evolution crawls forward

[spuriousmonkey]

http://www.nature.com/news/2006/060213/full/060213-4.html

The cane toad was artificially introduced in australia and wreaked havoc with the local fauna.

Scientists have been studying how fast it is migrating and they were surprised that these large toads could travel up to 1.8km per night! Moreover they prefer to move along roads. These large toads do not jump but crawl and the scientists were quite surprised they could move such long distances.

They compared modern toads with specimens in museums and records and such and found that they have become '25% leggier and fivefold faster over a 60-year period'.

Although insects and bacteria quickly adapt to changing circumstances, Skelly says this study is one of the first known examples of a vertebrate rapidly evolving in a new environment. "People have this deep-seated feeling that vertebrates don't evolve on of these sorts of timescales. But this work shows that it can happen," says Skelly. Cane toads typically start breeding at the age of one year, and can produce some 200,000 eggs in an average ten-year lifespan.

There you have it. Evolution right in front of your eyes (if you live in australia).

 

[Hercules Rockefeller]

That’s mega interesting. But what about this statement......

Skelly says this study is one of the first known examples of a vertebrate rapidly evolving in a new environment.

I thought there were a number of such vertebrate examples in the Galapagos Islands. “Darwin’s Finches” spring to mind. They radiated out into different species in the space of a few decades. I believe the same has happened with tortoises and lizards there.<P>

 

[Ophiolite]

That radiation surely took more than a few decades?

 

[Hercules Rockefeller]

Whoops. I think I meant to say centuries which is what makes the Australian cane toad story so amazing as that situation has a time frame of ~60 years.

"When Darwin arrived in the Galapagos Islands in 1835 he found a remarkable group of finchlike birds that provided a very suggestive case for the development of his theory of evolution. The Galapagos archipelago is a cluster of 29 islands and islets of different sizes lying on the equator about 600 miles off the coast of Ecuador. Finches are generally ground-feeding seed eaters with stout bills for cracking the tough outer coats of the seeds. The Galapagos species, though clearly finches, have an immense variation in how they make a living and in their bill shapes and their behaviors, which underly these ecological differences. For example, the vegetarian tree finch eats fruits and leaves, the insectivorous finch has a bill with a biting tip for eating large insects, and, most remarkable of all, the woodpecker finch grasps a twig in its beak and uses it to obtain insect prey by probing holes in trees. This diversity of species arose from an original population of a seed-eating finch that arrived in the Galapagos from the mainland of South America and populated the islands. The descendants of the original colonizers spread to the different islands and to different parts of large islands and formed local populations that diverged from each other and eventually formed different species."

 

[Golgi is my Homeboy]

There you have it. Evolution right in front of your eyes (if you live in australia).

Interesting! Now think of how many cases there are out there that we haven't observed.

 

[spuriousmonkey]

http://sciencenow.sciencemag.org/cgi/content/full/2006/420/2

Despair Not, Frumpy Guys

Always going after the attractive guy can have its downsides. Female birds gravitate toward flashy fellows, for example, but if they always picked mates with the same showy traits, the population would eventually become inbred. A new study of wild finches suggests a solution to the puzzle: All the males with showy feathers get paired in the spring. In the summer, still-single females fly far from home, where they settle for males with more subdued plumage and thereby contribute to the genetic diversity of the population.

Once female finches hatch, they instinctively leave their parents' neighborhood. But the team found that by the time the females got to their new digs, all the flashy males were already taken. That's because the older females in that location had had their pick of the male litter earlier in the season. Thus, the newcomers were forced to settle for the drab males that were left. This influx of females from another location keeps the population genetically healthy, even though all the girls still prefer the same bright coloration in a guy, says Badyaev, whose team reports its results online April 18 in Proceedings of the Royal Society B.

"It's a nice way of resolving the paradox," says ornithologist Peter Dunn of the University of Wisconsin in Milwaukee. "It's something that a lot of people have been scratching their heads about for five or ten years."

I like to read these kind of stories. It reminds me that we know so little, and that there is still so much to learn out there. And some people are actually doing this kind of research instead of finding the cure for cancer.

 

[firecross]

Always going after the attractive guy can have its downsides. Female birds gravitate toward flashy fellows, for example, but if they always picked mates with the same showy traits, the population would eventually become inbred. A new study of wild finches suggests a solution to the puzzle: All the males with showy feathers get paired in the spring. In the summer, still-single females fly far from home, where they settle for males with more subdued plumage and thereby contribute to the genetic diversity of the population.

They make it sound like there are only a few dozen of these finches and that genetic degradation is in danger of arising, thus the need for "diversity" that is such a popular cliche these days.

