1) Dave Kelly Lectures Flashcards
1
Q
Metapopulation Definition
A
A subdivided and patchy population with population dynamics at two levels:
- within patch dynamics
- between patch dynamics
Some suitable patches may be empty; occupied patches may have negative population growth rate
2
Q
Within Patch Dynamics
A
determined by local births, deaths, immigration, and emigration
3
Q
Between Patch Dynamics
A
dynamics, determined by local extinction and recolonization of patches
4
Q
Explain the Graph - Metapopulation dynamics in Mountain Sheep in the USA
A
- Mountain sheep in the USA.
- The red patches are suitable habitat, pink are suitable but not occupied.
- Black arrows are movements between patches.
- Most movements are from one occupied patch to another.
5
Q
Explain the Graph - Butterfly Metapopulations
A
- Left - large persistent patches of habitat and most of them didn’t go extinct or get colonised.
- On the right - smaller patches so more colonisation and extinction. Because of the habitat size.
6
Q
For a strict metapopulation it needs to have:
A
- A patchy habitat
- All patches are at risk of extinction and can be recolonized
- dynamics of local patches are not synchronous - if all the patches are good at the same time it will get bad at the same time.
7
Q
Patchy will vary in:
A
- Habitat quality - some are bad where organisms can’t repopulation.
- Habitat size - varies and determines how many species can fit which determines the chance of extinction.
- Patch isolation - might be a long way or close to other patches.
8
Q
Colonisation vs extinction rates: explain the graph
A
- he rate of extinction and rate of colonisation are affected by the proportion of all occupied patches in the area.
- The rate of colonisation increases and then the rate of colonisation decreases because at the start there are more empty patches nearby and then the patches get filled.
- The rate of extinction is a linear function assuming that the patches are all the same so the rate of extinction is constant.
- The equilibrium number is where extinction and colonisation balance.
9
Q
Example: Swedish Bush Cricket
What do the graphs show?
A
- Patches over 1 hectare stay occupied - because they are big enough areas. The bigger the patches the higher the population size.
- Big populations are unlikely to go extinct.
- Almost half of the small patches went extinct.
- Small patches are much more likely to go extinct because small areas have smaller populations.
- Most nearby patches were colonised. Nothing far away from other patches got colonised.
10
Q
What is the chance of a patch being occupied being dependant on?
A
- The chances of a patch being occupied are dependent on how close it is to another patch and how big it is.
- The diagram plots these two together. The top left is likely to be occupied because these are big patches close to other patches. Will get recolonised quickly.
- Bottom left - patch is likely to be empty if it is small and a long way away.
- The probability of occupancy for skipper butterfly is highest in large well connected patches.
11
Q
Predicting Occupancy
A
- Can predict occupancy. Different patches have different extinction rates. The extinction lines are steeper for a smaller patch because they are more likely to go extinct.
- The colonisation curve is higher up if they’re near because the probability of getting colonised is higher if it is close to other patches than if it is far away.
- A small patch that is far will have the lowest proportion of occupied patches and a large patch that is near will have the highest proportion of occupied patches.
- Where the lines intersect give average occupancy overtime.
12
Q
Dispersal and mortality rish for emigrant (white) and resident (black) butterflies versus connectivity.
A
- Shows Mortality of butterflies if they ever stay in a patch.
- If they stay in a patch the morality is relatively constant (balck dots - linear line). Doesn’t matter if its a remote patch or if its near.
- X axis is the connectivity so the left side is very isolated.
- The mortality risks of butterflies if they leave and its well connected they are likely to find another patch and survive. But if they leave and it turns out there aren’t any other patches nearby they have very high mortality rates.
- Relates to the graph above because if a patch is far from other patches, animals are likely to die before they find it, so probability is lower.
13
Q
Consequences 1: Stabilising predator-prey dynamics
Explain the experiment
A
Set up an experiment where there are models with plants (hosts) and prey (herbaceous mite) being eaten by a predatory mite. Plants on islands. And they had lollipop sticks that connected the islands that the mites can walk along. They had another system with 90 plants - single population.
