Life expectancy

I thought this might warrant its own thread as it is more of a general topic about life expectancy in chameleons and how their life history strategies play into it.

Earlier this month I attended a conference for the Society for Integrative and Comparative Biologists (SICB). One of the talks I attended I found to be particularly interesting and thought provoking and I thought a few people on this forum would have appreciated it. It was a talk by Kris Karsten on some of the research he's done in Madagascar titled "Living life like there is no tomorrow: growth, sex, and death in a remarkable chameleon in Madagascar". In the talk, he discussed his observations over a couple years on Furcifer labordi. His observations indicate that this species seems to have the shortest natural life span of any known tetrapod (any vertebrate having or evolutionarily ever having had four limbs). His research found that this species has a natural post-hatching life span of 4-5 months in which they grow to full adult size from hatching from the egg, reproduce and deposit eggs for the next generation having reached sexual maturity in less then two months. During peak growth rates, he recorded that males can increase in mass by as much as 4% per day and in body size by 2% per day, while females increased in mass by as much as 2% per day and in body size by 2% per day. There then seems to be a complete cohort die off in the population at the onset of the dry season and the only living individuals of the species are the developing eggs which hatch in 8-9 months. In effect, this species spends approximately 75% of its life cycle in the egg with no cohort carry over between generations. Talk about living to reproduce and the success of your species depending on it!

On the other side of the spectrum in chameleons, it seems we have species like Calumma parsonii which are reported to be capable of living upwards of 20 years. These species are relatively slow growing and get extremely large while living a generally slower life. Rather then complete dependence on a single reproductive event to pass on their genes, species such as this reproduce over a number of years repeatedly. The life history strategies of these two species couldn't be more different!

When Furcifer lateralis come in from Madagascar, it seems that ever female, unless a very young animal, is gravid. People who have worked with them can tell you that once they become gravid, it seems like they pump out eggs constantly. The species is also considered to typically be on the shorter end of the life expectancy spectrum and seems to be of the "living to reproduce" strategy. On the other side, species like Chamaeleo (Trioceros) deremensis have arguably been referred to as seasonal breeders that take a couple years to mature and need specific conditions to reproduce. They'd appear to represent the other side of the reproductive strategy spectrum.

More then anything this thread is just me thinking out loud (so-to-speak) about my amazement with this family. There is such a diverse array of species, life history strategies, ecological niche specification, morphological variations and extreme examples of specialization and for a family which is generally regarded as so fragile, how have they managed to evolve to be so incredibly diverse and specialized in ways and extents that few or no other tetrapods have succeeded?

Chris

Wow, thanks for sharing that. No wonder F. labordi never did well long-term in captivity. Just to make sure I understand correctly, they were dieing of "old age" rather than something in the environment making life impossible (prolonged drought, famine, etc)?

Will and I were just discussing the F. labordi rape scene, as I like to call it, in the CIN dvd. That somewhat extreme interaction makes a lot more sense now. I never would've thought I was looking at a couple of 4 month old lizards though. Fascinating. Is anything published or in the works to be?

This topic is very fascinating to me, and leads me to the question of whether or not we can have some level of control in a captive environment.
Lynda is keeping female veileds to and past their 7th year without ever producing an egg by controlling temperature, diet and exposure to males
(keeping them cooler, not over feeding and keeping them visually separated from their counterparts).
On the flip side we have females that are in breeding projects or are "well loved" pets, getting very warm basking areas and lots and lots of food producing multiple clutches per year and living to be only 2 or maybe 3 years old.
Okay ... that was me thinking out loud
And I may not be done.

-Brad

I am not sure how old this is, but here is a link. It may or may not be based on his studies.

http://en.wikipedia.org/wiki/Furcifer_labordi

Kent67 said:

Is anything published or in the works to be?

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Yes, it will be published next week, sometime after June 30 in PNAS.

I wonder if they would live longer if kept on a "diet" and a little cooler too...or would they be more like the pardalis, where the diet doesn't prevent the cycling to produce eggs?

I wouldn't be surprised of we could extent the life expectancy of any animal beyond what it would be in nature by carefully controlling their environment, however the question then becomes if it would be right to do so.

I once read a study about guppies that showed that a male guppy kept in a communal tank with other males and females will live for about 2 -3 years, while one kept in complete isolation can live as long as 7 years. Question is - which one lived a more fullfilling life?

If you could live for a 150 years by spending the rest of your days is a carefully controlled laboratory, would you want to?

Just to add some more food for thought

Always interesting to hear your thoughts when you think out loud. We have hobbyists and scientists, but few that are both.

Life expectancy seems to be very similar in other groups of lizards - phelsuma, for instance, all live ridiculously long lives. Even the tiny little klemmeri live over 20 years. I have some female standigi that we've owned for 15 years, and were imported as large adults (and they're STILL breeding).

