One of the lessons that evolution teaches us is that you really shouldn’t release alien species onto remote, isolated islands (or other such isolated habitat). This is because 1) these places often contain unique species that have evolved to fit their particular, often predator-free locale. And 2) newly introduced species, finding abundant prey and few of their own predators, are likely to run amok, quickly adapting to local conditions and killing everything in sight. If you care about biodiversity, keep the aliens away.
Unfortunately, we’ve got this kind of problem on our hands in the South Atlantic. While the victims of the feast are not some flightless, defenseless animal that’s been living in paradise too long, they are mostly dependent on one particular island for nesting, meaning that the sudden predation they’re suffering could threaten them with extinction. And the best part is, the perpetrators are… house mice! Mice that have quickly evolved to 3 times their normal size, and have recently started taking on prey that is much, much larger than themselves, acting extremely aggressive and voracious. If not for the threat this poses to endangered sea birds, this would actually be cool. Here is the story :
Rare island birds threatened by ‘super mice’.
“Gough Island hosts an astonishing community of seabirds and this catastrophe could make many extinct within decades,” said Dr Geoff Hilton, a senior research biologist with Britain’s Royal Society for the Protection of Birds (RSPB).
“We think there are about 700,000 mice, which have somehow learned to eat chicks alive,” he said in a statement.
The island is home to 99 percent of the world’s Tristan albatross and Atlantic petrel populations — the birds most often attacked. Just 2,000 Tristan albatross pairs remain.
“The albatross chicks weigh up to 10 kg (22 lb) and … the mice weigh just 35 grams; it is like a tabby cat attacking a hippopotamus,” Hilton said.
The house mice — believed to have made their way to Gough decades ago on sealing and whaling ships — have evolved to about three times their normal size.
This is a common phenomenon on island habitats — for reasons much debated among scientists — where small animal species often grow larger while big species such as elephants display “dwarfism” and become smaller.
In the case of the mice of Gough Island, their remarkable growth seems to have been given a boost by a vast reservoir of fresh meat and protein.
AGONISING DEATH
The rapacious rodents gnaw into the bodies of the defenseless and flightless chicks, leaving a gaping wound that leads to an agonising death. Scientists say once one mouse attacks the blood seems to draw others to the feast.
While predation by oversized mice is unusual, birds on small islands are especially vulnerable to extinction from human activities such as the introduction of alien species.
This is because many birds that have evolved on isolated islands with no predators have become what biologists term “ecologically naive” — meaning they do not recognize danger from other animals.
The image of rapacious packs of killer house mice devouring prey which dwarfs them in size is really too much. I don’t think I’ll be sleeping well tonight.
Update: In comments, nihilan was nice enough to point out that Nature News has an article on this as well, with a video of the carnage.
62 Comments
harold · 26 July 2005
This is fascinating, although disturbing from a human emotional perspective.
And also reminiscent of the horrible fate of Bishop Hatto, in the infamous Mouse Tower of Mainz...
http://www.great-castles.com/mauseturmtale.html
BlastfromthePast · 26 July 2005
Steve Reuland · 26 July 2005
Though no one was there to see it in real time, presumably yes.
nihilan · 26 July 2005
This site
http://npg.nature.com/news/2005/050718/full/050718-2.html
has some really disturbing video of the phenomena. It's actually pretty sad.
Dave Carlson · 26 July 2005
But they're still mice!! They're still the same kind!
....sorry...couldn't resist. ;)
Dave
harold · 26 July 2005
Blast From the Past -
"Was this "quick evolution" to 3 times their normal size through random mutations and natural selection?"
Of course it was through genetic variation and natural selection (some of the alleles leading to larger size may already have been present in the population, at low levels, or new mutations could have occured - probably did - but further study would be required to determine that with precision). Are you suggesting that some supernatural entity magically made the mice larger, so that they could attack baby seabirds?
Failure to answer this post will be construed as inability to come up with an answer, and refusal to honestly admit it.
Steve Reuland · 26 July 2005
Changes in size can happen in an evolutionary blink of the eye, given that it's often just a matter of slighly more or less growth hormone. Witness the large diversity between human sizes.
ts · 26 July 2005
nihilan · 26 July 2005
If you watch the video, it actually appears that the chick feels nothing. Of course, I don't know that.
ts · 26 July 2005
Steviepinhead · 26 July 2005
SEF · 26 July 2005
harold · 26 July 2005
t.s. -
You are correct. In fact, I was going to make another post in the interest of accuracy, but no-one seemed interested in Bishop Hatto.
There were two historical bishops of Mainz named Hatto. This is from memory, but...the earliest was in the eighth or early ninth century, and known to have been extremely unpopular. The second was in the tenth century, and believed to have been less unpopular. The legend is usually said to apply to the second one, but this is believed by some historians to be an unfair incidence of confusion.
At any rate, the tower in the picture is certainly unlikely to date from either the eighth of the tenth century. The fact that it is round, alone, makes that very unlikely. It's just a toursim site.
