Lecture 2 part 2 Floral biology and pollination Flashcards
(31 cards)
What is name for pollination by insects?
entomophily
What are the three main classes of flower visiting insects?
Hymenoptera (social/solitary bees and wasps).
Diptera (Flies).
Lepidoptera (butterflies and moths).
How are flowers generally structured for insect pollinated species?
Insect pollinated species generally have large vividly coloured flowers which can be seen from afar. If the plant has evolved small flowers, then they are usually in the form of an inflorescence (a bunch).
What vision are insects most efficient in?
Since insect vision is most efficient in the blue/UV region of the electromagnetic spectrum.
What colour are the majority of insect pollinated species flowers?
So the majority of insect pollinated species have yellow, blue or white flowers.
How does the shape of the perianth varie?
The shape of the perianth varies according to the species of insect that has coevolved to pollinate a particular flower species.
What are flower scents?
Since most insects have a good sense of smell, so perfumes have evolved as attractants. These flower scents are volatile essential oilts
What is known of the ecology of scent production for flowers?
Little is known of the ecology of scent production by flowers. Diurnal (follow 24 hour cycle) species emit scent in daytime (Roses), where as nocturnal species produce scent at night (Durio spp).
How does scent of nocturnal flowers differ from day flowers?
The scent of nocturnal flowers differs from day flowers: Night flowers are very sweet compared to the day flowers spicy smell (Bat pollinated flowers are sour/mousy in smell).
Define deception and given examples
Deception - this is performed in a variety of ways by both pollen flower and nectar flower species.
E.g. certain pollen flowers replace fodder pollen by structures mimicking full anthers to attract and thereby “trick” pollinators; the most bizarre deception is the sexual deception performed by certain orching species.
Give more examples of deception
For example the European mirror orchid (ground dwelling plant about 1 foot high which produces few flowers on a single stem).
Describe the mirror orchid flowers
The mirror orchid flowers have an oval lip that glistens with a metallic blue-violet colour, and has a yellow border fringed with long red hairs. Each flower actually looks like species of wasps and bees native to the region in which the orchids grow. The function of this mimicry is amazing
What is the first reason for how and why did birds evolve to become pollinators?
Among the hypotheses proposed to explain this phenomenon is that bird mediated pollination is a development from the destructive eating of flowers still observed even in present day temperate bird species (e.g. sparrows destroying crocuses in spring if they are desperate for food).
What is the second reason for how and why did birds evolve to become pollinators?
It has also been proposed that wood-peckers may have been tempted to change their diet (fruit eating).
What is the third reason for how and why did birds evolve to become pollinators?
A third explanation proposes that birds obtained this habit from chasing insects into flowers, and just happened by chance to find the nectar or to puncture succulent tissues; or fourthly that some species may have originally drunk water collected in the blossoms to quench their thirst in tropical forests.
What is the difference between birds and insect pollinators?
Birds differ from the insect pollinators in that they can obtain only one of their staple foodstuffs from flowers, namely nectar, a Hummingbird may eat up to half its body weight in sugar daily! These species do no usually eat pollen, except incidentally whilst drinking nectar, and in order to obtain the protein component of their diet they eat small insects.
Where can bird pollinators exist?
These bird species can only exist in regions of the world that can provide an abundant and continuous supply of insects and nectar throughout the year ie. The tropics and subtropics of the world. THe equatorial belt in America between 5 degrees north and 5 degrees south, is the main centre of the hummingbirds (Trochilidae).
Where are sunbirds found?
The tropics and sub-tropics of Africa and S.E. Asia
where are the sugarbirds found?
the sugarbirds (Promeropidae) are found in South Africa
Where are the honeyeats found?
Honeyeaters (meliphagidae) are found in the S.W. pacific region.
Where are hummingbirds found?
Hummingbirds live only in the new world. Most of which are found in Central America. Ecuador contains half the known species (130 out of 319 exist in this country).
List the features of the bird flowers
Diurnal anthesis
Vivid colours often red, yellow or orange.
Flower tubular and/or hanging.
Hard flower wall,well protected nectary.
Absence of scent.
. Nectar very abundant
Often deep tubular
flowers.
Nectar guides absent
List the features of flower-birds
Diurnal.
See best in red part Of em spectrum.
Too large to land on Flower itself.
Hard bill.
Little or no sense of smell.
Large appetite!
Long bill and Tongue.
High intelligence
Why are bird-pollinated bigger?
Birds are relatively large animals compared to insects therefore bird-pollinated plants have to be large enough to accommodate the head of a bird as it drinks its nectar and collects its pollen. Furthermore, the petals must been strong enough to take this treatment.
