Monthly Archives: February 2019

Whose Wednesday: Anders Sparrman

by Piter Kehoma Boll

Leia em português

Today we celebrate the birthday of one of Linnaeus’ apostles and fellow countrymen.

Anders Sparrman was born on 27 February 1748 in Tensta, Sweden, and was the son of a clergyman. When he was only nine years old, he was enrolled at Uppsala University and began medical studies. At the age of 14, he became a pupil of Linnaeus, one of the outstanding ones.

In 1765, aged 17, Sparrman went to China as a ship’s doctor. In this voyage, he had a tough time treating the crew members, many of which died of the yet little known malaria, and many also suffered from Guinea-worm disease. Nevertheless, he also collected many plants and animals in this troublesome experience, which he described two years later after returning to Sweden.

Portrait of Anders Sparrman, around 1770.

In January 1772, aged 23, he moved to the Cape of Good Hope, South Africa, to work as a tutor. His time there was short, though, because in October of that same year James Cook arrived in his second voyage and Sparmann joined the crew as assistant naturalist to Johann and Georg Forster, who were the ship’s naturalists.

Sparrman returned to the Cape of Good Hope in July 1775 and, by practicing medicine, was able to finance a journey to the interior of the country. He was guided by Daniel Ferdinand Immelman, who had previously guided the botanist Carl Peter Thunberg. During this journey, he met groups of Khoi and Xhosa people and was very interested in their culture, describing many of their practices in his work about his travels in the Cape and around the world.

In 1776, Sparrman returned to Sweden and found out he had been awarded an honorary doctorate. Except for an unsuccessful expedition to West Africa in 1787, Sparrman spent most of his life in Sweden after that, which, giving his adventurous spirit, was likely torture to him. He became a member of the Royal Swedish Academy of Sciences in 1777 and was appointed keeper of the Academy’s natural history collections in 1780.

In 1781, Sparrman was appointed Professor of natural history and pharmacology and, in 1790, assessor of the Collegium Medicum. Despite publishing several scientific works, Sparrman’s most famous work continued to be his account about his adventures around the world and in South Africa.

Sparrman died on 8 August 1820 in Stockholm, aged 72.

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References:

Eagleton T (2010) Anders Sparrman—masterful tale of a scientific vagabond. The Lancet 376(9749): 1291–1292. doi:
10.1016/S0140-6736(10)61901-0

Wikipedia. Anders Sparrman. Available at < https://en.wikipedia.org/wiki/Anders_Sparrman >. Access on 26 February 2019.

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Green turtles mistake plastic debris for dead squids, eat them, and die

by Piter Kehoma Boll

Plastic pollution is a popular topic recently and it is not rare to find pictures of animals that died due to plastic ingestion or other complications, such as asphyxia, caused by plastic pieces. However, the cause of plastic ingestion by most species is yet unknown.

Albatross with its stomach filled with plastic pieces.

The leatherback turtle, Dermochelys coriacea, is often mentioned as a species that suffers from plastic ingestion due to its diet composed primarily by jellyfish, which floating plastic bags can be mistaken for. However, another widespread sea turtle, the green turtle, Chelonia mydas, is also a common victim of plastic ingestion and amounts as small as 1 g are enough to kill juvenile specimens by blocking their guts. The diet of juvenile and adult green turtles is composed mainly by seagrass and algae, so the ingestion of plastic must be the result of another cause and not its similarity to jellyfish.

A decaying plastic bag in the ocean looks like a jellyfish. Photo by Wikimedia user Seegraswiese.*

Despite being almost strictly herbivorous, green turtles ingest animal matter when they are very young and can eventually consume animals as adults too, probably as a strategy to survive when their main food source is scarce. The ingestion of animal matter is usually done by scavenging, and a common scavenged item in their diet are dead squids.

