According to the UN’s figures of 2007, in Spain a 36 % of the territory is suffering desertification at different states. This means that over a third of the land is gradually becoming unproductive and infertile. This phenomenon specially affects the Mediterranean watershed and the Canary Islands, though the issue is spreading in most part of the state. This fact positions Spain as the European country with the higher risk of desertification.

Map of risk of desertification in Spain

What has triggered this problem is the damaging of soil which can be due to natural processes such as erosion or changes in the vegetative cover. Even though, the truth is that the human impact is the major cause and if not, it usually enhance the intensity of the others. Agricultural activities,fires, aquifer deplantation (taking water from subterranean springs) and urbanisation – among others – increase the stress the ground undergoes and therefore fasten the desertification. The unusual high percentage of Spain might be due to the dryness of the place as droughts are usual and deforestation (especially due to arson or accidental fires) is a growing problem.

By now at least a 6% of the affected land is irreversibly damaged and the percentage of threaten areas increases constantly (in 2008, already a 38% of soil was affected). This hazard entails other dangers as the environment is lost, the lifestyle of local populations is altered and may lead to their extinction and so, to the decrease of biodiversity.

Desertification in Aragón:

In Aragón the chances of desertification are quite similar to the Spanish average; around a third is in danger. Even though, we must remember this figure is still very high meaning that over 750 thousand hectares are in high risk of desertification.

We must add to this the fact that most of the territory, a 91,2%, has negative hydrologic levels – the soil losses more water than it absorbs -. As well, the territory is formed mainly by semiarid areas, which are especially sensible to desertification and droughts are usual. This is why Miguel Ángel Ena head of the Forestal Management and Planification department of the DGA (Aragonese county council) stated ‘Como se ve, en Aragón se dan la mayoría de las condiciones que favorecen la desertificación (As we can see, most conditions which favour desertification can be found in Aragón). Even though, despite showing most climatologic and geographical features leading to desertification, places with similar conditions such as Murcia or Valencia have over 90 % of its soil in risk. This remarkable difference between the percentages is thought to be due to the human abuse of natural resources, which in Aragon seems to be, fortunately, milder.

Nevertheless, prevention for avoiding ending in the same way is necessary. That’s why the Spanish government launched PAND (National Action Plan against Deforestation). The aims of it are to reduce the possibilities of deforestation happening and to enhance sustainable agriculture and the recovery of vegetable cover. In Aragon, this meant starting to plant over 5 million trees in 2008 as well as a detailed study for having a proper view of the problem. This project let us know that the most affected province in Aragón is Teruel with 21,31% of land in danger, being the first step towards getting people involved and aware of the lost of biodiversity.

Sources:

¤ Last three are in Spanish.

 

”Kids do ecology”

You bet it’s for kids. Anyhow, it outlines the basis for further studying of ecology. In it you can find: good explanations of ecology concepts ( go to Learn about ecology →Frequently asked questions), a list of main biomes with their characteristics and an article about endangered species; among other stuff.

I also recommend this page, especially for the ones doing the IGCSE. It’s simple, in a wikipedia style, but helpful as a summary (note some things belong to higher years) if you’re revising.

We already know that different species cannot interbreed – have fertile offspring-, so gene flow is stopped.  Why does that happen?

This is due to the prezygotic and postzygotic reproductive isolation. These are barriers which prevent interbreed happening. They avoid it either before fertilization, in prezygotic ones; or after fertilization has occurred, postzygotic.

The prezygotic reproductive isolation mechanisms are :

  • Habitat: living beings from different areas cannot mate as they cannot possibly meet either.
  • Behavioural: during the selection of a possible mate, individuals from different species may discard each other as they don’t have the same mating rituals.
  • Temporal: individuals from different species may be in season at different times in the year so they won’t be interested in copulating at the same time.
  • Mechanical: different species may have different sex organs which aren’t compatible. It just won’t fit.
  • Gametic: for fertilisation to occur, the sperm must reach the ovum. For this to happen they usually attract each other through chemical means, but the chemicals might vary from one specie to another. In this case gametes won’t recognise each other and fertilization won’t take place.

The postzygotic reproductive isolation mechnisms are the following:

  • Hybrid viability: sometimes the hybrid dies prematurely.
  • Hybrid fertility: even if an offspring is produced from the mating of different species usually they are infertile as they generally have a random mixed number of chromosomes (so it’s not the same even between hybrids).
  • Hybrid breakdown: if the hybrid results to be fertile, the hybrid population might dissappear along time as from one generation to the next they may result weaker, less fertile, etc.

