Online: invasivespecies. Translation limitations and disclaimer. African clawed frog. Photo by Brian Gratwick. Pair of African clawed frogs. Photo by Tim Vickers. African clawed frog tadpole. Photo by Gary Nafis. Category : Amphibians. Common names : African Clawed frog. Invasive species classification: Prohibited. Invasive species family : Pipidae.
Description and Range Physical description. Geographic range. The idea that an animal invading a new environment will have fewer natural enemies, such as parasites, is intuitive. Our study provides some. Every time the African clawed frog invades a new area, most of its parasites are left behind.
Most — but not all. First, a note about the hypothesis we used. The Enemy Release Hypothesis proposes that an animal in a new environment will thrive because it has left some or all of its natural enemies behind.
These include predators, pathogens and parasites. This might seem logical, but the idea is not really backed up by evidence. Loss of parasites in invading frogs, for example, has been investigated only twice in Puerto Rican and Cuban tree frogs and only in Central America.
In our study we compared the parasite communities of African clawed frogs in southern Africa, where the frog occurs naturally, with those from African clawed frogs from Chile, California, Portugal and France , where the frog is an invader. Our results confirm the long-standing suspicion held by biologists. This frog always has fewer kinds of parasites in the invasive populations in Europe or America than it has in its native Africa. On top of this, a smaller proportion of frogs are infected with parasites in the invasive range than their counterparts in Africa.
So these invasive frogs are relieved of many of their natural enemies. And even with the enemies that remain, their encounters are less frequent. This means that they can allocate more resources to producing the next generation and invading new territories. We noticed that two kinds of parasites, namely a polystome and a tapeworm , almost never lose sight of the African clawed frog, no matter where it travels. Although African clawed frogs have been widely studied as a model for understanding the early development of eggs after fertilization, at least six species fooled researchers for more than a century with their nearly identical appearances.
The discovery of six new and one redescribed species increases the number of known African clawed frogs in the group from 22 to Now researchers can begin asking questions about the genetic structure of the frogs, nearly all of which are the product of hybridization among ancestral species, and some that have up to six duplicated sets of DNA. To distinguish the species, study researchers used new analytical techniques involving voice recordings, CT scans of internal anatomy, DNA and chromosome analysis and even documentation of different parasites among the frogs.
Researchers studying evolutionary genomics and hybridization are interested in African clawed frogs because within this single genus there are diploid, tetraploid, octoploid and dodecaploid species, meaning their genomes duplicate up to six times, as was the case for two of the new species.
0コメント