Category Archives: Conservation

The Dying Melody: Habitat fragmentation is killing the songs of our birds

by Piter Kehoma Boll

Birds, especially passerine birds (those of the order Passeriformes) are known for their ability to produce complex and melodic calls, or songs, used for a variety of purposes. Who doesn’t love to hear the birds singing beautifully in the forest?

Passerine birds include two main groups: the Passeri (songbirds), also called Oscines, and the Tyranni (tyrants), also called Suboscines. Both groups are able to produce complex calls, but those of the Oscines are usually more smooth and melodic and sound less mechanic.

However, there is one more difference between the calls of both groups. The calls of the tyrants are genetically transmitted from the parents to the offspring, i.e., they do not need to learn how to sing with adult birds. Among the songbirds, on the other hand, the complexity of the call is largely culturally inherited, i.e., they learn how to sing with other birds of the same species.

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The orange-billed sparrow is a songbird found in the Neotropical region. Photo by Francesco Veronesi.*

A recent study published in the journal Animal Behavior (see reference) analyzed the complexity of the calls of two passerine birds found in the forests of Costa Rica: a songbird, the orange-billed sparrow Arremon aurantiirostris, and a tyrant, the scale-crested pygmy tyrant, Lophotriccus pileatus.

791px-scale-crested_pygmy-tirant

The scale-crested pygmy tyrant is a tyrant found in the Neotropical region. Photo by Chris Jimenez.*

The team compared the complexity of the calls in different populations of each species living in forest fragments of different sizes. The conclusion was that, while fragment size did not affect the complexity of the call in the tyrant bird, it significantly affected the call of the songbird.

Populations of the orange-billed sparrow that live in smaller fragments show a less complex song than those living in larger fragments. As the call in this species is culturally transmitted, this reduction in complexity is most likely a result of cultural erosion. As smaller fragments only support smaller populations, the birds do not interact that much with other individuals of the same species while they are growing up, and as a result their song becomes simpler and simpler.

We, humans, are the ones to blame for that, as you may already know. Our irresponsible practices are not only reducing population size in other species, but are destroying their culture as well.

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Reference:

Hart, P. J.; Sebastián-González, E.; Tanimoto, A.; Thompson, A.; Speetjens, T.; Hopkins, M.; Atencio-Picado, M. (2018) Birdsong characteristics are related to fragment size in a neotropical forest. Animal Behavior 137: 45–52. https://doi.org/10.1016/j.anbehav.2017.12.020

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Hundreds of lionfish were released in the Atlantic out of pity

by Piter Kehoma Boll

The red lionfish, Pterois volitans, is a beautiful and venomou coral fish native from the Indo-Pacific region. Due to its great beauty, it is a very popular in fish tanks all around the world.

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A red lionfish in its natural and native habitat in Indonesia. Photo by Alexander Vasenin.*

Since the 1980s, the lionfish started to be found in the waters of the Atlantic ocean around Florida. How did they get there? Certainly humans had something to do with it, but the exact way is yet unknow. Originally a small population, the species spread quickly by the beginning of the 21th century and in 2010 had colonized the Caribbean and the Gulf of Mexico.

Some original studies on the genetic diversity of the Atlantic population estimated that the minimum number of introduced specimens was around 10. If that was true, the established population may have been the result of an accident, like, for example, the fish of a single aquarium accidentally ending up in the sea.

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A red lionfish photographed in Curaçao, Caribbean. Photo by Laszlo Ilyes.**

A recently published study (see reference), however, reestimated this number using new models and additional data. The conclusions are that the number of fish that colonized the Atlantic was much bigger, around 272 individuals. Such a large introduction would unlikely occur by accident. Introductions by fish being transported from the Indo-Pacific region in the ballast water of ships is unlikely, as they would hardly survive the transport. The most likely answer is that these fish were introduced through several small releases that happened in Miami. How and why? Well, many people like to have fish in beautiful fish tanks at home, and when they get tired of managing the animals or cannot afford continuing to have them, they decide to simply release them in the ocean out of pity, because the alternative would be to kill them.

Now can you see what are the consequences of thinking this way? You care too much for a single specimen, has no ecological knowledge, and simply decide to release them in the wild. Years later, they have depleted whole ecosystems and caused a large-scale disaster. That’s what humans do. As they say, the road to hell is paved with good intentions.