14
Q
Mites experiment
Consequences 1: Stabilising predator-prey dynamics
A
- If you have a single big island at the top, the prey does well and then the predator comes and it does well and eats all the prey and then they all disappear. Large population - unstable predator prey system because the predators find all the prey, eat them and then the predators have nothing to eat. No refuges, simple habitat, no hide and seek going on.
- The island system - both predators and prey persist though the duration of the experiment. Because there are multiple islands, the predators cant easily search all that without putting in a lot of effort, the prey have places that they can do well in before the predators find them. The predator prey cycle is more stable in the long term. Still variable but didn’t go extinct.
- Metapopulations are in general more stable than if you don’t have a metapopulation structure. The real environments are patchy so you would expect almost every species to have a metapopulation structure.
15
Q
Consequence 2: Source Sink Dynamics
Example - North American Rodent - Pika
A
- You can have patches in a metapopulation system where one species is present but it won’t survive in there if it was isolated.
- They had a northern network, middle and southern network. They measured the population size and were able to simulate the dynamics because they know how big the patches are and reproduction rate, immigration and emigration.
- They found that if you run it with everything connected then the population size in the north is big.
- The population size is present in the middle but at a low density but they persist in the metapopulation.
- Middling numbers in the south as well.
- If you run this model and you don’t let them move between patches, what happens is the middle area goes extinct. The growth rate isn’t high enough, there aren’t enough patches. So if they stop getting immigrants from the north and the south the middle goes extinct. They disappear in the middle, persist in the north because it’s good habitat, but once they disappear from the middle the south gets in trouble eventually too and go extinct.
- The northern population is the source population - producing more individuals than are needed to replace themselves. There is net emigration. There are Pikas being born in the north that move to the middle area. The middle is the sink population - producing less Pikas than are needed to replace it. Pika immigrants come in all the time. The southern population is evenly balanced, if you lose the imigration of Pika coming from the blue area which are dependent on immigrants from the red area then eventually the south can’t maintain itself either.
- The sink populations are dependent on the source populations.
16
Q
Source Sink dynamics
Example - Plant on sand dunes
A
- Plant that grows on sand dunes. If you measure the density of plants on the sand dune. The highest density on the middle dunes, lower on the seaward and landward side. Seeds are thrown inland by wave action and wind. Most of the seeds are produced on the seaward side, the only part of the habitat where british succeed deaths is on the seaward side. So if you clear the area nearest the beach, although the biggest population is inland it is completely reliant on seeds being produced further inland. The death rate is much higher. Source population of the seaward side - lower density population. Sink population is the highest density inland.
17
Q
Source sink populations for birds
A
- Towns tend to be the sink popualtions.
- Across Dunedin the annual catch by cats (the bars) and the population size - how many birds of different species are present in dunedin. In fantails the cats are catching more than the popular;ioin size. Fantails move into dunedin to die.
- Same is true for bellbird, blackbird and song thrush. Dunedin is a sink population and the surrounding population is a source.
18
Q
Nest success for natives on UC campus
A
- Percentage of nest success that don’t fail due to predation by mammals.
- Fantails and silvereyes - native birds, have low nest survival on campus. They aren’t replacing themselves on campus and are moving into towns from the pirt hills and other forests where they do better. The purple bars are the best estimates of how well they do in the countryside.
- For ⅔ exotic birds the nest survival on campus is pretty much as good or even better as sparrow compared to elsewhere.
- Significant difference between native birds and exotic birds. The exotics were doing as well as they were elsewhere, the natives were doing badly. At the moment UC is a sink for the birds, they come here to die. We can improve that by doing predator trapping - issue surrounded by housing with cats.
19
Q
Galaxiid and trout interactions - source sink
Evidence for predation
A
- Brown trout prey on baby galaxiids.
- The galaxiids can get around becaue they can climb waterfalls and trout cannot.
- The streams with no trout are usually above waterfalls - physcial barrier.
- In streams with no trout or small trout there were a range of galaxiids, in streams with big trout there are only big galaxiids because the big trout ate the little galaxiids.
