Author Archives: Piter Keo

About Piter Keo

I'm a biology student, currently working with land planarians. I love biology, astronomy, languages and mythology, among other things.

Having few females turns male tortoises into rapists

by Piter Kehoma Boll

The war between the sexes and the endless conflicts that result from that are a common theme in behavioral and evolutionary research and have been addressed several times here too.

As we know very well, even from examples in our own species, males are usually not very good parents, being more interested in producing as many descendants as possible with little effort. Females, on the other hand, due to their great investment on eggs (and usually other resources for the offspring) are much more selective and will not accept any male to mate with them.

One of the most common solutions for males to resolve this sexual conflict is by forced copulation, or rape as it is called when it happens in our own species. Sometimes this forced copulation is extreme, with males heavily injuring females in order to make them surrender. One of those violent species is the Hermann’s tortoise, Testudo hermanni, a tortoise found around the Mediterranean areas of Europe.

800px-small_male_on_big_female

“I’m gonna bang you, bitch!” This photo of a juvenile male trying to mount on an adult female may look funny, but sex is no fun for female tortoises. Photo by Wikimedia user Palauenc05.*

Forced copulation is much more common in species in which males are bigger and stronger than females. This is not the case with tortoises, but male Hermann’s tortoises have found a way to deal with that. They pursue the females, sometimes for hours, pushing them, biting them, sometimes to the point of making them bleed, and eventually the poor females surrender. It is also common for the males to “stimulate” the cloaca of the females with their pointed tail, resulting in a swollen cloaca and sometimes severe injuries that let the females with horrible scars and deformities. Yes, it is not a nice face of nature.

800px-astuccio_corneo3

The tail of a male. Photo by Wikimedia user Bizarria.**

A recent study with two populations of the Hermann’s tortoise in Macedonia revealed that male aggressiveness is linked to female availability. The team of researchers studied one population in which the female:male ratio was close to 1:1 and other in which it was extremely male-biased to the point of 1 female to 17.5 males.

The results indicate that in the more balanced population forced copulation was less common and usually only adult females presented injuries caused by males, while in the male-biased population the lack of females made males go mad to the point that they forced copulation even with immature females. The situation as a whole is clearly maladaptive, as females end up injured and males end up exhausted and no offspring is generated.

I can only see two possible outcomes for such a population: either more resistant females will be selected or the population will go extinct after all females die by male violence.

As we see, sexual conflict is one of those deleterious side effects that natural selection created. Afterall, nobody is perfect, not even the fundamental laws of life.

– – –

You may also like:

Male dragonflies are not as violent as thought

Gender conflict: Who’s the man in the relationship?

Badass females are unpopular among praying mantids

Having more females makes you gayer… if you are a beetle

Male resistance: when females disappear and hermaphrodites don’t like you

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

Reference:

Golubović, A.; Arsovski, D.; Tomović, L.; Bonnet, X. (2018) Is sexual brutality maladaptive under high population density? Biological Journal of the Linnean Society 124(3): 394–402. https://doi.org/10.1093/biolinnean/bly057

– – –

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

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

Advertisements

Leave a comment

Filed under Behavior, Evolution, Zoology

Friday Fellow: Truncate Trapdoor Spider

by Piter Kehoma Boll

Today I’m bringing you a species that fascinates me and that I was willing to introduce for a while. Unfortunately, there isn’t much information available about it, that being the reason for my delay in showing it here. However, as new information seems unlikely to appear soon, I can only show it with whatever is avaible.

Named Cyclocosmia truncata, today’s fellow is a trapdoor spider found in the East of the United States and sometimes referred to as truncate trapdoor spider. As all trapdoor spiders, it is a mygalomorph spider, such as tarantulas, and lives in a tunnel that it burrows in the ground and that is covered by a trapdoor. Trapdoor spiders in general rarely leave their burrows and hunt prey at night by standing behind the closed trapdoor and waiting for a prey to pass nearby, then jumping out and capturing it.

