user1590: One of the big problems we are having is the number of poorly referenced answers on the site. They often make unsubstantiated and contentious claims without any supporting material, and that's not the standard we should be accepting. Until recently, we had three options on what to do with an uncited answer/statement:
i) Comment and request references, ideally drawing attention to specific points of contention
ii) Downvote (though an accompanying comment would be useful)
iii) Add references yourself to other peoples answers if you think you can provide the material needed
A recent feature was added whereby we could flag for moderator attention and a banner would be added below the answer.

Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

However, this has been largely ineffectual.* Most of these banners, along with comments and downvotes, are ignored by the original poster and answers continue to attract upvotes. If we continue to allow poor standards of content checking we'd be no better than PLoS One with the Creator's hand paper (or #AddMaleAuthorgate)...
I suggest we need to find a more effective way of enforcing the provision of citations and references where required.
I've posted some possible answers, but by no means do I think one or any are the perfect solution, and this should be a discussion - answer, comment, and edit posts as necessary (e.g. to add pro's and con's). This is intended to be an open discussion, and abstract and creative solutions are very welcome! Any weaknesses in solutions can be much more easily dealt with as a collective group.

Also it's key to discuss how much time is it fair to give a user to support their material with references before we were to start punishment?

* Examples: Answer 1, Answer 2, Answer 3, Answer 4, Answer 5, many answers here

user19099: Short answer- I think an effective method to solve this problem would be to lock upvoting and allowing only downvoting on unreferenced or poorly referenced answers till proper references are added (just like that line 'some parts of this answer require proper references...' is shown below such answers). Also, as @Chris said in comments, we can disallow answering by unregistered users.

Expanded by rg255:
Locking out (up)votes
Answers without suitable references can be locked from being (further) upvoted.
How it could work
Once the post has been flagged, and the citations needed banner added, we could simultaneously block upvoting on the answer. This would prevent further rep gain from answers until suitable references are added. Moreover, we could also stop -1 reputation fine on downvoting the answer. Many users avoid downvoting by the fear of getting -1, this could be prevented on answers lacking citations.
Pros

Prevents gain of rep from poorly referenced answers
Allows downvoting and feedback from the entire community (incl. low rep users)
Can be reversed

Cons

The post is still part of the wider community, and may be read (and treated) like a quality answer by visitors
No existing SE system


user1590: Deletion
Deleting answers which do not meet the referencing standards we strive for.
How it could work
High rep users can vote to delete the post on the basis of lacking (suitable) references. After 3-5 votes the post is deleted.
Pros

Existing system for votes to delete
Community democracy
Effective mechanism against regular users and one timers
Can be undeleted (?) so is reversible

Cons

OP would need to be given fair time and opportunity to make the requested edits, making it a slow response, allowing poor posts to persist for an unnecessarily long time in the public domain
Could remove content which has the potential to be good for the site (some answers just need some references to make them good - "diamond in the rough") so we would need to be cautious about what gets deleted


1590: <p><strong>One of the big problems we are having is the number of poorly referenced answers on the site.</strong> They often make unsubstantiated and contentious claims without any supporting material, and that's not the standard we should be accepting. <strong>Until recently, we had three options on what to do with an uncited answer/statement:</strong></p>

<p><em>i)</em> Comment and request references, ideally drawing attention to specific points of contention</p>

<p><em>ii)</em> Downvote (though an accompanying comment would be useful)</p>

<p><em>iii)</em> Add references yourself to other peoples answers if you think you can provide the material needed</p>

<p><strong>A recent feature was added whereby we could flag for moderator attention and a <a href="https://biology.meta.stackexchange.com/questions/3282/functionality-request-community-voting-for-answers-citations-need-banner">banner would be added below the answer</a>.</strong></p>

<blockquote>
  <p>Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.</p>
</blockquote>

<p>However, this has been largely ineffectual.<sup>*</sup> Most of these banners, along with comments and downvotes, are ignored by the original poster and answers continue to attract upvotes. If we continue to allow poor standards of content checking we'd be no better than PLoS One with <a href="http://www.independent.co.uk/news/science/scientific-study-paper-creator-intelligent-design-plos-one-creatorgate-a6910171.html" rel="nofollow noreferrer">the Creator's hand paper</a> (or <a href="http://www.sciencemag.org/news/2015/05/plos-one-ousts-reviewer-editor-after-sexist-peer-review-storm" rel="nofollow noreferrer">#AddMaleAuthorgate</a>)...</p>