A green turtle surrounded by seagrass, its main food source. Photo by Wikimedia user Danjgi.**

A recent study has investigated the relationship between scavenging behavior and plastic consumption in the green turtle and found out that the amount of plastic ingested by individuals feeding on dead squids is much higher than that ingested by individuals that do not present a scavenging behavior. In Brazil, plastic ingestion accounts for about 10% of the deaths of green turtles but this number may be as high as 67% among green turtles that feed on squid carcasses.

The ingestion of dead animals used to be an efficient way for green turtles to gain high amounts of protein. However, the fact that, currently, most floating material in the ocean is plastic and not dead animals turned a successful strategy into a deadly trap. If humans do not start controlling plastic waste production there will be only two possible outcomes for the green turtles in face of this new selective pressure: adaptation or extinction.

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References:

Andrades R, Santos RA, Martins AS, Teles D, Santos RG (2019) Scavenging as a pathway for plastic ingestion by marine animals. Environmental Pollution 248: 159–165. doi: 10.1016/j.envpol.2019.02.010

Mrosovsky N, Ryan GD, James MC (2009) Leatherback turtles: the menace of plastic. Marine Pollution Bulletin 58(2): 287–289. doi: 10.1016/j.marpolbul.2008.10.018

Santos RG, Andrades R, Boldrini MA, Martins AS (2015) Debris ingestion by juvenile marine turtles: an underestimated problem. Marine Pollution Bulletin 93(1–2): 37–43. doi: 10.1016/j.marpolbul.2015.02.022

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Friday Fellow: Galapagos Giant Centipede

by Piter Kehoma Boll

Leia em português

The Galapagos Islands are famous for many of their animals, such as the tortoises, finches and iguanas. However, the island also harbors a variety of invertebrates and today I am going to talk about one of them.

The Galapagos giant centipede, Scolopendra galapagoensis, is very similar to another famous centipede species, the Amazonian giant centipede Scolopendra gigantea. Despite the name, the Galapagos giant centipede is not restricted to the Galapagos Islands, but can also be found in nearby areas in Peru and Ecuador, although these populations were originally considered a subspecies of S. gigantea, which is found around Venezuela, Colombia and the Caribbean.

Scolopendra galapagoensis on Fernandina Island, Galapagos Islands. Photo by Libby Megna.*

The body of the Galapagos giant centipede varies from brown to black and the numerous legs vary from orange to dark brown or black. It can reach up to 30 cm in length, therefore being as large as its cousin S. gigantea. The main difference being in the number of hairy segments in their antennae.

A predator as most centipedes, the Galapagos giant centipede feeds on a variety of other small animals, mainly invertebrates, although it can also feed on small vertebrates, such as newborn rodents, which it subdues using its powerful venom.

When threatened, the Galapagos giant centipede assumes a defense position in which it raises its last pair of legs, called the ultimate legs, and some of the last pairs of walking legs, displaying them to the attacker in a way that resembles the warning display used by some spiders such as wandering spiders and tarantulas.

Galapagos giant centipede in a warning position. Credits to Kronmüller & Lewis (2015).**

Recently, the Galapagos giant centipede has become a popular animal among those that like raising unusual pets, such as spiders and centipedes, so that you can find a lot of information and videos on the species produced by people that have them at home in their aquaria.

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References:

Clark DB (1979) A centipede preying on a nestling rice rat (Oryzomys bauri). Journal of Mammalogy 60(3): 654.

Kronmüller C, Lewis JGE (2015) On the function of the ultimate legs of some Scolopendridae (Chilopoda, Scolopendromorpha). Zookeys 510: 269–278.
doi: 10.3897/zookeys.510.8674

Shelley RM, Kiser SB (2000) Neotype designation and a diagnostic account for the centipede, Scolopendra gigantea L. 1758, with an account of S. galapagoensis Bollman 1889 (Chilopoda Scolopendromorpha Scolopendridae). Tropical Zoology 13(1): 159–170. doi: 10.1080/03946975.2000.10531129

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*Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

**Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License.

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Antidepressants in wastewater are unbalancing food webs

by Piter Kehoma Boll

Leia em português

Wastewater is one major cause of water pollution on a global scale and this includes domestic wastewater. With the increase in the use of pharmaceuticals of many types to treat a variety of health conditions, these substances end up in domestic wastewater and, even in places with wastewater treatment, such drugs are not always completely removed.

