by | June 7, 2017 · 4:51 pm

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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by | June 2, 2017 · 8:00 am

Friday Fellow: Field Hornwort

by Piter Kehoma Boll

Three weeks ago our Friday Fellow was a moss, being the third non-vascular plant to be introduced. And before going back to vascular plants, let’s take a look at another non-vascular fellow from the only non-vascular division that was not yet introduced here, the hornworts.

The species I chose to start the participation of hornworts is the field hornwort, Anthoceros agrestis.

Anthoceros_agrestis

A piece of soil with the field hornwort growing on the top. Photo by Wikimedia user BerndH.*

As with other hornworts, the field hornwort has a dominant gametophyte phase which appears as a small flattened plant growing very close to the soil. The sporophyte grows over it and has the form of an elongate vertical horn, hence the name hornwort.

Found in Europe and North America, the field hornwort usually grows in wet places and is often surrounded by  mosses. Its gametophyte has some internal cavities filled with muscilage that are a favorite place for species of cyanobacteria of the genus Nostoc to grow. This association is what makes hornworts acquire their slight bluish tinge.

The field hornwort has the smallest genome of all non-vascular plants studied until the present and because of that it has been cultivated to serve as an interesting model organism.

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ResearchBlogging.orgReferences:

EOL – Encyclopedia of life. Field Hornwort. Available at <http://eol.org/pages/399515/overview&gt;. Access on May 18, 2017.

Szövényi, P., Frangedakis, E., Ricca, M., Quandt, D., Wicke, S., & Langdale, J. (2015). Establishment of Anthoceros agrestis as a model species for studying the biology of hornworts BMC Plant Biology, 15 (1) DOI: 10.1186/s12870-015-0481-x

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by | May 26, 2017 · 8:00 am

Friday Fellow: Hummingbird Bobtail Squid

by Piter Kehoma Boll

If you are digging through the sand at the bottom of the clear tropical waters around Indonesia and the Philippines, you may end up finding a colorful little creature, the hummingbird bobtail squid, Euprymna berryi, also known as Berry’s bobtail squid.

Euprymna_berryi

A beautiful specimen photographed in East Timor. Photo by Nick Hobgood.*

Measuring about 3 cm if male or 5 cm if female, the humminbird bobtail squid is actually more closely related to cuttlefish than to true squids. Its body has a translucent skin marked by many black chromatophores, and to the human eye the animal seems to have a color pattern formed by a blend of black, electric blue and green or purple dots.

During the day, the hummingbid bobtail squid remains most of the time buried in the sand, coming out at night to capture small crustaceans, which it hunts using a bioluminescent organ in its gill cavity.

In some areas around its distribution, the hummingbid bobtail squid is captured and sold in small fisheries, but as the data on the distribution and population dynamics of this species are very poorly known, there is no way to say whether it is vulnerable or endangered in any way. As a result, it is listed as Data Deficient in the IUCN Red List.

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ResearchBlogging.orgReferences:

Barratt, I., & Allcock, L. (2012). Euprymna berryi The IUCN Red List of Threatened Species DOI: 10.2305/IUCN.UK.2012-1.RLTS.T162599A925343.en

Wikipedia. Euprymna berryi. Available at <https://en.wikipedia.org/wiki/Euprymna_berryi&gt;. Access on March 8, 2017.

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by | May 19, 2017 · 11:21 pm

The warmer the dangerouser, at least if you are a caterpillar

by Piter Kehoma Boll

Scientist all over the world agree that species diversity is higher at the tropics than at polar regions, i.e., the closer you get to the equator, more species you will find. But apart from making food webs more entangled, does it increase the overall number of interactions that species experience? Afterall, despite the increase in species richness, the population size usually decreases. For example, while there are hundreds of different tree species in the Amazon forest, the number of individuals of each species is much lower than the number of individuals of a species in a temperate forest in Europe.

