Lecture 10: Mammals (pp.757-759) Mammal evolution Mammals The bottom of the ocean is a nearly constant temperature. Hence, sea cucumbers living at the bottom of the ocean are BEST characterized as: a. ectothermic homeotherms b. ectothermic poikilotherms c. endothermic homeotherms d. endothermic poikilotherms Which of the following is NOT an amniote? a. Turtle b. Lizard c. Cat d. Bluejay e. Frog Figure 34-34 Reptiles Lizards, Turtles Snakes Crocodiles Birds LDC=lactose digestion capacity LDC = lactose digestion Capacity, so low LDC ~ lactose intolerant -lactose intolerance is a genetically determined trait -It has simple Mendelian genetics (tolerance is dominant, intolerance is recessive). -Lactose intolerance is the ancestral condition in humans -Lactose tolerance evolved twice in humans, why? Mammals can be divided into three large groups: 1) The monotremes (lay eggs, found only in Australia and New Guinea). 2) The marsupials (or Metatheria) 3) The Eutherians (or placentals) Monotremes inlclude the echidnas and platypus Short and long-beaked echidna Platypus Monotremes are oviparous (they lay a leathery egg). Platypus possess a spur connected to a venom gland and a rubbery bill with thousands of touchsensitive and electro-sensitive receptors. Choose the INCORRECT association: a. amphibians – tetrapods b. reptiles – amniotes c. lancelets – chordates d. lampreys - jawed vertebrates e. birds- bony vertebrates Some freshwater snails are brooders; they give live birth to offspring that are nourished inside a brood sac with yolk. These snails are best described as: a. Viviparous b. Aviparous c. Oviparous d. Vivoviparous e. Ovoviviparous Marsupials (≈270 species) Feathertail glider bandicoot water opposum virginia Opposum wombat ≈70 species ≈200 species honey possum gray kangaroos koala Tasmaniand devil Sugar glider Marsupial young are tiny at birth. Greater bilby (Macrotis lagotis) The Eutherians (placentals) complete their embryonic development within the uterus and are joined to their mothers by the placenta The Eutherians are diverse Whales are embedded within the even-toed ungulates. This makes the Artiodactyla? a.Aphyletic b.Monophyletic Recent fossil evidence shows c.Paraphyletic that the ancestors of whales d.Polyphyletic were aquatic deer! Whales are embedded within the even-toed ungulates. This makes the Artiodactyla? Paraphyletic! (unless you want to refer to Recent fossil evidence shows Whales as ungulates!) that the ancestors of whales were aquatic deer! Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Primates Family: Hominidae* Homo sapiens You will spend an inordinate amount of time studying this organism…. Fig. 34.38 .