phy

[moderator's note: Please note that sci.bio.evolution is a moderated
newsgroup; this post is well on-topic so I'll let it go, but any
discussion of creation/evolution controversies is banned. Stray off
topic and you'll be booted. - JAH]


I just wanted to cross-post this to sci.bio.evolution so you people could
get a lesson in how it *really* works.

-phy

brett aubrey

I wish that this post had a bit more context around it (What, for instance,
does the initial "No" relate to?) Also, from what group did this thread
originate?

My take on what's above - as a non-scientist - is that some is right and
some is not. I'll concentrate on the large paragraph near the end. The
statement around "if it's TOO easy to kill your prey..." seems right on to
me, but not the next part on nutrition - specifically: "the equation tends
to work out in such a way that the more difficult your prey is to kill, the
better it is (nutritionally) for you to eat." Predator/prey relationships
are more complicated than that (even with the "tends"), but the emphasis
realistically is more around ease and opportunity than it is around
nutrition. (While obviously nutrition is the whole point of any
predator/prey relationship, it's not a major deciding factor in who goes
after what.)

Take lions, for instance. They'll take down zebras, wildebeeste, kudu,
gazelles, cape buffalo and more. While taking down a cape buffalo is likely
more difficult than taking down 8 wildebeest, the 8 wildebeeste are better
for the pride in a number of ways (nutritionally, the total amount of food
is more, the ability to space out the eating over time is advantageous, the
reduced danger of widebeest over buffalo as prey, etc.)

Of course, from a purely "meat" perspective (pound for pound), I assume that
all are roughly equally nutritious, but what lions choose to go for largely
depends on *ease and opportunity*. I've seen lions go straight past zebras
and nail wildebeest, not (I don't think) because the wildebeest has any
greater nutritional value, but because there were so many of them that there
was a better opportunity in more easily splitting a huge wildebeest herd to
single out the unlucky victim than running down a smaller number of zebras.
There was surprizing efficiency displayed against wildebeest - one lioness
had a three or four minute fast jog which developed into a perhaps 10 second
sprint to nail its prey. (Had the wildbeeste not exhibited such blatant
herd mentality, they could have made it far, far harder for the lion.) When
I've seen lions get zebras, there was no large wildbeest herd around.

The upshot of all this is that even if there there could be a case made for
any relationship around how difficult your prey is to kill and how
nutritioius it is, this is not, IMO, of any real importance.

(The second last sentence in the same paragraph is a bit of a red herring in
most normal contexts, I think: predators will try to run anything down if
they're hungry enough; and the fatcats killing off all the prey is pretty
rare, unless the predator is human, or we're talking about unusual cases
like when the Isthmus of Panama was created to allow N. American predators
into S. America.)