In order to test whether an increase in species richness would also mean an increase in biotic interactions, a group of ecologists all over the world engaged in a worldwide experiment using nothing else but small fake caterpillars made of plasticine. The small models were placed in different areas from the polar regions to the equatorial regions and the number of attacks that they suffered were counted and grouped according to the type of predator, which was usually identifiable based on the marks left on the models.

170518143812_1_900x600

A fake caterpillar in Tai Po Kau, Hong Kong. Photo by Chung Yun Tak, extracted from ScienceDaily.

The results indicate that there is indeed an increase in predation rates towards the equator, as well as towards the sea level. Areas close to the poles or at high elevations have a smaller number of interactions. But even more interesting was the revelation that this change is really driven by small predators, especially arthropods such as ants. The rate of attacks by birds and mammals was fairly constant across the globe.

Such an evidence on the importance of arthropod predators at the tropics may make us reevaluate our ideas on the evolution of species in such places, as the main concern for small herbivores such as caterpillars in tropical forests may not be birds, but ants. And this means a completely different way to evolve defense strategies.

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ResearchBlogging.orgReference:

Roslin, T., Hardwick, B., Novotny, V., Petry, W., Andrew, N., Asmus, A., Barrio, I., Basset, Y., Boesing, A., Bonebrake, T., Cameron, E., Dáttilo, W., Donoso, D., Drozd, P., Gray, C., Hik, D., Hill, S., Hopkins, T., Huang, S., Koane, B., Laird-Hopkins, B., Laukkanen, L., Lewis, O., Milne, S., Mwesige, I., Nakamura, A., Nell, C., Nichols, E., Prokurat, A., Sam, K., Schmidt, N., Slade, A., Slade, V., Suchanková, A., Teder, T., van Nouhuys, S., Vandvik, V., Weissflog, A., Zhukovich, V., & Slade, E. (2017). Higher predation risk for insect prey at low latitudes and elevations Science, 356 (6339), 742-744 DOI: 10.1126/science.aaj1631

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by | May 19, 2017 · 8:00 am

Friday Fellow: Common Stinkhorn

by Piter Kehoma Boll

Today things are getting sort of pornographic again. Some time ago I introduced a plant whose flowers resemble a woman’s vulva, the asian pigeonwing, and now is time to look at something of the other sex. And what could be better than the shameless penis? That’s the translation of the scientific name of this mushroom, Phallus impudicus, whose common name in English is much more discrete: common stinkhorn.

Phallus_impudicus2

Standing proud and shameless. Photo by flickr user Björn S…*

Found throughout Europe and parts of North America in deciduous woods, the common stinkhorn is easily recognizable for its phallic shape and even more for its foul smell that resembles carrion. This odor attracts insects, especially flies, that carry the spores away. This is a different method from the one used by most fungi, which simply release the spores in the air. Some people may mistake the common stinkhorn for morels (genus Morchella) but the two are completely unrelated, being from different phyla.

Despite the foul smell, the common stinkhorn is edible, especially in its first stages of development, when it resembles an egg. Due to its phallic shape, it is also seen as an aphrodisiac in some culture, as it is common with genitalia-shaped lifeforms.

Phallus_impudicus3

The immature fruiting body of Phallus impudicus is the most commonly eaten form. Photo by Danny Steven S.*

The common stinkhorn seems to have some anticoagulant properties and can be used for patients susceptible to thrombosis in the veins, such as patients treating breast cancer.

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ResearchBlogging.orgReferences:

Kuznecov, G., Jegina, K., Kuznecovs, S., & Kuznecovs, I. (2007). P151 Phallus impudicus in thromboprophylaxis in breast cancer patients undergoing chemotherapy and hormonal treatment The Breast, 16 DOI: 10.1016/s0960-9776(07)70211-4

SMITH, K. (2009). On the Diptera associated with the Stinkhorn (Phallus impudicus Pers.) with notes on other insects and invertebrates found on this fungus. Proceedings of the Royal Entomological Society of London. Series A, General Entomology, 31 (4-6), 49-55 DOI: 10.1111/j.1365-3032.1956.tb00206.x

Wikipedia. Phallus impudicus. Available at <https://en.wikipedia.org/wiki/Phallus_impudicus&gt;. Access on March 7, 2017.

