Moritz Wagner (naturalist) facts for kids
Moritz Wagner (born in Bayreuth, Germany, on October 3, 1813 – died in Munich, Germany, on May 31, 1887) was a German explorer, collector, geographer, and natural historian. A natural historian studies plants, animals, and the natural world.
Wagner spent three years (1836–1839) exploring Algiers in North Africa. During this time, he made important observations about nature. He later developed these ideas, suggesting that being separated by geography could play a key role in how new species form.
From 1852 to 1855, Wagner traveled through North and Central America and the Caribbean with Carl Scherzer. In May 1843, he visited the Lake Sevan region of Armenia with Armenian writer Khachatur Abovian. Moritz Wagner passed away in Munich when he was 73 years old. His brother, Rudolf, was a scientist who studied the human body.
Moritz Wagner and How Species Change
Moritz Wagner started his career as a geographer. He wrote several books about the geography of North Africa, the Middle East, and tropical parts of America. He was also very interested in nature and collecting specimens. This is what he is best known for among biologists.
Ernst Mayr, a famous scientist who studied evolution, wrote about Wagner's importance. However, some other scientists do not fully agree with Mayr's view.
During his three years in Algeria, Wagner studied flightless beetles like Pimelia and Melasoma. He noticed something interesting about them. Many different species of these beetles lived along the northern coast. Each species was found only in a certain area between rivers that flow from the Atlas mountains to the Mediterranean Sea. As soon as you crossed a river, a different but closely related species would appear.
Wagner saw similar patterns in the Caucasus mountains and in the valleys of the Andes mountains. After Darwin's book On the Origin of Species was published, Wagner concluded:
" ... a new species will only start to form when a few individuals move beyond the usual boundaries of their living area... a new type of animal will never form ... without the new group being separated from the other members of their species for a long time."
This was an early description of a process called geographic speciation. This means new species form because groups are separated by geography. It also relates to the founder effect, where a new population starts from a small number of individuals. Another way Wagner put his idea was: "Organisms which never leave their old area will never change."
Wagner's idea received mixed reactions. Ernst Mayr noted that Wagner combined his good idea with some unusual thoughts about how living things change. Leading scientists like Darwin, Wallace, and Weismann disagreed with Wagner's idea that geographic separation was the only way new species form. His idea was not popular for a long time. Then, in 1942, Ernst Mayr brought it back. The importance of geographic speciation became a key part of the modern understanding of evolution.
Debates About Wagner's Ideas
Some modern experts, like Ernst Mayr, Jerry Coyne, and H. Allen Orr, believe that Wagner was a pioneer of the idea of geographical speciation. They argue that Darwin had not fully understood it. However, Wagner's "migration theory" was based on a simpler idea of evolution. He thought that changes happened mostly because of the environment, not just natural selection.
Wagner wrote letters to Darwin, arguing that Darwin had missed a vital geographic part in understanding how new species evolve. Darwin first replied in a friendly way. He agreed that geographic isolation was important, but not the only cause of new species. He also pointed out that he had already discussed geographic speciation in The Origin of Species.
In his later articles, Wagner completely rejected the importance of natural selection. He again stressed that mixing between groups prevented them from becoming different. Therefore, geographic separation was needed to allow them to become different. Wagner argued that Darwin had not understood this. However, these ideas are actually present in The Origin of Species. Darwin found Wagner's increasingly strong and one-sided arguments upsetting. He even wrote "most wretched rubbish" across his copy of one of Wagner's papers from 1875.
Besides Darwin, Reverend J.T. Gulick also thought Wagner's theories were too strong. Gulick was responding to David Starr Jordan, who had supported Wagner's ideas in a paper. Jordan later wrote a short correction, agreeing with some of Gulick's criticisms.
Gulick explained that:
- Being separated is needed for groups to evolve differently. But it's not needed for all members of a species to change in the same way.
- Separation does not always mean there are physical barriers or different places.
- Different types of natural selection are not always needed for different evolution.
- Different outside conditions are not always needed for different evolution.
- Separation and variation (changes not overwhelmed by mixing) are all that is needed for different types to appear from one group. This can happen even if conditions stay the same and the separation is not geological.
In a later paper, Gulick said that "Moritz Wagner, in his 'Law of the Migration of Organisms,' was the first to insist on the importance of geographical isolation as a factor in evolution." But Gulick added that when Wagner said natural selection could not create new species without geographic isolation, he went too far.
Mayr's explanation is thought to have clarified issues Wagner left unclear. Mayr suggested: "A new species develops if a group that has become separated from its parent species gains features during this time of separation that help or ensure isolation when the physical barriers disappear." The animal expert Bernhard Rensch also helped keep geographic speciation as an important idea in evolution. He saw geographic separation as the most common first step toward new branches on the evolutionary tree.
Today, the importance of Wagner's original idea is still debated. It is clear that geographic isolation is not the only way new species form. Also, it is generally accepted that natural selection is the most important cause of new species, even when groups are separated by geography.
There is also debate about whether Charles Darwin had reached similar conclusions at the same time. The Origin of Species was published almost twenty years after Wagner first wrote about his ideas. However, Darwin's notebooks are more relevant. These notebooks were not published until the mid-20th century. They show a clear description of how groups become unable to reproduce with each other. This is maintained by behavioral isolating mechanisms. The same ideas are also in The Origin of Species, but modern biologists often do not recognize them as such.
On the other hand, there is no single example in Darwin's notebooks as clear as Wagner's flightless beetles. Many good parts of Wagner's ideas are hidden by his other, mistaken beliefs. But his conclusions about geographical speciation were important insights. He gained them by observing insects in their natural homes.
One expert noted: "It took more than 60 years after 1859 until the leading specialists... [agreed] that this geographical approach was the way to solve the problem of speciation... a new species may evolve when a population acquires isolating mechanisms while isolated from its parent population."
However, speciation is not just about geography. It is more important that it involves a splitting that lasts, even if groups later live in the same area.
Legacy
Moritz Wagner is remembered in the scientific name of a species of venomous snake, Montivipera wagneri.
See also
In Spanish: Moritz Wagner para niños
