 Modern @-@ day cetacean evolution is largely affected by local culture and social network . Tool @-@ use for foraging in certain societies affects the diet , and allows them to access more varieties of food . This behavior is passed down from mother @-@ to @-@ child , as in the bottlenose dolphins residing in Shark Bay , where many use sponges to protect their beak while foraging . Social bonds between dolphins in a pod can affect overall fitness in a habitat , decreasing or increasing the survival chances for any particular individual in that pod . Social bonds between different species can sometimes cause interbreeding , which always results in infertile hybrids when it occurs . 