It's unlikely that mediaeval mice actually ate a living human being; I was just reminded of the legend by the post. Anyone else who checked the link got that it was a joke. It's conceivable that an unpopular figure went unburied, and partially eaten by mice, for some period of time. They were less fastidious then. Don't forget the "synod horrifica", at which the cadaver of pope Formosus was dug up and "put on trial".
I had thought that I understood why you were accusing me of "ignoratio elenchi" (the definition at the link you provided is identical to the one at the link I provided). Perhaps you though I was arguing that "religion is not incompatible with science BECAUSE this would make religious people feel excluded from science". This would indeed be logically incorrect, and arguably an example of ignoratio elenchi. But I'm making two seperate, logically unrelated, statements.
1) Claiming that someone's religion is incompatible with science, when they feel otherwise is a way of attempting to exclude them from science (if they want to initiate the claim on their own that's different). But this alone wouldn't be an argument that science isn't compatible with religion. It's just a fact.
Also,
2) Independantly, many people who know something about religion feel that in many forms, it is compatible with science...
http://www.talkorigins.org/faqs/faq-god.html......
http://www.uwosh.edu/colleges/cols/religion_science_collabor......
http://www.uwosh.edu/colleges/cols/clergy_project.htm......
Also the Dalai Lama, also at least one major rabbinical organization.
Your claim is that you don't want to exclude religious people from from science, but that you do want to tell them that their religion is incompatible with science. It is you who is in a position which is logically difficult to defend.
Dave Carlson · 26 July 2005
Does anybody have any clues as to what kind of selection pressures on this island caused the mice to grow so large?
Carl Hilton Jones · 26 July 2005
Chip Poirot · 26 July 2005
After reading this, I suspect the theme song from "Ben" will be playing in my head for days.
Henry J · 26 July 2005
Re "Does anybody have any clues as to what kind of selection pressures on this island caused the mice to grow so large?"
No clues, but I have a guess. In fights among themselves, larger ones would have an advantage. Otoh, when it comes to evading larger predators, small ones may be better at hiding, which may be what keeps them from getting larger in mainland ecosystems. In the absence of other size related pressures, I'd think that would do it.
Henry
nidaros · 26 July 2005
Sometimes this sort of "evolution" can be witnessed in a single generation. In humans!
Go to a university graduation ceremony at a prestigeous institution in the US or UK. There you will doubtless see a six foot tall graduate accompanied by his parents who may only be 5 feet tall!
Ample diets, clean drinking water and lack of parasites are wonderful things we take for granted in the wealthier countries.
ts · 26 July 2005
BlastfromthePast · 26 July 2005
Reed A. Cartwright · 26 July 2005
qetzal · 27 July 2005
Matt Inlay · 27 July 2005
35g is pretty big for a mouse, but it's not that big. I routinely come across mice that large in the lab. Check out the average sizes of mice from this distributor (such as this common mouse strain).
ts · 27 July 2005
Reed A. Cartwright · 27 July 2005
You'd think that if God was into front-loading, then he'd front-load some defensive mechanisms into these island species that keep going extinct without them.
harold · 27 July 2005
Blast From the Past -
"I quite agree with your evaluation; but, if the alleles are already present, then how can that be called evolution?"
Because that IS evolution. New mutations produce new genetic variability, but the genetic variability already present in the population, or genetic variability that arises from recombination of alleles during sexual reproduction, can also be acted on by natural selection. Both are still evolution.
I didn't suggest that new mutations necessarily WEREN'T part of this mouse evolution, either. A period of 150 years is many, many mouse generations. Some new mutations will have arisen within (not necessarily remained in) that mouse population, that's a guaranteed fact, that's chemistry. But new mutations may or may not be crucial to the change in size. Nobody knows yet.
"My point here is simply that whenever change in morphology occurs, it's termed "evolution"--with no questions seemingly being asked."
Well, again, change in morphology across generations in a lineage IS evolution. It's evolution no matter what the mechnanism; even a hard core young earth creationist admits that chihuahuas had wolf ancestors and these mice had smaller mice as ancestors. That's the FACT or OBSERVATION of evolution.
What the THEORY of evolution does is explain a scientific mechanism for how such changes occur. Genetic variability, which we now understand at the molecular and biochemical level (of course there's always a lot more to learn, thank goodness), usually in concert with natural selection. For significant adaptive, directional changes in morphology (such as seen with these mice), natural selection is effectively a requirement.
The theory of evolution absolutely does not "rule out" direct supernatural intervention in every single case, any more than any other scientific theory does, or ever can, for that matter. What it does do, is provide a natural explanation of what we observe, which can be verified empirically, and accepted by people of a wide variety of philosophical and religious backgrounds.
"As you stated, "further study" is required."
Absolutely, to determine with more precision exactly what happened in this case.
"But either way, this isn't what you would classicly call the kind of "slow, gradual" change that Darwin would insist upon."
