Download Chapter 24-Flowering Plant and Animal Coevolution coevolutionary

Chapter 24-Flowering Plant and Animal Coevolution
coevolutionary plant-animal associations
These examples show that plants have acquired traits that are attractive to particular animals, and the
animals’ behavior has evolved in ways that benefit plants.
-Fleshy fruits are evolutionary products of plant-animal
dispersal relationships.
Flowering plant-animal coevolution interactions are important in agriculture
The production of crops such as apples, cherries, and
other fruits rely on bee pollinators.
Co-evolution is important in global ecology
The continued existence of most flowering plants
depends on appropriate pollinators or dispersal agents.
Some plants rely on only a single species of
pollinator or dispersal agent.
If the population of a single pollinator or dispersal agent
declines or becomes extinct:
Ex: Brighamia, a Hawaiian flowering plant
-the population of any animals that rely on the plants for food may also
decrease or become extinct.
This plant has stopped reproducing naturally because the specific pollinator has become extinct.
It is important to understand the processes of pollination, dispersal, and coevolutionary interactions for:
-preservation of endangered plant and animal species
-restoration of damaged or altered habitats
-maintaining global biodiversity
Pollination
If pollination is accomplished and pollen and stigma are compatible, a pollen grain will germinate to form a pollen tube.
The sperm cells are then transported to egg cells within ovules in the ovary.
The flower is an adaptation that increases the efficiency of pollination.
Most angiosperms produce bisexual flowers.
Bisexual flowers are comprised of:
Bisexual flowers are both common and ancient.
The oldest living groups of flowering plants (Amborella
and some water lilies) have bisexual flowers.
Reproductive strategies
Some plants are self-fertile, and capable of self-pollination and self-fertilization.
Self-pollination (selfing)
Selfing results in reduced genetic diversity of the offspring compared to cross-pollination.
Many plants are capable of selfing, including many weedy species.
Reproductive strategies- Self pollination
Disadvantages
Advantages
• reduced genetic diversity
• only a single plant is
required for pollination
• less energy
• low population densities
• plants that invade new or
disturbed habitats.
Some common plants generally reproduce by selfing, including beans, peas, and tomatoes.
A few extreme examples of self-pollinating plants produce flowers that never open.
Almost all self-pollinating plants have flowers that are less showy than their cross-pollinating
relatives.
Cross-pollination (outbreeding) -
Reproductive strategies- Cross-pollination
Advantages
increased genetic diversity
Disadvantages
energy expenditure
Many plants have mechanisms to increase the chance of
cross-pollination even though they may be capable of selfpollination.
The most obvious mechanism to insure cross-pollination
is the separation of the sexes into different individuals
(dioecious plants).
The willows are dioecious, with
separate male and female
plants.
Self-pollination can be prevented (or greatly reduced) in monoecious plants by various factors including:
1)Different timing of production of pollen and the receptivity of the stigma
2) A genetic system that prevents the elongation of the pollen tube on a stigma of the same plant (selfincompatibility) (b)
3) A genetic system that prevents genes expressed in cells at the stigma surface allow genetically distinct
pollen from flowers of the same species, but not genetically identical pollen (a)
A flower’s own pollen can begin to grow through
the style toward the ovary.
Enzymes produced within the pollen tube destroy
pollen-tube RNA, which causes the tube to stop
growing.
These early roadblocks prevent the formation of unhealthy, inbred embryos, allowing eggs the change to successfully
outbreed.
A number of plants do not require pollination at all to produce seeds.
Apomixis is the general term for this type of reproduction,
Although there are showy flowers produced, pollen is not actually
involved in seed production and offspring are clones of the single
parent plant.
In many plants, pollination is affected by vectors.
A vector is some factor, either biotic or abiotic,
Different flowers have features that adapt them to pollination by different types of vectors.
The set of flower and pollen traits that adapt a plant for pollination by a particular vector is its pollination syndrome.
