Chapter 4 - The Geography of Life

Question 1

Alexander Selcraig / Alexander Selkirk

Answer 1

• Real life Robinson Crusoe.
• 1600s/1700s.
• Spent 4.5 years in solitude in Más a Tierra island in the Juan Fernández group.

Question 2

Endemic

Answer 2

Found nowhere else in the world.

Question 3

Juan Fernández

Answer 3

• 4 islands.
• No comparable area anywhere in the world has so many endemic species.
• It harbors not a single native species of amphibian, reptile, or mammals.
• This pattern of bizarre and efflorescent forms of endemic life, with many major groups strikingly absent, is repeated over and over again on oceanic islands.

Question 4

Island evolution

Answer 4

Oceanic islands are missing many types of native species that we see on both continents and continental islands.

• Compared to other areas of the world, life on oceanic islands is unbalanced.

Native: Plants, Birds, Insects and other arthropods.

Missing: Land mammals, Reptiles, Amphibians, Freshwater fish.

Species in the first row can colonize an oceanic island through long-distance dispersal; species in the second row lack this ability.

Terrestrial mammals are not good colonizers, and that’s why oceanic islands lack them.

But they don’t lack all mammals: Bats, Aquatic mammals (seals).

Question 5

Biogeography

Answer 5

The study of the distribution of species on Earth.

Biogeography not only makes predictions, but solves puzzles.

Question 6

Continental drift

Answer 6

a

Question 7

Molecular taxonomy

Answer 7

a

Question 8

Convergent evolution

Answer 8

• Species that live in similar habitats will experience similar selection pressures from their environment, so they may evolve similar adaptations, or converge, coming to look and behave very much alike even though they are unrelated.
• Polar bears & snowy owls are both white but not the same species.
• Convergent evolution demonstrates three parts of evolutionary theory working together:
  1. Common ancestry
  2. Speciation
  3. Natural selection

Question 9

Speciation

Answer 9

Speciation is the process by which each common ancestor gives rise to many different descendants.

And natural selection makes each species well adapted to its environment.

Question 10

Gondwana

Answer 10

Asia and North America were once well connected via the Bering land bridge, over which plants and mammals (including humans) colonized North America. And South America and Africa were once part of Gondwana.

Question 11

Humans evolved from Africa

Answer 11

• The co-occurrence of fossil ancestors and descendants leads to one of the most famous predictions in the history of evolutionary biology— Darwin’s hypothesis, in The Descent of Man (1871), that humans evolved in Africa:

Question 12

Continental Islands

Answer 12

Those islands once connected to a continent but later separated either by rising sea levels that flooded former land bridges or by moving continental plates.

(British Isles, Japan, Sri Lanka, Tasmania, and Madagascar.)

Question 13

Oceanic Islands

Answer 13

Never connected to a continent; they arose from the sea floor, initially bereft of life, as growing volcanoes or coral reefs.

(Hawaiian Islands, the Galápagos archipelago, St. Helena, and the Juan Fernández)