Tag Archives: exotic species

Going a long way with your mouth open to new tastes

by Piter Kehoma Boll

Everybody knows that human activities have driven our environment toward an unfortunate situation. The most popular forms of human impact include pollution, deforestation and overexploitation of natural resources, but certainly an important factor in remodeling ecosystems is the invasion of species.

While humans move around the world, they carry many species with them, either intentionally or not, an some of them establish successfully in the new environment, while others do not. But what makes some species become successful invaders while other are unable to do so?

It is clear for some time that having a broad niche, i.e., a broad tolerance in environmental conditions and a broad use of resources is very important to succeed in invading a new habitat. Food niche breadth, i.e., the amount of different food types one can ingest, is among the most important dimensions of the niche influencing the spread of a species.

I myself studied the food niche breadth of six Neotropical land planarians in my master’s thesis (see references below) and it was clear that the species with the broader niche are more likely to become invasive. Actually, the one with the broadest food niche, Obama nungara, is already an invader in Europe, as I already discussed here.

obama_marmorata_7

A specimen of Obama nungara from Southern Brazil that I used in my research. Photo by myself, Piter Kehoma Boll.*

But O. nungara has a broad food niche in its native range, which includes southern Brazil, and likely reflected this breadth in Europe. But could a species that has a narrow food niche in its native range broaden it in a new environment?

A recent study by Courant et al. (see references) investigated the diet of the African clawed frog, Xenopus laevis, that is an invasive species in many parts of the world. They compared its diet in its native range in South Africa whith that in several populations in other countries (United States, Wales, Chile, Portugal and France).

Xenopus_laevis

The African clawed frog Xenopus laevis. Photo by Brian Gratwicke.**

The results indicated that X. laevis has a considerable broad niche in both its native and non-native ranges, but the diet in Portugal showed a greater shift compared to that in other areas, which indicates a great ability to adapt to new situations. In fact, the population from Portugal lives in running water, while in all other places this species prefers still water.

We can conclude that part of the success of the African clawed frog when invading new habitats is linked to its ability to try new tastes, broadening its food niche beyond that from its original populations. The situation in Portugal, including a different environment and a different diet, may also be the result of an increased selective pressure and perhaps the chances are that this population will change into a new species sooner than the others.

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References:
Boll PK & Leal-Zanchet AM (2016). Preference for different prey allows the coexistence of several land planarians in areas of the Atlantic Forest. Zoology 119: 162–168.

Courant J, Vogt S, Marques R, Measey J, Secondi J, Rebelo R, Villiers AD, Ihlow F, Busschere CD, Backeljau T, Rödder D, & Herrel A (2017). Are invasive populations characterized by a broader diet than native populations? PeerJ 5: e3250.

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Obama invades Europe: “Yes, we can!”

ResearchBlogging.orgby Piter Kehoma Boll

This information was known by me and some other people for quite a while, but only recently has caught attention of the general public. Obama is the newest threat in Europe.

No, I’m not talking about the president of the United States. I’m talking about a land flatworm whose name is  Obama nungara.

obama_marmorata_7

This is the magnificent Obama nungara. This specimen is from Brazil and looks particulary yellowish due to the strong light of the camera flash. Photo by Piter Kehoma Boll.*

It has been a while since a new invasive land flatworm started to appear in gardens of Europe, especially in Spain and France and eventually elsewhere, such as in the United Kingdom. It was quickly identified as being a Neotropical land planarian and posteriorly as belonging to the genus Obama, whose name has nothing to do with Barack Obama, but is rather a combination of the Tupi words oba (leaf) and ma (animal) as a reference to the worm’s shape.

obama_nungara

When you find Obama nungara in your garden, it will look much darker, like this one found in the UK. Photo by buglife.org.uk

At first it was thought that the planarian belonged to the species Obama marmorata, a species that is native from southern Brazil, but molecular and morphological analyses revealed it to be a new species. Actually, much of what was called Obama marmorata in Brazil was this new species. Thus, it was named nungara, which means “similar” in Tupi, due to its similarity with Obama marmorata.

obama_marmorata

This is Obama marmorata, the species that O. nungara was originally mistaken for. Photo by Fernando Carbayo.**

Measuring about 5 cm in length, sometimes a little more or a little less, O. nungara is currently known to feed on earthworms, snails, slugs and even other land planarians. Its impact on the European fauna is, however, still unknown, but the British charitable organization Buglife decided to spread an alert and many news websites seem to have loved the flatworm’s name and suddenly a flatworm is becoming famous.

Who said flatworms cannot be under the spotlight? Yes, they can!

See also: The Ladislau’s flatworm, a cousin of Obama nungara.