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References:

Selwyn JD, Johnson JE, Downey-Wall AM, Bynum AM, Hamner RM, Hogan JD, Bird CE. (2017Simulations indicate that scores of lionfish (Pterois volitans) colonized the Atlantic OceanPeerJ 5:e3996 https://doi.org/10.7717/peerj.3996

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They only care if you are cute: how charisma harms biodiversity

by Piter Kehoma Boll

Which of the two species shown below is more charismatic?

Tangara_chilensis

Tangara chilensis (Paradise Tanager). Photo by flickr user ucumari.*

854px-apocrypta_guineensis2c_volw-wyfie_op_f_sur2c_manie_vd_schijff_bt2c_f

Apocrypta guineensis (a fig wasp). Photo by Wikimedia user JMK.**

You probably would pick the first one. And if I’d ask you which one deserves more attention and efforts to be preserved, you would likely choose the bird as well, or at least most people would. But what is the problem with that? That’s what I am going to show you now.

As we all know, the protection of biological diversity is an important subject in the current world. Fortunately, there is an increase in campaigns promoting the preservation of biodiversity, but unfortunately they are almost always directed to a small subset of species. You may find organizations seeking to protect sea turtles, tigers, eagles or giant pandas, but can you think of anyone wanting to protect beetles? Most preservation programs target large and charismatic creatures, such as mammals, birds and flowering plants, while smaller and not-so-cute organisms remain neglected. And this is not only true in environments that included non-biologist people, but in all fields of research. And more than only leading to a bias in the protection of ecosystems, this preference leads to thousands of understudied species that could bring biotechnological revolutions to humandkind.

In an interesting study published this week in Nature’s Scientific Reports (see reference below), Troudet et al. analyzed the taxonomic bias in biodiversity data by comparing the occurrence of data on several taxonomic groups to those groups’ diversity. The conclusions are astonishing, although not that much surprising. The most charismatic groups, such as birds, are, one could say, overstudied, with an excess of records, while other, such as insects, are highly understudied. While birds have about 200 million occurences above the ideal record, insects have about 200 million below the ideal number. And the situation does not seem to have improved very much along the years.

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The bias in interest is clear. The vertical line indicates the “ideal” number of occurrences of each group. A green bar indicates an excess of occurrences, while a red bar indicates a lack of occurrences. Birds and Insects are on the opposite extremes, but certainly the insect bias is much worse. Figure extracted from Troudet et al. (2017).***

Aditionally, the study concluded that the main reason for such disparity is simply societal preference, i.e., the most studied groups are the most loved ones by people in general. The issue is really a simple matter of charisma and has little to do with scientific or viability reasons.

The only way to change this scenario is if we find a way to raise awareness and interest of the general public on the less charismatic groups. We must make them interesting to the lay audience in order to receive their support and increase the number of future biologists that will choose to work with these neglected but very important creatures.

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See also:

Once found and then forgotten: the not so bright side of taxonomy

The lack of taxonomists and its consequences on ecology

Unknown whereabouts: the lack of biogeographic references of species

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Reference:

Troudet, J.; Grandcolas, P.; Blin, A,; Vignes-Lebbe, R.; Legendre, F. (2017) Taxonomic bias in biodiversity data and societal preferences. Scientific Report 7: 9132. https://dx.doi.org/10.1038/s41598-017-09084-6

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Old Italian trees: a step toward worldwide recognition?

by Piter Kehoma Boll

Some years ago I wrote an article (you can read it here) about the importance of trees, especially old trees, and how their ecological role is different from that of a young tree.

old_tree

Ancient trees are ecological preciosities and need to be preserved for the sake of their ecosystems. Photo by flickr user loshak.*

In Italy, there are specific laws erected to protect ancient trees, especially if they are unique for their species or have some sort of aesthetic or cultural value. Recently, their importance for the preservation of a variety of lifeforms has also started to be recognized. A recently published article by a group of Italian researchers (see below) compared the noteworthy old trees in Italy recorded in a previous list and a new list. They conclude that the new inventory has considerable improvements, although some issues remain, including the presence of exotic, even invasive, species in the list.

But such initiatives are at least important as a first step that may guide us to a better understanding and management of old trees, which are precious elements, but continue to decline worldwide.

Read the study for free:

Zapponi, L.; Mazza, G.; Farina, A.; Fedrigoli, L.; Mazzocchi, F.; Roversi, P. F.; Peverieri, G. S.; Mason, F. (2017) The role of monumental trees for the preservation of saproxylic biodiversity: re-thinking their management in cultural landscapes. Nature Conservation 19: 231–243.

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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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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.

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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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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.

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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 crystallinusBiological Conservation, 135 (2), 223-234 DOI: 10.1016/j.biocon.2006.10.023

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