The most commonly detected drugs in aquatic environments include antidepressants. Although in very low concentrations, their effects on organisms are poorly known.

A recent study investigated how the presence of two antidepressants, citalopram (a selective serotonin reuptake inhibitor) and tramadol (a serotonin-norepinephrine reuptake inhibitor) affect the predatory activity of dragonfly nymphs of the species Aeshna cyanea. The insects were exposed to concentrations of about 1 microgram per liter of the substances, a concentration similar to that found naturally in environments affected by wastewaters. Additionally, they used effluents from wastewater treatment plants that included a mix of several drugs in real concentrations.

A nymph of Aeshna cyanea. Photo by André Karwath.*

The results indicate that dragonfly nymphs increase the amount of time they spend searching for food in the presence of the two antidepressants and spend more time handling prey but their feeding rate decreased, i.e., they eat less than nymphs of the control group, i.e., in water without antidepressants. On the other hand, nymphs exposed to effluent from wastewater treatment plants ate more than nymphs of the control group. The exact reason for the opposite effect caused by normal wastewater is unknown, but may be related to the combined effect of several drugs.

Although the effects do not seem to be that problematic at first, an increase or decrease in feeding rate by predators may unbalance the population of the prey species by making it increase or decrease and eventually reach a point that leads to a collapse in the ecosystem.

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Reference:

Bláha M, Grabicova K, Shaliutina O, Kubec J, Randák T, Zlabek V, Buřič M, Veselý L (2019) Foraging behaviour of top predators mediated by pollution of psychoactive pharmaceuticals and effects on ecosystem stability. Science of The Total Environment 662: 655–661.

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*Creative Commons License This work is licensed under a Creative Commons Attribution-Share Alike 2.5 Generic License.

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Whose Wednesday: Carl Linnaeus the Younger

by Piter Kehoma Boll

Carl Linnaeus is certainly one of the most famous naturalists in history. His son, though, whose birthday we celebrate today, is not as famous and had a complicated and short life compared to his father.

Carl Linnaeus, the son, was born on 20 February 1741 in Falun, Sweden. He received his father’s name and is usually known as Linnaeus filius. His father always wanted him to follow his steps as a botanist and was so eager to do it that he had him enrolled at the University of Uppsala at the age of nine. Linnaeus’ best students, Pehr Löfling, Daniel Solander and Johan Peter Falk, were selected to teach Linnaeus filius.

Portrait of Carl Linnaeus filius by Jonas Forsslund.

Linnaeus filius did not seem to be very interested in following his father steps, though, and was not the best student at all. He never received an academic degree but, due to his father’s recommendations, was hired as a botanical demonstrator at the Botanical Garden in Uppsala when he was only 18 years old. Linnaeus hoped that this opportunity would make his son more interested in botany. During this time, Linnaeus filius described several new plant species.

In 1962, when Linnaeus retired, he was honored to choose his successor. His first choice was Daniel Solander but he declined because he had been appointed to the British Museum in London. Linnaeus’ second choice was Linnaeus filius, and thus he entered the University of Uppsala as head of Practical Medicine even without having the required academic degree. This caused resentment among his colleagues. And the situation became worse in 1963 when Prince Gustav (later King Gustav III) conferred a doctor’s degree of honor to Linnaeus filius.

In 1777, Linnaeus filius was promoted to professor. In the same year, his father, who was very debilitated, decided that his son would not inherit his large herbarium because he was never interested in botany. After Linnaeus the father’s death in 1778, the herbarium remained with his wife Sara Elisabeth. This later forced Linnaeus filius to write an acknowledgment of debts to his mother to receive access to the collection.

