Transcript STATION ONE - IISME Community Site

STATION ONE: Study this picture of the environment of
Galapagos Opuntias (prickly pears).
List at least 3 challenges the cacti would face living in this
environment.
STATION TWO:
Cacti are plants
(Kingdom Plantae). They
have the same
structures as all other
plants, but the structures
have been modified.
In this lab, you will see
modifications of the
stem, leaf and tissues in
Cacti.
A TYPICAL PLANT
Make a sketch of the piece of Opuntia
cactus at this station (cactus or photo).
Label your sketch using the
drawing above.
STATION THREE (1):
STEMS
The CLADODES (or pads) of Opuntia look like leaves but
they are actually modified stems. This is known from the way
they grow and from the tissues that carry water and carry out
photosynthesize inside them.
The trunk and leave-like pads are
considered homologous structures to the
stem of a typical plant.
STATION THREE (3): Stems of Opuntia are green.
They have tiny openings called stomates that let in carbon
dioxide needed for photosynthesis. These are usually
found on leaves.
stomates
During the evolution of cacti, the genes
for making stomates became active in
stems, when they are usually only active
in leaves. This is an example of a
homeotic mutation that was beneficial.
STATION THREE (2):
Stems
The cactus pads are round and fleshy so they have less
surface area - this reduces water loss. They also have a
waxy covering called the cuticle.
http://www.sbs.utexas.edu/mauseth/researchoncacti/cortex%20text.htm
How do the rounded shape of the cactus
pads and the waxy cuticle help the
cactus survive?
STATION FOUR (1):
LEAVES
The leaves of cacti are the spines. They contain all the
tissues normally found in green leaves. Leaves have been
modified for different uses in cacti such as defense against
herbivores and protection from the sun.
,
The tiny hairs are called glochids.
STATION FOUR (3):
The trunks of tree cacti are
covered with spines.
How do the spines and glochids help
the cactus survive in its environment?
STATION FIVE:
REPRODUCTION
Opuntia reproduce both sexually and asexually.
Sexual Reproduction:
How do offspring produced by sexual
reproduction compare genetically to the
parent plants? How could this help the
parent (and species) survive genetically?
STATION FIVE (2):
POLLINATORS
Cacti depend on pollinators to move pollen from one plant
to another to increase genetic variation in their populations.
Flashy flowers and nectar attract
pollinators.
STATION FIVE (3): ASEXUAL REPRODUCTION
Opuntia can reproduce asexually from fruits or pads that fall
from the parent plant.
New plants can
sprout from nodes
called aureoles.
watchingtheworldwakeup.blogspot.com
How do asexual offspring compare
genetically to the parent plant?
treeandplantnursery.com
How could asexual reproduction help
the parent plant survive?
STATION SIX: PHOTOSYNTHESIS
Cacti save water through a special form of
photosynthesis called CAM:
Plants need carbon dioxide from the air - but they
can dry out getting it!
STATION SIX (2):
Cacti take in carbon dioxide at night, when evaporation is
less, and store it in a C4 molecule to use during the day.
How does CAM photosynthesis help the
cactus survive and reproduce in its
environment?
STATION SEVEN (1): GROWTH FORM
Growth form refers to the shape of the plant. Tree cacti
have a tree-like or arborescent growth form. Some
Opuntia in the Galapagos have a bush-like form called
decumbant or prostrate.
ARBORESCENT
DECUMBENT
How is the arborescent growth form
an adaptation to their environment?
Frank J.Sulloway
http://www.skeptic.com/eskeptic/06-07-28/
STATION SEVEN(3):
Giant tortoises like to
eat cladodes that fall
from tree cactus. They
will eat the low-hanging
cladodes of the cacti.
Which islands have tree cacti on them?
How is the arborescent growth form an
adaptation to their environment?
STATION SEVEN (4)
+
+
X
STATION EIGHT: HUMAN USES OF OPUNTIA
Which of these are actually uses for prickly pear
cacti?
Fruit
Clothing
Vegetable
Anti-erosion
Source of dye for food Making bricks
Diabetes treatment
Decorative Garden
Plant
Vitamins
Alcoholic beverage
STATION EIGHT(2): HUMAN USES OF OPUNTIA
ANSWERS:
 Fruit
 Vegetable
 Source of dye for food
 Medicines
 Decorative Garden Plant
 Toothpaste
 Clothing ?????
 Anti-erosion
 Making bricks
 Vitamins
 Alcoholic beverage
STATION EIGHT(3):
Beetles grown on prickly
pear make an organic red
food dye. Mmmmmm!
STATION EIGHT (4):
Used to help stop desertification and provide food for animals.
http://www.fao.org/DOCREP/005/Y2808E/y2808e0d.htm
Can these human uses of Opuntia be
considered an adaptation of Opuntia??
Why not?
STATION NINE: CONSERVATION
In the Galapagos, Opuntia species are
affected by human impacts:
Habitat loss Farms displace natural
communities.
Invasive species  Goats, donkeys, pigs,
horses all eat Opuntia.
Climate change  El Nino rains and storms
can knock over tree cacti
STATION NINE (2):
STATION NINE (3):
Climate Change
• More frequent EL
NIÑOS
• Sea level rise
• Increased rainfall
Cacti live near the ocean. Their
habitat will be reduced by sea
level rise.
Cacti swell with water when it
rains and can topple over.
High winds can knock large cacti
over.
STATION NINE (4):
STATION 8: CONSERVATION
Vulnerability is mainly
Caused by habitat loss
or destruction.
Critically Endangered means that a
species' numbers have decreased, or
will decrease, by 80% within three generations.
An endangered species is
a population of organisms
which is at risk of becoming
extinct .
STATION 9 (last!): CONSERVATION
The six species of prickly pear cacti in the Galapagos are threatened by
habitat loss, invasive plants and animals.
SPECIES
Genus species
IUCN STATUS
Opuntia helleri
VULNERABLE
Opuntia galapageia
ENDANGERED
Opuntia insularis
ENDANGERED
Opuntia megasperma
VULNERABLE
Opuntia saxicola
Opuntia echios
CRITICALLY ENDANGERED
VULNERABLE
What are the threats to survival of Galapagos
Opuntia species?
What is a good reason to conserve these species?
Exit slip:
Describe an adaptation of Opuntia. Give the
specific environmental challenge it helps
the plant cope with and tell why it is an
adaptation.