Lecture 11- Plant and animal interactions

Question 1

What are the water (survival) strategies of xerophytes?

Answer 1

• CAM, C4 photosynthesis • Sclerophylly • Sunken (and closed) stomata • Low surface area (succulents, folded leaves) •Shedding of leaves in dry •Reflective leaves, azimuth and angle •Roots resistant to water loss to soil •Osmoregulation (lower cell water potential) • Increase root:shoot ratio (deep roots) (the more roots the more ability you have to get water -downside is that it costs energy) •Water storage (succulents, baobab) •Reproduction - mutualisms

Question 2

What are some more water saving or survival strategies of xerophytes?

Answer 2

-Many adaptations relate to radiation load (e.g. reflectance) -Many relate to modifying latent heat flux (e.g. roots, CAM) -Some relate to tolerating heat and dehydration -decreasing or using latent heat flux= CAM store water so can evaporate if needed

Question 3

What is a myrmecophyte?

Answer 3

– plant that has a mutualistic relationship with ants

Question 4

What is mutualism?

Answer 4

-both species benefit from the interaction • A form of symbiosis* in which both species benefit from the relationship

Question 5

What is the mutualism like in the mulga-ant mutualism?

Answer 5

-the mutualism occurs at several levels: nectar (sugary) ants eat it and in exchange they protect the plant from herbivores and fungi -invertase= due to that in the food, ants can only come here, dedication= obligate mutualism -elaiosome= on the seed, the ants want to eat it but seed left untached, (fatty food body on surface of seed) – seed dispersal/ favourable (heat and nutrients) germination environment

Question 6

How much of Australia is tropical forest?

Answer 6

-very little, only 2.7 % is tropical rainforest -sub-tropical and temperate rainforest is 4.4% -rest of the land is wet and dry schlerophyll forests (43%) and woodland (48%)

Question 7

What about the Aborigines and the tropical forest?

Answer 7

• Permanent populations of rainforest dwellers in North Queensland only; • Thesegroupsweredistinct- relatively small in stature • They did not clear rainforests. Shifting cultivation did not occur in Australia. • Rainforest Aborigines were hunter-gatherers.

Question 8

What is the rainforest productivity like?

Answer 8

-high net primary productivity per meter contrast to xerophytic community -much higher productivity, CAM plants per meter are not as productivity -if go up in water then go up in productivity= as stomata can be open and more CO2 can come in, more thing can grow -arid areas have the lowest net primary productivity

Question 9

What is the NPP (net primary productivity) of the rainforest?

Answer 9

-about zero -photosynthetic rate and -in net sense= beech forest more, have more mass -as when open stomata= can get lot of CO2 but lose from respiration

Question 10

What are the real carbon sinks?

Answer 10

-projects to try to measure net productivity -so high primary productivity but lost a lot to respiration -net productivity close to zero -so the carbon sinks are not tropical forests but trees in borial forests like in the US and Europe -the ones in cold latitudes -lower gross productivity though

Question 11

What happens to the water in the tropical forest?

Answer 11

-25% of water that falls as rainfall evaporates from leaf surfaces, so doesn’t get in, form of latent heat loss, lot of water never gets down -50% gets into stomata -25% runs into soil and river -almost all trees in the world= C3 plants -Amazon= major change is that chop C3 trees down and replace with C4 grasses -this changes the process from C3 to C4, C4 need less CO2, less water and have less leafs, so less wtare evaporates so less rainfall, runoff into river more

Question 12

What about rainforest in australia and fruit?

Answer 12

• 84% of 774 spp. of rainforest trees have fleshy fruits: • Birds disperse 97% of species (seeds < 2 cm in diameter) • Mammals and cassowaries disperse other 3% • Unlike any other rainforest —— aus rainforest is different: -only 3 mammals and cassowary that can disperse seeds larger than 2 cm= cassowary, musky kangaroo, white-tailed rat and tree kangaroo (2 species) -in the other rainforrests much more of the seeds are larger and dispersed by larger animals (not as many by birds)

Question 13

Are humans mutualists?

Answer 13

-humans are mutualists with fruit = as we need vitamin C, obligate mutualists -fruit is very important in the rainforest -well over a tonne of fruit per hectar in a rainforest falls on the ground in a year

Question 14

Why is cassowary important fro the rianforest?

Answer 14

cassowary= long distance mover, several kilometers -important for genetic diversity, the mutualism with the dispersers allows dispersal away from the parent tree -• Largest vertebrate in Australian rainforests • Only animal capable of long distance seed dispersal • Up to 2 m tall • 10 -13 cm claw on inner toe • How important are they in the Australian rainforest?