First of all, this isn't fair to Darwin - he didn't insist that all evolutionary change must be slow in this sense. It's making a straw man of his views. In fact, the famous "Darwin's finches" show similar levels of morphologic change over similar time spans (evolutionarily speaking), and he used them as an example. Darwin would certainly agree that these mice evolved.
Second of all, we know a great deal more about biology than Darwin did, and so even if he "would have been wrong" about some specific problem, it means little. We know vastly more physics than Gallileo did, but we don't disdain the contributions of Gallileo.
CONTINUED BELOW....
My sense is that there is just a simple interaction taking place between the environment and the genetic capacity of the mice, a simple trigger mechanism that involves genes that are normally suppressed ( one probably regulating growth hormone, as Steve Reuland noted in a late post. But, of course, the gene for the growth hormone remains unaffected in this scenario). I see this as demonstrating that organisms have an innate, powerful adaptive capacity. That's how I would design them!
'Rev Dr' Lenny Flank · 27 July 2005
'Rev Dr' Lenny Flank · 27 July 2005
'Rev Dr' Lenny Flank · 27 July 2005
harold · 27 July 2005
Blast From the Past - CONTINUED...
Third of all, this change took place over many mouse generations, so it isn't necessarily all that "slow". The only meaningful sense of the term "slow" in this context is with regard to the rate of things that impact on evolution, such as intensity of natural selection, mouse reproduction rate, level of genetic and phenotypic variability in the population at any given arbitrary time, and so on.
"My sense is that there is just a simple interaction taking place between the environment and the genetic capacity of the mice, a simple trigger mechanism that involves genes that are normally suppressed ( one probably regulating growth hormone, as Steve Reuland noted in a late post. But, of course, the gene for the growth hormone remains unaffected in this scenario)."
I'm not sure exactly what you are saying here. If you are saying that individual mice can adapt to and respond to their environment, to some degree, that's certainly true, especially for a mammalian genus like mice. That's a different type of "adaptation". This type of adaptation or environmental response in an individual, such as gain or loss of body fat or muscle mass, development of immunity to an infectious agent, growth of extra fur as a response to temperature or diurnal cues, etc, is a non-evolutionary source of change in an individual. Of course, individuals have these adaptive systems because of evolution, in the first place. At any rate, this type of adaptation doesn't explain why current mice are much larger than their ancestors.
You may also be arguing for a reasonable but discredited hypothesis of evolution, known as "Lamarckism" (a reference, some say unfair, to a great French biologist actively slightly earlier than Darwin). In essence, you may be saying that ancestor mice "knew" or "perceived" or "experienced", in some way, that larger size would be an advantage, and that as a result, their germ cell DNA changed, in just the right way, to include genetic basis for larger size for their offspring. This view was initially discredited on theoretical grounds, because it provides no mechanism. How could the experience of the parent mouse change the DNA sequence in its germ cells, IN JUST THE RIGHT WAY? For that matter, if mice have this power, why stop at becoming slightly larger? Later, this view was empirically discredited as well.
Individual adaptation does not explain the evolution of these mice over generations. Lamarckism does not explain it in a scientifically satisfying way. The theory of evolution DOES explain it.
"I see this as demonstrating that organisms have an innate, powerful adaptive capacity."
Some organisms have a lot of adaptive capacity at the level of the individual (eg humans). Some do not. All have limits in terms of the adaptive capacity of one individual to the surrounding environment.
Evolution causes populations to adapt to environments in a powerful way, across generations (although it can also cause them to go extinct).
"That's how I would design them!"
It's nice if you feel, personally, that life turned out just the way you would have designed it, but that's irrelevant. Others argue that life is very different from what THEY would have designed.
Why would you design the mice to attack the baby seabirds, and NOT design the seabirds to an advantage over the mice? The theory of evolution does not lead to this dilemma.
harold · 27 July 2005
Blast From the Past -
It looks as if you have a lot of posts to address. Just take it slowly.
t.s.
"The claim that religion is incompatible with science -- in the sense that they make conflicting claims -- is empirical; I make the claim because I believe it to be true, and I won't be bullied into not saying it"
The empirical observation that SOME religions make claims that directly conflict with science is absolutely correct.
To conclude from this that ALL religions are directly incompatible with science is an elementary example of flawed logic. It is quite literally the same as arguing that "some men are Greeks so all men are Greeks".
"by your assertions as to the consequences on science education of saying it -- claims which I find dubious. OTOH, what you claim is a "corollory (sic)" -- that I want religious people excluded from science -- is a normative statement that has nothing to do with the empirical statement."
Not in the slightest. I made, and make, an empirically testable, non-normative, conjecture about human behavior. If scientists and science educators routinely declare that all religious traditions are incompatible with science, religious people will be excluded from science, at the very least at a psychological and social level. This is not a normative statement, it could be true whether I feel that this would be a good thing or a bad thing or a neutral thing.
The best way for you to disprove it would be empirically - show me, with convincing laboratory or field data, that when students are told by scientists and science educators that their religious beliefs conflict with science, even if they and their clergy say otherwise, that this does NOT create an atmosphere of exclusion.