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References:

Álvarez-Presas, M., Mateos, E., Tudó, À., Jones, H., & Riutort, M. (2014). Diversity of introduced terrestrial flatworms in the Iberian Peninsula: a cautionary tale PeerJ, 2 DOI: 10.7717/peerj.430

Boll, P., & Leal-Zanchet, A. (2016). Preference for different prey allows the coexistence of several land planarians in areas of the Atlantic Forest Zoology, 119 (3), 162-168 DOI: 10.1016/j.zool.2016.04.002

Carbayo, F., Álvarez-Presas, M., Jones, H., & Riutort, M. (2016). The true identity of Obama (Platyhelminthes: Geoplanidae) flatworm spreading across Europe Zoological Journal of the Linnean Society, 177 (1), 5-28 DOI: 10.1111/zoj.12358

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Friday Fellow: ‘Orange Jaguar Snail’

by Piter Kehoma Boll

ResearchBlogging.orgLast week I introduced a land planarian that feeds on land snails, Obama ladislavii, or, as I called it, the Ladislau’s flatworm. Therefore, today, I thought it would be great to present a similar situation occurring backwards: a land snail that feeds on land planarians.

So let me introduce this little predator, the land snail Rectartemon depressus. Again, it is not a widely known species and thus it has no common names, but why not call it the ‘orange jaguar snail’? Species of the genus Euglandina, which are also predatory snails, are called ‘wolf snails’ by comparing them to a common predator in North America. As Rectartemon species are common in South America, we could perfectly call them ‘jaguar snails’, right?

Rectartemon depressus about to capture a land planarian Obama marmorata. Photo from Lemos et al., 2012

Rectartemon depressus about to capture a land planarian Obama marmorata. Photo extracted from Lemos et al., 2012

Found in areas of Atlantic Rainforest in Brazil, the orange jaguar snail has a yellow to orange body and a whitish shell. It is listed a vulnerable species in the Brazilian Red List, but it is not mentioned in the IUCN’s Red List.

Initially known as a predator of other land gastropods, the orange jaguar snail revealed a new item in its diet recently. During attempts to find the food items in the diet of some land planarians from southern Brazil, the orange jaguar snail was offered as a food option, but while the expectations were that the planarian would eat the snail, the opposite happened! After contacting the land planarian, the snail simply grasps it with its radula (the snail’s toothed tongue) and sucks it in very quickly, just as if it were eating a noodle!

The orange jaguar snail eagerly consumes several land planarians, both native and exotic species. It makes it one of the first known predators of land planarians. One of its prey is the Ladislau’s flatworm, so we have a snail that eats a flatworm that eats snails!

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References:

Lemos, V., Canello, R., & Leal-Zanchet, A. 2012. Carnivore mollusks as natural enemies of invasive land flatworms. Annals of Applied Biology, 161 (2), 127-131 DOI: 10.1111/j.1744-7348.2012.00556.x

Santos, S. B., Miyahira, I. C., Mansur, M. C. D. 2013. Freshwater and terrestrial molluscs in Brasil: current status of knowledge and conservation. Tentacle, 21, 40-42.

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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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Earthling Bulletin #14

by Piter Kehoma Boll

You have sex, loose your penis and it grows back the day after. That happens with this sea slug. Photo by Matthew Oldfield, extracted from nature.com

You have sex, lose your penis and it grows back the day after. That happens with this sea slug. Photo by Matthew Oldfield, extracted from nature.com

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Exotic Species: Are they always a trouble?

by Piter Kehoma Boll

In the last decades, non-native species became victims of discrimination by conservationists, land managers, policy makers, as well as among scientist, being condemned for driving native species to extinction and ‘polluting’ natural environments. However, current management approaches need to consider that natural systems are changing without return thanks to climatic changes, urbanization, eutrophication and other changes due to land use.

Certainly many species introduced by humans lead to extinctions and reduced valuable ecological services. The avian malaria, introduced in Hawaii with non-native birds brought by Europeans, kill more than half of the native species. The zebra mussel Dreissena polymorpha, originally native from Russia and introduced in North America, and the golden mussel Limnoperna fortunei, native from Southern Asia and introduced in South America, became a a great problem for clogging water pipes.

Zebra mussel, an invasive species in North America

Zebra Mussel, an invasive species in North America. Photo by GerardM, from Wikipedia.

But the majority of claims about the destructive role of invasive species is based on Wilcove et al. (1998) who claim that invasive species are the second greatest threat to endangered species after habitat loss, but that’s little supported by data. Actually, in many cases the introduction of species increased the species richness in a region.

The effects of an invasive species that doesn’t cause troubles now can became a harm in the future, but the same applies to native species. Nativeness is not a sign of a necessarily positive effect. The insect suspected of killing more trees than any other in North America is the native beetle Dendroctonus ponderosae. Many species of introduced fruit trees became important feeding sources for local birds, attracting them and so even helping the dispersion of native species.

The idea is not to defend invasive species in all cases, but to incite a more analytical approach of the situation. Instead of blindly condemning a species just for not being native, the management plans need to be based in empirical evidences and not in unsubstantiated claims.

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Reference:

Davis et al. 2001: Don’t judge species on their origins. Nature, 474, 153-154.

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