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by | May 12, 2017 · 8:00 am

Friday Fellow: Spreading Earthmoss

by Piter Kehoma Boll

If you still think mosses are uninteresting lifeforms, perhaps you will change your mind after knowing the spreading earthmoss, Physcomitrella patens.

Found in temperate regions of the world, except for South America, but more commonly recorded in North America and Eurasia, the spreading earthmoss grows near water bodies, being one of the first species to colonize the exposed soil around pools of water. Although widely distributed, it is not a common species.

Physcomitrella_patens

The spreading earthmoss growing on mud. Photo by Hermann Schachner.

Since the beginning of the 1970s, the spreading earthmoss has been used as a model organism, especially regarding gene manipulation. Differently from what occurs in vascular plants, the dominant life phase in mosses is the gametophyte, an haploid organism, meaning it has only one copy of each chromosome in its cells. This is an ideal condition for the study of gene expression, as the activation or inactivation of a gene is not hindered by a second one in another copy of the chromosome in the same cell.

Physcomitrella_patens_ecotypes

Physcomitrella patens growing in the lab. Credits to the Lab of Ralf Reski.*

By controlling gene expression in the spreading earthmoss, researches can track the role of each one of them in the plant’s development. Comparing these data with that known from flowering plants, we can have a better understanding of how the plant kingdom evolved.

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ResearchBlogging.orgReferences:

Cove, D. (2005). The Moss Physcomitrella patens Annual Review of Genetics, 39 (1), 339-358 DOI: 10.1146/annurev.genet.39.073003.110214

Schaefer, D. (2001). The Moss Physcomitrella patens, Now and Then PLANT PHYSIOLOGY, 127 (4), 1430-1438 DOI: 10.1104/pp.127.4.1430

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by | May 11, 2017 · 10:26 am

Land snails on islands: fascinating diversity, worrying vulnerability

by Piter Kehoma Boll

The class Gastropoda, which includes snails and slugs, is only beaten by the insects in number of species worldwide, having currently about 80 thousand described species. Among those, about 24 thousand live on land, where they are a very successful group, especially on oceanic islands.

The Hawaiian Islands alone, for example, have more than 750 snail species and there are more than 100 endemic species in the small island of Rapa in the South Pacific. This diversity is much higher than that in any continental place, but the reason for that is not completely understood.

Mandarina

A land snail of the genus Mandarina, endemic to the Ogasawara Islands, Japan. Photo by flickr user kmkmks (Kumiko).*

One of the most likely explanations for this huge diversity on islands is related to the lack of predators. The most common predators of snails include birds, mammals, snakes, beetles, flatworms and other snails. Most of those are not present in small and isolated islands, which allows an increase in land snail populations in such places. Without too much dangers to worry about, the community of land snails n islands can explore a greater range of niches, eventually leading to speciation.

Unfortunately, as always, the lack of danger leads to recklessness. Without predators to worry about, insular land snails tend to lay fewer eggs than their mainland relatives. If there is no danger of having most of your children eaten, why would you have that many? It is better to lay larger eggs, putting more resources on fewer babies, and so assure that they will be strong enough to fight against other snail species. Afterall, the large number of species in such a small place as an island likely leads to an increased amount of competition between species.

But why is this recklessness? Well, because you never known when a predator will arrive. And they already arrived… due to our fault.

The diversity of insular land nails was certainly affected by habitat loss promoted by humans, but also by predators that we carried with us to the islands, whether intentionally or not. These predators include rats, the predatory snail Euglandina rosea and the land flatworm Platydemus manokwari, the latter being most likely the worst of all.

800px-platydemus_manokwari

The flatworm Platydemus manokwari in the Ogasawara Islands. Photo by Shinji Sugiura.

