Have you ever wondered why some animals are solitary, while others are social? Let's consider these different hamsters, for example. Syrian Hamsters are territorial, therefore unwilling to share resources. Since they can't tolerate each other well, they will fight others entering their territory, and can injure each other, potentially fatally. On the other hand, Russian Hamsters typically live in small groups, sharing resources, and forming long-lasting bonds, especially with their mating partners.
Speaking of mating, you may have noticed that some animals exhibit something called Polymorphic Mating Systems, meaning that one sex, generally males, develop different phenotypes and mating strategies. In sea lions, for example, males are much bigger and have more powerful jaws and necks than the females. In terms of the different mating strategies, dominant males gather harems of females up on the beach and fight any challengers trying to take their mates. However, some non-dominant males stay in the water around these groups, as a strategy to mate with females who have left the beach temporarily. These distinct behavior strategies can affect an organism's fitness differently, and so o