One place, one parent, two species
10/02/06 16:03
Palms play lead role in bolstering the theory of
speciation without geographic isolation
Nature Advance Online
Publication: http://www.nature.com/nature/journal/vaop/ncurrent/index.html
08.02.2006. Sympatric speciation in palms on an oceanic island. Vincent Savolainen, Marie-Charlotte Anstett, Christian Lexer, Ian Hutton, James J. Clarkson, Maria V. Norup, Martyn P. Powell, David Springate, Nicolas Salamin and William J. Baker.
doi:10.1038/nature04566
In a study of endemic palms on the tiny Lord Howe Island in the Pacific Ocean, we have found one of the best examples yet of sympatric speciation. Sympatric speciation is the formation of two or more descendant species from a single ancestral species all occupying the same geographic location. This kind of speciation has so far largely been known from theory, and was rejected by one of the greatest evolutionary biologists of the 20th century, Ernst Mayr. He believed that speciation was mainly due to genetic differences building up after geographic isolation (allopatric speciation).
We have demonstrated that the two species of palms are sisters, and that their common ancestor arrived at Lord Howe Island long after the island was formed. As the island is so small (ca. 12km2) and effectually isolated from other landmasses, this makes it quite unlikely that the species have been geographically isolated during any part of their evolution, or that they are the results of multiple colonisations to the island. Furthermore, we have shown that they occur sympatrically but are still reproductively isolated. Hence we meet all the criteria for a sturdy case of sympatric speciaton. In our case we found that the two extant species of the Howea palm prefer different soil types and also flower at different times of the year. However, flowering has been observed to change if occasionally one of the species stray into foreign soil. Thus it seems that the mechanism that made the population of the Howea ancestor divide into two species is coupled to the genes controlling soil type adaptation, which in turn affect the flower-controlling genes.
Stories from the Danish press:
DR (Danish Broadcasting Production)
Jyllandsposten (daily national newspaper)
University of Aarhus, Faculty of Science
Stories from abroad:
News in Science
08.02.2006. Sympatric speciation in palms on an oceanic island. Vincent Savolainen, Marie-Charlotte Anstett, Christian Lexer, Ian Hutton, James J. Clarkson, Maria V. Norup, Martyn P. Powell, David Springate, Nicolas Salamin and William J. Baker.
doi:10.1038/nature04566
In a study of endemic palms on the tiny Lord Howe Island in the Pacific Ocean, we have found one of the best examples yet of sympatric speciation. Sympatric speciation is the formation of two or more descendant species from a single ancestral species all occupying the same geographic location. This kind of speciation has so far largely been known from theory, and was rejected by one of the greatest evolutionary biologists of the 20th century, Ernst Mayr. He believed that speciation was mainly due to genetic differences building up after geographic isolation (allopatric speciation).
We have demonstrated that the two species of palms are sisters, and that their common ancestor arrived at Lord Howe Island long after the island was formed. As the island is so small (ca. 12km2) and effectually isolated from other landmasses, this makes it quite unlikely that the species have been geographically isolated during any part of their evolution, or that they are the results of multiple colonisations to the island. Furthermore, we have shown that they occur sympatrically but are still reproductively isolated. Hence we meet all the criteria for a sturdy case of sympatric speciaton. In our case we found that the two extant species of the Howea palm prefer different soil types and also flower at different times of the year. However, flowering has been observed to change if occasionally one of the species stray into foreign soil. Thus it seems that the mechanism that made the population of the Howea ancestor divide into two species is coupled to the genes controlling soil type adaptation, which in turn affect the flower-controlling genes.
Stories from the Danish press:
DR (Danish Broadcasting Production)
Jyllandsposten (daily national newspaper)
University of Aarhus, Faculty of Science
Stories from abroad:
News in Science