This flatworm arrived at the Chichijima Island, part of the Ogasawara Islands in the Pacific Ocean, in the early 1990s and in about two decades it led most land snail species on the island to extinction and many more are about to face the same fate on this island and on others. Not being prepared for predators, these poor snails cannot reproduce fast enough to replace all individuals eaten by the flatworm.

We have to act quickly if we want to save those that are still left.

See also: The New Guinea flatworm visits France – a menace.

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ResearchBlogging.orgReferences and further reading:

Chiba, S., & Cowie, R. (2016). Evolution and Extinction of Land Snails on Oceanic Islands. Annual Review of Ecology, Evolution, and Systematics, 47 (1), 123-141 DOI: 10.1146/annurev-ecolsys-112414-054331

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

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by | May 5, 2017 · 8:00 am

Friday Fellow: Toxo

by Piter Kehoma Boll

If I had to bet on a parasite that you who are reading this probably have in your body, I’d go for today’s fellow, the protist Toxoplasma gondii, sometimes simply called toxo.

Found worldwide, the toxo is one of the most common parasites in humans, with estimations that about half of the world’s population is infected. Fortunately, this creature usually occurs in a latent form and does not offer great risks, but eventually it may develop into a more serious condition called toxoplasmosis, especially in people with weakened immunity.

But let’s take a closer look at this tiny fellow.

Toxoplasma_gondii_oocyst

Oocysts of Toxoplasma gondii. This is the form found in the environment and that can start an infection in your body.

The toxo is a protist belonging to the phylum Apicomplexa, a group of parasitic alveolates that also includes the agent that causes malaria. Although traditionally considered a protozoan, the apicomplexans are closely related to dinoflagellates (which are generally considered as a group of algae). They have a unique organelle called apicoplast, which they use to penetrate a host cell. The apicoplast is derived from a plastid (such as the chloropast), so in a certain way we can say that the apicomplexans are algae that evolved into intracellular parasites!

Toxoplasma_gondii_tachy

Tachyzoites of Toxoplasma gondii stained with Giesma from the peritoneal fluid of a mouse.

The life cycle of the toxo is kind of complex. Let’s start with the inactive form called oocyst, which may be found in the environment. If a warm-blooded animal ingests an oocyst, it will “burst” inside the gut of the animal and release several “quick-moving” forms called tachyzoites. The tachyzoites invade almost any cell of the body and multiply asexually inside it until the cell dies and release them, allowing them to infect more and more cells. When invading the brain, liver and muscles, the tachyzoites usually differentiate into cysts that become inactive. In this stage, the only thing that the toxo wants is that a cat (any species of the family Felidae) eats the host. It may even change the host’s behavior in order to make it bolder and more easily accessible to predators.

Toxoplasma_gondii_cyst

A cyst of Toxoplasma gondii that forms in the muscles, brain and liver of any warm-blooded anymal. All the cyst wants is to be eaten by a cat!

Now let’s assume that a cat ate the host (that was likely a bird or mouse). Inside the cat’s gut, the cyst burst and releases several “slow-moving” forms called bradyzoites. This form invades the epithelial cells of the cat’s intestine and multiply asexually inside them. Eventually, the bradyzoites differentiate into either tachyzoites or gametocytes (sperm- and egg-like cells). When two gametocytes fuse, they form a zygote that matures into an oocyst and is released into the environment, restarting the cycle.

Toxoplasma_life_cycle

The complex life cycle of Toxoplasma gondii. Credits to Mariana Ruiz Villarreal.

As always, the lifecycle of parasites is a wonderful adventure!

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ResearchBlogging.orgReferences:

Tenter, A., Heckeroth, A., & Weiss, L. (2000). Toxoplasma gondii: from animals to humans International Journal for Parasitology, 30 (12-13), 1217-1258 DOI: 10.1016/S0020-7519(00)00124-7

Wikipedia. Toxoplasma gondii. Available at <https://en.wikipedia.org/wiki/Toxoplasma_gondii&gt;. Access on March 6, 2017.

