# What is the evolutionary advantage of this?



## AFK (Jun 14, 2006)

The male orchid mantis is INCREDIBLY TINY compared to the female. Why?


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## Lukony (Jun 14, 2006)

Just how it is. I am assuming it is so that she has mass for the ootheca. Most every species of animal has one side that is larger than the other.


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## AFK (Jun 15, 2006)

yes, but with other mantis species, the male isn't THAT much smaller. the male looks like a BABY compared to the female with orchids!


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## Sheldon Johnson (Jun 15, 2006)

Orchid males become adult quicker than females due ot their size. In the wild, this often helps to prevent inbreeding.

The other reason is, when youve only got a 3-6 month adult life span and all you can do is mate, then do you really need to be large and therefore reduce your chance of survival by requiring more food in an already very competative world?


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## yen_saw (Jun 15, 2006)

Besides that, male praying mantis is also smaller so that it could fly around looking for mate, being lighter in weight. As female orchid has 2 extra molt than the male, it make sense that the female is considerably larger. Smaller orchid male probably survive better in the wild in my opinion, especially with a large ferocious female as mate.

Here is a pic of a mating orchid pair just couple of days ago.


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## Christian (Jun 16, 2006)

Hi.

There may be several advantages:

1. as Sheldon said, this may prevent inbreeding, especially in rare species, as the male is forced to leave the habitat in order to search for mates.

2. avoiding of cannibalism: there are two strategies regarding this point: to be very large compared to the female or to be very small. The second point is not very obvious, but a male as small as this sitting on the back of the female can hardly be grabbed by her. He is simply out of reach. This is also found in _Parhymenopus_ and _Theopropus_.

3. At least in _Hymenopus_: the male guards the female to avoid other males copulating with her. In this case it is better to be small to not disturb the female very much. First, she is not hindered from moving around, secondly, he is safer from her (see above).

Noone exactly knows if these are the real reasons for the adaptation. But it makes at least sense from an evolutionary point of view.

Ragards,

Christian


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## AFK (Jun 17, 2006)

great points. i think you guys have made it very clear of the advantageS. thanks guys!


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## Rob Byatt (Jun 19, 2006)

The theories from both Sheldon and Christian are more than likely true, but there is also another underlying reason why males of alot species of invertebrate are small by comparison.

It is not necessary for males to have a large body mass because they are simply the carriers of sperm; it is the females that need to be large to produce large numbers of eggs.

It would also appear to be a trend (not a generalization) that males of cryptic species of mantis are small in comparison to the female. This may be because cryptic females do not want to advertise their presence to predators (hence the crypsis), so attract males with species specific pheromones.

It may be an advantage to a male that is unaware of the exact location of a female to be less conspicuous while flying towards the source of the pheromone.

But these are just theories !

Cheers, Rob.


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## OGIGA (May 28, 2007)

> Besides that, male praying mantis is also smaller so that it could fly around looking for mate, being lighter in weight. As female orchid has 2 extra molt than the male, it make sense that the female is considerably larger. Smaller orchid male probably survive better in the wild in my opinion, especially with a large ferocious female as mate. Here is a pic of a mating orchid pair just couple of days ago.


Oh so that's how it's done. I have been wondering how something can mate with a considerable larger counterpart.


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## markdneck (May 28, 2007)

Look at spiders where the male is really tiny compared to the female. In mammals males are larger as they (we?) fight for the right to mate and size is helpful in a fight. I think even male cats are usually almost twice the size of females.

I'm glad not to be a mantid. My wife already figuratively bites my head off. God, if she were five times my size I'd never see a football game!


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## AFK (May 28, 2007)

> Besides that, male praying mantis is also smaller so that it could fly around looking for mate, being lighter in weight. As female orchid has 2 extra molt than the male, it make sense that the female is considerably larger. Smaller orchid male probably survive better in the wild in my opinion, especially with a large ferocious female as mate. Here is a pic of a mating orchid pair just couple of days ago.


it's like throwing a hot dog down a cave.


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## randyardvark (May 28, 2007)

thats comment has actually made my day..


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## yen_saw (May 28, 2007)

> My wife already figuratively bites my head off. God, if she were five times my size I'd never see a football game!


Ha! That was funny...



> it's like throwing a hot dog down a cave.


It wasn't that bad really!! Male is so small compares to the female so they can escape better being lighter (and able to fly better), aslo more difficult for the female to catch while he is on her back.


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## OGIGA (May 28, 2007)

How well do the females fly? Their wing-to-body ratio is much larger than most species.


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## hibiscusmile (May 28, 2007)

:lol: lol, u guys are 2 funny, and thats not the reason at all... God figured since us girls had to carry u guys around so much that he would make the load lighter! ha ha


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## jplelito (May 29, 2007)

As to the 'How well do females fly?' question:

Not that great, and only until they get heavy with food and eggs. A newly molted female can fly for short distances but usually only if they are really warm. They do a lot of the "flying leaps" between objects but that's about it. Once they bulk up with eggs flight is difficult if not impossible for most female mantids as far as I know.


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## skinnylegs (May 29, 2007)

in all those pictures the male looks like a bit of a perv :lol:


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## OGIGA (May 30, 2007)

I had a dream this morning that when I tried to mate my pair, the female grabbed the male and took a big bite out of him before I could rescue him. I hope that doesn't happen in real life...


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## OGIGA (Jun 1, 2007)

Okay, so I finally got my orchid male to get one top of my orchid female. The male bent his abdomen down to make contact a couple of times, but it was really quick. How long (generally) are they supposed to stay connected for them to count as "mated"?