A truncate trapdoor spider in southeastern United States. Photo by iNaturalist user jimstarrett.*

Because trapdoor spiders are highly sedentary, they are very vulnerable to predators and parasites that can easily find them by locating their burrows. Species in the genus Cyclocosma have developed a fascinating morphological adaptation to cope with that. Their abdomen is abruptly truncated, giving the impression that someone just cut half of the abdomen off. This region of the abdomen is covered by a heavily sclerotized disc. When the spider is not active, it enters its burrow head first and the sclerotized disc fits perfectly to the walls of the tunnel, forming a false bottom that is impenetrable.

twikq3h

A nice view of the peculiar disc of Cyclocosmia truncata. Author unknown. Photo taken from imgur.com

Not much more is known about the truncate trapdoor spider or its close relatives. They seem to be considerably rare, living in very restrict habitats, and their burrows are so well hidden that it is hard to find them in the wild.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Gertsch, W. J.; Platnick, N. I. (1975) A revision of the trapdoor spider genus Cyclocosmia (Aranae, Ctenizidae). American Museum Novitates 2580: 1–20.

Hunt, R. H. 1976. Notes on the ecology of Cyclocosmia truncata (Aranae, Ctenizidae) in Georgia. Journal of Arachnology 3: 83–86.

– – –

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

Leave a comment

Filed under Arachnids, Friday Fellow, Zoology

Friday Fellow: Common giardia

by Piter Kehoma Boll

Parasites are always a group eager to be featured here, and human parasites have a special place in our hearts… sometimes literally. Today’s species, however, has a special place in our small intestine.

Called Giardia lamblia, sometimes also identified under the outdated synonyms Giardia duodenalis or Giardia intestinalis, our species has not a common name, but as it is the most popular and widespread species of the genus Giardia, I decided to call it simply the common giardia.

The common giardia is a flagellated unicellular organism that affects not only humans but several other mammal species. In the wild, the common giardia exists in the form of an inert cyst that can survive for prolonged periods and under different environmental conditions.

giardia_cyst_wtmt3

A cyst of Giardia lamblia. Credits to Centers for Disease Control and Prevention.

When the cysts are ingested by humans or other mammals, they develop into the active stage, called trophozoite, once they reach the small intestine. The trophozoite is a flagellated cell with two well-developed nuclei that make it look like a smiling face. In this stage, the common giardia reproduced by simple binary fission. For a long time, it was thought that sexual reproduction did not occur at all in this species, but some recent evidence indicate that recombination may occur, although it is not very clear yet how it happens.

800px-giardia_intestinalis_28259_1729

Two trophozoites of the common giardia under the microscope. Credits to Josef Reischig.*

The ventral surface of the trophozoite is concave, forming an adhesive disk that attaches the cell to the wall of the intestine, preventing it to be transported downward the intestinal tract. Although not invading the intestinal cells, the infection of Giardia lamblia usually causes diarrhea and malabsorption. When exposed to biliar secretions, the common giardia may develop into a cyst and is thus eliminated with the feces, allowing the cycle to begin again.

Humans are very often contaminated by several means, such as by ingesting contaminated water, which may include both urban untreated water or clear water in the wild where other mammals may have defecated. It is, therefore, a common infection among hikers, people living under poor sanitary conditions and so on.

The common giardia has some peculiarities, such as the lack of mitochondria, which for some time led to the assumptions that they may belong to a very primitive group of Eukaryotes. Recently, however, a vestigial organelle that likely derived from mitochondria, named mitosome, has been found in this species, suggesting that this feature is a secondary loss caused by its parasitic life in an anoxic environment.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Adam, R. D. (2001) Biology of Giardia lambliaClinical Microbiology Reviews 14(3): 447–475.

Wikipedia. Giardia lamblia. Available at < https://en.wikipedia.org/wiki/Giardia_lamblia >. Access on 28 June 2018.

– – –

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

Leave a comment

Filed under Parasites, protists

Friday Fellow: Sharp-Toothed Venus Seed-Shrimp

by Piter Kehoma Boll

We reached again one of those problematic weeks in which I have to talk about something I know very little. This time the problem is called Euphilomedes carcharodonta, a small crustacean of the class Ostracoda, known as ostracods or seed shrimps. I decided to adapt the name of this species as sharp-toothed Venus seed-shrimp.

Although seed shrimps form a very diverse and species-rich group of organisms, I cannot find much details on particular species, so it is a challenge to present one here, but I decided to talk a little about the sharp-toothed Venus seed-shrimp, so let’s go.