20
Q
Galaxiid distribution
A
- If you have as stream with big trout there may be big galaxiids present but if they produce offspring they are just producing trout food - they wont be replacing themselves.
- Examples of some streams in Canterbury. Where are the trout present, and where are free of trout. Where it is trout free is where you go over a little water fall. The trout can’t get up that but the galaxiids can.
- Above where trout are present you get big and little galaxiids and where there are trout present you only get big galaxiids.
21
Q
Galaxiid and trout source sink - explain
A
- No trout - source area - glaxiids are upstream - babies hatch here. The babies and various sized glaxiids can go down the waterfall and if they are down there the big ones survive but any offspring produced are lost.
- If you lost the upper part of the stream or if you put a pipe there then the trout can get up the stream so co-existence can depend on having an area free of trout.
- Just because the galaxiids are present downstream doesn’t mean they can survive there - sink population.
- Fragmentation makes this worse - human induced fragmentation. Two different rivers and galaxiids can move between by going to sea and then going to another stream. Before trout introduced, all these streams were suitable habitat for galaxiids. Then we put trout in the lower reaches. The trout can eat anything that comes down stream. Now movement of galaxiids between the patches is much more difficult. We have broken the metapopulation structure - if they went locally extinct in one of the streams we’ve prevented them from recolonising. Humans tend to clear some of the habitat so we have fewer smaller patches, because they are smaller that increases the extinction rate so the patches are further apart. Which means you get a lower colonisation. If you have smaller patches they are more likely to go extinct and if they are further apart they are less likely to be coloniesed - setting up metapopuaktion for d=failuer when we remove habitat.
- The recolonisation between streams is important for the non-migratory fish. Now difficult for the non-migratory fish to recolonise a stream if it happened to be cleared out by maybe a really dry summer or a chemical spill.
22
Q
Metapopulations of tui in Canterbury
A
- Tui are common on the west coast but lost from banks peninsula around 1990
- Disperal across plains might be reduced by farming.
- We’ve messed up the metapopulation by making it harder for the tui to get across the plains.
- We have changed the plains so that they used to have shelter belts, house gardens and sheep. Now we have taken out shelter belts and put in irrigators and the habitat is probably worse.
23
Q
Metapopulations: conclusion
A
- Most species have a metapopulation dynamics because the real environment is patchy.
- A species may be present at a site where it cannot persist without immigration.
- Humans remove habitat and make them smaller.
24
Q
Pollination
- Outcrossing
- Mixed mating
- Self-pollination
- Apoximis
A
- Pollination: breeding systems
- Outcrossing - pollrn from another plant
- Mixed mating - mix outcrossing and selfing
- Self-pollination - own pollen, post-meiosis.
- Apoximis - no meiosis, making seeds without shuffling genes.
25
Q
Pollen delivery modes
Abiotic and biotic
A
- Abiotic
- wind, water
- wind is especially common in gymnosperms and conifers. Cheaper by not having to make big petals and nectar but making pollen is expensive - need to make lots of pollen.
- Biotic
- insects, birds, bats and lizards.
- especially in angiosperms.
- Requires investement in attractants - reward.
- Animal pollinatd plants produce little pollen because it’s delivered accurately.
26
Q
Global patterns - pollination vs latitude
A
- The closer you are to the tropics most things are animal pollinated. The closer to the cold temperature zone more abiotic pollination.
27
Q
Bird nectar feeders (polliantion) and latitude
A
- Bird pollination is more common in tropics and in the Southern temperate zone.
- more common near the equator and in the southern hemisphere than the northern hemisphere. Left is south, right is north.
28
Q
NZ pollination systems:
pollination of NZ plant genera
A
- ⅔ native genera are pollinated by insects. Not in the cold places - insects are limited by temperature and wind. Insects are not very specialised - NZ pollinators.
Solitary bees 41 spp.
Flies
Beetles
Moths
Butterflies - few species in NZ 16 species.
The rest are wind pollinated. Wind pollination in species that are dominant.