The sources of information are these videos:

Moray Eel

Moray Eel

Moray eels are elongated snakelike fish which are cosmopolitan, meaning they are found all around the world either in temperate or tropical seas and even in fresh water. However, the true is that their ‘favourite’ habitats are reefs or rocky areas in the warmer seas.

Therefore, as they inhabit in a variety of environments, the different species of moray eels are of different sizes and colours. They go from the Snyder’s moray of about 11.5 centimetres to the giant morays of about 3.5 metres, and have a large catalogue of skins going through the patterned to the plain and from brownish colours to blue and yellow. This is, of course, an adaptation, as it allows them to mimetize with the environment they live in. Even though, the disguising technique is not one for avoiding predators, as in other animals, but instead for hunting easily without being noticed by the unfortunate prey (the same purpose that ones from jaguars and tigers).

But despite the large range of appearances, the are a lot  of common features for all morays. The first one is their long cilindrical body, resulting as well from their necessity of blending with the environment for hunting. Thanks to this anatomy with slender body and lacking pectoral and pelvis fins morays can hide in rock cavities and coral concretions, leaving outside only their snout.

There morays will stay until a suitable prey (maybe a fish, octopus, crab or another moray; no matter if it’s dead or alive) gets near. When this happens the morays notice it with their superdeveloped sense of smell – as most of them are nocturnal and live in hidden places their eyes wouldn’t be of much help and therefore are rather small -.  Next step is catching the food. For this, morays have three rows of razor-like teeth that can as well be used for defense. But due to their shape, morays have problems swallowing. For resolving this trouble, morays had developed a second pair of jaws, pharyngeal jaws.

Pharyngeal jaws

Pharyngeal jaws

These are found in the throat and as they are retractile they can ”throw” the lunch towards the stomach.

Another common feature for all morays is the way they move. They go twisting and winding impulsed by their dorsal fin – which goes along their whole body – and the strengh of their muscular body. For helping in this task, the morays have a scaleless body covered in mucus, which allows them to swim faster as well as to hide better in complicated spaces.

A behavioral adaptation of morays are their cooperative relations with other fish. They sometimes associate with groupers for hunting together, as well, they are known to allow small cleaners such as cleaner shrimps or others to feed on the food remainders that keep in their mouths so they have a free dental cleaning.

Though, not everything in morays are facilities, these eels have some troubles which they have solved through other adaptations.

Green moray eel with open mouth.

Green moray eel. Notice the patterned interior of mouth.

For example, the already mentioned problem to swallow; or the fact that their round gills are not efffective enough. For balancing this situation the morays keep their mouth opened most of the time (in fact, it is also patterned for mimetizing), so they’re constantly creating water currents inside it for enhancing breathing effectiveness.

Those are the main adaptations of moray eels to their habitat. But, how did they evolved into their nowadays shape and characteristics ?

Well, this leads us to natural selection. As a general process, moray eels as part of anguilliformes may have developed from an early ancestor of this order. Along years, the early ancestors may have showed variation (due to mutations or sexual reproduction) between themselves. If any of these variations was favourous for the survival of the specimens with it, they would be more than the others and therefore their offspring (with the same chacteristics) would be greater in number and eventually become another specie. But there is a problem with moray eels, species develop as different advantages prove to be better for living in that concrete environment; even though, several species of moray eels are actually living in the same place with similar diets all over the world. So, how can moray eels comprise over 150 different species despite being a cosmopolitan fish? The mystery remains unsolved by now; you can read more here.

 If you want to know more about these animals  you can visit the following websites:

Images from:

DNA drawingDNA is a chemical that determines how we are. Even though, its structure is the same in every organism, so what makes the difference? The multiple combinations of its components. That means that each of us has an specific DNA. That’s how we can identify people, like a fingerprint. And that’s what DNA fingerprinting is about!

But DNA fingerprinting doesn’t compare all the DNA’s structure. Instead, it compares the different cuts made by restriction enzymes. For doing so scientists have to follow a complex process:

  • First the DNA is removed from the sample cells with chemicals (like we did in the lab).
  • Then the strands that form the double helix are separated.
  • Restriction enzymes are added to the DNA strand. These enzymes identify particular sequences in the DNA and cut them forming free lengths of genetic material.
  • The next step is to order the several fragments in length order. In thisElectrophoresis drawing process electrophoresis is used. Electrophoresis is made by applying an electric field to a fluid. This makes dispersed particles in the fluid to move. In this case, this results in the different DNA cuts moving towards one side depending on their molecular weight – the largest ones weight more so they won’t move as much as the others- .
  • After electrophoresis other enzymes are added. These enzymes make the DNA sequences visible when exposed in photographic paper (either due to radioactivity or to chemiluminiscent properties).

