Plant And Animal Interactions- Test 4

Front 1

Why might defenses angiosperms not have evolved more effective against nectar robbers?

Back 1

Nectar robbing results in only a slight fitness cost to the plant – weak natural selection for greater defense

Defenses against nectar robbers might negatively affect pollinators also

Allocation costs of constructing such defenses

Front 2

Direct negative fitness consequences of nectar robbing?

Back 2

Energy Costs-some contain amino acids

Water lost in dry conditions

Nectar Robbers Damage Reproductive parts

Front 3

Indirect negative fitness consequences of nectar robbing

Back 3

– reduce visitation of efficacy of legitimate animal pollinators

Front 4

Extent to which nectar robbers will reduce pollinator efficacy depends on

Back 4

- ability of pollinators to detect nectar reduction / depletion from afar

- amount of nectar removed by the nectar robber

Front 5

Reasons why nectar robbers may have slight, if any negative effects on plant fitness

Back 5

Bees make longer flight distances between stops after visiting “low” nectar flowers – reduces inter-breeding with close relatives

Bees visit fewer flowers on the same inflorescence when to encounter “low” nectar flowers – reduced self-pollination

Nectar robbers transfer some pollen

Front 6

Fitness advantages of seed dispersal to plants

Back 6

Departure-related benefits: benefits that result from escaping the surroundings of the parent plant

Front 7

What are some examples of departure-related benefits?

Back 7

-Avoid highly competitive environment due to overshading and sibling competiton

less herbivory by specialist herbivores

more competitive seeds get disperesed to new microsites (leptokurtic seed dispersal

escape from pathogens

chemical influence of parent, alleopathy of parent

Front 8

Arrival related benefits:

Back 8

benefits that result from arrival at a specific location that is particularly conducive to survival, growth and reproduction

1. Colonization of unpredictable, vacant, resource-rich habitats (recently disturbed sites)

2. Directed dispersal – movement to predictably favorable sites for germination and growth (bell birds, Wenney and Levy)

Front 9

Herrera’s three modes of vertebrate-mediated seed dispersal

Back 9

Imperfect harvesting: granivores cache seeds for later consumption, but those cached seeds that are never re-located and germinate are dispersed

External “contamination” by seeds: seed with hooks or barbs adhere to the outside of an animal’s body

Interal “contamination” by seeds: seeds are consumed by the animal and are dispersed when the animal spits, regurgitates or defecates out the seed

Front 10

Binary seed dispersal

Back 10

“two-stage” seed dispersal; seed dispersal initially away from the parent is by one dispersal mechanism then a second dispersal mechanism moves the seed from its original deposition point

Front 11

Primary seed dispersal

Back 11

process that moves the seed from the parent plant to a new location

Front 12

Secondary seed dispersal

Back 12

process that moves a seed that has already been removed from the parent plant

Front 13

Ecological Patterns in Vertebrate-mediated Seed Dispersal

Back 13

Vertebrate-mediated seed dispersal is more common in:
Plant species with large seeds
Woody plants (trees and shrubs) than herbaceous plants
Woodlands, shrublands and forests than in grasslands
More productive (NPP) ecosystems, within a ecosystem type

Front 14

Hypotheses for why there is a positive relationship between ecosystem productivity and the proportion of plant species that are vertebrate-dispersed?

Back 14

Westoby et al. 1990 tested these two hypotheses

In more productive communities, seeds must be larger to contain large endosperm and cotyledons required in low light environments; large seed are only effectively dispersed by vertebrates

In more productive communities, parent plants are larger and, therefore, the seeds must be dispersed further to receive “departure-related” benefits

Neither proved very good.

Front 15

Eliasome

Back 15

A food body on a seed which ants like, fatty

Front 16

Additional hypotheses for the positive relationship between vertebrate seed dispersal and ecosystem productivity

Back 16

3. Dispersal structures required to attract vertebrates are energetically expensive and the resources to produce them are only adequate in productive ecosystems

4. In low productivity sites, vertebrate populations are too small to efficiently disperse seeds

Front 17

Do vertebrate seed dispersers act as agents of natural selection that determine plant fruiting phenology?

Back 17

Overall, no not really...

But, fruiting might coincide with avail. of seed dispersers

Could produce either staggard or synchronous fruiting.

Front 18

What might be an advantage of “staggered” or “over-dispersed” fruit production by plant species in a community?

Back 18

-Reduces competition for animal seed dispersers

staggard decreases satiation, all species benefit... (but doesn't hold very true, frugivores aren't specialists)

Front 19

Advantages of synchronized fruit production by plant species in a community

Back 19

synchronized, large bursts of fruit production will attract large numbers of vertebrate frugivores / seed dispersers

Front 20

Factors other than phenology of frugivore / seed disperser abundance that might acts as agents of natural selection on fruiting phenology

Back 20

Avoidance of frugivores that do not disperse seeds

Avoidance of microbes that might infest fruits making them less appealing to frugivore / seed dispersers

Seasonal availability of abiotic resources required for reproduction, including fruit production

Timing of fruit production may be constrained by selection acting on the timing of flowering

Front 21

Color evolves in response to frugivores?