Some birds pollinated, some by bat and some by water.
29
Q
NZ specialist insect pollinator - Hawkmoth
A
- One hawkmoth in NZ - specialist pollinators, day flying. Introduced. Visits kumara plants. Moari bought kumara here and then the hawkmoth arrived not long after.
- They can hover.
36
Q
Ipmopsis nectar robbing
A
- Long tube and red coloured - hummingbird pollinates this. Bumble Bees will bite a hoel in the bottom and suck the nectar out.
- Areas of high nectar robbing and areas where no nectar robbing.
- Study looked at the success of these plants getting their pollen onto other plants to become a father of seeds.
- Its reduced, low nectar robbing is the black bars, when plants had high nectar robbing they didn’t export as much pollen because visitors didn’t come to the flowers as much because of a reduced reward.
- Theres a cost - cost to the plants of the nectar robbing. Male and female fitness reduced. Cost to the plants if animals cheat.
40
Q
Frugivory global dispersal versus latitude
A
- Dispersal is mainly by animals in the warmer areas, increasingly abiotic in the colder areas.
- Animal dispersed species uncommon above 30 degrees north or south.
- Across the whole native flora in NZ 12% have fleshy fruit.
- % of trees with fleshy fruit in the tropics somewhere around 90%, in the USA 35%, NZ 59%.
43
Q
Rewards: fruit composition
A
- Rewards - coming for food.
- 11 spanish plants - little lipids and proteins. Mostly carbohydrates. Sugars and simple nutrients because they are quick for uptake.
47
Q
Scatterhoarding - Chipmunk example
A
- The chipmunks take the seeds. He watched the chipmunks followed what happened. He found that some of the seeds were buried 5 different times. 25% were eaten from the frist cache. 800 had been eaten and 133 were germinated - relatively low number of germinated but moved to a really good spot and dispersed far. Northern hemisphere nuts are Not well defended nuts - easy to open because the plant benefits from the animals from getting them.
48
Q
Stealing of scatterhoarded seeds.
A
- Birds remember well when they put the caches. Rodents have a good sense of smell and can find caches made by other rodents. The probability of the chipmunk that buried the seeds finding them again is about 60%. If the soil is dry a chipmunk that didn’t bury them has a very low chance of finding the cache but if the soil is wet they can smell where the seeds are and can dig them up. They move the caches around so that they aren’t stolen by other rodents.
Birds do it more memory rather than smell.
50
Q
Mycorrhizae help plants in low phosphorus
A
- Cilantro grown in low phosphorus soil, low growth. Low plant density on the left and high density on the right.
- At low phosphorus concentrations the plants with the fungus, growth is better (more pale bars). At low and high density. The plants benefit - they grow faster when the fungus is present at low density.
- At high phosphorus density the plants are doing worse because they are feeding the fungus sugar (losing sugar), too much phosphorus where the plants can get it on their own.
51
Q
Mycorrhizae provide protection
A
- Fungi protect the roots of plants from other fungal pathogens.
- This experiment - english dune grass. Plants are grown in 4 different conditions, soil pathogen and mycorrhizal fungus. The left two are grown with or without the fungi and without the soil pathogen. On the right is adding the pathogen. If you have the pathogen but not the fungi that plants do much worse - growth rate is half as big, the pathogen is affecting the growth of the plant. You put the fungus in and the pathogen doesn’t affect the plant anymore.
55
Q
Hosts becoming immune - cycles
A
- Outbreaks of measels and then a lot of people have had so they are immune so the transmission rate drops and then 6-8 years later you get another outbreak.
- If you look at england and wales. Outbreak in Wales, everyone is immune so it disappears then a tourist brings it in and then everyone gets it again and so on.
- Very density dependent and the disease can disappear from a small population.
57
Q
Pathogen virulence in rabbits
A
- The most strong strain kills all the rabbits quickly so the disease isn’t passed on because all the rabbits die. High virulent to less virulent. All depends on what gives you the best transmission.