96158_580_360

A male of the sharp-toothed Venus seed-shrimp. The dark spot is a lateral eye. Photo by Ajna Rivera.*

Measuring only a few milimeters, the sharp-toothed Venus seed-shrimp is found in the sea along the west coast of the United States. It has a typical ostracod appearance, looking like a small shrimp within a bivalvian shell.

Males and females of the sharp-toothed Venus seed-shrimp show sexual dimorphism, part of which is not only related directly to sex, but actually to the different niches that each sex occupies in the environment. Females pass most of their time buried in the sediments where light and predators are limited and, as a result, they have poorly developed eyes. The males, on the other hand, spend a lot of their time swimming in the water and are very vulnerable to predators, such as fish. Therefore, males have very well developed eyes that allow them to see fish from the distance. Experiments have shown that the eyes do not help them to identify the tiny females, but are essential to survive predation.

20172_580_360

A female sharp-toothed Venus seed-shrimp. Notice how she does not have the lateral eye seen on the male. Photo by Ajna Rivera.*

And that’s what I got about this fellow. As I asked before while talking about other groups of organisms, such as foraminiferans, if you have good resources on more detailed knowledge about species in this group, please share them in the comments. We need to give more visibility to those tiny and neglected souls that share this planet with us.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Sajuthi, A., Carrillo-Zazuetta, B., Hu, B., Wang, A., Brodnansky, L., Mayberry, J., & Rivera, A. S. (2015). Sexually dimorphic gene expression in the lateral eyes of Euphilomedes carcharodonta (Ostracoda, Pancrustacea) EvoDevo, 6 : 10.1186/s13227-015-0026-2

Speiser, D. I., Lampe, R. I., Lovdahl, V. R., Carrillo-Zazueta, B., Rivera, A. S., & Oakley, T. H. (2013). Evasion of Predators Contributes to the Maintenance of Male Eyes in Sexually Dimorphic Euphilomedes Ostracods (Crustacea) ntegrative and Comparative Biology, 53 (1), 78-88

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommerical-NoDerivs 2.0 Generic License.

Leave a comment

Filed under Friday Fellow, Zoology

Friday Fellow: Crescent-Cup Liverwort

by Piter Kehoma Boll

Today’s fellow is once more a small forest dweller, more precisely a liverwort. Scientifically called Lunularia cruciata, its common name is crescent-cup liverwort. The names Lunularia and crescent-cup come from the shape of its cups, structures that contain mass of cells called gemmae that are released in the environment and  can grow into a new plant, a form of asexual reproduction.

57980_orig

This close up of a crescent-cup liverwort reveals the crescent-shaped cups containing the gemmae. Credits to BioImages – the Virtual Fieldguide (UK).*

The crescent-cup liverwort appears to be native from Southern Europe, around the Mediterranean, but in the last decades, possibily due to human interference, it has expanded its distribution to the north of Europe and has reached other continents as well, especially the Americas.

In the United States, the crescent-cup liverwort has become a very common species living in green houses. Its quick spread is certainly related to its asexual reproduction. The gemmae found in its cups are usually released by water drops and germinate as soon as they fall on a humid surface, quickly originating a new plant.

Although most populations seem to reproduce only asexually, sexual reproduction occurs as well and follows the basic pattern seen in other liverworts. In sexual populations, the female gametophytes produce a long stem with four archegonia (the structure that bears the female gametes) arranged as a cross, hence the specific epithet cruciata (“crossed”).

12189_orig

The cross-shaped archegonia of the crescent-cup liverwort. Photo by Ken-ichi Ueda.**

Some extracts from the crescent-cup liverwort has shown the potential to be used for the development of new antibiotics.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Basile, A., Giordano, S., Sorbo, S., Vuotto, M. L., Ielpo, M T. L. & Cobianchi, R. C. (1998). Antibiotic Effects of Lunularia cruciata (Bryophyta) Extract Pharmaceutical Biology, 36 (1), 25-28 : 10.1076/phbi.36.1.25.4612

Wikipedia. Lunularia. Available at < https://en.wikipedia.org/wiki/Lunularia >. Access on May 26, 2018.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 Unported License.

