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When a Hybrid Takes Hold, the Outcome Can Be Bad
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by tigers9 on June 29, 2009
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Hmmm, this is interesting, the whole idea of species (as i was informed early on in my life) is that they can’t successfully reproduce with other species, and if they do, and manage to make an offspring, it is usually infertile.
So if these hybrids are fertile, should we be talking about 2 different species or subspecies?
Also, many animals often hybridize in teh wild (box turtles for example), as subspecies often happen in some cases because some scientist wanted something named after him/her, that si likely why at one time we had like 30 different cougar subspecies but nobody could tell them apart.
Animals in the wild don’t know we have different states, such as TX and CA, if they can keep coming they will keep coming, unless Grand Canyon or new freeway is in the way.
Anyway, not sure why is it making news now, I think something like this was originally published in 2007? Add to Hysteria regarding all the invasive and python bills introduced lately???
Z
http://www.nytimes.com/2009/06/30/science/30obhybrid.html?ref=science
June 30, 2009
OBSERVATORY
When a Hybrid Takes Hold, the Outcome Can Be Bad
By HENRY FOUNTAIN
The ecological effects of invasive species are often well known, particularly their impact on native plants or animals. But the invaders sometimes make love as well as war: they mate with related local species, producing hybrids. And the effects of such hybridization have not been the subject of much study.
Now, research involving invasive and native salamanders in the Salinas Valley of California shows how devastating this can be: the hybrids have voracious appetites and can practically wipe out other species.
Maureen E. Ryan and Jarrett R. Johnson of the University of California, Davis, and Benjamin M. Fitzpatrick of the University of Tennessee studied hybrids between native California tiger salamanders and barred tiger salamanders, brought in huge numbers from Texas beginning 60 years ago by California bait dealers. Tiger salamander larvae are high on a pond’s food chain, gulping down larvae of other species with their big mouths.
The researchers built artificial ponds, stocked them with salamanders and other species, notably the California newt and the Pacific chorus frog (both of which are found in the Salinas Valley) and monitored what happened. Their findings appear in The Proceedings of the National Academy of Sciences.
Hybrid larvae had a greater effect on the newts and frogs than native salamander larvae did, nearly wiping them out. Hybrids even affected the survival of native salamanders in the ponds. “The implication is they’re ecologically quite different than the native species,” Ms. Ryan said.
That could spell trouble for other “third-party” species in the valley, like the California red-legged frog and the Santa Cruz long-toed salamander.
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by LarryDFishel on June 29, 2009
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"Hmmm, this is interesting, the whole idea of species (as i was informed early on in my life) is that they can’t successfully reproduce with other species, and if they do, and manage to make an offspring, it is usually infertile."
That's often the case, but has nothing to do with the definition of species or how they are classified. Lots of species can hybridize. It probably has a lot to do with how long ago they diverged.
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by pictigaster1 on June 29, 2009
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I am waiting for the gators to cross with the pythons and mabie the pigmy rattlers, pigmypythonrattlegators would then take over the world and eat all the peta people.One thing I will never under stand is why this is such big news It is very old news most herpers have known quite awhile daaa.
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by tigers9 on June 29, 2009
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larryDfishel, so what is species? if they hybridize and produce infertile offsrping, r they species? if they hybridize to produce fertile species, r tehy still the same thing, aka species or what????
Horse+ass=mule, usually infertile
lion+tiger = liger/tigon, depneds on whch species is father, usually infertile too
domestic+serval cat=savannah=usually infertiel too
So what is species and what is subspecies?
So do we start when we humans learned how to take notes, or where do we start to define species???
Z
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by kacz on June 29, 2009
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Another delineation that I learned years ago seems to have gotten lost in this age of genetic mapping. That is, two forms were considered different species if they were separated geographically. Regardless of their ability to breed successfully, their mutual isolation assumed a divergence in evolution, past or future. This is assuming that there were significant differences in form, color or habit that would differentiate the animals beyond the subspecies level.
I kind of liked the old rules. Even at the subspecies level it gave individual identities to, and acknowledged forms like the canebrake rattlesnake. The newer, genetic systems seem to muddle the practical picture. It's kind of like defining a person by how much money they have in the bank rather than what they do with their lives.
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by FLherp on July 1, 2009
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There are a number of definitions of species -
Biological species concept (Ernst Mayr): "species are groups of interbreeding natural populations that are reproductively isolated from other such groups."
The phylogenetic species concept (PSC) says that diagnosable geographic forms of the same basic "kind" of bird should be treated as distinct species. This is less restrictive than the BSC concept.
In the cladistic species concept, a species is a lineage of populations between two phylogenetic branch points (or speciation events).
The ecological species concept is a concept of species in which a species is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognize as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters.
Baker, R. J. and R. D. Bradley. 2006. Speciation in mammals and the Genetic Species Concept. Journal of Mammalogy 87(4):643-662: We define a genetic species as a group of genetically compatible interbreeding natural populations that is genetically isolated from other such groups. This focus on genetic isolation rather than reproductive isolation distinguishes the Genetic Species Concept from the Biological Species Concept. Recognition of species that are genetically isolated (but not reproductively isolated) results in an enhanced understanding of biodiversity and the nature of speciation as well as speciation-based issues and evolution of mammals.
Morphological Species Concept: A more subjective classification. Organisms are classified in the same species if they appear identical by morphological (anatomical) criteria. This is used when species do not reproduce sexually, some are known only from fossils. This definition is the working definition used by biologists that cannot, or should not, use the “Biological Species Concept”
Also see: http://evolution.berkeley.edu/evosite/evo101/VA1BioSpeciesConcept.shtml
There are a number of definitions because come organisms do not meet the criteria of come of these concepts. Some organisms do not have reproductive populations, they are asexual. In other cases some organisms share genetic material via horizontal gene flow - the movement of genes between disparate, unrelated species (occurs with plants and microbes for instance)
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by tigers9 on July 1, 2009
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so when we r reading all the scary hybrid/invasive reports, which definition shooldl we use, the definiton of a person crying wolf?;-)
Z
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RE: When a Hybrid Takes Hold, the Outcome Can Be B
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by FLherp on July 1, 2009
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No, the biological conceept of species seems to work here - originally these animals were reproductively and geographically isolated from one another until transported by humans and released. Hybrids occur which can be reproductively viable - this appears to be the case here.
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