Superfast evolution in sea stars

Jul 24, 2012
The sea stars Cryptasperina hystera and C. pentagona are close relatives with very different ways of reproducing but difficult to tell apart. A new study shows the species separated just a few thousand years ago. Credit: Jon Puritz/University of Hawaii at Manoa

(Phys.org) -- How quickly can new species arise? In as little as 6,000 years, according to a study of Australian sea stars.

"That's unbelievably fast compared to most organisms," said Rick Grosberg, professor of evolution and ecology at UC Davis and coauthor on the paper published July 18 in the journal .

Grosberg is interested in how new species arise in the ocean. On land, groups of can be physically isolated by mountains or rivers and then diverge until they can no longer interbreed even if they meet again. But how does this isolation happen in the wide-open ocean?

Grosberg and colleagues studied two closely related "cushion stars," Cryptasperina pentagona and C. hystera, living on the Australian coast. The animals are identical in appearance but live in different regions: Hystera occurs on a few beaches and islands at the far southern end of the range of pentagona.

And their sex lives are very, very different. Pentagona has male and female individuals that release sperm and eggs into the water where they fertilize, grow into and float around in the for a few months before settling down and developing into adult .

Hystera are hermaphrodites that brood their young internally and give birth to miniature sea stars ready to grow to adulthood.

"It's as dramatic a difference in life history as in any group of organisms," Grosberg said.

The researchers looked at the diversity in from sea stars of both species and estimated the length of time since the species diverged.

The results show that the species separated about 6,000 to 22,000 years ago. That rules out some ways new species could evolve. For example, they clearly did not diverge slowly with over a long period of time, but were isolated quickly.

Over the last 11,000 years, the boundary between cold and warm water in the has fluctuated north and south. A small population of the ancestral sea stars, perhaps even one individual, might have colonized a remote area at the southern end of the range then been isolated by one of these changes in ocean currents.

Other authors on the paper are: Jonathan Puritz and Robert Toonen, University of Hawaii; at Simon Fraser University in British Columbia, Canada Michael Hart and Carson Keever, who earned his undergraduate degree from UC Davis; Jason Addison, University of New Brunswick, Canada (previously a postdoctoral researcher at UC Davis); and Maria Byrne, University of Sydney.

The work was supported by a grant from the National Science Foundation to Grosberg and Toonen, a former UC Davis graduate student.

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User comments : 14

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verkle
1 / 5 (22) Jul 24, 2012
The word "evolution" is used in several different ways, and scientists must differentiate between them. Otherwise the title could be misleading.

In this article, I take it to mean that there was isolation of certain genes in the gene pool, which created different sub-species. This must be clearly stated.

The word "evolution" in this article does not mean that new genes arose from spontaneous happenings and caused another specie to develop. This meaning is the general use of "evolution" and one that has little mathematical chance of ever happening, and has never been observed.

davhaywood
5 / 5 (4) Jul 24, 2012
Given that this is a clear case of how "quickly" a species can develop, which was "as little" as 6,000 years, and we as a human species have only known about evolution for less than 200 years (though some, like the person above, are apparently still in the dark), would you expect that we would have observed a multitude of such events? If you're so keen on mathematics, shouldn't this have occurred to you? Of course not, because you have no idea what you're talking about.

In spite of the difficulty of observing speciation, we have witnessed it. Check it:

http://www.talkor...ion.html
roboferret
5 / 5 (6) Jul 24, 2012

This meaning is the general use of "evolution" and one that has little mathematical chance of ever happening, and has never been observed.

I would love to see your mathematical disproof of evolution. It would be a huge contribution to both the fields of biology and non-linear dynamics. You did use non-linear methods, right? How did you demonstrate that the self-organised criticality that emerges from chaotic systems cannot apply to biological reproduction?
Maybe_maybe_not
5 / 5 (3) Jul 24, 2012
This is amazing! I would like to see some researchers begin the search for the common ancestor!
Shootist
5 / 5 (4) Jul 24, 2012
Given that this is a clear case of how "quickly" a species can develop, which was "as little" as 6,000 years, and we as a human species have only known about evolution for less than 200 years (though some, like the person above, are apparently still in the dark), would you expect that we would have observed a multitude of such events? If you're so keen on mathematics, shouldn't this have occurred to you? Of course not, because you have no idea what you're talking about.

In spite of the difficulty of observing speciation, we have witnessed it. Check it:

http://www.talkor...ion.html


Finches. Look at the finches in Hawaii and Galapagos. American bison and old world cattle. Camels (old world) and Llamas/Alpaca (new world). Dogs and wolves.
Torbjorn_Larsson_OM
5 / 5 (4) Jul 24, 2012
Fast for an animal, but plants can hybridize new species quicker.

@ verkle:

Creationists shouldn't comment on science, it is hilarious.

- The subject is biology, and since biological evolution is a comprehensive additive (adds mechanism) theory, there is only "evolution". The other sense is "development". Look at the history of biology.

Arms develop according to the genetic recipe and environmental constraint of mother and fetus, cancers evolve under variation of the genetic recipe and selection for survival in the environment of immune system and later chemotherapy.

The evolution of new cancers, as well as new influenza species almost yearly, shows that new populations can evolve in historical time.

