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I have this biology assignment with this chosen topic. I have no idea where to start researching. I have studied the mechanisms and theories of evolution. I just don't know which relates to the topic. The task is to persuade an audience of one side, either yes evolution produces perfectly adapted organisms or no evolution does not produce perfectly adapted organisms. I have started research on the blind spot of the vertebrate eye and that might be case scenario for the topic. If you have anything to add at all that would help me complete this project. It is much appreciated. Thank you in advance!

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closed as too broad by kmm, David, another 'Homo sapien', Bryan Krause, James Aug 21 '18 at 9:35

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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  • $\begingroup$ I'm voting to close this question as off-topic because it is not about Biology in the terms of SE Biology. $\endgroup$ – David Aug 16 '18 at 22:39
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Perhaps an angle which hasn't been covered yet, which can be used as an argument against the vague question "does evolution produce adaptations to better suit an organism's environment":

Sexual selection contributes to the acquisition of traits which are favorable in mate choice or competition for mating. For instance, ornaments such as antlers are considered attractive for others in the species (female mate choice); they also aid in male-male competition (resource-defense or female-defense mating systems)

Here is an excerpt from an essay I wrote many years ago:

Sexual selection in particular has the peculiar tendency to exaggerate traits even beyond their ecological optimums. [...] Megaloceros giganteus, the Irish elk, is an extreme example of a recently extinct animal (estimated to have disappeared 10,600BP) whose antlers and body size were grossly unfit for the increasingly distressing requirements of its woodland habitat. It stood at 210cm at the shoulders and its antlers spanned a width up to 365cm, weighing as much as 40kg. It is conjectured that extinction came as a result of the inability to further sustain the exaggerated trait, which required calcium and phosphorus replenishment as well as repletion of fat reserves from a rapidly shrinking high-quality forage density as a result of climate and eventual environmental change.

Of course, there are hundreds of examples of this. I just like the Irish elk. It was imposing, to say the least.

Irish elk to scale

I must also stress that your original question betrays ignorance on the topic. Evolution is not teleological, it has no end goal. Also, very crucially, the environment is ever-changing - abiotic factors such as temperature, as well as various pressures from other cohabitants in the ecosystem, are always changing. Perfection implies an end, stable state. A 'perfectly' healthy, immune individuals will eventually become vulnerable to a pathogen or parasite. Perfection is also subjective, and means nothing in biology. In photosynthesis, the theoretical maximum efficiency of solar energy conversion is approximately 11%. Yet plants are ubiquitous. Birds have light, hollow bones to aid in flight; the eyes of eagles are better suited for visual feats not shared by humans; cats have great night vision; bats have an expanded range of hearing due to their use of echolocation; insects have well-developed and highly sensitive olfactory systems, etc. None are perfect, and can always be improved upon, theoretically speaking. And what use is night vision if there is no night? What use are exceptionally light bones if you are a flightless bird such as an ostrich?

My answer to your question is this: evolution never produces perfect adaptations, it may only sometimes produce traits which, to humans, are impressively advantageous. Biology is full of imperfections; evolution can only work with pre-existing structures so it does not explore all possible solutions, where you could likely find something resembling perfection. Evolution produces organisms with traits which are or once may have been capable of allowing the organism to survive. Nothing more.

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You should most definitely have a look at a very introductory course to evolutionary biology such as evo101 for example.

Does evolution produce organisms perfectly adapted to their environment?

There is a lot to say about this question. The question is very broad and cannot be fully answered in a single post. The very very short answer is "no". I will very briefly develop this "no" below.

Concept of perfection

There are semantic (and hence philosophical) issues of the concept of perfection in this question but I shall not go into these issues. Typically, in the fact of sexual selection (and other arms race), the concept of "perfection" becomes very unclear (see S Pr's answer).

There is variation in populations

Evolution is all about genetic variance in populations. The fact that variance exists makes that necessarily there is no notion of perfectly adapted for a population (or for a species) as not all individuals are the same!

"Drivers" of evolution

Evolution is a change in allele frequency over time. There are a number of drivers of such changes, including natural selection, genetic drift and mutations.

While natural selection is a deterministic process, genetic drift and mutations aren't. There is hence constantly departure from a "hypothetical perfect" caused by genetic drift and mutations.

Mutations, while being a "random process" (see Are mutations random?), most mutations are deleterious, hence constantly inputting "imperfection" into populations.

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  • $\begingroup$ Hi Remi. I see what you're doing ;) You're stiff competition, friend! $\endgroup$ – S Pr Aug 15 '18 at 13:38
  • $\begingroup$ Sorry, I failed to refer to your answer. Obviously, I added a note inspired by your answer and I should have linked to your answer. Done, now! That being said.... Wow you've been fast at detecting it! $\endgroup$ – Remi.b Aug 15 '18 at 13:42
  • $\begingroup$ No problem, just joshing. I wanted to say hi because I see your answers quite frequently and I'm more-or-less a new person here. Hello! $\endgroup$ – S Pr Aug 15 '18 at 13:44
  • $\begingroup$ Another factor here is that natural selection pressure is asymptotic. Even if we could provide a constant environment, and define what is perfect adaptation to it, the closer individuals get to that perfect adaptation, the less pressure there is to improve. Reaching perfection would take infinite time, so evolution generally settles for "good enough". $\endgroup$ – jamesqf Aug 15 '18 at 17:28
  • $\begingroup$ @jamesqf Interesting point. While it is true that selection pressure decreases with decreases additive genetic variance and hence with increased allele frequency (past a certain frequency threshold that depends upon the dominance coefficients), a statement like "the more fit an individual is, the less likely it is for a new mutation to be very beneficial" would be true depending upon the mutational effect model considered. It is standard to use a geometric model and empirical estimates appear to be quite supportive of this model. $\endgroup$ – Remi.b Aug 15 '18 at 17:33
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The term "perfectly" is a problem because perfect adaptations may not be available via mutation and because the environment is constantly changing anyway, so what is perfect in one environment when selection occurred may not be perfect a minute or an hour later.

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