urbpan | The island effect produces giant predatory house mice

The island effect produces giant predatory house mice

I found out about this on "Wait Wait, Don't Tell Me: The NPR News Quiz."

‘Monster mice’ are eating island’s seabirds
Rodents evolved to triple normal size, attack much larger chicks

The island effect produces giant tortoises, giant (flightless) pigeons, and my favorite, giant monitor lizards (Komodo dragons). For some unknown reason, it also produces dwarf humans (Homo florensis) and dwarf elephants (which, according to island biogeographer David Quammen, were originally the chief prey of Komodo dragons).

EDIT: I originally spelled the name "Kwammen," for some reason

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Excuse me Mr. smarty pants zoo keeper person, but some of us in the Pacific time zone haven't heard that yet. while you're at it, why don't you call me about 10 o'clock my time and tell me all the punchlines from SNL. Hrumph.

No worries, it was one of the limericks, which you can only get wrong if you have some kind of rhyme/rhythm impairment disorder.

The punchlines from SNL:

Someone has an irritating personality, and is annoying for 10 minutes. The first 30 seconds makes you kind of chuckle, the remaining time makes you drink more.

Yeah, if I'm up and alone, I usually turn it on a little before midnight to catch Weekend Update. Other than that, it usually hurts to watch it. I think it was Eric Idle who said "what's the difference between life and a Saturday Night Live Sketch? Life eventually ends."

Quammen?

Wow, what a kwazy misspelling! I must need more coffee!!

You wascally wabbit, you.

In other news, I replaced the ballcock thing with the only thing they had at the hardware store - damn home depot, why must you be so far away?! - and it works, kinda. The original fancier one had a special doohickey that hooked up to the water in pipe that made water flow into the bowl. The cheapass mofo of a thing that I got doesn't have that so no water is going in through those holes (but the bowl still fills fine). Nothing more fun than lying on your back on the damp tile floor trying to figure out why the freaking thing doesn't work.

You said ballcock. Tee hee.

Hee hee!! :)

it also produces other kinds of dwarves -- e.g., the smallest hummingbird in the world is in cuba, which also has numerous other tiny representatives of species.

and i meant of genus(es), not species. :still sleepy:

Oh, and a dwarf elephant would be a great member of our zoo - can we get one? :)

We need some elephants, an island, and a time machine. (actually, if we had the time machine, we could just go grab us a pygmy elephant calf).

And seed the elephants on the island and come back in a while when they've gotten smaller? Sounds like a plan to me.

Not unknown. FLying animals (like pigeons) expend a lot of energy in flying. It's not a useful thing to expend energy upon if you're not a very strong flyer in the first place. If there are a lot of predators, you get selection for stronger flight (because if you're not a strong flyer, you get blown out to sea; that's why small islands and Northern California don't have many mosquitos). If there aren't a lot of predators, you're just as well giving up flight and using the energy for something else... like getting bigger or running faster.

Most mammals compensate for island living by getting smaller because there's less to eat, and a smaller body needs less food. The same thing happened with dinosaurs when part of Romania was an island, too. Island-dwelling mammals usually get smaller. However, mice are generalist critters, so they can evolve in multiple directions more quickly because they can survive in a wider range of conditions than can elephants or humans, which are much more specialized animals. Big, carnivorous mice aren't that surprising... there used to be giant rats on some islands off South America (I think) that were also carnivores and got as big as dogs. Rodents are the most adaptable family of mammals; just look at naked mole rats!

Tortoises are very low-energy creatures, so if they don't have competition for food, their genetics tend to select for larger and larger size. In the Galapagos, there aren't many (if any) other grazers, so the tortoises have all the grass to themselves, and they can afford to get so big that no potential predator will other with them. Not much eats tortoises to begin with.

All it takes is a founder effect, with the founders having a bunch of recessive and/or breakable genes, and speciation picks up very quickly if there's little competition and a new niche or two to exploit.

Thanks for the info! Do you have any handy references for me, for when I write my article "The redodofication of Earth"?

I said unknown because the mouse article claimed that scientists disagreed about the reasons for the island effect.

It's basic biology, really. The thing scientists can't agree on is how to predict it, but the mechanisms are well known.

I don't have a link handy (this is stuff I learned in biology classes), but if you search around for information about things like "founder effect," "genetic drift," natural selection, etc., you should be able to find lots of information about this. Really, the "island effect" is just particular set of pressures that, all together, addup to natural selection.

Have you read the Quammen book?

GREAT read. Interesting AND entertaining. :)

ig, carnivorous mice aren't that surprising... there used to be giant rats on some islands off South America (I think) that were also carnivores and got as big as dogs.

Carnivorous is one thing - many rodents are. Predatory is something entirely different.

Rats (and mice) will eat insects, and rats are predatory, especially on smaller rodants. The giant rats I mentioned were also predatory on several other species, including birds and reptiles. While predatory rodents may be in the minority now, there were more predatory rodents in the past, and modern mice and rats still carry the genes. It's an odd thing to think about now, because we're used to mice being basically harmless (as long as you don't count Hanta virus, I guess), but it wasn't that long ago in evolutionary terms that relatives of parrots were the top predators in South America. We don't think of parrots as predators today, but keas in New Zealand have been known to attack sheep (http://www.nzbirds.com/birds/kea.html) and eat their fat, kidneys, etc! Polly want a lambchop NOW! Again, an island species adopts a unique strategy here.

That's the thing about nature; no matter what any given human thinks of as the norm, there really isn't one. I've met millipedes that have hit me with something resembling tear gas in my own backyard. Who'd have thunk it?

There might be some difference between predatory and territorial as in the case of rats vs. other rodents that threaten their niche/food sources. Mostly, rats just eat eggs (any kind) and babies (any kind). I was more thinking of the innate motor pattern required to be a predatory animal (birds of prey included).

Don't lots of insects and such emit horrible sprays to deter their predators?

I used to have a pet rat, and he loved to eat mice. Rats will hunt if there's something good to be hunted. They're total generalists.

Some insects do, but most don't. Only the ones I forget to be careful with while I'm photographing them consistently have solid defenses.

Rats are opportunists and will eat just about anything. There's a difference, imo, between predatory behavior/motor patterns and being omnivorous.

Seems like pretty much any animal will happily evacuate when they're nervous. :)

hat's why small islands and Northern California don't have many mosquitos

There weren't mosquitos on Hawaii prior to the mid 1820s.

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The island effect produces giant predatory house mice

Wait, wait, don't tell me. Seriously.

Re: Wait, wait, don't tell me. Seriously.

Re: Wait, wait, don't tell me. Seriously.

Re: Wait, wait, don't tell me. Seriously.

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