Back 21

Seed dispersal by bird frugivores often involved red or black fruits

Mammals-fruit is pretty drab

Birds discriminate among fruits based upon color, birds chose red over orange (Gervais)

Color selection might act as selective force.

Front 22

Do larger-bodied vertebrate seed dispersers explain larger fruit sizes in the Old World tropics than in the New World tropics?

Back 22

Mack 1993 shows trends suggesting yes

Might be ecological filtering... only those frugivores with correct gape size survive and colonate.

Differences in fruit sizes between the Old World and New World tropics cannot be explained only based upon differences in the plant families present

Front 23

Palatability-defense trade-off hypothesis

Back 23

plant species whose fruits are dispersed less quickly should have higher levels of secondary compounds in the fruit pulp

Front 24

Nutritional challenges of eating fruit

Back 24

Extensive nutrient dilution

Lots of water/carbs not much protein/fat

Nutritional imbalance – low in N content

Secondary compounds

Strong temporal variation in fruit availability, including strong seasonality in fruit production

Front 25

Advantages/Disadvantages of secondary compounds in mature fruits.

Back 25

Disadvantages:
-deter see disperesers, fewer fruits consumed before leaving
-reduce number of species as dispersers
-induce a learned avoidance response

Advantages:
-Deters parasitic frugivores (insects)
-secondary compounds may be antimicrobial
-inhibit premature seed germination
-compount regulates rate of gut passage in frugivore
-not bad to eat fewer fruits, more likely to move on before deficating

Front 26

Behavioral, Anatomical and Biochemical Adaptations in Frugivores to deal with Nutrient Dilution

Back 26

Regurgitation, rapid gut passage of seeds

Long small intestines, seasonal adjustment of intestine lengths

Fast gut passage rates – more fruit consumed per unit time

4. Adjustment of activity of carbohydrate assimilating enzymes

-Gut retention time is a function of amt of fruit consumed, not body mass

Front 27

Adaptations that aid Frugivores in dealing with Nutrient Imbalance in Fruit Pulp

Back 27

Generalized diet – many frugivores consume some animal matter also

Consumption of a wide range of fruits from different plant species

Compensatory consumption – amount of fruit consumed may depend on the protein or lipid content of the fruit

Physiologically many frugivores are highly efficient at extracting N from low protein food

Front 28

Adaptations that aid Frugivores in dealing with High Levels of Secondary Compounds in Fruit Pulp

Back 28

Consume fruits of a variety of plant species during individual foraging bouts (recall Toxin Dilution Hypothesis)

Anatomical and physiological adaptations for enhanced detoxifying ability – frugivorous species have larger livers than non-frugivorous species

Front 29

Adaptations in Frugivores to deal with Pronounced Seasonality of Fruit Production

Back 29

Expand home range size in seasons of low fruit production

Seasonal shifts in habitat to track seasonality of fruit production (altitudinal migration)

Broaden diet to include animal or non-fruit plant material

Reproductive cycles synchronized with seasonal peaks in fruit production
-Tamarans in Peru... all births occur in corresponance to wet season when most fruit is available.

Front 30

Coevolution

Back 30

evolution in two or more species brought about by reciprocal selective effects between the entities

Front 31

Specific coevolution

Back 31

two species interact closely with one another and changes in one species select for adaptive changes in the other species and vice versa

Front 32

Diffuse coevolution

Back 32

groups of species interact with groups of other species leading to adaptations that cannot be identified as arising from specific pairwise interactions between species

Front 33

How to quantify the degree of specificity in species interactions?

Back 33

Proportion of interactions in the community that are strictly pairwise (meaning one-on-one)

Mean number of species with which each species interacts (e.g. mean number of pollinators with which each plant interacts)

Front 34

Connectance

Back 34

the proportion of potential interactions between species pairs in a community that actually occur; greater connectance indicates less specificity in interactions

Generally, plant pollination systems have less connectance than Seed Systems

5 host plant species X 7 pollinator species = 35 potential species pairs interactions
11 species pairs interactions actually occur
Connectance = 11 / 35 = 31.4%

Front 35

Why is there less specificity in vertebrate seed disperser – host plant interactions than in animal pollinator – plant interactions?

Back 35

Vertebrate dispersal of seeds limits opportunities for local genetic divergence and specialization

Opportunities for plant specialization are limited by the absence of a specific target site

Temporal variability in fruit availability limits opportunities for specialization on a single host plant species by frugivores
-Natural selection favors a generalist diet
-In different years, vertebrate frugivores are likely to be exposed to conflicting selection pressure

Front 36

Myrmecochory

Back 36

seed dispersal by ants; occurs in up to 3000 plants species from 80 families

Front 37

Ecological distribution of myrmechochory

Back 37

Southern hemisphere: low nutrient, fire-prone shrublands of South Africa and Australia (2700 plant species). Generally secondar dist by ants.
Life form: small shrubs, canopies usually <2m diameter, not serotinous


Northern hemisphere: temperate deciduous forests (300 plant species). Primary distribution by ants.
Life form: understory herbaceous plants, weight of seed bends the shrub to the ground where ant picks it.