1 Comment

Filed under Botany, Friday Fellow

Why everybody laughs at Wickramasinghe and should continue to do so

by Piter Kehoma Boll

More than six years ago, when this blog was just starting, I wrote an article about a poor old scientist, Donald I. Williamson, and his absurd ideas of hybridogenesis, i.e., the idea that new organisms could arrive by hybridizing very distantly related species, such as crossing a beetle with an earthworm. Williamson passed away two years ago and continued to defend his baseless hypothesis to the end.

Later on, I presented two other scientists with similarly ridiculous ideas: Retallack and his land Ediacara hypothesis, and Duesberg and his AIDS conspiracy theory. Now, I’m here to talk about an even more severe case of dellusion, and one that is as serious as Duesberg’s, because it is also followed by a bunch of crazy people.

The dellusion has a name, the Hoyle-Wickramasinghe “””””theory”””””, or H-W theory for short. His main follower currently is Wickramasinghe himself, more precisely Chandra Wickramasinghe, since the other guy, Fred Hoyle, is already decomposing and emitting Galactic Center infrared waves (you’ll understand it soon).

chandra-wickramasinghe

Professor Chandra Wickramasinghe and cabillions of bacteria glowing behind him. Photo by Wikimedia user Davidnoy.*

Wickramasinghe is a Sri Lankan-born British mathematician, astronomer and astrobiologist who since the 1960 worked with the now galactic-center-like deceased astronomer Fred Hoyle. They seem to have found in each other someone to support their mental disorder, as they formulated the hypothesis that life came to Earth from space. No, wait… it’s not that simple. They stated that life COMES to Earth from space… all the time!

giphy

Excuse me?

We all have heard of panspermia, right? The idea that life perhaps did not originate on Earth, but arrived here from space. Well, that may be a plausible idea. Perhaps the first microorganisms that appeared on Earth indeed came from space, but we know for sure, based on molecular analyses, that all current life forms originated from a single ancestor that is thought, based on fossils AND molecular data, to have existed about 3.5 billion years ago. We are, therefore, all part of a big family.

The problem with Wickramasinghe and his puppies (which are more than I expected, I have to say) is that they claim that new organisms are arriving all the time in comets and asteroids. They consider that the “sudden” complexity of life on Earth as seen in the fossil record, such as, for example, the appearance of the first cyanobacteria or the Cambrian explosion, could not have happened by simple neo-Darwinian evolution. So the logical explanation for them is… ALIENS! Alien viruses arrive, infect cells, mix their genetic material with that of the host and, voilà, a new complex lifeform appears.

giphy1

During his career, Wickramasinghe made several statements that did not please the scientific community. He said, for example, that some pandemics, such as the 1918 flu pandemic and several other outbreaks of viral diseases are the result of cometary dust bringing the virus to Earth and scattering it throughout the planet. This view is, of course, dismissed by all serious researchers.

Recently, to my surprise, an apparently reputable journal, Progress in Biophysics and Molecular Biology, published a paper authored by Wickramasinghe and his puppies that defends again this nonsense idea of continuous extraterrestrial delivery of life. They suggest that the entire Galaxy comprises a gigantic biosphere and that life is being transported from here to there and back for billions and billions of years. But perhaps the most astonishing claim, and the one that made so many people become aware of this comedy disguised as science, is that octopuses came from space as eggs.

giphy2

Yes, that’s exactly what the team proposed! They propose that the genetic and structural complexity of octopuses, squids and and cuttlefish, which is, according to them, hard to explain by “tradional neo-Darwinian evolution or even by massive horizontal gene transfer from viruses” is the result of these creatures having evolved somewhere else in the Galaxy and later coming to Earth in frozen eggs.

Another hilarious evidence they present about the existence of life across the whole Galaxy is by comparing the mid-infrared spectrum emitted by a source in the Galactic Center to the mid-infrared spectrum emitted by partially degraded bacteria. The patterns are very similar and this is, according to them, an evidence that the Galactic Center is crowded with bacteria. But what are the references that sustain these data? Guess what? It’s Wickramasinghe’s own previous works! Throughout the whole paper the only thing that the team can find to sustain their claims is their own previous work. No one else publishes on this subject because it does not make sense!

I think we can all agree that Wickramasinghe would fit better in a sensationalist and anti-scientific place such as the nonsense shows of History Channel than in a science lab.