This system almost always includes some kind of reward for the vector, such as nectar or pollen.
Flower color
Beetles, flies and bats are generally not attracted by flower color.
Plants pollinated by these vectors have dull colored flowers.
Visual pollinators often prefer different colors.
Bee flowers are often blue (and generally ultraviolet), whereas bird flowers are red or orange.
Nectar guides
Nectar guides are generally present
Patterns on flowers act
somewhat like a “bull’s eye”
guiding the pollinator to the
nectar reward.
In some bee flowers, the nectar
guides are most visible with UV light.
Bees can see in the UV spectrum.
Odor
Pollinators that are not attracted by colors are usually attracted by strong odors.
They can pick out pale or white flowers, but they are strongly attracted to sweet odors.
Nectar and Pollen
Most biotic
vectors are
rewarded with
nectar.
The nectar is usually “hidden” so that only the vector with special structures can access the nectar.
This feature is best seen in butterfly and moth flowers, where nectar often is in
deep spurs that require a long proboscis to access.
Pollen is another reward for vectors, but the amount varies among the flower types.
Beetle and bat flowers typically have the most pollen reward.
Flower shape
Flower shape is also quite different for each type of pollinating vector.
Beetle Flowers
The flower is regular, with a dish shape.
There is abundant pollen and numerous stamens and pistils.
The beetles are attracted to the flower by the abundant
pollen and can often eat significant portions of the flower.
Nasturtium
Fly Flowers
The main feature of fly flowers is their stench
of putrid meat.
This attracts the flies without requiring a
reward.
The largest flowers are fly flowers found in the tropics.
Bee Flowers
Bee flowers come in many colors and
shapes, but they do not have spurs that are
found in butterfly and moth flowers.
Abundant high-sugar nectar is normal.
Butterfly and Moth Flowers
These two flower types often
have similar tubular shapes, but
butterfly flowers are adapted to
the visual foraging of butterflies
and moth flowers are adapted
to the nighttime foraging of
moths.
Bird Flowers
Bird flowers are often pendant (hang
downward) and tubular.
The bird vectors have long, thin
beaks to access the nectar.
Bat Flowers
Bat flowers are fairly
common in the tropics.
Most are pendant, large
flowers that open at night.
Wind Flowers
Wind pollinated flowers are not showy, produce massive
amounts of pollen, and have the anthers and stigmas
exserted (emergent from the flower)
Water is also a pollen vector in a few plants.
Vallisneria male and female flowers
Study outline-Chapter 24 Flowering Plant and Animal Coevolution
Understand the importance of coevolutionary plant-animal associations
-agriculture
-gardening
-global ecology
Understand the importance of processes of dispersal, pollination, and coevolutionary interactions for:
-preservation of endangered plant and animal species
-restoration of damaged or altered habitats
-maintaining global biodiversity
Understand the importance of pollination for seed production
Understand the different reproductive strategies of self-fertilization and cross-pollination (outbreeding)
Understand different types of biotic and abiotic vectors for pollination
Understand pollination syndromes: traits of flowers pollinated by different vectors
-flower color
-nectar guides
-odor
-nectar and pollen
-flower shape-beetle, fly, bee, butterflies and moths, birds, bats, wind and water
Study outline for Chapter 24 Flowering Plant and Animal Coevolution
Define coevolutionary plant-animal association .
Name three examples of coevolutionary plant-animal associations.
Why is co-evolution is important in global ecology? Give an example.
Why is it important to understand the processes of pollination, dispersal, and coevolutionary interactions?
Define pollination.
Define self-fertilization (selfing).
Define cross-pollination (outbreeding).
Describe the different reproductive strategies of self-fertilization (selfing) and cross-pollination (outbreeding).
Define apomixis.
Define vector. Give an example.
Define pollination syndrome.
Fill in the information below for the following vectors: bees; beetles; flies; bats; birds; butterfly; moth ; and wind.
Flower color:
Nectar:
Flower shape:
Pollen: