The bright colors and sweet smell of flowers attract animals that help the plant to Quizlet

Natalia Dudareva, an associate professor in the department of horticulture and landscape architecture at Purdue University, explains.

Flowers of many plant species produce a scent. This scent is typically a complex mixture of low molecular weight compounds emitted by flowers into the atmosphere and its structure, color and odor are critical factors in attracting pollinators. Although flowers can be identical in their color or shape, there are no two floral scents that are exactly the same because of the large diversity of volatile compounds and their relative abundances and interactions. Thus, scent is a signal that directs pollinators to a particular flower whose nectar and/or pollen is the reward. Volatiles emitted from flowers function as both long- and short-distance attractants and play a prominent role in the localization and selection of flowers by insects, especially moth-pollinated flowers, which are detected and visited at night. Species pollinated by bees and flies have sweet scents, whereas those pollinated by beetles have strong musty, spicy, or fruity odors.

To date, little is known about how insects respond to individual components found within floral scents, but it is clear that they are capable of distinguishing among complex scent mixtures. In addition to attracting insects to flowers and guiding them to food resources within the flower, floral volatiles are essential in allowing insects to discriminate among plant species and even among individual flowers of a single species. For example, closely related plant species that rely on different types of insects for pollination produce different odors, reflecting the olfactory sensitivities or preferences of the pollinators. By providing species-specific signals, flower fragrances facilitate an insect's ability to learn particular food sources, thereby increasing its foraging efficiency. At the same time, successful pollen transfer (and thus, sexual reproduction) is ensured, which is beneficial to plants.

Plants tend to have their scent output at maximal levels only when the flowers are ready for pollination and when its potential pollinators are active as well. Plants that maximize their output during the day are primarily pollinated by bees or butterflies, whereas those that release their fragrance mostly at night are pollinated by moth and bats. During flower development, newly opened and young flowers, which are not ready to function as pollen donors, produce fewer odors and are less attractive to pollinators than are older flowers. Once a flower has been sufficiently pollinated, quantitative and/or qualitative changes to the floral bouquets lead to a lower attractiveness of these flowers and help to direct pollinators to unpollinated flowers instead, thereby maximizing the reproductive success of the plant.

b. Adaptations to manipulate pollinators

The goal: Manipulate pollinators to visit individuals of your species more than other flowering species in the area (LOYALTY)
-minimizes LOSING your own pollen to other plant species
-minimizes RECEIVING pollen from other plant species

i. Floral size
Pollinators prefer:
-Larger individuals flowers, Larger inflorescences, more open flowers per plant
-Sterile edge flowers increase perceived size and attraction
-BUT, tradeoff; plants with multiple flowers must balance increased risk of self pollination
-some plants retain old flowers to increase floral display size

ii. Floral symmetry can affect how a pollinator approaches it and how it holds on and collects nectar and pollinates
(Radial symmetry, dissymmetry(2 planes think 4 quadrants), bilateral (one plane, mirror like reflection)

iii. Flower shape
Important b/c of where pollen makes contact with animal/ where it will transfer

Bilateral symmetry (zygomorphy)
~forces pollinators to enter in a certain way
~facilitates pollen deposition/retrieval on certain body part
~Pollinators learn an unusual shape: temporarily specialize on that shape b/c of experience

Flower depth/reward concealment
~resists spectrum of pollinators

Flower shape is very important with packaged pollen
~Pollen packets glue on and are pulled off: forcible removal required to transfer to other flower: placement is essential

Flower shape restricts pollinators:
~Pendant flowers: restrictive to only certain pollinators:
they have to hover, or not be too heavy. Requires pollinators to have a 'search image' for the less obvious flowers
~Changing flower shape or color:
Flowers 'indicate' to pollinators which have been visited least (open for less time)

iv. Flower color
~Many reflect UV; some pollinators only see in UV
~Distinct nectar guides (like maps on the flower) point pollinators to rewards
~Change individual flower color to indicate reward availability
~Color identity may be less important than simply distinguishing from surrounding flowers or areas
Ex. Long tongued African flies and the nectar guides on specific flowers sharpied out by researchers (they wouldn't feed without the guide marks)

v. Nectar
-Nectar is highly variable!
-Sugar type & concentration attract different pollinators
-Amino acids attract carrion-feeding insects-turned-pollinators
-Repellant compounds to deter unwanted visitors
-'Toxic' nectar can shorten individual visits, reduce nectar consumption & promote outcrossing

vi. Olfactory cues
Major classes:
mono- and sesquiterpenes,
fatty acid derivatives, phenolics, sulfides (smell like poo / decay)

Roles:
-long-distance attraction
(especially at night!)
-short-distance cue to orient to
specific flower parts
-repel unwanted visitors
-attract specialized herbivores
-communication between
pollinators Ex. Bumble bees smell floral odor on a successful nest-mate to make priorities on a foraging bout (may flock to the plant that give off that particular odor smelled on nest mate)

vii. Auditory cues
Flowers can deflect sound creating an acoustic guide

viii. Unusual rewards cater to particular pollinator tastes
~Resins and fragrances offered rather than nectar
~Specialized floral tissues
~amino acid
~heat
Ex. Beetles attracted to warm flowers that are in male phase: beetles will hang out and eat nutritious petals while being covered in sticky pollen: then the petals will drop off and make the beetle move on to female flowers which heat up 30 minutes after the male phase flowers eject them
Ex. Nursery mutualism: seeds
~specialized interactions
Ex. Fake sex: flowers that advertise themselves as females to attract males: they mate with the flowers and retrieve/deposit pollen