The process must be repited several times with different selections of enzymes to build up a detailed fingerprint.

DNA fingerprint

DNA fingerprinting has many applications:

  • Paternity and maternity: as some specific DNA patterns are inherited you can prove genetic relations between people (familiar relations).
  • Criminal Identification and Forensics: DNA from samples in a crime scene can be compared with the DNA of a criminal suspect.
  • Personal Identification: DNA can be used to identify yourself, but this doesn’t seem practical as the process is too complex and having a DNA database is expensive. 

Further reading:

Images from:

Other related websites:

Post creators: Ruth Moreno & Ángela Sedeño

In modern days we’re constantly seeking equality between men and women, but we all know it has not always been the same. Women have had to struggle for achieving a fair and similar treatment in respect to that given to the men. We celebrate this in the International Women’s Day

Women and science

Women and science

marked on the 8th of March, and we wanted to take the chance to honour the memory of those scientific women who have made possible nowadays developments but who have been forgotten. This lack of recognition for women along history is still obvious as history books and dictionaries hardly make reference to their contribution until a few recent years. But, what triggered this mistreatment?

Since prehistoric times, humans started building up science. Of course women were included, they started developing tools and classifying the different plants into edible, poisonous and the ones they could use in medicine. In fact, they were part of one of the greatest periods of developments that can just be compared to the improvements of the 20th and 21st centuries. But then, societies began to grow and unfortunately many of them believed that women were inferior. These caused women to be relegated to unimportant positions in society and science and, even, to being let aside of learning institutions.

Anyway, these didn’t discourage women who continued researching and working. In ancient Greece the first woman to work as a doctor appeared. She was Agnódike, she was able to study medicine disguised as a man. She saved many lives because women, who otherwise would feel apprehensive and refuse visiting a doctor man, could be treated and assisted in childbirth by her. Despite her labour, when Agnódike confessed to the society she was a woman, she sentenced to death. But the women to whom she had helped defended her. As a result, women were allowed to study medicine in the following.

Hildegard of Bingen

Even though later, in medieval Europe, women were still kept out from universities; instead some went to medieval monasteries where they were taught in Latin, natural science, prayer and liturgy. This was the case of Hildegard von Bingen, the youngest daughter of a family with ten children. Her parents sent her to the Benedictine convent of Disibodenberg. She wrote texts on botany, ethics, theology and medicine, eventually becoming a very important person visited by people from distant places for advice. Despite this, at the same time, women in more practical fields were accused of witchcraft.

In the Scientific Revolution, the superstitions disappeared but women still weren’t allowed to attend college and inequalities between genders became greater as scientists supported the belief of women being their subordinates. This happened to Maria Winckelmann, who had knowledge of astronomy, and was married with an astronomer. She gained a position of assistant in the astronomical observatory in Berlin but after the death of her husband, despite being qualified and having discovered a comet, she was fired as he was no longer under her husband’s trail.

During the Enlightenment period the number of women involved in science, as Nicole Lepaute, increased. Nicole was a French astronomer who calculated the exact time of a solar eclipse in 1764 and determined how the gravity of the planets can affect the trajectory of a planet. He also calculated the table of the pendulum oscillations per unit time and according to their length, but this work was published as her husband’s work, who took the merit – something usual – making it clear that women still needed time to be accepted in society as a equal to men.

In the early 20th century women finally began to be recognized in the fields of science education through admission to learned societies. The daughter of the mathematician Annabella Milbanke and the poet Lord Byron, Augusta Ada Byron was an important personality in the world of mathematics. She was assistant to the mathematician Charles Babbage, and they collaborated to develop the “analytical machine” predecessor of the first computer, which allowed calculating any function of algebra, which led Ada Byron to be considered the first programmer in history. At the end of the century thanks to the Nobel Prize awarded to Marie Curie – the first woman awarded with one ever – for her experiments with radioactivity women gained more importance in science.

