CH. 4 (Geography of Life) Flashcards
What and where is the Juan Fernandez Archipelago?
4 land masses totalling 40 square miles 400 miles west of Chile. Home of marooned sailor Alexander Selkirk for four years. Home to many rare and endemic flora and fauna.
endemic
found nowhere else in the world
What does Juan Fernandez lack?
any native species of amphibian, reptile, or mammal
biogeography
study of distribution of species on earth
What can be used to estimate divergence time of species?
DNA, fossil records, and geography and plate movement (knowing where land masses were connected and how it coincides with fossils)
convergent evolution
species that live in similar habitats will experience similar selective pressures and will thus adapt in similar way (converging adaptation) even though they are unrelated
examples of convergent evolution
- sugar glider (marsup.) vs flying squirrel (placental)
- banded anteater vs anteater
- marsupial mole vs. mole
(each can thrive in the others environment)
How did marsupials get to Australia?
oldest marsupial fossils are in North America, they evolved and spread to SA (40 million years ago), crossed over Antarctica to Australia when they were connected (meaning there are marsupial fossils dating between 30-40 mil years old.
What is the Bering Land Bridge?
Connected Asia and NA (during ice age, ocean levels dropped and revealed land bridge that connected continents)
Where did humans evolve? What evidence do we have of this?
Humans evolved in Africa (Darwin made this prediction), fossils of earliest ape human transitional species in Africa.
continental island
island once connected to a continent but were later separated by rising sea levels that flooded land bridges or moving plates
Oceanic Islands
Islands never connected to a continent, arose from sea floor as growing volcanoes or coral reefs
Examples of continental islands and oceanic islands
cont. - Australia, Madagascar, British Isles, Sri Lanka, Japan, Tasmania
oceanic - Hawaiian Islands, Galapagos archipelago, St. Helena, Juan Fernandez
What happens when mammals, fresh water fish, and reptiles are introduced to oceanic islands and why?
They do extremely well and often wipe out native species. They are well suited for life on oceanic islands but the island ecosystems developed without predators and thus collapse
Adaptive radiation
process by which organisms rapidly diversify from ancestral species into multitude of new forms (especially when environment changes or niche opens up).
Examples of adaptive radiation?
- galapagos finches (of 28 species of bird on the islands, 14 of them are finches)
- Hawaiian honeycreepers (finch like bird)
What do oceanic islands have and what do they lack?
They have plants, insects, arthropods, birds (in short anything that can colonize over water or through long-distance dispersal) but do not have land mammals, reptiles, amphibians, or freshwater fishes (exception bats and seals which are mammals that can fly/swim)
Characteristic of plants and animals on oceanic islands?
Most similar to species found on nearest mainland (climates/environments might be different but the species evolve from others nearby)
What happens when you have a very old continental island?
Features of both oceanic and continental islands combine in very old continental islands. We see endemic species on very old continental islands because they’ve spent enough time geographically isolated.
Ex. Madagascar (lemurs most closely related to african species) and New Zealand (flightless birds like giant moa, kiwi, fat parrot, only a few endemic reptiles and two native mammals both bats)
