VL 2

Question 1

4 types of species interactions

Answer 1

Mutualism
Commensalism
Antagonism
Competition

Question 2

Definiton Mutualism

Answer 2

An association between two species which is beneficial to both

can be:
obligate - necessary association for survival and reproduction

facultative - beneficial but not essential

Question 3

How do mutualisms develop?

Answer 3

If selective advantages to both species to associate -> rapid development

Usually develop between organisms using different resources, not competitors

Both organisms should gain / lose roughly the same amount

Possible development: parasitic -> commensalism -> mutualism

Question 4

Dispersal

Answer 4

Insects disperse seeds or pollen or spores

Eliasomes (like fruit)
Edible Flesh attached to seeds encouraging dispersal by eg. ants

Pollination
Fertilization and sexual reproduction in exchange for:
Food / home for larvae - fig wasps
Nectar / pollen - bees, butterflies, moths, ants

Question 5

Nutritional mutualism

Answer 5

New resources made available:
- Partner ofers new food source or facilitates access to one
- Insect provides transport, care, pollination or a place to live

Examples:
Digestion of wood / cellulose
(partner: fungi/yeast/bacteria)
Termites
Wood wasps

Digestion of plant tissues
(partner: fungi)
Leafcutter ants
Termites

Nectar and Pollen
(partner: plants)
Moths + butterflies
Bees
Ants

Question 6

Protective mutualism

Answer 6

Insects protect plants / other insects

The protected species offers some kind of reward to the partner

Protection against enemies:
Parasitoids/predators are recruited by plant volatiles
Ants protect plants and feed on extrafloral nectaries
Ants protect aphids in exchange for honeydew
Ants protect lycanenid larvae for sugar secretions

Protection against environment / pathogens:
Bacteria protect aphids

Question 7

Why do plants need pollinators?

Answer 7

Some plants self pollinate or seeds are carried by wind and water, but 75% of crop plants need insect pollination
-> need an insect to visit, then visit another of the same flower species

Question 8

Buzz pollination

Answer 8

10% flowering plant species require specialist ‘buzz’ behaviour by bees, including all solanaceous crops

pollen release is restricted by modification of the stamens - poricidal flowers

has evolved independently in plants multiple times

Question 9

Solitary bee

Answer 9

Solitary bees do not live in colonies, produce honey or have a queen

Examples: mason bees, mining bees, leafcutter bees, wool carder bees

A single red mason bee is as effective at pollinating as 120 worker honeybees

Question 10

Plant signals

Answer 10

Higher successful pollination rate if encourage fidelity

Plant must therefore be recognisable / distinguishable and rewarding

Floral pigments, UV spectra, volatile organic compounds

Different signals in the day / night

Flowers may signal they have already been pollinated

Question 11

Plant signals - visual

Answer 11

Diverse bee species have conserved colour visual system and flower colour in angiosperms worldwide is coded by this system

-> if flowers are lookd at under UV light, special patterns can be seen, see page 14

Question 12

Plant signals - olfaction

Answer 12

Night blooming plants may focus more on having a strong scent than visual cues

Odour plumes maintain specific volatile ratios, allowing detection in ‘bursts’ at many meters away

Manduca sexta hawkmoths detect the volatile blends of flower species and choose the ones they have a matching proboscis length for

Question 13

Plant signals - electric fields

Answer 13

bees have positive electric potential, flowers negative

when bee lands, pollen is more likely to stick on bee

flower will change its potential -> important for bee to know where there is pollen left

Question 14

Plant signals - multimodal

Answer 14

more than one signal leads to enhanced foraging efficiency and pollination in bumblebees

Question 15

Insect signals - bee damage

Answer 15

when bees bite plants, it’s a signal for plant that there are pollinators nearby

Question 16

Figs and fig wasps

Answer 16

S. 19
Fig is not a fruit, it’s an inversive flower

1. A pollen-laden female wasp enters an unripe fig
2. the wasp pollinates the flowers and lays her eggs
3. Flowers with wasp larvae form galls, and some other flowers produce seeds
4. Male wasps leave the galls first and fertilize the females. The males will die before leaving the fig
5. Females then leave their galls and collect pollen from mature male flowers within the fig

6a. Females exit the fig through a tunnel and search for another fruit where they will lay a new generation of eggs -> 1

6b. In some cases, though, females exit the fig without first collecting pollen

7. Females without pollen will still enter another unripe fig, where they will lay their eggs. But without being pollinated, the fig will not grow seeds and may be aborted by the tree. Any offspring in the dropped fig will die.

Question 17

Nectar robbing

Answer 17

Insects puncture the back of the flower to ‘rob’ the nectar

non specialist species can tackle flower shapes they otherwise couldn’t

Flowers may then be ignored by pollinators

Question 18

Deception pollination: orchids

Answer 18

Spider orchids mimic solitary wasp sex pheromones

Hammer orchids use both smell and visual cues - looking like a female wasp

Lords-and-ladies flowers use odours of rotting meat to trap owl midges and force pollination

Question 19

Plant protection

Answer 19

Ants can provide protection to trees / shrubs they have nests in, as well as surrounding plants, as they will hunt herbivorous insects for food

Ants produce antimicrobials that can reduce pathogens in the host plant

For some species, they can also scare off inefficient pollinators, allowing only larger species through thet result in higher fruit production

Question 20

Ants and acacia trees

Answer 20

About 10% Acacia species don’t use traditional chemical defenses and instead specialize in ant partnership

The ants live in the swollen thorns and the plant provides sugar from extrafloral nectaries

In return the ants ‘patrol’ the plant attacking herbivores, fungus and competing plants

Question 21

Ants and acacia tees - manipulation

Answer 21

In order to keep ant species with more effective defenses, the tree will produce more sugar as a reward

When occupied by weak defenders, acacia trees locate extra floral nectaries at the tips of leaves to encourage ants to patrol more

The tree may also manipulate the ants by disabling their ability to digest sugar from other sources, forcing them to stay

Ants may attack the flowers, ‘castrating’ the plant causing more vegetative growth instead

More vegetative growth = more living space, allowing for bigger colonies

In acacias, while it halts reproduction, it may not affect lifetime fitness