Also, heat measurements of zebra, impala, buffalo, and giraffe in the wild show that zebras are no cooler than these other species with whom they live.

划线部分是定语从句。with whom 是关系代词 whom 之前加了介词。they 指主语zebras “斑马”，whom 指文中提到的斑马以外的那些动物 these other species。