<p><strong>I suggest we need to find a more effective way of enforcing the provision of <a href="https://biology.meta.stackexchange.com/questions/3334/when-are-citations-needed-in-an-answer">citations and references where required.</a></strong></p>

<p>I've posted some possible answers, but by no means do I think one or any are the perfect solution, and this should be a discussion - answer, comment, and edit posts as necessary (e.g. to add pro's and con's). <strong>This is intended to be an open discussion, and abstract and creative solutions are very welcome!</strong> Any weaknesses in solutions can be much more easily dealt with as a collective group.</p>

<hr>

<p>Also it's key to discuss how much time is it fair to give a user to support their material with references before we were to start punishment?</p>

<hr>

<p><sup>*</sup> Examples: <a href="https://biology.stackexchange.com/questions/42050/if-evolution-is-not-about-increased-complexity-why-does-so-much-complexity-evol/42064#42064">Answer 1</a>, <a href="https://biology.stackexchange.com/questions/43019/could-a-prolonged-amount-of-antibiotics-severely-affect-the-digestion-gut-microb/43057#43057">Answer 2</a>, <a href="https://biology.stackexchange.com/questions/42050/if-evolution-is-not-about-increased-complexity-why-does-so-much-complexity-evol/42053#42053">Answer 3</a>, <a href="https://biology.stackexchange.com/questions/17410/could-a-sperm-be-altered-to-contain-a-females-genetics/17412#17412">Answer 4</a>, <a href="https://biology.stackexchange.com/questions/37154/if-a-given-dna-oligo-is-an-aptamer-will-the-corresponding-rna-oligo-with-the-sa/37156#37156">Answer 5</a>, many <a href="https://biology.stackexchange.com/questions/10632/whats-a-non-allelic-gene">answers here</a></p>
 19099: <p><strong>Short answer-</strong> I think an effective method to solve this problem would be to lock upvoting and allowing only downvoting on unreferenced or poorly referenced answers till proper references are added (just like that line 'some parts of this answer require proper references...' is shown below such answers). Also, as @Chris said in comments, we can disallow answering by unregistered users.</p>

<hr>

<p>Expanded by rg255:</p>

<p><strong>Locking out (up)votes</strong></p>

<p>Answers without suitable references can be locked from being (further) upvoted.</p>

<p><strong>How it could work</strong></p>

<p>Once the post has been flagged, and the citations needed banner added, we could simultaneously block upvoting on the answer. This would prevent further rep gain from answers until suitable references are added. Moreover, we could also stop -1 reputation fine on downvoting the answer. Many users avoid downvoting by the fear of getting -1, this could be prevented on answers lacking citations.</p>

<p><strong>Pros</strong></p>

<ul>
<li>Prevents gain of rep from poorly referenced answers</li>
<li>Allows downvoting and feedback from the entire community (incl. low rep users)</li>
<li>Can be reversed</li>
</ul>

<p><strong>Cons</strong></p>

<ul>
<li>The post is still part of the wider community, and may be read (and treated) like a quality answer by visitors</li>
<li>No existing SE system</li>
</ul>
 1590: <p><strong>Deletion</strong></p>

<p>Deleting answers which do not meet the referencing standards we strive for.</p>

<p><strong>How it could work</strong></p>

<p>High rep users can vote to delete the post on the basis of lacking (suitable) references. After 3-5 votes the post is deleted.</p>

<p><strong>Pros</strong></p>

<ul>
<li>Existing system for votes to delete</li>
<li>Community democracy</li>
<li>Effective mechanism against regular users and one timers</li>
<li>Can be undeleted (?) so is reversible</li>
</ul>

<p><strong>Cons</strong></p>

<ul>
<li>OP would need to be given <em>fair</em> time and opportunity to make the requested edits, making it a slow response, allowing poor posts to persist for an unnecessarily long time in the public domain</li>
<li>Could remove content which has the <em>potential</em> to be good for the site (some answers just need some references to make them good - "diamond in the rough") so we would need to be cautious about what gets deleted</li>
</ul>