YOU attach normative value to this conjecture.
"It's not a view I hold, nor do I think it's a view that anyone holds."
I have repeatedly acknowledged that you, personally, don't want to exclude religious people from science.
"And it is downright stupid to claim that there is any basis in logic by which I must hold such a view."
However, you do express a strong emotional desire to repeatedly state that all religion is incompatible with science, even religions whose clergy and adherents feel otherwise.
This is a view which, if expressed by someone presumed to be a scientific authority, could make religious people feel excluded from science. Yet you do not wish to exclude religious people from science. Thus, a logical dilemma presents itself.
The easiest way out of this dilemma would be to restrict claims that religion is incompatible with science to those specific religious positions which do, overtly conflict with science. You could still critique the ethical or logical claims of other religions, as well, just not by reference to a non-existent conflict with science.
ts · 27 July 2005
Steve Reuland · 27 July 2005
Do you guys have to derail every thread with a religion vs. science debate? Not that there aren't appropriate places for that, but it doesn't have much to do with mutant killer mice, which are awesome.
ts · 27 July 2005
Steve Reuland · 27 July 2005
Steve Reuland · 27 July 2005
harold · 27 July 2005
Steve Reuland -
You're right of course. As you'll note, one of us HAS made a number of posts about the evolution of giant mutant killer mice.
As for ts, I think his final words on the subject tell us everything we need to know...
"You insist on continuing to dig your dishonest lying hole. I pointed out before that a) you're obsessed with me and b) there are more constructive things you could do. I honestly don't give a flying ... about the content of your comments on this subject, which are steeped in dishonesty and irrationality. As I said before, I will continue to make critical comments about religion whether you like it or not. And there are no "logical dilemmas" that prevent me from doing so."
I give you the final word, my rational friend.
ts · 27 July 2005
Steviepinhead · 27 July 2005
I didn't read Blast's speculation about a switch being turned on or off as necessarily suggesting that an individual mouse in its individual lifetime generates a "somatic" response which is then somehow transmitted to its offspring (i.e., Lamarckism).
On the other hand, Blast may indeed have been making one more trip to the old "front-loading" well, as Lenny suspects.
That doesn't necessarily mean he's wrong in this particular case, though, although being right almost certainly has different implications for evolution than Blast might wish.
A good deal of phenotypic variation in animals is modulated by genetic "switches," if by this WE mean (whatever Blast means...) that the variation results from changes in cis-regulatory regions and signalling genes, rather than in protein-coding genes.
This, there could well be existing potentials for a range of non-"normal" sizes in mice that are, in their usual environment, suppressed by networks of regulatory and signalling genes. A relatively minor change to a network of this kind might lift the suppression on an existing growth hormone (or permit it to act longer, or at different points in development and maturation) without any need for the mice to evolve a new or different growth hormone.
This would be a testable hypothesis. If it turned out to explain some part of this picture, it would not, of course, validate Blast's poorly-articulated ID-drenched "front-loading" theories. It would merely reinforce one standard and well-understood means by which animals adapt to meet new selective pressures.
harold · 27 July 2005
Steviepinhead -
Well, I may have misunderstood Blast's comments. He sounded like he might be proposing what I took to be a Lamarckist explanation - that the mouse's "need" for larger size DIRECTED germ cell genetic sequences in some way.
In some expressions of classic Lamarckism, the phenotype of the parent adapts as well. Guy gets big muscles working at the docks, and his germ cells magically carry genes for bigger muscles to his kids, so to speak. But I'm not sure if the infamous giraffes were ever supposed to actually develop longer necks from stretching. They just sense a "need" to reach higher leaves, and made an effort, and their kids are born with longer necks.
I guess it comes down to the definition of the somewhat inexact and historically inaccurate, but still useful, term, "Lamarckism". I think of it as meaning the idea that the germ cells of the parent are genetically modified in a DIRECTED way, to "deliberately" make the offspring more adapted. With or without somatic morphologic adaptation of the parents.
(No doubt a certain humorless poster will obsessively draw our attention to some arbitary dictionary definition of Lamarckism that "proves me wrong", and refer to me as a "liar".)
"This, there could well be existing potentials for a range of non-"normal" sizes in mice that are, in their usual environment, suppressed by networks of regulatory and signalling genes. A relatively minor change to a network of this kind might lift the suppression on an existing growth hormone (or permit it to act longer, or at different points in development and maturation) without any need for the mice to evolve a new or different growth hormone."
This is an extremely plausible explanation. This would be a straight case of mutation and natural selection. The minor change you mention being a mutation in a regulatory gene.
Another thing that could have happened, and these things are not at all exclusive, is that existing alleles in the original mouse population (relevant to the growth regulation systems you mention), could have been sufficient for larger body size, when in the right combination, and expressed in the right environment. And the selection of larger mice could have led to more and more mice with allele combinations for big size. Eventually, alleles correlated with smaller body size would become very rare, and very unlikely to occur in a homozygous state or together in the same genome.
