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Chapter 4

BIO120H1 Chapter Notes - Chapter 4: Cactus, Glossopteris, Glyptodont

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June Larkin

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Chapter 4 the geography of life:lec 2 The main lesson from this chapter is that only evolution
can explain the diversity and distribution of life on continents and islands. Topics included in the
chapter include convergent evolution, dispersal to islands and how it favours some groups and not
others, human origins in Africa, and differences in the biotas of continental vs. oceanic islands
-Some of the loneliest places on earth are the isolated volcanic islands of the southern oceans
-Alexander selcraig sailing on ship demanded to be put on shore hoping for rescue of the
Clinique ports to take him on from the mas a tierra island
-Mas a tierra was unhabited and the only mammals were goats, rats, and cats
-After a while Selkirk adapted to the ways of life by hunting goats
-He was rescued by 1709 spending 4 and a half years there by a English ship and headed t
-When there he made a journals of his adventures called The Englishman but he could not
adapt to ashore so he returned to sea and died in 1720 from fever
-Selkirik was a story of contingencies and time
-Selrick did not know that mas a tierra now called alejandro Selkirk was inhabited by earlier
decendedents of castaways –plants, birds, insects who found their way thousands of years
before silkirk
-He was living in a lab of evolutionary change
-The island juan Fernandez has rare and exotic plants and animals that are endemic- found
nowhere else in the world
-These include species such as 5inch rust brown humming bird 126 plants , fur seal, and
handful of insects
-The island however is missing many things such as: amphibian, reptile, or mammal –groups
common on continents around the world
-This endemic, and absent groups are repeated over and over on oceanic islands giving
evidence for evolution
-It was Darwin who took a look at these patterns and realized that evolution was necessary not
just to explain the origins and forms but of plants and animls but also their distribution
around the globe
-Darwin answered questions as to why this is the way it is in origins by the field of
biogeography- study of distribution of species on earth and evolutionary explanation of geo
of life
-Roots of biogeorgraphy lie deep in religion because natural theologian tried to show
distribution of organisms can be reconciled with noahs ark in the bible – all animals were
descendents of the paris noah tool aboard but explanation had problems – how did kangaroos
and earth wroms come from ocean to Australia??
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