Geology Reference
In-Depth Information
Pangaea broke apart and moved around, new habitats were created on land as well as in
the sea. In response to these new habitats, it appears that plants evolved two specific
characteristics that proved very advantageous:
Enclosed seeds:
Seeds that are
enclosed
or protected by a shell can travel longer
distances and survive through poor environmental conditions longer than unen-
closed (and therefore unprotected) seeds. This means that they can wait until
conditions are just right to begin growing a new plant.
Flowers:
Flowers provide food to insects. In exchange, the insects carry pollen
from one plant to the next, acting as the fertilizing agents of plant reproduction.
This gives flowering plants a huge advantage, spreading their genetic information
and reproductive success far and wide across the landscape.
Evolving together: Flowers and insects
The evolution of flowering plants and the evolution of insects are closely intertwined, so much so that
scientists call it
co-evolution.
This symbiotic relationship benefits both of them: Flowers provide food
for the insect, and when the insect collects that food, it unknowingly carries the plant pollen from one
flower to the next. In this way the insect is an important part of the plant's reproductive system. This
relationship began in the Mesozoic. Once they were entwined, the fates (and evolutionary character-
istics) of flowers and insects continued to shape each other for millions of years.
I'm sure you've noticed the wide range of flower diversity: They are different shapes, sizes, colors, and
scents, and they even bloom at different times of the year. Each of these characteristics evolved to en-
tice a particular insect into a reproductive dance with a particular flower. For example, bees cannot
see the color red, so bees are usually attracted to blue or yellow flowers. When a bee lands on one of
these flowers, the pollen, which must be carried to another flower in order to produce a seed, sticks to
the legs of the bee and flies with it to the next flower. A close look at the shape, size, and features of
some pollen grains makes it clear that they have evolved to hitch a ride with visiting insects and travel
to the next flower.
A more spectacular example is the Stinking Corpse Lily. Yes,
corpse,
which means dead creature. The
Stinking Corpse Lily is a large, odorless flower most of the time. But when it is ready to reproduce it
blooms, it sends out a strong scent — the scent of something dead and rotting. This scent attracts flies,
who love a dead, rotting corpse for dinner. When the flies swarm onto the flower, they pick up its pollen
and carry it with them to the next Stinking Corpse Lily they find.
More recently, this type of co-evolution has also been seen in birds and flowers — for example, in
hummingbirds and the large, red flowers they drink nectar from. Unlike bees, they can see the color
red, and the beak of a hummingbird is long and thin, perfect for dipping into the bright red bell-shaped
hibiscus flower.