Front 38

Diaspore

Back 38

seed plus the attached elaisome

Front 39

Why do ants eat elaisomes?

Back 39

-Most ants are carnivores, so many of the rules we consider with herbivore nutrion do not apply

--Hughes 94, eliasome close to fatty acid composition of insects more than seeds

diglyceride 1,2 diolein is strongest ant attracter, very prevalent in insects preyed upon by ants

-ant collects the entire seed, takes back to nest, eats elaisome, and discards the seed in the nest. This puts the seed in optimal position for germination.

-ants disperse seeds over short distances

Front 40

Some advantages to plants of ant-mediated seed dispersal

Back 40

Departure-related benefits, such as reduced parent-offspring and sibling competition

Transfer of seeds to nutrient rich sites (middens in nests) – an arrival-related benefit (directed dispersal)

Escape from granivorous rodents and granivorous ants – ant-mediated seed dispersal is one of the surest ways to get a seed belowground (directed dispersal)

Front 41

Why does myrmecochory occur in the plant community types and with the plant life-forms that it does?

Back 41

Plant body sizes are relatively small – short distances that ants disperse seeds are adequate to escape the parent

Serotiny may incompatible with ant-disperal because long-term storage in a sealed cone may cause the eliasome to deteriorate

Burial of seeds is advantageous in fire-prone ecosystems because the soil insulates from the heat of the fire

Front 42

Patterns in seed selectivity by harvester (granivorous) ants

Back 42

Often harvest seeds of the most common plant species in the community

Correlation between ant body size and the size of seeds consumed

Front 43

Ecological consequences of ant granivory (harvester ants)

Back 43

Ant removal increases the densities of an equal number of winter annuals as does rodent removal, but rodents have larger indirect effects
Ants reduce densities of more summer annual species than do rodents (Samson Et. Al)

Ants can structure desert rodent communities through interspecific competition for seeds (brown 79)

Front 44

Myrmecophyte

Back 44

plant that is defended by ants

Front 45

Adaptations of myrmecophytes to attract ants

Back 45

Extrafloral nectaries

Food bodies produced from epidermal tissue that are harvested by ants (e.g. Beltian bodies)

Domatia-spines that can house ants.. plants can regulate size of ant which can use it.

Front 46

Relationship of Ants, plants, and herbivore, simple.

Back 46

Ants can have a net fitness advantage.

Front 47

What are the advantages to ants of tending myrmecophilous herbivores, like hompoterans and some lepidopteran larvae?

Back 47

Aphids are phloem suckers, lepidopterns eat plant and secrete sweet substance. Ants then eat some byproduct of the herbivore.

This makes the relationship more complex.


Ants often tend some herbivores on myrmecophytes while deterring other herbivores

Ant guarding with aphids present actually increases damage by leaf-chewing herbivores (OLiver 07), Ant guarding with aphids present decreases host plant fitness

Front 48

What are the advantages to the myrmecophilous herbivores of being tended?

Back 48

Ants deter predators and parasitoids

Ants reduce pathogen contamination

Ants shelter the herbivores by carrying them into domatia

Ants move herbivores around on the plant to higher quality tissue patches

Front 49

If ants often guard homopterans or lepidopteran larvae on host plants and the presence of ant guards decreases plant fitness then why are extrafloral nectaries still present?

Back 49

No genetic variation to lose extrafloral nectaries

Conflicting selection pressures across years

3. Extrafloral nectaries are adaptive because they attract non-ant predators and parasitoids

Extrafloral nectaries draw ants away from flowers where they could deter pollinators

5. Distraction hypothesis – extrafloral nectaries provide an alternative for ants to tending herbivores on plants, may prevent ants from guarding herbivores

Front 50

Common effects of ant nest building on physical properties of soil

Back 50

Reduce soil bulk density

Move smaller-sized soil particles to the soil surface

Homogenize soil horizons

Front 51

Common effects of ant nest-building on chemical properties of soil

Back 51

Increase quantities of N, P and K

Increase organic matter in soil

Sometimes alter soil pH, usually making both acidic and alkaline soils more neutral

Front 52

How is decomp. rate altered?

Back 52

-Actinomycse are less abundant, they are involed in later stages of decomp/hummus breakdown

Microbes involved in early decomp are more abundant

Front 53

metapleural gland (ants)

Back 53

produces antibodies secretion to prevent fungal infections (spread all over nest and on larvae) maybe this stuff ends up in refuse piles... making the pile good for seeds

also involved in chemical defense, territory marking and pheremones

Front 54

Why are grasses more abundant than forbs on mounds than off?

Back 54

Soil temp on the nest is higher than off, Favors the grasses

Maybe... rate of ant import, and maybe diff. rate of germination due to soil antibodies.

Front 55

Refuse Piles (ants)

Back 55

More nutritionally rich than surrounding forest floor. When in this soil during a study, fewer seeds died due to fungal infection (perhaps from secretions of ants), more seeds germinate.