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## wuwu (Jun 1, 2007)

i think the shortest would be around 10 minutes, but generally they mate for hours, sometimes overnight.


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## OGIGA (Jun 1, 2007)

Believe it or not, I have been watching almost all night (over 4 hours now). I noticed that the male has been trying to connect, but his abdomen isn't long enough. I'm afraid that if I just leave them as they are so they can do their thing, the female will eat the male. He's the only one I have so if he gets eaten, I want to make sure he at least fertilized something.


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## critterguy (Jun 10, 2007)

Another thought...with vastly different sizes the two sexes of orchid mantis likely eat slightly different foods in the wild which keeps the males from directly competing with the females for food.


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## Way.Of.The.Mantis (Jun 10, 2007)

The male only has to fertilise, not support the life of hundreds of nymphs in an ooth.


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## OGIGA (Jun 10, 2007)

My male hardly ever eats. It's been a little over a week and the last thing he ate was maybe half of a blue bottle.


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## Villosa (Jun 12, 2007)

In some ants, colonies produce males that are less expensive to make. Some species have males that have small heads, small mouth parts, and large eyes for the single purpose of mating and ultimately dying. Males often out number females in this case so that every female will have 3-5 males each to ensure successful matings.

In mantids I suspect this is also true. I've never counted but I wonder what the se.x ratio is in, say, a single orchid mantis ooth. The s.exual dimorphism is basically due to females needing more time to develop into egg laying machines imo and thus need to be extremely large. Males on the other hand are numerous and quick to mature and smaller sized (less waste on resources) to wait for the females to mature.

Oh come on censorship, it's scientific talk here...


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## Christian (Jun 12, 2007)

Hi.

If this to be the most important reason, why isn't it expressed in all species?

The point is: what is the difference between this and other highly dimorphic species and other ones? Every generalistic theory has to answer these questions first. I think I tried to do it.

Regards,

Christian


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## Asa (Jun 12, 2007)

I agree with Christian, you must have a generalistic theory. Though I doubt generalistic is a word.


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## Villosa (Jun 12, 2007)

What works for one may not always work for another. Even slight differences in habitat, food, stresses, and living styles can change the need for dimorphism. The ant genus pheidole has a highly dimorphic caste because minor sisters are small and cannot carry out larger tasks. So more expensive, and larger, sisters are made to help with large tasks and for defending the nest from army ant intruders that seem to favor running raids on pheidole colonies. A genus such as pogonomyrmex lack any serious polymorphism because there really is no need for it yet the two listed above live right next to each other at times. I have not studied mantids as much as I should but there is going to be a specific reason, a very specific reason, why orchids exhibit huge dimorphism that other mantids lack.

Every insect out there is only after one thing, to reproduce and more often than not, they will have very odd and clever ways of being successful. That's why you can't have a general theory that matches for all species of every mantid genus on this planet because you can't expect species from Africa to live the same life as species from Australia or China. Every evolutionary change is to benefit the population because it works, they don't choose to change, it's just smaller males seem to work well for them, so they've become the norm of the species.


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## Asa (Jun 12, 2007)

Actually in ant colonies, it is more often the female that is more abundant. All the reasons I can consider for the dimorphism between the female and male orchid, are listed above. If it is so specific, why are there other rarer mantid species who follow this pattern and have no difference in number of male to female ratio? Quite a deep topic, I like it. Wonderful discussions, Villosa and Christian.


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## Villosa (Jun 12, 2007)

I think you may has misunderstood my previous reply Asa. Yes it is true there are more females in a colony of ants because the cast is made up of sterile females plus the queen. If you were talking about reproductives then that is incorrect, or most of the time it is, as males die (or are extremely exhausted to the point of death) shortly after matings and so by evolutionary standards, if a colony releases 100 females to 80 males then 20 females are wasted which is a big no no in reproduction.

If we go in reverse with lucanus stag beetles, the s.exual dimorphism favors males because of their need to compete with other males for a single tiny female. Females mature faster than the males but are able to dig underground to hide during the day while males, due to their large weapons, cannot. Females are then kept safer than the males, who are buit for toughing it out with one another for the right to mate. The ones usually caught by blacklighting or seen during the day are the males. Which bring me to a interesting segment I saw on video once where a large orange beetle species prefers large females because in the narrator's words "large is beautitful" and this makes me wonder if orchids have something like this going for them too.

Internal server error is stopping me from psoting my last paragraph...why?


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## Asa (Jun 12, 2007)

Interesting, perhaps 'big means better' is 'better' for the orchids. I now understand what you meant by the ants. If the 'big means better' is true, that could lead to a lot of answers that I've been wondering about some of the mantids in India that sometimes have bizarre size differences. However with them, even within the same species, the dimorphism between them varies incredibly.

Some species of roaches also do this. As to the evolutionary advantage of this, I do not believe their is evolution. A prime example of this is the theory that Darwinism is based on 'a little at a time leads to big results'. This is untrue. In a conclusive test based on the islands near I forget which island, some finches were tested on beak size. During a drought there beaks got bigger in order to crack the harder seeds. The scientists hoped to prove that that would mean that in the next few hundred years there would be a whole new race of finches.

Needless to say, after the drought, the finches beaks returned to normal. This cycle kept on going for the next 30 years. At the end of these tests the bird's beak size were exactly the same as when they started.

Somehow there must be some way to prove that the orchids or any species size difference must be based on something more general. Sorry for the long post.


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