An argument in favor of this second type of mechanism playing a role is that, as has been noted by previous posters, body size change is a common and rapid evolutionary adaptation (and it happens both ways). On the other hand, a lot of investigations of the molecular basis of evolutionary adaptations seem to uncover a mutation. That example of cats not having a sweet detecting protein is a good one (it's a minor adaptation, but they save energy, and possibly avoid maladaptive behaviors, by not having it).
Steviepinhead · 27 July 2005
Actually, Harold, I think your hypothesis is the more likely one--that there is a range of alleles in mouse genes affecting size in the current "mainland" mouse population, and that this existing pool of variation is probably sufficient to support the increase in size in the "island" mice. Something similar was suggested by the post about the size that lab mice can attain ("working" in a lab is also a new niche that mice can exploit without the usual constraints on their size encountered in the wild).
(I keep wanting to write "country" mice and "city" mice, for some odd reason...)
Of course, as several have pointed out, a change in allele frequency is still evolution.
I was simply suggesting that--stripped of its "front-loading" dross--Blast had (for a change) actually suggested a plausible--if perhaps not the most likely--mechanism for these observations. And one that, as you have also emphasized, perfectly consistent with current evo-devo science.
'Rev Dr' Lenny Flank · 27 July 2005
Steviepinhead · 27 July 2005
Come to think of it, the human genome has ALSO been sequenced.
Probably that's why there's gonna be a slight hold-up: Blast is still digging through the human genome, trying to find the switch that will grant him access to the "Instant Understanding of Genetics Without Having to Study" stretch of DNA (hint, Blast, it's in one of the junk sections).
I'm sure that, as soon as Blast achieves instant karma, he'll start in on Mickey and Minnie and let us know...
Henry J · 27 July 2005
qetzal,
Re "It sounds like [Blast] predict they will find some pre-existing 'switch' that was flipped in the island mice, allowing them to grow larger. [...] but no evidence of any switch-like mechanism."
Question - couldn't the changing of a base pair to a different one be regarded as a "switch"?
Henry
'Rev Dr' Lenny Flank · 27 July 2005
BlastfromthePast · 28 July 2005
Reed A. Cartwright:
Blast wrote:
I quite agree with your evaluation; but, if the alleles are already present, then how can that be called evolution?
Because that is what evolution is. "Evolution" refers to the heritable change in characteristics of a population of organisms. Change in an allele frequency in a population is clearly a change in a heritable characteristic of that population. (Don't forget that the origin of a new allele is also a change in allele frequency: p(t) = 0, p(t+1) > 0.)
I suggest that, if you want to refer to someting other than that, then you need to use a term other than "evolution."
{{My suggestion for that "other" word would be: adaptation. If Darwin had written the "Origin of Adaptations," I'd be promoting it today.
As to "evolution": (this remark is applicable to a number of posts) if you want to call morphological change in a species evolution (and hence the formation of a "new" species), then let me ask you this: if I take a few Great Danes and end up with a couple of chihuahuas, would you agree that some "alleles" likely have changed (at least in terms of expression/repression). Now, do you really want to call that change "evolution"?}}
quetzal:
Blast wrote:
If the alleles are already present, then how can that be called evolution? My point here is simply that whenever change in morphology occurs, it's termed "evolution";with no questions seemingly being asked.
You may be right that evolution is being assumed here. It sounds like no one has (yet) explored the molecular basis of these morphological changes.
But it's a perfectly reasonable assumption. Evolution is an extremely well-supported theory, it's easily capable of producing/explaining these changes, and there is no other well-supported mechanism that can.
{{I think the modern synthesis has real problems explaining these changes, and just because it enjoys full support, that doesn't make it right: you know, might is not right.}}
This isn't what you would classicly call the kind of "slow, gradual" change that Darwin would insist upon.
I'm not sure if Darwin would have insisted on only slow, gradual changes, but the modern synthesis does not. Remember, evolutionary theory has come a long way since Darwin's time.
{{The modern synthesis hangs together by the thin string of Fisherian mathematics, which is based on the accumulation of numerous small changes. That's how the mathematics is said to work.}}
My sense is that there is just a simple interaction taking place between the environment and the genetic capacity of the mice, a simple trigger mechanism that involves genes that are normally suppressed ( one probably regulating growth hormone, as Steve Reuland noted in a late post. But, of course, the gene for the growth hormone remains unaffected in this scenario).
Interesting. This almost sounds like a testable prediction! Suppose someone performs genetic comparisons between these mice and 'normal' mice. It sounds like you predict they will find some pre-existing 'switch' that was flipped in the island mice, allowing them to grow larger. Is that right, or am I overinterpreting your comments?
In contrast, I think evolutionary theory would predict mutations in genes related to growth &/or increased frequecy of certain pre-existing alleles associated with larger size, but no evidence of any switch-like mechanism.
Do you agree that this is a valid way to distinguish between evolution and your alternative?