If you want to laugh more or torture yourself with more bullshit, you can read the whole paper:

Steele EJ, Al-Mufti S, Augustyn KA, Chandrajith R, Coghlan JP, Coulson SG, Ghosh S, Gillman M, Gorczynski RM, Klyce B, Louis G, Mahanama K, Oliver KR, Padron J, Qu J, Schuster JA, Smith WE, Snyder DP, Steele JA, Stewart BJ, Temple R, Tokoro G, Tout CA, Unzicker A, Wainwright M, Wallis J, Wallis DH, Wallis MK, Wetherall J, Wickramasinghe DT, Wickramasinghe JT, Wickramasinghe NC, & Liu Y (2018). Cause of Cambrian Explosion – Terrestrial or Cosmic? Progress in Biophysics and Molecular Biology 136: 3–23.

And you can also read more about the adventure that is Wickramasinghe’s dellusional life on Wikipedia:

Wikipedia. Chandra Wickramasinghe. Available at < https://en.wikipedia.org/wiki/Chandra_Wickramasinghe >. Access on June 11, 2018.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

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

Leave a comment

Filed under Evolution

Friday Fellow: Common Pelomyxa

by Piter Kehoma Boll

It’s time to dig deep into the mud again and bring up a peculiar protist, the third species of the clade Amoebozoa to be featured here. Its binomial name is Pelomyxa palustris, and I decided to call it the common pelomyxa.

Measuring up to 5 mm in length, although usually having less than 1 mm, the common pelomyxa is considered a “giant amoeba”. In fact, the Giant Amoeba Chaos carolinense, previously featured here, was once classified in the genus Pelomyxa, but currently we know that they are not closely related at all. While the true giant amoebas of the genus Chaos are closely related to the common amoebas of the genus Amoeba, the species in Pelomyxa belong to a completely different group of amoebas.

02807_orig

A specimen of the common pelomyxa. The large pseudopod is to the right and the small uroid can be seen projecting from the cell at the upper left. Credits to Proyecto Agua.*

The cell of the common pelomyxa has a somewhat cylindrical shape with a single, large, semicircular pseudopod at the front, thus moving basically always in the same direction, forward, differently from the more classical amoebas with several pseudopods and the ability to move in any direction. At the opposite side of the cell, the common pelomyxa has a small, also semicircular appendix called the uroid that is covered by several small non-motile flagella. The flagella are surrounded by small cytoplasmic projections (villi) that are easily seen under the microscope.

The common pelomyxa lives buried in the sediments of freshwater lakes throughout the northern hemisphere, especially those rich in decaying organic matter. It slides through the mud while feeding on smaller microorganisms and organic debris. Such an environment is characterized by the complete absence or extremely low concentrations of oxygen. As a result, the common pelomyxa is anaerobic and even lacks mitochondria. For this reason, it was once considered part of a very primitive group of eukaryotes that diverged before the incorporation of the endosymbiotic bacteria that would evolve into mitochondria. Currently, however, it is known that their lack of mitochondria is actually due to a secondary loss and they seem to be related to true amoebas and slime molds.

More than only lacking mitochondria, the cell of the common pelomyxa has a lot of peculiar features. Depending on the size of the cell, it may contain a few to several hundred nuclei. The cytoplasm also appears to lack several typical eukaryotic organelles, such as the Golgi apparatus and the endoplasmic reticulum. There are, however, many, many small vacuoles, so many that the cell usually has a foamy appearance.

Endosymbiotic bacteria are also found in great numbers in the cytoplasm of the common pelomyxa. After several years of research, it seems that these bacteria are obligate symbionts. Perhaps they help this strange amoeba to perform some of the tasks that should be done by the several organelles that it lacks.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Goodkov, A. V.; Chistyakova, L. V.; Seravin, L. N.; Frolov, A. O. (2004) The concept of pelobionts (Class Peloflagellatea): Brief history and current stateEntomological Review 84(Suppl. 2): S10–S20.

Wikipedia. Pelomyxa. Available at < https://en.wikipedia.org/wiki/Pelomyxa >. Access on May 26, 2018.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic License.

Leave a comment

Filed under Friday Fellow, protists