sharing of parental roles and egalitarian nest building in couples

Prairie voles (Microtus ochrogaster) have long been of interest to neuroscientists and endocrinologists who study the social behaviour of animals, in part because this species forms monogamous pair bonds, essentially mating for life. The voles' pair bonding, sharing of parental roles and egalitarian nest building in couples makes them a good model for understanding the biology of monogamy and mating in humans.

Source: Nature Gene switches make prairie voles fall in love

I don't clearly understand "sharing of parental roles and egalitarian nest building in couples". Is the grammatical structure "sharing of parental roles and (sharing of ) egalitarian nest building in couples"? Does "in couples" mean "together with both the 'busband' and the 'wife' "?

GoodTaste said:

Is the grammatical structure "sharing of parental roles and (sharing of ) egalitarian nest building in couples"?

Click to expand...

The sentence refers to three characteristics of voles (note the possessive apostrophe in voles').
1. Pair bonding,
2. Sharing of parental roles (between the male and female partners), and
3. Egalitarian nest building [that is seen] in couples.

GoodTaste said:

and (sharing of ) egalitarian nest building in couples"?

Click to expand...

"Egalitarian" here means that they both take responsibility for nest building. "Sharing of egalitarian nest building" would be redundant and wrong.

GoodTaste said:

Does "in couples" mean "together with both the 'busband' and the 'wife' "?

Click to expand...

It refers to a male and a female who have mated.

GoodTaste said:

makes them

Click to expand...

This should be "make" (the plural form of the verb) as it refers to multiple characteristics.