Chameleons are indeed unique in their varied niches and lifespans. I wonder if this is indicative of an early split from other saurians.

I haven't read much on the evolutionary history of lifspan. Could be one of those adaptations that's relativly quick in - especially when we have animals adapting to constantly changing climates and ecosystems.

It has not been my goal to get my animals to just live long. I do not believe there's anything immoral with creating an artificial environment in order to do that. Tot he contrary, such experimentation, like what kinyonga has done, helps us better understand the physiology of these animals. I have had all sorts of ideas as to how to get female veileds to live longer, but I'm not incorperating any controls.

I limit food and temps, but it's for a "balance" between long life and lots of eggs.

One small clutch a year, I can say, leads to a very long life. 5 years plus.
Two clutches a year, and you're probably not going to get many of them beyond 4 years.
A good number of triple-clutchers will be dead in 2 years.

With deremensis, I found that slow reproduction is pretty much hard-wired, unlike veileds. feed them more and keep them warm, they don't (always) lay more eggs more often, they tend to get fat and die.

Very interesting differences.

Deremensis and parsonii, though not closely related as far as chameleons are concerned, are very similar in behavior and appearance. Some of them even have those "parsonii lines" and yellow side dot - not to mention the highly photo-sensitive skin. evolution is so much fun.

how have they managed to evolve to be so incredibly diverse and specialized in ways and extents that few or no other tetrapods have succeeded?

this is the last sentence of the original post.

who says that they ever evolved. might it be that they were all created to match their environment and maby all created to do exactly what they do. every chameleon out there is made to do what it does, and made for its environment. some live longer than others some dont. some grow fast and reproduce and others dont. some live in hot humid climates others cant. people and even scientist use the species word on chameleons too much. they are all chameleons just different KINDS of chameleons not species because when you take it all away you still have a chameleon, one with horns and one that dont, but its still a chameleon. the question is not how they all evolved, i have never seen anything evolve, but how all life is created for its specefic environment and its specific purpose. now with that said if an animal is in captivity of corse someone can make them lay more eggs or live longer than normal because its in a controlled enviroment. thats no news. take all things that affect and shorten its life in the wild and do away with it all and now you have an animal that normally lives 2 years now living 6 or more years and re-producing like crazy.

(p.s. im not trying to get people mad at me i just dont like the word evolve and how people/scientist try to put a scientific explination on every single thing out there on as to why it is.)

just my humble opinion.

i respect your opinion, do not get me wrong, but you're basically saying evolution doesn't exist.........

I don't like the words "intelligent design" either, but that's just me. Panther chameleons are an excellent example of speciation, in any case. To me, it's amazing to see animals that are so related but that have experienced reproductive isolation for so long that they are now no longer sexually compatible with their closest relatives... i.e. evolution.

In any case, a group of scientists found that half-starved rats lived significantly longer than ones who were fed twice as much. For some reason, the lack of food allows the body to work more efficiently. Would that mean that a longer life caused by a scarce diet would be a healthier one, or would the animal be constantly stressed by hunger?

i too respect everyones opinion, like i said i just dont want to get on peoples bad side. i just felt like stating that there are reasons for the way things are and not always is it the reason of evolution. plus it is no big supprise that things live longer and can reproduce more in controlled environments you take away all the things that kill it, and you feed it all the things that are good for it and it lives longer.

but there is good information to be found with such experiments

IE: what has the most effect on the animal, good or bad.

it is good for almost everything to fast. it puts a stress on living things on a cellular level, sorta like exercise

things are they way they are for reasons though, there is always an explanation, even if we havent found it. the ant eaters' specialized mouth and tongue came after ants, not before

i mean there are other black and white examples of things being the way they are for a reason, thats a fact. and because there are provable examples the idea that things that are, just are, and thats how they will always be can no longer be reasonably argued IMHO

Jeremy l said:

how have they managed to evolve to be so incredibly diverse and specialized in ways and extents that few or no other tetrapods have succeeded?

this is the last sentence of the original post.

who says that they ever evolved. might it be that they were all created to match their environment and maby all created to do exactly what they do. every chameleon out there is made to do what it does, and made for its environment. some live longer than others some dont. some grow fast and reproduce and others dont. some live in hot humid climates others cant. people and even scientist use the species word on chameleons too much. they are all chameleons just different KINDS of chameleons not species because when you take it all away you still have a chameleon, one with horns and one that dont, but its still a chameleon. the question is not how they all evolved, i have never seen anything evolve, but how all life is created for its specefic environment and its specific purpose. now with that said if an animal is in captivity of corse someone can make them lay more eggs or live longer than normal because its in a controlled enviroment. thats no news. take all things that affect its life in the wild and do away with it all and now you have an animal that normally lives 2 years now living 6 or more years and re-producing like crazy.

