Hi Folks,
I’m looking for a few examples of evolutionary specialisation being a disadvantage.
The one example I’ve got is the Cheetah, being able to run really fast has ther advantage that it can catch prey, but the disadvantage that it’s so winded that it often can’t defend its prey from scavengers. The fact that it also has a body optimisted for speed and not defence also contributes to this.
I’d also like a couple of example of extreeme over specialization.
Thanks so much for the help
schpat
Any number of symbiotic dependencies or host-specific parasitic relationships would seem to fit the bill - if your symbiote or host species goes extinct, you’re screwed.
Needless to say though that you’re only going to find things that are disadvantageous under certain conditions - if they were seriously disadvantageous in a general sense, they would cause extinction in short order. My boss once said to me that giraffes were the perfect example of an insoluble problem for the theory of evolution (for the record, he’s not a creationist), saying that it’s ridiculously implausible that something so unfit for survival could ever emerge as the end result of ‘survival of the fittest’ - I pointed out that if giraffes were truly unfit for survival, we just wouldn’t have any giraffes.
I agree with you about the giraffe thing, personally I think they’re adapted just fine to their environment.
I suppose another example of the evolutionary specialization as a disadvantage would be the sloth. It’s slow lifestyle enables it to live on the very little energy that leaves provide, but being slow leaves it vulnerable to predators.
I suppose as long as the benefits outweigh the disadvantages it’s a success.
Specialization is more of an advantage. Until. Conditions change.
Specialists shoot to extract the last drop of a given resource and that gives them a clear advantage over any other competitor (or allows them to tap an unexploited resource). The tradeoff is that they are less flexible to face changes in conditions.
That’s actually not true. Cheetahs are often seen resting after making a kill, but that’s so that they can cool down: running that fast produces deadly amounts of heat, and they’d die if they didn’t stop. Similarly, they never hunt for very long, since cheetahs run the risk either of overheating or of expending too much energy for the meal if they keep going.
Cite: (with cites of its own) Cheetah
Cheetahs are unable to defend their prey from some other predators such as lions and hyenas because they are weaker than them, not because they are winded. And this is part of the trade-off for their specialization - if they were much larger or were more heavily muscled, they wouldn’t be able to run as fast.
Specialization is not necessarly a disadvantage. Many specialized organisms are highly sucessful.
Hummingbirds are highly specialized to feed on flower nectar, yet there are more than 320 species of them, living from Alaska to Patagonia. Sloths are actually generalists in terms of diet, being able to feed on many different kinds of plants. In terms of biomass, they are the most abundant herbivorous mammals in the tropical forests of the New World. Cheetahs at one time had an very broad range, extending from Africa to southern Asia. Figs have an extremely close specialized relationship with their pollinationg fig wasps, but are one of the most successful plant groups in tropical forests.
Of course, if flowering plants or tropical forests disappeared entirely, hummingbirds and sloths would be in trouble. But this is not likely to happen any time soon.
Another example of a highly specialized species that is abundant in appropriate habit through most of its very large range, although the US population, which was small to begin with, has been in decline.
One current example would be a comparison between polar bears (Ursus maritimus) and brown bears (Ursus arctos)*. Although closely related and able to interbreed, polar bears are more specialized hunters of seals, relying on sea ice for rest stops while swimming after their prey. Within the bear family, they are the most carnivorous. Brown bears, on the other hand, are more omnivorous, and some subspecies get most of their calories from plant matter.
As has recently been reported, the US Interior Department want to list polar bears as threatened due to the melting of the sea ice they rely on while hunting. Grizzlies, though, seem to do quite well (as long as people don’t over hunt them as has been done in most of the lower 48 states).
*Grizzly bears are one N. American varient of the brown bear.
In a more general sense, how about flightless birds? On smaller islands with no major predator species, some birds lose the ability to fly. That’s sort of a specialization, in that the organism discards a trait that’s unnecessary to its environment. If that environment changes, e.g. larger predators are introduced, that specialization becomes a severe disadvantage.
http://www.blackwell-synergy.com/links/doi/10.1111/j.1523-1739.2004.00155.x/abs/
Just a glance through the abstract suggested that dietary specialization didn’t have much affect, but habitat specialization did.
I may have misread…but there it is.
Yeah, you’d have to be a dodo or somthing to give up flight! 
Thanks for all the replies,
however I think I didn’t state my question clearly enough. I suppose what I really meant was examples where and advantage leads to a direct disadvantage. Examples like the cheetah not being able to defend prey because of it’s built for speed and not fighting; or the sloth not being able to run from predators because it’s built to conserve energy. Obviously these disadvantages must be out weighed by the advantages or the species would not have experienced a net success.
I’m not really looking for examples where a change in the system has created the disadvantage.
I’m really sorry for not putting my point across properly and wasting you time, but again I thank you very much for the replies so far.
schpat
You can pretty much take any organism and identify aspects of its biology that are advantages or disadvantages depending on the context.
Rats are to an extent generalists (although they have highly specialized teeth) in that they are omnivores and can live in many different habitats. But they have disadvantages in that they don’t have wings so they can fly away from predators, nor great speeed so they can run away.
I’m sorry, but your question is much too broad to admit of a real answer.
If something evolves as and advantage, and the environment doesn’t change, then how can it be a disadvantage? Basically what you’re asking could apply to every animal that isn’t perfect-- ie, any animal that isn’t capable of doing every possibel things. Humans walk upright and have big brains, but that makes giving birth very difficult, and leaves us prone to back problems. Chimps don’t walk upright and have smaller brains, but which is the more successful species (in strict biological terms)?
all terrestrial animals lost their ability to breath underwater. A specialization that is a disadvantage (of sorts, I guess). I am not trying to be facetious, is it just that any adaptation can be seen as a disadvantage to the opposite conditions that led to it.
The only real straight out disadvantages would be those produced by sexual selection and even then, it is a frail case.
What about humans’ relative (physical) weakness? I’m sure people here could come up with several specifics, if this is what you’re looking for.
I’ve heard that bulldogs are the only dogs that can’t swim. I don’t know if that has anything to do with how they were bred, of if that’s the kind of example that you’re looking for, but I thought I’d throw it out there.
Bulldogs are the result of selective breeding, not evolution by natural selection. That’s a whole different kettle of (dog)fish. 
I think that perhaps you should give us an example of a species where you think that their advantages don’t leads to a direct disadvantage. All species are the reuslt of natural selection and as a result any advanatge came as a trade off against disadvantges. Placental mammals have an advanatge in that their young are better shielded from the envrioenment during development, but that is a disadvantage in giving birth. Elephants have an advanatge in large size but that is a massive disadvatage in that they can’t run. Cattle have an advantage in being ruminants but that leads to frequent cases of botulism.
I really don’t understand your question as phrased. Every single species has massive disadvantages that they took on in order to to achieve adaptiev advatages. No exceptions.
Humans aren’t physically weak, relatively or otherwise. With skeletal muscle making up over 50% of their body mass human males are amongst the strongest animals on the planet, weight for weight. Only the cats and (arguably) some of the great apes are stronger.
Really? Can you cite something to back that up? Canids aren’t also stonger, weight for weight. And other primates besides great apes? And many insects?