Question 15

What are the australian animals capable of dispersing large fruit?

Answer 15

• cassowary • musky rat-kangaroo • white-tailed uromys

Question 16

Is large fruit/seeds an advantage?

Answer 16

-• resistance to predation • energy reserves for seedling establishment big advantage in having large seeds -monocots or dicots= so have 1 or 2 cotyledons but here has 3= called the idiot tree, can have 3, 4 or 5 cotyledons

Question 17

What was the research into cassowary role?

Answer 17

phd of the student on that -has fruit on the trunk at 1-2 m so perfect for cassowaries -similar to apricots -4 hours to -ryparosa= need to go through a cassowary to germinate -tested it and they did germinate only if through a cassowary -96% germination in the cassowary -extreme mutualism -• Seeds from cassowary gut: 96% germination rate • No other treatment could do this • Vital vector for large seed dispersal • Currently being tracked by Botany’s cassowary team

Question 18

What are seeds of ryparosa like?

Answer 18

-seeds are full of toxins to protect themselves from herbivores and bacteria -ryparosa seeds are full of cyanide= need only 1mg per kg of body mass -they are really full of cyanide but the fleshy bits of the seed loose it as it matures and so cassowary can eat it

Question 19

How does cyanogenesis work? (getting the cyanide out)

Answer 19

• it is hard to contain= the cyanide
• locked up in a more complicated molecule= gynocardin (cyanide is bound here to keep it from non toxic)
• it is released by process of cyanogenesis: locked up in organic molecule cyanogenic glycoside, when herbivore disrupts the tissue (leaf or fruit) get mixing of compunds the cyanogenic glycoside in the vacuole with the molecules in the tissue calle beta-glycosidase
• these cut the sugar of the cyanogenic glycoside and that releases the sugar, release

Question 20

What is cyanogenesis?

Answer 20

Production of toxic HCN gas from CN containing compounds in plant; identified in > 2000 plants; HCN inhibits respiration

Question 21

Can herbivores get around cynogenesis?

Answer 21

• Humans cleverly mix the cyanogenic glycoside with the “-glucosidase • Cassava or manioc (Manihot esculenta) -cassava= has cyanide -so mix it -if you massera it and dry it, then mix with water and that ixes the cyanogenic glycoside with b glucosidase -cyanide evaporates away and the root is then sweet -lot of cyanide poisoning if drought as they don’t use enough water

Question 22

What is symbiosis?

Answer 22

-a close relationship that benefits at least one

Question 23

What are some structural adaptations of myrmecophytes in mutualism?

Answer 23

a )extrafloral nectaries b) food bodies= epidermal structures containing lot of fat, ants eat it, ryparosa produces it too c) domatia= housing, plants house the ants -all of these are a level of mutualism

Question 24

What are the food bodies?

Answer 24

Food bodies (epidermal structures that contain nutrients – can be removed by foragers): Ryparosa javanica (Java Ash) feed high energy fat to ants

Question 25

Why is myrmecotrophy called that?

Answer 25

• Named after plants in genus Myrmecodia

Question 26

What is special about the Myrmecodia

Answer 26

• Plants have tuber-like base inhabited by ants (chambers called domatia) • Nutrients from ants (and rotting prey) are provided to the plant (special roots may grow into domatia) –ants can live there, the plants gets protection, the plant also gets leftovers from waste etc the nutrients

Question 27

What is the mutualism in Dischidia?

Answer 27

• Leaves fold together to make cavity used by ants • Cavities also full of plant roots • Ants provide nutrients and water is trapped in cavities

Question 28

What is the ant farmers mutualism?

Answer 28

1. • Golden ants collect eggs of endangered Apollo Jewell Butterfly • Ants look after larvae, which enlarge domatia • Larvae also secrete syrup like substance which ants eat • Larvae pupate, hatch, fly away -the ants pick up the eggs of butterfly, they bring into the domatia -they hatch into larvae and enlarge the domatio for ants as they eat some of the plant

Question 29

WHat do some ants also farm?

Answer 29

• Some ants “farm” sap sucking insects in domatia -aphids= nymphen like insects, syphen sap out of trees -ants befriend these aphids -the ant gently pick it up -then aphids sleep with ants -in teh mroning ants take it out to work= sap sucking from teh phloem -when the aphids are gently stroked they secrete sweet stuff that ants eat up