In 1781, Linnaeus filius took a two-year trip to visit England, France, The Netherlands and Denmark. In London, he acquired jaundice and shortly after returning home he suffered from fever and had a stroke, from which he died on 1 November 1783, aged 42.

Linnaeus filius did not have children. As a result, the name Linnaeus, created by his grandfather, died out after only three generations.

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References:

Naturhistoriska riksmuseet. Carl Linnaeus fil. Available at < http://www2.nrm.se/fbo/hist/linnefil/linfil.html.en >. Access on 19 February 2019.

Wikipedia. Carl Linnaeus the Younger. Available at < https://en.wikipedia.org/wiki/Carl_Linnaeus_the_Younger >. Access on 19 February 2019.

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Friday Fellow: Leatherleaf Fern

by Piter Kehoma Boll

Leia em Português

You may have seen parts of today’s fellow at least once in your life, as it is a very popular plant in flower arrangements.

A flower bouquet including leaves of Rumohra adiantiformis.

Rumohra adiantiformis is how it is known by botanists, and common names include leatherleaf fern, seven-weeks fern and iron fern. This fern species is widely distributed in Australasia, southern Africa and the Neotropics, as well as several islands of the Pacific Ocean.

Living in forested areas, especially where there is not too much shade, the leatherleaf fern has a biology that is not very different from that of other ferns. It usually grows on the soil, although it may eventually occur on rocks or on trees. What makes this fern special is that its mature fronds are somewhat hard and, after being cut off, continue to have a green and live appearance for a very long time, usually several weeks. This amazing resistance to wilt makes it an ideal species to be used in flower arrangements.

Leatherleaf fern growing in South Africa. Photo by Wikimedia user JMK.*

Currently, most of the leatherleaf fern’s production for commercial use occurs in the state of Florida, USA, where it is cultivated in irrigated shaded nurseries. Other large producers are South Africa and Brazil, especially southern Brazil, but in these two countries the plant is exploited through extractivism, i.e., it is harvested in the wild and not cultivated. Although the extraction of the leatherleaf fern is a widespread activity in both South Africa and southern Brazil and is a major source of income for many families, it is illegal under national or regional laws. However, at least in southern Brazil, where the leatherleaf fern occurs in the highest recorded densities in the world, the main reason for its populations to be diminishing does not seem to be its extraction but rather natural forest succession. As forests grow older and become darker, they become unsuitable for the leatherleaf fern to grow.

It is, of course, necessary to establish limits for its harvest. Otherwise, its increasing demand in the florist market may end up causing concerning effects on its occurrence. The best alternative continues to be cultivating the fern, as it protects wild populations and allows the harvest of high-quality fronds and a faster recovery after defoliation.

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References:

Geldenhuys CJ, van der Merwe CJ (1988) Population structure and growth of the fern Rumohra adiantiformis in relation to frond harvesting in the southern Cape forests. South African Journal of Botany 54(4): 351–362.

Milton SJ (1987) Growth of Seven-weeks Fern (Rumohra adiantiformis) in the Southern Cape Forests: Implications for Management. South African Forestry Journal 143: 1–4.

Souza GC, Cubo R, Guimarães L, Elisabetsky E (2006) An ethnobiological assessment of Rumohra adiantiformis (samambaia-preta) extractivism in Southern Brazil. Biodiversity and Conservation 15: 2737–2746. doi: 10.1007/s10531-005-0309-3

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*Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

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Love thy neighbor’s son: why do some animals care for the young of others?

by Piter Kehoma Boll

Leia em Português

Parental care, here defined as any behavior in which an animal takes care of its young, is a widespread practice in the animal kingdom, having evolved repeatedly in many taxa. It is not difficult to see, considering natural selection, why parental care is an adaptative trait. It enhances the chance of one’s offspring to survive and thus carry one’s genes to the next generation.