Marie Curie, first woman awarded with a Nobel prize

So, finally, in the 20th century the number of women scientists increased as there were universities for women, giving them the same importance as men in Europe and America. Thanks to this renewal of women recognition in science, Rachel Carson, an American biologist who made one of the first studies on the harmful effects of human activities on the environment, was able to alert on pollution.

Nowadays the society has advanced and women, in most of the working fields, are recognized as what they really are, people as prepared to develop any job as any men – even though they still suffer multiple discriminations at work, like earning less money than a men on the same job -. But the point is that, even in science which has always been seen as a men’s thing (when we think of a scientist, we usually think of the image of a man),  it is true that history collects the memory of several women scientists that have reached the success in different aspects of science. And thanks to their effort now some of the most relevant scientists are women.

Links:

Images from:

Authors: Ruth Moreno, Santiago Rodrigo, Ángela Sedeño and Iratxe Uranga.

 First weekly summary of the scholar year, this week has been especially short due to San Valero ‘s  holiday so we have had only two biology classes.
 

Tuesday 26 of January:

We welcomed Paula, the new (for us first) English assistant. As an introduction to the subject for her we reviewed what we’ve already seen in this topic:

  1. Origin of life:
    1. Abiogenesis: theory that states that life first arose from inorganic matter.
      • Oparin hypothesis: this theory says that in some specific conditions such as a reducing atmosphere (atmosphere without oxygen) and the presence of a source of energy ; some chemical reactions were triggered in the primordial soup originating organic compounds.
      • Miller & Urey experiment: this experiment recreated the hypothetical circumstances thought to be in the origin of life, and proved that – according to Oparin hypothesis- organic matter (amino-acids) appeared.
    2. Spontaneous generation: obsolete theory that accepted that life forms could spontaneously form from non-living matter, like from rotting meat for example. Discarded thanks to experiments made by Francesco Redi and, especially, Louis Pasteur.
  2. Cell :
    1. Levels of organisation of living organisms:
      • Subatomic particle →Atoms →Biomolecules→Organelles →Cells → Unicellular organism or (→ Tissues →Organs →Systems →) multicellular organism →Population →Community →Ecosystem (relation with living and non-living matter) → Biosphere
    2. Cell theory (developed by Schleiden and Schwann):
      • The cell is the structural and functional unit of life
      • Every organism is made of one or more cells.
      • All cells arise from previous cells (added by Virchow).
         
    3. Types of cells
      • Eukaryotic (have nucleus, either animal or plant cells)
      • Prokaryotic (have no nucleus)
    4. Organelles: subunits within a cell with a specific function.
    5. Cell cycle
      1. Interphase
      2. Cell division
        • Mitosis: replication of cells for growing and repairing.
        • Meiosis: division of cells for creating gametes for reproduction purposes.
    6. Sexual & asexual reproduction
      • Sexual reproduction: two parents are involved,  offsprings show variation but are less in quantity ,(closely related with meiosis)
      • Asexual reproduction: only one parent, offsprings are genetically equal to the parent (they are clones) and offsprings are made faster (so more quantity), (closely related with mitosis).

Then we saw some new concepts as DNA:

 DNA is the chemical that stores the genetic information in the cell. Its usual representation is the following:

You can see it is shaped in a ladder-like structure called double-helix. In it the ‘rungs’ (‘steps’) of it are couples of paired nitrogenous bases (A,T,G,C). These bases can only get paired in a specific way: A with T and G with C or vice versa but in no other way, because they are complementary between them (like puzzle pieces). Bases are attached to a kind of backbone.

 
The homework consisted on looking for what are nucleotides.
 

 ♦ Thursday 28 of January:

Despite the visit of some English people we had a normal lesson beginning with the correction of our homework. So, what are nucleotides?

Nucleotides are the structural units of DNA (and of RNA), that is to say, they are the building blocks of this chemical. Nucleotides are composed of a phosphate and a nucleoside (sugar, deoxyribose in DNA and ribose in RNA, plus the bases), so they are where bases are attached.

Nucleotides link together forming long chains, these are the ‘backbone’ of DNA. DNA is formed by two complementary chains of nucleotides which contains the genetic information.

The double-helix structure of DNA was discovered by Watson and Crick.

After this, we rearranged some definitions with the concept they referred to in groups. They were a revision of the concepts covered along this topic such as mitosis, cytokinesis, etc. You can see all of them here: http://www.slideshare.net/zombraweb/glossary-dna-cards?src=embed

The homework for the weekend was looking for the definitions of gene and of trait.