- There are no artificial limits for evolution of course or it wouldn't be the factual basic theory for biology it is. Evolution is contingent but as speciation shows also deterministic by way of selection. If not, we wouldn't see separable species.
Torbjorn_Larsson_OM
5 / 5 (3) Jul 24, 2012
[cont] More generally, an efficient criticism of evolution, which since it is the best tested theory of all of science would be a tall order of substituting it with a more predictive theory, would garner you a Nobel prize and immortal fame.

Claiming that such a well tested theory has errors (unlikely) or internal problems (extremely unlikely) doesn't mean that creationist "poofing" (no mechanism) out of nowhere (no mechanism), could make a species (no mechanism).

- Mathematics by itself can not show anything on the natural world, since it can't do observations and testing.

The mathematical realization of the process of evolution, whereby living populations changes into living populations, is of course population genetics. This application of mathematics on observable quantities shows that genetic change happens and becomes fixated all the time.
Torbjorn_Larsson_OM
5 / 5 (4) Jul 24, 2012
"Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population structure. It attempts to explain such phenomena as adaptation and speciation."

"Before the advent of population genetics, many biologists doubted that small difference in fitness were sufficient to make a large difference to evolution.[4] Population geneticists addressed this concern in part by comparing selection to genetic drift. Selection can overcome genetic drift when s is greater than 1 divided by the effective population size. When this criterion is met, the probability that a new advantageous mutant becomes fixed is approximately equal to 2s.[5][6] The time until fixation of such an allele depends little on genetic drift, and is approximately proportional to log(sN)/s."

[Wikipedia]
Torbjorn_Larsson_OM
5 / 5 (5) Jul 24, 2012
I note that you can't name even the branch of mathematics that would describe "little ... chance", even less give examples. Combinatorics describes small chances close to 0, such as the chance of winning a lottery. Even so we know that a fair lottery always has a winner, the chance is exactly 1.

The same goes for evolution, it doesn't matter how small absolute chances there are for fixation as long as they suffice relative to population size. Because a living population must descend to a living population even under hereditary change, fixation will eventually happen.

That your children doesn't look like clones of you, there is change, is enough to test evolution under such a process (heredity). There is no feasible constraint, outside of exact cloning, which could prevent evolution.

[And astrobiology speaking, which is my interest, we don't observe clonal species much. They can't adapt much, hence they can't compete with the sloppier bunch of non-clonal populations.]
PeterKinnon
5 / 5 (1) Jul 24, 2012
Yes, contrary to the silly claims of creationists there is abundant evidence that speciation is alive and well and demonstrably occurring on this planet.

The "improbabilty" myth has also been quite well dealt with in various comments here.

However, it should perhaps be emphasized that it is natural selection which provides directionality to the otherwise largely stochastic components of biological evolution.

Also that although there is considerable evidence for "fine tuning of our universe for the fitness for life" this in no way lends support to the superstitious notions of a creator or "intelligent design" which are derive solely from mythology.

These considerations are expanded upon within the context of a broad evolutionary model , extending well beyond the field of biology, which is outlined in The Goldilocks Effect: What Has Serendipity Ever Done For Us? Itis a free download in e-book formats from the Unusual Perspectives website.
Lurker2358
1.5 / 5 (8) Jul 24, 2012
Also that although there is considerable evidence for "fine tuning of our universe for the fitness for life" this in no way lends support to the superstitious notions of a creator or "intelligent design" which are derive solely from mythology.


If you had a true premonition of a precision, accuracy, and complexity beyond coincidence, how might that change your world view?

How would you react if you experienced such an event which contradicts the mainstream "fundamental" laws of physics, respecting thermodynamics, causality, or the speed of light postulate, future knowledge, or something similar?

Would you lie to yourself and hide it from others for fear of rejection and being labeled a lunatic or a crank?

Would you inform others and try to prove the event happened and propose a new theory to explain it?

By the way, the Big Bang theory is itself a creationist theory, and was in fact introduced by a Christian. It is in every way a creationist theory, independent of religion.
Deathclock
4.2 / 5 (5) Jul 25, 2012
By the way, the Big Bang theory is itself a creationist theory, and was in fact introduced by a Christian. It is in every way a creationist theory


No, shut up. It was a christian scientist that first proposed it, but not a young earth creationist retard. It is not a creationist "theory" made up prior to finding any evidence, it is a scientific theory that developed from the evidence, from the observation of the CMBR and the recession of other galaxies, among others.
Torbjorn_Larsson_OM
5 / 5 (3) Jul 25, 2012
@ Lurker2358:

- "If you had a true premonition".

What is a "premonition" and how do you test it as a fact? If you can, you can use it. If it can't be tested, it has nothing to do with reality and so science and it isn't a "theory".

- Big Bang theory is replaced, subsumed or extended by the inflationary standard cosmology, depending if you define "big bang" as the hypothesis of a single singularity (not needed or evidenced in inflation), singularities (an outstanding question, now moved to inflation) or the expansion from Planck scales.

We don't know if there is and and how to handle singularities in inflation. The simplest inflation theories like eternal inflation has nothing specific that could be thought of as an event associated with creationist ideas.
Torbjorn_Larsson_OM
5 / 5 (3) Jul 25, 2012
[cont]

In fact Susskind, the founder of modern string theory AFAIU, asks if not eternal inflation is past eternal. A simplest "Tree" model gives that "... for all but a vanishing fraction of observers, with probability unity the root is in the infinite past." In statistical terms, an eternal inflating universe is naturally eternal. [ http://arxiv.org/...89v1.pdf ]

The Planck probe results on CMB are planned to be released before years end. They may test if eternal inflation is the case, or not.