A bird feeding its babies. Photo by JJ Harrison.*

On the other hand, the related behavior known as alloparental care is not that easy to explain in every instance of its occurrence.

While parental care means caring for your own offspring, alloparental care means caring for the offspring of another individual. If you spend time and resources in taking care of an animal that is not your direct descendant, you must have a good reason to do it, a reason that somehow benefits you. Or you may just be too dumb.

Most animals reject or even kill the offspring of other individuals of the same species. A classic example is a male lion that kills the cubs that he knows are not his. He does that because he sees no advantage in allowing the offspring of another male to survive.

An extreme example of caring for juveniles that are not your direct offspring is found in social insects such as bees and ants. Worker ants usually do not reproduce but they raise their siblings as if they were their own children. In this case, it is more advantageous to make siblings than to make children because of the peculiar reproductive system of hymenopterans. I will not enter in details but, basically, ants share 100% of their father’s DNA and 50% of their mother’s DNA, so that two sibling ants have 75% of their genes in common, while the relationship between a female ant and her female offspring is of only 50%.

Bees help their mother to raise their siblings. Photo by Wikimedia user Waugsberg.*

However, alloparental care is found in many other animals, especially in mammals. Although not having 75% of similarity between siblings as in ants, many mammals and other animals help their mothers and/or fathers to raise their siblings. This has less direct advantages but they are still there. After all, your siblings (if they are of the same mother AND father) share 50% of your DNA, the same amount that you share with your children. But alloparental care may also happen with more distantly related relatives, such as grandchildren and half-siblings, which share only 25% of their DNA with you. This is not a problem, though, because if you are unable to have your own kids at that time, it is better to help raise those juveniles that share some DNA with you than to do nothing because 25% of your genes is still better than nothing.

A recently published paper reports the first observation of alloparental care in the field in the cichlid fish Neolamprologus savoryi. The team observed a male fish helping take care of the eggs of another male that was found to be his father, although the mother of the eggs was not his mother. The male helper was small and probably sexually immature, so that, as said above, helping his half-siblings, which have 25% of his genes, survive is better than doing nothing.

An immature male of Neolamprologus savoryi taking care of the eggs of his father with his stepmother. Credits to Josi et al. (2019).

A really hard thing to explain is why some animals accept to take care of the offspring of unrelated individuals, in which there is no clear adaptative advantage. Such a situation was recently discovered to occur with the common earwig Forficula auricularia. Females that had their egg clutches replaced with the eggs of an unrelated female took care of them as if they were their own. No advantage of any kind can be extracted from this behavior, so the most likely explanation is simply the lack of adaptative pressure to reject unrelated eggs. It is likely that, under natural conditions, a female earwig never encounters the eggs of another female. Thus, there was never a scenario in which the capacity to recognize one’s own eggs (and differentiate them from others) could evolve. Natural selection needs opportunities to act.

Forficula auricularia with a clutch of eggs. Photo by Tom Oates.*

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You may also like:

Endosperm: the pivot of the sexual conflict in flowering plants

Your mother loves you more when she loves your father… if you are a fish

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References:

Josi D, Taborsky M, Frommen JG (2019) First field evidence of alloparental egg care in cooperatively breeding fish. Ethology 125(3): 164–169. doi: 10.1111/eth.12838

Royle NJ, Moore AJ (2019) Nature and Nurture in Parental Care. In: Genes and Behaviour, pp. 131–156. John Wiley & Sons, Ltd. doi: 10.1002/9781119313663.ch7

Van Meyel S, Devers S, Meunier J (2019) Love them all: mothers provide care to foreign eggs in the European earwig Forficula auricularia. Behavioral Ecology. doi:10.1093/beheco/arz012

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*Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

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Filed under Behavior, Entomology, Evolution, Fish