Transcript human interactions with plants, and pollination

Pollination: how to play the game
alternatives.
Some flowering plants have
reverted to use of wind. Flowers
very minimal
Ultraviolet patterns (right) that insects can see.
Red trumpet shaped flowers designed for hummingbirds.
Tropical Heliconia – flower designed to match hermit (hummingbird) bill
shape.
CP51: Perhaps the most
striking of all orchid flower
mimics are the Ophrys family
members that grow in Europe.
This specimen from Turkey
has flowers whose lips look
like the abdomen of a female
bee. The male bee's energetic
efforts to mate with it scatters
the pollen everywhere. The
orchid gets pollinated and the
frustrated bee gets nothing.
Natural selection has molded the flowers of
these orchids (many in the genus Ophyrys)
into mimics of the insects that pollinate
them. Horny male insects, thinking that the
petals are a female, land on them and
engage in fruitless attempts to copulate
(“pseudocopulation”). During the barren act,
the insects’ heads or bodies contact the
orchids’ pollen sacs, which break off and
attach to the insect. The frustrated insect
flies off, but soon tries to copulate with
another orchid, which puts the hitchhiking
pollen in contact with the new orchid’s
stigma. In such a way the bees/wasps
serve as “flying penises,” helping the
orchids have sex. Here are some
specimens:
Ophyrys insectifera (fly orchid), which deceives male digger
wasps.
Meat smelling flower – attracts flies
as if to carrion – a specialty
pollinator.
Human caused problems for plants
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Fire ( frequency)
Water supply
lowering of water table in Arizona
Diseases
dutch elm disease
new insects.
New Competators
Fire: if an area regularly burns, all plants
living there have a way of surviving.
- annuals as seeds
- perennials – resistant bark
- underground storage roots.
Number of fires has gone down
But severity of fires has gone up.
Reason: wood is a resource to be protected = prevent fires
Get fuel build up – now fires more severe that before.
Frequent fires keep fuel from building up – get rid of small plants, fire burns on
ground and does not crown (get to top of trees)
Natural forest
Widely spaced trees,
older trees. Ground fire
cannot reach branches.
If fuel buildup – trees burn –
If frequent fires – forest becomes
grassland
Local chaparral after fire; everything burns. If too hot,
sterilizes the ground.
In deserts, little soil moisture.
Plants must reach ground water for
supply. How deep is it??
Ground water use.
No rules about saving
any for organisms.
Western U.S.; less rain = more use of ground water, especially in
southwest.
Result: streams dry up, ground water is deeper – new seedlings cant reach it.
Desertification.
Result of lowering water table
Winners: annual plants and drought resistant (cactus)
Losers: trees and perennials
So savannas and dry area forests slowly turn into grasslands.
Arizona desert community – lots of perennials, can reach ground water
Arizona grasslands; annuals replace perennials when water table drops
Plant diseases - introduced
• Movement of plants from other continents
– brings diseases never seen before by
native plants.
• These diseases are in closely related
plants and can infect our plants.
Dutch elm disease in the U.S.
A fungus spread by bark beetles.
Even as a kid, there was something about the story of the American
Chestnut tree that made me yearn for a past I never knew. The blight
first appeared in Brooklyn in 1904, and within 50 years they were gone.
Millions of trees stretching from New England to Georgia, along the
spine of the Appalachians, spilling across the Great Lakes into Ontario,
and along the Ohio Valley, gone. Mere ghost trees, whose trunks still
exist, stumps ten foot in diameter, slowly succumbing to rot over
generations.
The Passenger Pigeon, once probably the most numerous bird on the
planet, made its home in the billion or so acres of primary forest that once
covered North America east of the Rocky Mountains. Their flocks, a mile
wide and up to 300 miles long, were so dense that they darkened the sky for
hours and days as the flock passed overhead. Population estimates from
the 19th century ranged from 1 billion to close to 4 billion individuals. Total
populations may have reached 5 billion individuals and comprised up to 40%
of the total number of birds in North America (Schorger 1995). This may be
the only species for which the exact time of extinction is known.
Chestnut blight; killed American chestnut.
Chinese resistant.
Another fungus
Red Gum eucalyptus – CMC campus
Lerps = an infectious aphid like organism (psyllid), finally arrived in California
from Australia
Lerps suck out plant juice – kill leaves, tree gets sick and less resistant to
disease as no leaves for photosynthesis.
Solution: bring in a parasitic wasp from
Australia to kill the lerps
Or ignore it. Why?