- The reason you can get a high R0 with a highly virulent disease with high transmission, the virulence is the rate at which the pathogen is turning the host into more copies of itself, which makes you more sick - you might die. It also means you are much more infectious because you are producing more virus particles.
- Whether the disease will be harder on the host or kinder on the host depends on how well the disease is being passed on.
- High transmission rates - vectors such as eg. fleas and mosquitos, waterborne.
- The flu relies on being kind to people to get spread because people don’t get sick enough to stay home so they go out and spread it.
- Yellow fever is hard on the host - the host is bed ridden and has high transmission because mosquitos get the blood from someone with yellow fever and go spread it to someone else.
61
Q
Ecological effects of pathogens
A
- Introduced species in a new area do well because they get away from their diseases. Showing how weedy and invasive the species are. If you move the plants you leave natural enemies like insects and pathogens. The more pathogens a plant has left behind the more likely it is to become weedy.
63
Q
Isoclines show for each species the “carrying capacity”
A
- Too crowded the population will decrease and not crowded then it will increase.
- The line shows where the combined crowding on species one is equivalent. For species two its shown in red.
64
Q
Which species will win?
A
- Which species will win? The species with the higher line copes with crowding better and can increase while the other is decreasing. If they cross it can go either way.
- The species with the higher line can increase at a density where the other species is decreasing = competitive exclusion
- Only panel C gives stable co-existence.
65
Q
Competitive exclusion in algae
A
- Red is phosphorus being soaked up by algae.
- If they do well in low phosphorus then they do well in competition. The species pull the phosphorus down until one species can’t cope but one can and then that one wins.
66
Q
Nothofagus species effects on N. fusca
A
- Model the predicted density of different tree species throughout the country as a function of site mean annual temp.
Left is further south and right is further north.
Looking at interaction within nothofagus. How much red beech do we expect as a function of whether other species are present.
Solid line is how much nothofagus we expect to have as a function of temperature. The peak is about 8 degrees, when sites get warmer you get less. With another nothofagus, mountain beech copes better with cold temps so in competition mountain beech squeezes red beech out of the colder sites so the peak abundance of red beech shifts to warmer sites and the abundance drops. Less red beech when mountain beech is present. This reduces the density of both of them to some degree. When silver beech is present, red beech does present. Silver beech mau leep species out that may compete with red beech.
67
Q
Competition: Nothofagus effect on 4 NZ trees
A
- Measured hwo density of other species changes when nothofagus is present.
- Abundance of a,b,c drops in the presence of nothofagus and shifts to warmer sites.
- Nothofagus are good in colder conditions.
- D, increases and can deal with colder sites with nothofagus present. Mutualism? Or does D) benefit from the other species being squeezed out.
71
Q
Four main factors helping coexsistence:
Infrequent competition due to aggregation
A
- Once you are rare you don’t interact with other species very often.
- Aggregated - clumped. Because of poor dispersal most species tend to appear in clumps most of the time. The real world is patchy becasue dispersal is imperfect.
- Stellaria does worse when it’s aggregated than it does randomly, it’s being constrained by its own species as neighbours.
- Capsella does better in a random group because it doesn’t end up next to the superior stellaria so often.
- Because species are not perfectly distributed its easier for the rare species.
73
Q
Four factors helping coexsistence:
Importance of natural enemies
A
- Natural enemies are really important.
- Protected from herbivores or whether they were in a gap.
- Being protected by herbivores is more important than being in the sun.
- biggest contributor to species diversity was getting away from natural enemies.
- In two tropical forests, protection from herbivores was more important than being in a gap (full sun)
- So the main contributers to species diversity are intraspecific competition (for the common species) and the biotic environment (suppresion, natural enemies) for rare species
74
Q
Four factros helping coexsistence:
Janzen Connell effect
A
- Seeds survive better if they disperse away from conspecifics
- Effect is reduced by fungicide
- Acer didn’t benefit from fungicide but tsuga did benefit from fungicide, they survived better when fungicide were there.
- Tsuga was suffering from pathogens, pathogens stop things from getting so common.