{{My prediction is that the genome would look the same before and after. The cytoplasmic skeleton is involved in protein activation (methylation), and we have no way of completely ruling out some kind of environment/cell interaction as the "triggering" mechanism involved here--unless technology has advanced to the point of proving otherwise.
As to your prediction of increase frequency of certain pre-existing alleles, if you're suggesting some kind of duplication of genes is involved, well, that's nice, and I guess that's plausible, but that's not really what the mathematics of the modern synthesis is based on.}}
If mice can change so dramatically (both structurally and behaviorally) in so short a time, then how is it that mice have remained relatively the same over millions of years?
Mice don't normally find themselves in isolated environments with limited resources and no other mammals to compete with. In a 'full' ecology (e.g. on the mainland), mice are presumably best adapted to a niche for mouse-sized animals. Larger than normal mice no doubt occur on the mainland, but they don't become predominate because there's already another animal occupying the larger-rodent niche: the rat.
{{If you are going to argue that a changed environment has led, through Darwinian mechanisms, to this morphological change. then you are faced with the difficulty of explaining why the mouse has remained essentially the same for 14 million years. This is a two-edged sword. Also, if Darwinian adaptation can happen so quickly, why do species go extinct?
As to the size: this is what Matt Inlay posted: "35g is pretty big for a mouse, but it's not that big. I routinely come across mice that large in the lab. Check out the average sizes of mice from this distributor (such as this common mouse strain)."}}
I don't mean to suggest this is the 'true' explanation. I'm just trying to illustrate that the problem of stasis isn't really a problem for evolutionary theory.
{{Stephen J. Gould (who wrote the book Panda's Thumb) thought it was. Hence, punk-eek.}}
Reed A. Cartwright:
You'd think that if God was into front-loading, then he'd front-load some defensive mechanisms into these island species that keep going extinct without them.
{{Maybe these island species need another 150 years?}}
Harold:
Blast From the Past:"I quite agree with your evaluation; but, if the alleles are already present, then how can that be called evolution?"
Because that IS evolution. New mutations produce new genetic variability, but the genetic variability already present in the population, or genetic variability that arises from recombination of alleles during sexual reproduction, can also be acted on by natural selection. Both are still evolution.
{{My answer to Reed Cartwright applies here.}}
I didn't suggest that new mutations necessarily WEREN'T part of this mouse evolution, either. A period of 150 years is many, many mouse generations. Some new mutations will have arisen within (not necessarily remained in) that mouse population, that's a guaranteed fact, that's chemistry. But new mutations may or may not be crucial to the change in size. Nobody knows yet.
{{Just because the species has changed its appearance is no guarantee that genes have changed. Now the chemistry may have changed. But Goldschmidt was able back in the 20's and 30's to imitate the changed patterns of butterfly wings by simply regulating the temperature and other such physical manipulations. He called such artificially changed patterns "pseudocopies". Care is needed in accurately determining causes of change.}}
"My point here is simply that whenever change in morphology occurs, it's termed "evolution";with no questions seemingly being asked."
Well, again, change in morphology across generations in a lineage IS evolution. It's evolution no matter what the mechnanism; even a hard core young earth creationist admits that chihuahuas had wolf ancestors and these mice had smaller mice as ancestors. That's the FACT or OBSERVATION of evolution.
{{This is a FACT or OBSERVATION of CHANGE! Evolution is inferred. Again, Goldschmidt could artificially duplicate changes that taxonomists would call a "species" change. And, in place of your example, substitute mine: i.e., Great Danes (and not wolves) and chihuahuas. Now you're dealing with the same species--i.e., there's been NO evolution--and yet BOTH varieties of dog, with extremely different forms, are "descended" from the same wolf ancestors.}}
What the THEORY of evolution does is explain a scientific mechanism for how such changes occur. Genetic variability, which we now understand at the molecular and biochemical level (of course there's always a lot more to learn, thank goodness), usually in concert with natural selection. For significant adaptive, directional changes in morphology (such as seen with these mice), natural selection is effectively a requirement.
{{Yes, but in the example of Great Danes becoming chihuahuas, we have large-scale changes being affected completely by "artificial selection." That's why I say, if you can turn a dog into a cat, then I'm a Darwinist! (But, of course, the canine genome won't permit this since as it's pushed too heavily in any one direction, the dogs that are born are sickly, i.e., unfit for further selection--contrary to everything Darwin believed.)}}
The theory of evolution absolutely does not "rule out" direct supernatural intervention in every single case, any more than any other scientific theory does, or ever can, for that matter. What it does do, is provide a natural explanation of what we observe, which can be verified empirically, and accepted by people of a wide variety of philosophical and religious backgrounds.
{{Because we can't "rule out" the supernatural "element", I purposively wrote: "That's how I would design them." Life is not robotic. It is not mathematical to the extreme. Something more powerful than raw mathematics is at play. The mathematical properties of matter are being used--and that's why design and intelligence are suggested, since only intelligent agents can manipulate mathematical properties for their own use.}}
Blast:"But either way, this isn't what you would classicly call the kind of "slow, gradual" change that Darwin would insist upon."