In 2002, the anthropologist John H. Moore estimated that a population of 150–180 would allow normal reproduction for 60 to 80 generations—equivalent to 2000 years.
http://en.wikipedia.org/wiki/Space_colonization

 

[valich]

There's no better example of evolution occuring right before your eyes, at the same time, then the socalled "ring species" of salamanders in California of the genus Ensatina, and of course Darwin's Galapogas Finches as shown above. The Ensatina have evolved into seven distinctive subspecies arranged geographically in a "ring" encircling the central valley of California. "Hybridization and intergradation occur between adjacent subspecies in the ring except where coastal and inland populations make contact at the southern end of the geographic range of the species. This geographic pattern is interpreted to illustrate gradual evolution of reproductive barriers between populations, an important component of the formation of species." http://tolweb.org/tree/

see: Wiltenmuth, E.B. & K.C. Nishikawa. 1998. Geographic variation in agonistic and sensory behaviour in a ring species of salamander, Ensatina eschscholtzii. Animal Behavior 55:1595-1606 http://jan.ucc.nau.edu/~kiisa/pdfs/Wiltenmuth and Nishikawa 1998.pdf

I wonder if all this has anything to do with the socalled "Ring of Life" replacement hypothesis for the "Tree of Life"?

"The ring of life! Two molecular biologists in California have compared a dozen whole genomes from yeasts and prokaryotes to conclude, "The eukaryotic genome resulted from a fusion of two diverse prokaryotic genomes, and therefore the tree of life is actually a "ring of life." Using a new algorithm called "conditioned reconstruction," the informational genes of eukaryotes are shown to be primarily derived from Archaea and the operational genes are primarily derived from Bacteria. A substantial and continuous influx of mitochondrial DNA to the eukaryotic nucleus has been documented. The extensive horizontal transfer observed among prokaryotes can obscure the identities of those prokaryotes that may have contributed genes to eukaryotes. The conclusion strengthens our hunch that eukaryotes (not just prokaryotes) must acquire new genes, by whatever method, from beyond their own genomes." http://www.panspermia.org/whatsne34.htm#040909

 

[sniffy]

several species and mosquitoes particularly come to mind here adapt very quickly to changing environments/external influences. It's sometimes called immunity. Adapt and survive all yea who fear change! Survival of the quick fitters.

 

[Walter L. Wagner]

Valich:

That's interesting about the Archaea and Bacteria. Is that to mean that an ancient Bacteria tried to eat an Archaea (or vice-versa), but they became symbiotic instead?

Just exactly how did the complex nucleus of the Eukaryote, with loop DNA on chromosomes, develop from a far simpler cell with circular DNA loose in the cell?

I've read that even the spindle apparatus for meiosis/mitosis is potentially derived from incorporated bacterial-type cells, but I know very little about that major transformation in cell type to the advanced Eukaryote. Presumptively, all higher multi-celled organisms, plants, fungi and animals, are derived from the earliest such eukaryotes, complete with spindle apparatus, nucleus, choromosomes, and probably even mitochondria. I believe several different plant lines developed thereafter by incorporating various cyanobacteria. You got any insights in the development of the Eukaryotes?

 

[Ophiolite]

Eat or be eaten.

 

[GeoffP]

Well, there's a paper by Hendry about rapid evolution in introduced Chinook salmon in NZ (13 generations; about 40 years as I recall). So I'd argue that this paper isn't necessarily the first vert example.

Geoff

 

[valich]

Valich:

That's interesting about the Archaea and Bacteria. Is that to mean that an ancient Bacteria tried to eat an Archaea (or vice-versa), but they became symbiotic instead?

Just exactly how did the complex nucleus of the Eukaryote, with loop DNA on chromosomes, develop from a far simpler cell with circular DNA loose in the cell?

I've read that even the spindle apparatus for meiosis/mitosis is potentially derived from incorporated bacterial-type cells, but I know very little about that major transformation in cell type to the advanced Eukaryote. Presumptively, all higher multi-celled organisms, plants, fungi and animals, are derived from the earliest such eukaryotes, complete with spindle apparatus, nucleus, choromosomes, and probably even mitochondria. I believe several different plant lines developed thereafter by incorporating various cyanobacteria. You got any insights in the development of the Eukaryotes?

All forms of life are said to be derived from the Last Universal Common Ancestor (LUCA). We know that Archaea are more related to Eukarya than they are to Eubacteria, so the branch starts there. This is a very intensive ongoing subject of research. See our other thread.

 

[valich]

Walter: You seem to be entranced by the notion of loop DNA and symbiosis in prokaryotes. Plasmid loop DNA occurs in multiple areas of the unicellular structure but this should not be an inhibitant to evolution? Endosymbiosis is only a hypothesis. What about unicellular fusion?

 

[usp8riot]

Is this news? Evolution is not much different than selective breeding, which we know exists. Is there supposed to be a debate here?

 

[valich]

Evolution is certainly much more than selective breeding but the above refers to comments made elsewhere and is not intended to be a debate issue at all. Sorry.