Is there a correlation between body size and life span?

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Darby
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Post by Darby » Thu Jul 13, 2006 6:47 pm

The size - life expectancy thing is generally a comparison among, not within, species.

Dogs would not be a very good example, because breeding for one set of traits often picks up "piggy-backed" (closely linked) genes for other traits, and increased size could be linked to any number of things that could reduce average life expectancy.

I wouldn't trust the whale data that much, since it would be largely anecdotal, limited mostly to limited numbers of captive specimens and captive species. I doubt that field studies are even now sophisticated enough to get reliable data on wild whales (and, since you have to wait for study subjects to die, even if they now have the means, it would take decades to amass the data).

dellingsdawn
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Post by dellingsdawn » Mon Jul 17, 2006 8:31 am

Couldn't lifespan be more link to rate of reproduction rather than actually size.

For example, bats are very small animals but unlike other small animals they tend to have small litters - the majority of bats species only give birth to one young at a time. This is because most female bats have to fly with their young.

Bats tend to live much longer than any other animal of a similar size. They have to produce enough young to keep their population going.

Most large animals produce small litters and therfore have to live longer to replace their population.
Last edited by dellingsdawn on Wed Jul 19, 2006 11:01 am, edited 1 time in total.

muxer
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Post by muxer » Mon Jul 17, 2006 4:12 pm

Darby wrote:
Dogs would not be a very good example, because breeding for one set of traits often picks up "piggy-backed" (closely linked) genes for other traits, and increased size could be linked to any number of things that could reduce average life expectancy.


Please read the entire thread, that point has been made and effectively dismissed (why do the "
piggy-backed
" life expectancy genes have an exceptional linear correlation with size across all breeds? Why does the same exceptionally linear correlation also occur across mutts where the "
piggy-backed
" conjecture would not apply?

Darby wrote:
I wouldn't trust the whale data that much, since it would be largely anecdotal, limited mostly to limited numbers of captive specimens and captive species. I doubt that field studies are even now sophisticated enough to get reliable data on wild whales (and, since you have to wait for study subjects to die, even if they now have the means, it would take decades to amass the data).

You should publish a paper exposing this flaw. By using old photographs, log books and other recorded sources - the age of each animal is well established. (each whale has a unique dorsal fin and is as easily identified by experienced observers). This data is not questioned because of the extensive records kept on each mammal.

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