First, though it is indicated by an apostrophe in modern texts, elision also occurs in ancient Greek poetry. The rules were different from Latin, though. I quote Smyth for them:
Elision is the expulsion of a short vowel at the end of a word before a word beginning with a vowel. An apostrophe ( ’ ) marks the place where the vowel is elided.
Elision of a vowel (or vowel + m) occurs when it's at the end of the word, and the next word starts with either a vowel or h + vowel.
At the discretion of the poet, the last vowel of a word can be kept even if the next starts with one; in this case, it's considered to be in hiatus. However, this is very, very rare.
However, if the second word is a form of ...
This is discussed in great detail in Allen’s classic Vox Latina ch. 4. His conclusion is (briefly) that a final short vowel followed by another vowel in the next word was elided (elisio), but a long vowel in the same position was reduced to a semivowel (synizesis).
It seems to have been a long process, but apparently there was was a trend towards using less elision that started before the end of Classical Latin.
The article Elision and Hiatus in Latin Prose, by Andrew M. Riggsby (Classical Antiquity, Vol. 10, No. 2 (Oct., 1991), pp. 328-343) refers to E. A. Sturtevant and R. G. Kent's "'Elision and ...
It's a hiatus because it's located at the principle caesura:
et vera | inces|su patu|it dea. || Ille ubi | matrem
In fact, Lodge specifically references this line in the section on hiatus, as I'm sure do a few others.
Note that hiatus isn't impossible anywhere, but it's common specifically here. The grammars will typically say "most" or "usually", and I'...
Elision in Latin is a complicated topic and I only know basic information about it.
I think it is normal in any period to elide final -ae, as in meae, before a following vowel.
András Cser ("Aspects of the Phonology and Morphology of Classical Latin", 2016) puts it like this:
Word-final [aj] is elided in poetry just like any vowel (including the nasal ...
The shorter ac is not the same thing as atque with elision.
The former is a short (light) syllable, the latter a long (heavy) one.
Latin seems to want to preserve syllable length in sound changes, so its importance is not limited to poetry.
So yes, the -e will be elided, but there still is a difference between atqu' and ac.
The original form is atque (at+...
I haven't read any linguist's comments on this matter, so my post is just a collection of guesses.
Perhaps for grammatical reasons
Elision frequently deletes vowels that are part of grammatical endings, or sometimes part of highly grammaticalized monosyllabic words such as est (with "prodelision"). Grammatical endings often have a certain amount of ...