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

Turtles Lizards, Snakes Crocodiles Birds

-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?

LDC=lactose digestion capacity

LDC = lactose digestion Capacity, so low LDC ~ lactose intolerant

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)

≈70 species ≈200 species

virginia Opposum

Feathertail glider

water opposum bandicoot

wombat

gray kangaroos

koala

Sugar glider Tasmaniand devil

honey possum

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 c. Paraphyletic d. Polyphyletic

Recent fossil evidence shows that the ancestors of whales were aquatic deer!

Whales are embedded within the even-toed ungulates. This makes the Artiodactyla?

Paraphyletic! (unless you want to refer to Whales as ungulates!)

Recent fossil evidence shows 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