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penis_in_my_hand t1_iw7l8h2 wrote

Pepsis wasps (tarantula hawk) will fight a single tarantula, paralyze it, drag it back into the spider's burrow, and lay a single egg it. Then when the egg hatches the baby wasp eats the tarantula alive, going for the least vital organs first.

The parent puts considerable effort into a single offspring.

But the momma wasp doesn't hang around and care for the baby. It's more of the entomological equivalent of a trust fund...

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PlaidBastard t1_iw7lzj1 wrote

Evolutionarily, investing the time and resources while the offspring are gestating, after birth, or before fertilization is probably as good as the same thing. At least as far as K-strategy etc terminology is concerned, right? One new tarantula hawk per tarantula is a strategy based on it working most of the time, vs sea turtle hatchling death gauntlets for a vertebrate opposite example.

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UDPviper t1_iw8q8al wrote

I saw a vid of sea horses where it stated only 1-2% of around 1000 or so births per father survive to adulthood. Brutal odds.

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mabolle t1_iwhzend wrote

You can actually do this math for any species at all, without knowing anything about its biology except how many offspring they tend to have.

Think of it this way: animal and plant populations may fluctuate wildly from year to year, but in the medium-term, we can assume that the per-year average total population of a species is more or less stable — neither increasing or decreasing. This necessarily means that (assuming equal sex ratios, which most species have) each female is having, on average, two offspring per year that survive long enough to have their own offspring. That's one offspring per female to replace herself, and one to replace her male partner. Some females will have much more than two offspring survive to adulthood, and some will have none, but the per-female average is approximately two.

So if you find out that a species tends to have approximately 1000 offspring, you can divide 2 by 1000 to get the survival rate. If the typical litter size is four, you know that only half of them on average will make it. If a species tends to have a million offspring, it's two in a million.

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SunburntWombat t1_iwa95m4 wrote

Does that mean that social insects are k-strategist? Think about it. For one queen bee to beget the next queen bee, she produces an entire colony of workers and drones, which in turn put in an enormous amount of work to build and maintain a hive. That’s a lot of work just for the genes to be passed down to the next colony.

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KingoPants t1_iwahnfk wrote

I think its better to think of the colony as a single reproductive evolutionary unit, not as a collection of individuals. Ant colonies produce a large number of new queen's and drones for nuptial flights. Unless they are very lucky to find a good unoccupied spot most of the next generation perish.

In that sense ants don't put too much investment into reproduction.

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Cephandrius17 t1_iwadoo6 wrote

Maybe. They probably have fairly low infant mortality, since the babies are all being fed/cared for until they are mostly grown up.

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gh411 t1_iw7zyk9 wrote

I find it interesting that the Pepsis wasps link their success with that of tarantulas. It seems counterintuitive to need tarantulas in order to breed, but each offspring kills a tarantula. Do they have the ability to change host incubators if tarantulas were to become unavailable?

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Kevjamwal t1_iw8d3cd wrote

This is true of any specialist predator though. Basically it just can’t be TOO successful or it wipes out it’s host/prey opportunities

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NorthernerWuwu t1_iw8tgjf wrote

It's often true of more generalist predators as well, even though they are dealing with a broader spectrum of prey species. Population booms and crashes are quite normal over any reasonable timeline.

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riptaway t1_iwaia7l wrote

Well, it's self correcting. If there are plenty of tarantulas, they have plenty of opportunities to make babies. If they hunt them to scarcity, there won't be as many babies and tarantuals will again flourish. Seems pretty clear they have an equilibrium going. At least until humans destroy the habitat of either.

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immibis t1_iw8acfz wrote

Isn't this the same as any parasite species for example?

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Infernoraptor t1_iwxpsdu wrote

Not always. It depends on the mode of infection. If a parent hunts down a host for direct infection, they don't need many offspring. For other parasites, especially those that don't have a free-living adult form, they often produce huge amounts of eggs or larva. Think of parasitic worms, for example. Most of the young never find a host, so they need numbers.

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PostPostModernism t1_iw8mk8j wrote

Evolution doesn't plan through logic, just what works. And it certainly doesn't account for the interruption humans have imposed on the natural order of things (except for some modern responses we're beginning to see from anthropogenic pressures).

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gh411 t1_iw8o4sl wrote

I agree, I understand how natural succession works…and clearly it works in this case. I just find it interesting to see one species place its entire future on one other species…kind of an all the eggs in one basket approach. I suppose if tarantulas were to disappear, the wasps would also go extinct, unless some had the ability to adapt and use another host. Is there cases where we see these wasps successfully, albeit rarely, use another host for their eggs?

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Alblaka t1_iwbfyjs wrote

You're anthropomorphizing the very concept of 'a species'. There is no 'species of these wasps' entity that specifically places it's future onto any thing... it's just a load of individual wasps bumbling about doing whatever and just so happening to have genetically condensed on doing something that kind of works well enough.

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googlecansuckithard t1_iw8htu3 wrote

There are many therophosids wich are not tarantulas but are commonly misidentified as such. (Trapdoors, mose spiders, and funnel webs are examples) the ecologocal difference as might pertain to darwinistic theory is geographic distribution, their relative speed, the strength of their venom, and the nature of their exoskeleton.

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ImGCS3fromETOH t1_iw98c8m wrote

How long between the egg laying and hatching? Is the tarantula paralysed the whole time until hatching, or does it wear off and it goes about its life for a while with a ticking bomb inside it?

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iAmRiight t1_iw9y42r wrote

I hate when somebody asks a question that I didn’t even realize I wanted to know and there hasn’t been an answer yet… now I’m going down the rabbit hole.

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iAmRiight t1_iwa2db3 wrote

Accordingto this article the tarantula is gravely wounded and the wasp eats the blood and innards that come out of the wound before burying it alive. The paralysis eventually wears off before the larvae hatches and eats it, but doesn’t recover enough to escape the buried tomb before being eaten alive.

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