zoology

Articles in ‘zoology’

Allen’s rule and the Iberian lynx

July 25th, 2007

Leafing through a dictionary of zoology I came across a definition for Allen’s rule. It strikes me that this might apply to the lankiness of the Iberian lynx in comparison with its cousin the heftier Eurasian Lynx. (For size difference see below)

It states (from wikipedia) that:

“endotherms from colder climates usually have shorter limbs than the equivalent animals from warmer climates.The theory behind Allen’s Rule is that endothermic animals with the same volume may have differing surface areas, which will aid or impede their temperature regulation.”

“In cold climates, the greater the exposed surface area, the greater the loss of heat and therefore energy. Animals (including humans) in cold climates need to conserve as much energy as possible. A low surface area to volume ratio helps to conserve heat.

In warm climates, the opposite is true. An animal will overheat quickly if it has a low surface area to volume ratio. Therefore, animals in warm climates will have high surface area to volume ratios so as to help them lose heat.

In a nutshell, it simply means there is a ratio between body surface to body mass.”

Given that the Eurasian Lynx is much larger than the Iberian Lynx, also perhaps applicable is Bergmann’s Rule which “correlates environmental temperature with body mass in warm-blooded animals. It asserts that within a species, the body mass increases with latitude and colder climate. Among mammals and birds, individuals of a particular speciesin colder areas tend to have greater body mass than individuals in warmer areas. ” This is no doubt the case further north and when comparing areas with similar levels of rainfall, but also coming into play is the the extremely limiting factor of the Mediterranean summer drought, which also tends to reduce body size. There simply isn’t as much prey in the Mediterranean summer.

Top, a Eurasian Lynx, bottom Iberian lynx. Not sure if these pictures do justice to my idea.

Origin of the Iberian lynx and relation to Eurasian lynx.
The ancestors of both the Iberian lynx and the Spanish Imperial Eagle came originally from far to the East in the steppes of Asia Minor, and did not arrive in the Peninsula until one million years ago. The Iberian species separated from their Eurasian counterparts around one million years ago at the start of the Quaternary, when a series of intense ice ages swept across Eurasia. As the weather grew colder both south western populations were pushed into the Mediterranean in search of ground squirrels until they finally reached Iberia. With the cold, prey must have become scarce from Greece to Italy and the Eurasian imperial eagle and the lynx died out there. The populations which reached Iberia were saved by the presence of rabbits. The Eurasian lynx then moved back into Europe from Asia as the ices receded. To the north of Spain, the Eurasian Lynx was eliminated in Western Europe during the 18-19th centuries, but unlike its Iberian cousin its range is much greater, once extending from the Pyrenees to Siberia. (The Eurasian Lynx possibly existed in Spain and formed the northern boundary of the Iberian Lynx). Eurasian Lynx are still relatively common in parts of the ex-URSS which is enabling reintroduction programmes in Switzerland, France and Germany. A million years ago there was probably one species from Cadiz to Vladivostok. More on the Iberian Lynx

New species in Spain

February 21st, 2007

26/11/2006 150 new species are discovered every year in Spain

An interview with Mario García París of the Museo Nacional de Ciencias Naturales in today’s (El Pais) . I paraphrase.
“There are some 60,000 species of animals in Spain, of which some 40,000 are insects. And we are incapable of knowing how many are catalogued. A species is a group of animals which are genetically compatible. There are worms which look the same but are different species and frogs which are as similar as an egg to chestnut tree, but which can breed.
It is impossible to know how many species are still to be recorded. One knows when most of the biological wealth of a country has been recorded when the rate of discovery slows down. This does not seem to be likely in the short term in Spain. We’ve been discovering some 150 new species a year since the late 1970s. And this rate has continued unabated. Since 1978, 3,627 new species have been discovered in the Peninsula, with a further 1,417 in the Canaries at an almost constant rate of 150 a year. “In the distribution maps of species there are dark areas around Madrid, Barcelona and Las Hurdes, in Extremadura. The county of Las Hurdes appears because several people from the museum spend their holidays there”.
There are even big gaps in knowledge with groups such as amphibians despite the legions of amateur naturalists out and about recording them. “A year ago we discovered a new midwife toad which only lives in the fountains of villages. We called it Alytes obstetricans pertynas. “Pertinacious” because while most amphibians are becoming extinct, this one is resisting in human settlements”.
Spain because of its geographical position and the variety of its climate is particularly rich in biodiversity, but much of this being lost. “In the county you can’t hear anything anymore. Ten years ago you heard and saw lots of insects. Now they are spraying everything and all is quiet. When I look at my field notes from 15 years ago describing swarms of bugs I think I must have been exaggerating, but the truth is I was only describing what I saw. When we visit Morocco today we see animals everywhere, just as it was here years ago. If a Goya is burnt. It’s a national tragedy, because it cannot be replaced. The same is true for a species but nobody seems to care”. See also Montseny Brook Newt