Natural selection favors individual birds that achieve the greatest lifetime reproductive success. The investments of males and females in small sperm and large eggs, respectively, drive different options, including their mating opportunities and how best to invest in quality offspring. Most birds pair with a single male and both then raise the offspring together. Both parents are needed to provide adequate care for their young. Females strive to protect their investments in large, expensive eggs. Males must balance the options of mating with extra females against caring for their own young. Conversely, females can improve the quality of their offspring through extra-pair copulations with high-quality males.
Comments
suggestion
You can combine both these sentences, "Most birds pair with a single male and both then raise the offspring together. Both parents are needed to provide adequate care for their young." You can say, "Most birds pair with a single male and both parents then raise their offspring together in order to provide adequate care for their young."
suggestion
"The investments of males and females in small sperm and large eggs, respectively, drive different options, including their mating opportunities and how best to invest in quality offspring." seems a little wordy maybe split it somehow
Suggestion
I feel ike the title does not tie into the overall paragraph. You mention a little about mating in the start but seeing as it is the title, I feel like it should fom the core of your paragraph.