The association was made by deduction, based on the term “mackaw” used by Atwood, where Clark notices that “his macaw is a bona fide member of the genus Ara”. That, however, didn’t exclude the possibility of being a similar but separated genus that evolved by isolation in the island.

Reconstruction following the picture published in David Day's ''The Doomsday Book of Animals''. Picture by Rafael Silva do Nascimento, 2009.

From the excerpt describing its physical characteristics and based in close species, some reconstructions of how it looked started to appear, though in shyer steps than in other more popular extinct birds. The most widely known is the one present in David Day’s work “The Doomsday Book of Animals” (1981), which depicts a macaw well distinguished from the species whose appearance was known, not having the portion of bare skin on its face, consisting merely of a closed portion, but following the color pattern described by Atwood. Most posterior reconstructions are based on this picture. Other obscure species with a similar history are portrayed, like Ara erythrocephalus from Jamaica, which was also reported having green and yellow feathers, but with a red head. The color as it was described and the observation of extant species suggest a pattern similar to the one found in Ara ararauna and maybe in A. martinicus from the neighbor island Martinica (another hypothetical extinct species), with blue replaced by green. Also reported from Jamaica, but not creditable by most sources, is A. erythrurus, said to be similar to A. ararauna, but with an entirely red tail. Julian Hume in his book “Extinct Birds” to be released in February 2012, which also have Michael Walters as author, portrayed the species according to this idea, however without having the portion of bare skin on the face painted red, but only the forehead of this color. Since I didn’t have access to the work of Walters and Hume, I’m not aware of the reason for such a reconstruction, but considering that the reddish facial portion, usually seen as a distinct feature of A. atwoodi, may be simply excitation as observed in A. ambiguus, A. militaris and A. rubrogenys, this macaw may have been represented in a “calm” situation. Both A. ararauna and A. glaucogularis can show traces of redness on the face, being more evident in the last, so if A. atwoodi was truly a close relative, this feature might be more advanced in this species. A color pattern that recalls the described by Atwood is found in the pet market as in the hybrids Catalina (A. ararauna x A. macao) and Harlequin (A. ararauna x A. chloropterus), where the back is green and the belly varies from shades of yellow to bright orange.

Ara atwoodi by Rafael Silva do Nascimento

I've made this reconstruction following the theory that A. atwoodi was closely related to A. ararauna. Some elements, such as the black patch below the bill, are highly speculative.

While I see sufficient evidences to declare the existence of a different form of macaw that once inhabited Dominica, its real appearance will remain a mystery until new evidences came to the surface, whether they are lost reports or subfossil bones.

– – –

References:

Atwood, T. 1791: The History of the Island of Dominica. London: Frank Cass and Co.

BirdLife International (2011) Species factsheet: Ara atwoodi. Available on-line in: < www.birdlife.org/datazone/speciesfactsheet.php?id=30080>.  Acess on December 6th, 2011.

Clark, A. H. 1908. The Macaw of Dominica Auk, 25, 309-311

Forshaw, J. M. & Cooper, W. T. 1977: Parrots of the World. T.F.H. Publications, Inc. New Jersey.

Fuller, E. 1987: Extinct Birds. Facts on Files Publications. New York.

Maas, P. H. J. 2007: Dominican Green-and-Yellow Macaw. In: TSEW. The Sixth Extinction Website. Available on-line in: <www.petermaas.nl/extinct/speciesinfo/dominicanmacaw.htm>. Acess on December 6th, 2011.

Many-feathers. Catalina Macaw. Available on-line in: < www.many-feathers.com/Catalina-Macaw.htm>. Acess on December 6th, 2011.

Rothschild, W. 1907: Extinct Birds. Hutchison, London.

Williams, M. I. & Steadman, D. V. 2001: The historic and prehistoric distribution of parrots (Psittacidae) in the West Indies. Pp 175-489 in Biogeography of the West Indies: patterns and perspectives. 2nd ed. (Woods, C. A. & F. E. Sergile, eds.) Boca Raton, FL: CRC Press.

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