user-1: We all know that scientific names must be italicised. However, Stack Exchange does not support markdown for question's title.
This can create a problem in questions like this one, in which I edited the genus and species names in the body of the question, but obviously I couldn't do the same in the title of the question. Technically speaking the title is wrong the way it is now (italicising the name is not optional: we must italicise it).
So, we can do two things regarding scientific names (and also genus names) in the question's title:

Nothing. Leave them the way they are now.
Propose an alternative to highlight the name.

I wrote highlight above because old people here (like me) will remember that, in the time of typewriters and before personal computers became popular, the rule was not italicising the name, but highlighting it somehow, and the most common way those days was using an underline (like B̲o̲s̲ t̲a̲u̲r̲u̲s̲).
Underlines as such were deprecated in HTML5 and don't work with markdown... even if they did we would face the same problem of using markdown in the title.
So, my suggestion is using quotation marks (") for highlighting scientific names in question's title.
That way, instead of something like this is the title:

How many teeth does Canis lupus have?

We would have:

How many teeth does "Canis lupus" have?

This suggestion, if agreed upon, is not for (normally new) users writing the questions, but for people editing them. 
Edit in 10/12/2017
So far we have two nice answers (one using LaTeX and other using Unicode). I like both, and we could reach a consensus. However, both of them have drawbacks, not working on all user agents (aka browsers) and OS.
Therefore, it seems to me that the solution will end up being doing "nothing", that is, leaving those titles the way they are now.
Edit in 12/12/2017
Unfortunately, Unicode is out: read this comment. This leaves us with LaTeX or "nothing", which increasingly seems to be the better option. 

user6307: This is not an answer, but I thought it may be useful to show, since it was suggested in the comments, what LaTeX would look like for this use case. Note that this may suffer the same pitfalls as outlined in this meta post.
$Canis\ lupus$

$Canis\ lupus$


user22057: This is really not worth bothering about. 
The standard of titles on SE Biology is in general awful: lack of initial capitals, lack of question marks and poor English. It would be nice if it were possible to apply more sophisticated markup to titles for other reasons (subscripts, Greek characters), but, until SE does that, there is nothing to be done. 
In my opinion energy would be better spent ensuring that titles are clear, appropriate and indexable.

user37000: Just use unicode
For example Canis lupus can be written as  . I did not use markdown for that, but unicode characters, which does work in question titles. You can use this utility to convert regular text to italic text (I was using the Math sans italic font). This one also looks good.

-1: <p>We all know that scientific names must be italicised. However, Stack Exchange <a href="https://meta.stackexchange.com/questions/237125/can-we-get-markdown-support-in-questions-title-field">does not support markdown</a> for question's title.</p>

<p>This can create a problem in questions like <a href="https://biology.stackexchange.com/q/68371/24284">this one</a>, in which I edited the genus and species names in the body of the question, but obviously I couldn't do the same in the title of the question. Technically speaking the title is wrong the way it is now (italicising the name is not optional: we <strong>must</strong> italicise it).</p>

<p>So, we can do two things regarding scientific names (and also genus names) in the question's title:</p>

<ol>
<li>Nothing. Leave them the way they are now.</li>
<li>Propose an alternative to highlight the name.</li>
</ol>

<p>I wrote <em>highlight</em> above because old people here (like me) will remember that, in the time of typewriters and before personal computers became popular, the rule was not <em>italicising</em> the name, but <em>highlighting</em> it somehow, and the most common way those days was using an underline (like B&#818;o&#818;s&#818;&nbsp;t&#818;a&#818;u&#818;r&#818;u&#818;s&#818;).</p>

<p>Underlines as such were deprecated in HTML5 and don't work with markdown... even if they did we would face the same problem of using markdown in the title.</p>

<p>So, my suggestion is using quotation marks (<code>"</code>) for highlighting scientific names in question's title.</p>

<p>That way, instead of something like this is the title:</p>

<blockquote>
  <p>How many teeth does Canis lupus have?</p>
</blockquote>

<p>We would have:</p>

<blockquote>
  <p>How many teeth does "Canis lupus" have?</p>
</blockquote>

<p>This suggestion, if agreed upon, is not for (normally new) users writing the questions, but for people editing them. </p>

<h3>Edit in 10/12/2017</h3>

<p>So far we have two nice answers (one using <a href="https://biology.meta.stackexchange.com/a/3773/24284">LaTeX</a> and other using <a href="https://biology.meta.stackexchange.com/a/3775/24284">Unicode</a>). I like both, and we could reach a consensus. However, both of them have drawbacks, not working on all user agents (aka browsers) and OS.</p>

<p>Therefore, it seems to me that the solution will end up being doing <em>"nothing"</em>, that is, leaving those titles the way they are now.</p>

<h3>Edit in 12/12/2017</h3>

<p>Unfortunately, Unicode is out: read <a href="https://biology.meta.stackexchange.com/questions/3772/scientific-names-in-questions-title-what-to-do?cb=1#comment5266_3775">this comment</a>. This leaves us with LaTeX or <em>"nothing"</em>, which increasingly seems to be the better option. </p>
 6307: <p>This is not an answer, but I thought it may be useful to show, since it was suggested in the comments, what LaTeX would look like for this use case. Note that this may suffer the same pitfalls as outlined in <a href="https://meta.stackexchange.com/a/237128/278314">this meta post</a>.</p>

<pre><code>$Canis\ lupus$
</code></pre>

<p>$Canis\ lupus$</p>

<p><img src="https://i.stack.imgur.com/B8pl3.png" alt="enter image description here"></p>
 22057: <p><strong>This is really not worth bothering about.</strong> </p>

<p>The standard of titles on SE Biology is in general awful: lack of initial capitals, lack of question marks and poor English. It would be nice if it were possible to apply more sophisticated markup to titles for other reasons (subscripts, Greek characters), but, until SE does that, there is nothing to be done. </p>

<p>In my opinion energy would be better spent ensuring that titles are clear, appropriate and indexable.</p>
 37000: <h2>Just use unicode</h2>

<p>For example Canis lupus can be written as  . I did not use markdown for that, but unicode characters, which does work in question titles. You can use <a href="http://qaz.wtf/u/convert.cgi?text=Canis+lupus" rel="nofollow noreferrer">this utility</a> to convert regular text to italic text (I was using the Math sans italic font). <a href="https://yaytext.com/bold-italic/" rel="nofollow noreferrer">This one</a> also looks good.</p>