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Jeremy,

As obviously useless as arguing this type of thing is, I'm going to go ahead and let you know that your logic is the filled with enormous holes. Sorry Jeremy, you're welcome to your opinion but it is very clear that you do not have the understanding base on the complexity of the topic or the evidence supporting it to get into a debate about evolution.

Your statements about species designation being arbitrary or used too much because they are all just chameleons is hilarious on so many levels. To use your own logic, why do we differentiate the human species from that of a gorilla (they're both apes). Take it a step further (since you seem to be suggesting that diversity is unimportant, only that it is a living thing), why differentiate between any mammal? Any vertebrate? Any multicellular organism? The use of the designation of a genus, species, subspecies, genetically distinct population, etc., are all valuable designations to define diversity at relevant levels. Saying that they're all just chameleons and shouldn't be treated as anything different is the same thing as equating yourself to no different then a cactus or any other living organism on this planet.

As for you never having seen anything evolve and the fact that you're resulting opinion is that evolution thus does not exist, all you're doing is proving the point of evolutionists (you can't prove ANYTHING to validate creationism so it must not exist). Since you're already dead set on the opinion that any evidence for evolution is bogus, you obviously wouldn't acknowledge it if it bit you in the face. You may not study evolution and the processes that drive it (if you did and were open minded, you'd see it) but just because I've never been to India myself, there is a lot of evidence around to make me pretty sure it exists. Choosing to ignore scientific research and documented evolutionary processes and deciding not to believe something exists or does not occur simply because you believe something different (that has no supporting evidence in itself) is your choice but you're getting left behind by the rest of the world who realizes that refusal to accept an overwhelming volume of evidence and failing to incorporate those findings into your beliefs is ignorance at its finest. This mentality is the reason the US is falling off the global education rankings in almost every field. Ignorance is bliss but eventually it'll catch up and bite you in the butt.

Chris

Jeremy l said:

i too respect everyones opinion, like i said i just dont want to get on peoples bad side. i just felt like stating that there are reasons for the way things are and not always is it the reason of evolution. plus it is no big supprise that things live longer and can reproduce more in controlled environments you take away all the things that kill it, and you feed it all the things that are good for it and it lives longer.

Click to expand...

Funny thing is, "the reasons for the way things are" can be largely explained by scientific evidence on many levels, many of which are grounded on evolutionary principles yet your theory has nothing more to back it up then stories passed down over the years and the fall back of "well, if you can't explain everything yet, you must be completely wrong."

If every organism "is made to do what it does, and made for its environment", why would putting it into an environment that it was not made for change its survival? If a species was created specifically to live 4-5 months from hatching to death and was created to breed and live in this period of time alone, why would changing its environment change its natural history? Its because these organisms overcome hardships to expoit resources that other species are unable to exploit which gives them the advantage to thrive themselves, even they could possibly survive better under a different environment if there were not other competitive reasons pushing it toward its niche. This is very much evolution.

Chris

Has anyone done a captive experiment within Mada's borders, of recording the labordi lifespan, keeping them perpetually at optimal wet season temp and humidity?

It sounds like drying out signals the end of the party, so to speak...

The question of whether we should artificially extend life in captivity is very close to the question of whether captivity should happen at all... tricky footing. Many species have longer recorded lives in captivity than in the wild. The thing that keeps captivity palatable to sympathetic observers and captives alike is "enrichment". A longer life with no enrichment is not a good life, and not even humane incarceration. But on the other end, a cushy life of no predation, no difficulty in finding food or mates, with "safe" enrichment thrown in, is a positive thing.

And now I hear a couple keepers laughing at me for the use of the word "enrichment"... I mean, GOOD stress!

ok, well, i guess i now look like a dumb a$$ well its not that i am not open minded, my point i guess was not written like it maby should have been. i ,in no way am arguing with any of yall or you Chris, you guys are way more smart on these chams than me, and there has been alot of great science done on these animals, but not everything about the way they are is been based on evolution. ya i made a dip sh*% out of my self but i guess we all have too sometime. hey look at the bright side yall got to point your fingers at me and laugh !

Chris Anderson said:

This mentality is the reason the US is falling off the global education rankings in almost every field. Ignorance is bliss but eventually it'll catch up and bite you in the butt.

Chris

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i dont know whats in my chicken nuggets, and I wouldnt have it any other way


you didnt make yourself look bad for thinking how you think............. it was when you spoke so " as a matter of fact " on a topic without having the facts

Jeremy l said:

i have never seen anything evolve, but how all life is created for its specefic environment and its specific purpose.

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Have you ever gotten a flu shot?