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Preparing for the AP Exam Visual Representation 2 Biodiversity in the Galápagos Islands: Biodiversity refers to genetic,
species, and habitat diversity. At each of these levels, biodiversity is a good indicator of environmental
health and a source of ecosystem services. The Galápagos Islands, located about 600 km west of South

Natural Disruptions Succession
The Islands originated from volcanoes. Bare rock is succeeded by pioneer species such as lichen, lava cactus,
Natural disruptions such as volcanic and carpetweed. Over hundreds or thousands of years, these plants
activity and weather pattern changes have die and create soil conditions in which small herbaceous plants such
affected ecosystems on the Galápagos. as common sow thistle and grasses such as Mexican lovegrass can
grow. Eventually these are succeeded by shrubs and small trees such Woodpecker
as leatherleaf and manchineel. Finally, in higher, humid zones a climax nch
forest can consist of a combination of plants including the giant daisy
trees, which are endemic to the Galápagos. Invasive Species
Some species brought to the
islands by humans have
become invasive and threaten
native plants and animals. Vegetarian
Among these species are
goats and blackberries. nch

Common
cactus
nch

Volcanic Lichens Small Shrubs and Daisy tree
rock herbaceous small trees forest
plants

Blue-footed Flightless
booby Sea lion coromant

Adaptations
Over time, organisms evolve adaptations
that help them survive and reproduce in a
speci c environment. For example, the Large ground
marine iguana, the only sea-going lizard nch
in the world, has adaptations that allow it Marine iguana
to dive into the ocean for algae and
seaweed and to expel excess salt.
The ightless cormorant evolved with
reduced wings and adaptations that allow
it to dive to the ocean oor to hunt for sh.

Evolution
Galápagos Genetic variation is at the heart of biodiversity
and makes evolution possible. The birds known
penguins as “Darwin’s nches” are all descendants of
one original nch. Over many years nches
Island Biogeography evolved adaptations to ll different ecological
Over 600 km from the mainland in South America, the niches on the islands. For example, the large
Galápagos Islands were initially populated by plants and ground nch has a bill adapted for picking and
animals that could reach them by oating, swimming, crushing seeds. In contrast, the woodpecker
ying, being blown, or carried. Some initial colonizers nch has a sharp bill adapted for extracting
evolved over time to take advantage of available and eating insects. The vegetarian nch has
resources, making the islands rich in biodiversity with evolved adaptations to pull buds off trees.
many species found nowhere else on Earth. Darwin’s nches continue to evolve today.
Uncorrected proofs have been used in this sample.
Copyright © Bedford, Freeman & Worth Publishers.
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