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by | April 28, 2017 · 8:00 am

Friday Fellow: Hooker’s Lips

by Piter Kehoma Boll

We are always fascinated by plants that have some peculiar shape that resemble something else. And certainly one of them is the species I’m introducing today, Psychotria elata, also known as hooker’s lips or hot lips.

Found in the rainforests of Central America, in areas of middle to high elevation, the hooker’s lips is an understory shrub and produces an inflorescence that is surrounded by a pair of bracts that resemble bright red lips. Don’t look too much or you may be tempted to kiss them.

psychotria_elata

“Kiss me”, beg the hooker’s lips. Photo by Wikimedia user IROZ.*

Certainly some creatures do kiss it, especially hummingbirds, which are its pollinators, but also many species of butterflies and bees. However, when they come to kiss the red lips, they have already spread to much, in order to allow the flowers to be exposed, and do not resemble a mouth anymore.

psychotria_elata2

Once the mouth is open, the magic of the kiss is gone. Photo by Dick Culbert.**

After pollination, the flowers develop into blue berries that are easily spotted by birds, which disperse the seeds. As the hooker’s lips produces fruits through the whole year, it is an important food source for fruit-eating birds.

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ResearchBlogging.orgReferences:

EOL –  Encyclopedia of Life. Psychotria elata. Available at <http://eol.org/pages/1106123/overview&gt;. Access on March 5, 2017.

Silva, C., & Segura, J. (2015). Reproductive Biology and Herkogamy of Psychotria elata (Rubiaceae), a Distylous Species of the Tropical Rain Forests of Costa Rica American Journal of Plant Sciences, 06 (03), 433-444 DOI: 10.4236/ajps.2015.63049

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by | April 21, 2017 · 8:00 am

Friday Fellow: Crystalline crestfoot

by Piter Kehoma Boll

Even in the smallest pools or ponds of freshwater lost in a field, the diversity of lifeforms is amazing. Sadly, these environments are one of the most damaged of all ecosystems on earth and we probably have led many tiny species to extinction. Today’s fellow, however, is still alive, and its name is Lophopus crystallinus, or as I decided to call it, the crystalline crestfoot.

lophopus_crystallinus

A colony of Lophopus crystallinus. Photo by Natural History Museum, London.*

The crystalline crestfoot is member of the phylum Bryozoa, sometimes called moss animals. In fact, it was the first bryozoan to be described. As other bryozoans, the crystalline crestfoot lives as a colony of individuals attached to substracts in the lakes and ponds where they exist, which includes Europe and North America. The individuals are not fully independent and have specialized functions within the colony, thus acting as a single superorganism. As a general rule, bryozoans, including the crystalline crestfoot, are filter feeders, extracting particles and microalgae from water.

Despite being considerable tolerant to eutrophication (increase of  organic matter in water) and heavy metal pollution, the crystalline crestfoot is yet threatened by other forms of human impact, such as climate change and certainly by the destruction of its habitat. Once an abundant species, the crystalline crestfoot is now rare and declining. It is currently regarded as a threatened species in the United Kingdom and is the only bryozoan to have a Species Action Plan. Let’s hope we can find a way to avoid it to be wiped out from this world.

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ResearchBlogging.orgReferences:

Elia, A., Galarini, R., Martin Dörr, A., & Taticchi, M. (2007). Heavy metal contamination and antioxidant response of a freshwater bryozoan (Lophopus crystallinus Pall., Phylactolaemata). Ecotoxicology and Environmental Safety, 66 (2), 188-194 DOI: 10.1016/j.ecoenv.2005.12.004

Hill, S., Sayer, C., Hammond, P., Rimmer, V., Davidson, T., Hoare, D., Burgess, A., & Okamura, B. (2007). Are rare species rare or just overlooked? Assessing the distribution of the freshwater bryozoan, Lophopus crystallinus. Biological Conservation, 135 (2), 223-234 DOI: 10.1016/j.biocon.2006.10.023

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