First of all, this isn't fair to Darwin - he didn't insist that all evolutionary change must be slow in this sense. It's making a straw man of his views. In fact, the famous "Darwin's finches" show similar levels of morphologic change over similar time spans (evolutionarily speaking), and he used them as an example. Darwin would certainly agree that these mice evolved.
{{Thomas Huxley argued vehemently with Darwin about Darwin's insistence on slow, gradual changes since Huxley was aware of how problematic it might become. But Darwin insisted that natura non facit saltus (Nature does not make jumps.)}}
Second of all, we know a great deal more about biology than Darwin did, and so even if he "would have been wrong" about some specific problem, it means little. We know vastly more physics than Gallileo did, but we don't disdain the contributions of Gallileo.
{{I believe that animals adapt to environments, and that natural selection is at play in this process of adaptation, but I wouldn't call this evolution as it is usually understood, i.e., macroevolution. Galilean transformations still serve a limited importance in physics, but these transformations don't make sense of the electro-magnetic forces nor of celestial gravity. Darwin and Galileo are valid, but limited, theories.}}
"My sense is that there is just a simple interaction taking place between the environment and the genetic capacity of the mice, a simple trigger mechanism that involves genes that are normally suppressed ( one probably regulating growth hormone, as Steve Reuland noted in a late post. But, of course, the gene for the growth hormone remains unaffected in this scenario)."
I'm not sure exactly what you are saying here. If you are saying that individual mice can adapt to and respond to their environment, to some degree, that's certainly true, especially for a mammalian genus like mice......Of course, individuals have these adaptive systems because of evolution, in the first place.
{{This last statement begs the question. We don't "know" that it was evolution that brought about this ability to adapt. This is being supposed. So it is an error to use a hypothesis to "prove" that what is "observed" is a result of what is being hypothesized.}}
At any rate, this type of adaptation doesn't explain why current mice are much larger than their ancestors.
{{Please look at Matt Inlay's comment which I quoted above.}}
You may also be arguing for a reasonable but discredited hypothesis of evolution, known as "Lamarckism" (a reference, some say unfair, to a great French biologist actively slightly earlier than Darwin).
{{Modern-day biologists are much more open to what might traditionally be characterized as a Lamarckian interpretation. We are just beginning to understand the intracacies of the cell. As I stated in an earlier part of this post, the cell is actively and essentially involved in protein activaction/de-activation. It is entirely possible that environmental influences can affect the cell, which, in turn, can become part of inherited change (We live in a post-Weismannian world, who averred that somatic and germ cell lines are independent of each other.) Changes can come from other than nuclear DNA.}}
Individual adaption does not explain the evolution of these mice over generations. Lamrchkism does not explain it in a scientifically satisfying way. The theory of evolution DOES explain it.
{{If I believed that the theory of evolution explained all this in a satisfying way, I wouldn't be arguing the point. I say, "Show me the beef!" Where are the transitional forms?}}
"That's how I would design them!"
It's nice if you feel, personally, that life turned out just the way you would have designed it, but that's irrelevant. Others argue that life is very different from what THEY would have designed.
Why would you design the mice to attack the baby seabirds, and NOT design the seabirds to an advantage over the mice? The theory of evolution does not lead to this dilemma.
{{You're missing the point about design. Your argument against design is basically this: Evolution is a morally superior theory. Shall we now argue that raw nature is morally superior to what a divine Creator can do? Let's leave arguments from morality out of this. Scripture says, "God's foolishness is greater than man's wisdom." So, it's fruitless to argue along these lines.}}
Henry J:
qetzal,
Re "It sounds like [Blast] predict they will find some pre-existing 'switch' that was flipped in the island mice, allowing them to grow larger. [...] but no evidence of any switch-like mechanism."
Question - couldn't the changing of a base pair to a different one be regarded as a "switch"?
Henry
{{The change of a base pair would have to become "fixed" in the entire population in Fisherian fashion. If we're dealing with a protein molecule of some sort, this kind of change very likely would have very minor, to no effect. However, if it affects a micro-RNA transcribed by the affected base pair, then, due to the new-found regulatory influence of micro-RNA's, this might have some effect.}}
To end this extremely lengthy post, I return to the original question: why, if there is some morphological change in an organism, must evolution be invoked like a knee-jerk reaction? Other branches of science have theories that don't have all the answers. In the standard model of particle physics, they're still waiting to detect the Higg's boson. In cosmology, the standard model can't explain the nature of dark energy nor of dark matter. There's tentativeness,yet these fields go forward with very important elements unresolved. On the other hand, in biology, there's an explanation for everything. Evolution is invoked to explain whatever it might be. Did the insect turn left? Evolution did it. Did the insect turn right? Evolution did it. Why can't biologists ever say, "Yea, that doesn't fit evolutionary theory," and then scratch their head and ponder things a little bit more deeply?
