BISC 120Lg Lecture Notes - Lecture 16: Sexual Dimorphism, Eutheria, Marsupial
Document Summary
Bisc 120: general biology: organismal and evolutionary biology- lecture 16: Mammals are typically defined by the presence of mammary glands. These are the first organisms we have discussed that produce milk. Mammals also tend to have hair, made of keratin. Hair and layer of subcutaneous fat to retain metabolic heat. Are cancer-free because they have a gene that kill the cells to prevent crowding (contact inhibition). If it becomes really cold, they will stop trying to produce enough heat and will become ectoderms so they are unusual in that way. Fertilization is internal, embryo develops in uterus. In eutherian (placental) mammals & marsupials lining of the uterus & extraembryonic membranes from placenta, which nourishes embryo. Generally larger brains with greater capability for learning. Relatively long parental care extends time for learning skills from parents. Feeding adaptations of jaws & teeth (differentiation)