'Rev Dr' Lenny Flank · 28 July 2005
(snip Blast's latest round of BS)
Let me know when you can point to this "frontloaded" stuff in the mouse genome, Blast.
Pierce R. Butler · 28 July 2005
On the topic of rapid evolution, see "New animal species evolved in an instant", a New Scientist report on a new sort of fruit maggot living exclusively on Asian honeysuckle, but which seems to be a hybrid of other species which are found only on blueberries & snowberries.
Steve Reuland · 29 July 2005
BlastfromthePast · 30 July 2005
Steviepinhead · 30 July 2005
Blast, it's really not that hard, honest. These processes are all part of a continuum. I know that the "slippery slope" inherent in that makes you very nervous, but breathe deep and try really hard this time:
Various well-understood mechnisms generate variation, even in species with "stable" phenotypes established in stable environments. That you ARE phenotypically different from your parents is one example and expression of that accumulating variation.
When the environment begins to shift--and that's not just changing temperatures, or climate, but changes in the behavior of any of the other critturs in the environment, including humans and including breeding pressures--then distinctive subpopulations can begin to develop and, if the shifts and changes are persistent or disruptive enough--speciation can occur.
Call it "microevolution" if that helps you to wrap your mind around the beginning of the process. But before proclaiming that it can't lead to speciation, or that speciation--viewed from hundreds of millions of years of further cycles of replication, variation, selection, and speciation--can't lead to different lineages and even different body plans, please explain IN DETAIL why--if the changes and pressures continued long and forcefully enough--any of these processes would necessarily hit some "invisible" and inexplicable Wall or Stop Point What observed facts, principles, or processes preclude or prohibit ongoing change.
In short, Blast, you may be right that the mice or the finches or (your old standby) Goldschmidt's exemplars contain a fair amount of intraspecific variability--that they may just be trembling on the verge of speciating, approaching and retreating, but not really crossing some human-imposed definitional line--but WHY, if those same pressures were cranked up a little higher, for a little longer, do you imagine that the process could not go slightly further, become irreversible?
It's like the sound barrier, Blast, it's not really there. Or if you seriously think you have evidence for some "Go No Further" process, please lay it out for us, once and for all: where do we find the invisible evolutionary traffic cops who would blow their whistles and constrain the process inside the ruts you wish for?
Alan · 30 July 2005
BlasfromthePast
Are you sure you are not confusing the concept of evolution with progress?
Steviepinhead · 30 July 2005
Blast, it's really not that hard, honest. These processes are all part of a continuum. I know that the "slippery slope" inherent in that makes you very nervous, but breathe deep and try really hard this time:
Various well-understood mechnisms generate variation, even in species with "stable" phenotypes established in stable environments. That you ARE phenotypically different from your parents is one example and expression of that accumulating variation.
When the environment begins to shift--and that's not just changing temperatures, or climate, but changes in the behavior of any of the other critturs in the environment, including humans and including breeding pressures--then distinctive subpopulations can begin to develop and, if the shifts and changes are persistent or disruptive enough--speciation can occur.
Call it "microevolution" if that helps you to wrap your mind around the beginning of the process. But before proclaiming that it can't lead to speciation, or that speciation--viewed after hundreds of millions of years of further cycles of replication, variation, selection, and speciation--can't lead to different lineages and even different body plans, please explain IN DETAIL why--if the changes and pressures continued long and forcefully enough--any of these processes would necessarily hit some "invisible" and inexplicable Wall or Stop Point? What observed facts, principles, or processes preclude or prohibit ongoing change?
In short, Blast, you may be right that the mice or the finches or (your old standby) Goldschmidt's study critturs contain a fair amount of intraspecific variability--that they may just be trembling on the verge of speciating, approaching and retreating, but not quite crossing some human-imposed definitional line--but WHY, if those same pressures were cranked up a little higher, for a little longer, do you imagine that the process could not go slightly further, become irreversible?
It's like the sound barrier, Blast, it's not really there.
Or, if you seriously think you have evidence for some "Go No Further" process, please lay it out for us, once and for all: where do we find the invisible evolutionary traffic cops who would blow their whistles and constrain the process inside the ruts you wish for?
Steviepinhead · 30 July 2005
Oops. Sorry for the near-double post. It took EVEN longer than usual to appear.
'Rev Dr' Lenny Flank · 30 July 2005
(snip Blast's latest round of BS)
Let me know when you can point to this "frontloaded" stuff in the mouse genome, Blast.
'Rev Dr' Lenny Flank · 30 July 2005
qetzal · 30 July 2005
'Rev Dr' Lenny Flank · 30 July 2005
BlastfromthePast · 30 July 2005
qetzal: Thanks for your response, and the tone of it as well.
I could respond right now. There's some things I will likely quibble with you about. But I'm going to chew on your response for a while longer if you don't mind.
'Rev Dr' Lenny Flank · 31 July 2005
'Rev Dr' Lenny Flank · 31 July 2005
Steve Reuland · 31 July 2005