lecture 5 ecology

Question 1

communtiy dynamics the three components

Answer 1

function, structure, dynamics

Question 2

function – community

Answer 2

– species interactions (predation, competition)
– energy and nutrient flow

Question 3

structure – community

Answer 3

– species richness (number of species)
– composition (relative abundance of species)

Question 4

what does relative abundance of species mean

Answer 4

do you have an equal distribution, or species that are rare and some that are not

Question 5

dynamics community

Answer 5

change in structure or function over time

Question 6

trophic interactioons

Answer 6

interactions related to feeding, – predation, herbivory, paratisism

Question 7

what do food webs represent

Answer 7

trophic interactions

Question 8

trophic level – what is it

Answer 8

verticle position in the food web

Question 9

what do the arrows in a food web represent

Answer 9

direction of energy flow

Question 10

what are primary producers typically relative to food web and trophic level

Answer 10

trophic level one – as you go up in consumers, trophic level increases one by one

Question 11

Tundra food web characteristics

Answer 11

mostly short food chains – lemmings graze on almost all of primary producers, and are eaten by most predators – they are important connector to the food web

Question 12

species with large impact

Answer 12

dominant species, ecosystem engineers, keystone species

Question 13

dominant species

Answer 13

high biomass/abundance, can feed on a variety of species – large impact due to high biomass

Question 14

ecosystem engineers

Answer 14

large impact because they alter physical environments – think beavers and dams and how they affect water flow by building their dams

Question 15

keystone sp[ecies

Answer 15

not a lot of them – relatively low in abundance – large impact despite how low biomass and abundance, usually predators

Question 16

reason why predators are important

Answer 16

top down control

Question 17

what is top down control

Answer 17

higher trophic level reduces abundance or biomass of lower trophic level.
- primary producers –> herbivores (direction of energy flow)
herbivores –> primary producers (direction of impact)

herbivores graze grass, increase in herbivores, decrease in grass

Question 18

trophic cascadxe

Answer 18

cascading down trophic levels – indirect – impact of top predators extends to lower trophic levels

primary producer –> herbivore –> predators (energy flow direction)
predators –> herbivores –> primary producers (direction of impact)

the predators prey on herbivores, decreasing their abundance, and because of this decrease in herbivores the primary producers recover and increase in abundance.

Question 19

pacific coast, sea otters, british columbia 1960

Answer 19

1960 – no sea otters
top-down control – sea urchins were abundant, they cleared out all kelp.

Question 20

british columbia 1970

Answer 20

sea otters return, top down control between otters and urchins, – urchins reduced because of food source of otters

Question 21

british columbia 1970 putting it all together

Answer 21

because sea otters reduced abundance of urchins, kelp was able to rewcover and grow forests. (trophic cascade)

Question 22

what is a sea otter an example of

Answer 22

keystone species – impact on community
– 1. fewer herbivores (sea urchins, starfish)
– 2. more kelp – more productive, physical structure , provided habitat for fish therefore richness increase

Question 23

Alaska 1990s

Answer 23

due to overfishing, Ocras diet switched and it preyed on otters. reduction of otters meant increase in urchins which meant decrease in kelp

Question 24

Atlantic coast –historical top down

Answer 24

large predatory fish – hunted sea urchins – increased kelp

then overfishing caused increase in urchins and decrease in kelp

Question 25

why is there a fluctuation on the atlantic coast

Answer 25

urchin disease -- depends on temperatyure, warmer it is, pathogens can entewr ecosystem and affect urchins.

Question 26

regime shift

Answer 26

abrupt shift to a very different and persistent community

Question 27

what causes regime shifts

Answer 27

usually external drivers -- removeal of keystone species, arrival of disease, climate change, nutrient inputs

Question 28

top down vs bottom up controm

Answer 28

top down -- higher trophic level controls abundance or biomass of lower trophic level (herbivores limit primary producer biomass) dottom up lower trophic level controls abundance or biomass of higher trophic level (primary producers limit herbivore biomass)(food limited)`

Question 29

top dowqn critical points

Answer 29

- Top predators frequently exert top down control - without predators, heerbivores often have strong impacts on primary producers.

Question 30

applications to top down control

Answer 30

-- wildlife managment in absence of top predators (reintroductions to re establish ecosystem) -- management of insect pests -- management of natural resources (limits to fishing)

Question 31

zoonotic disease

Answer 31

disease transferred from animals to humans

Question 32

what is lyme disease

Answer 32

caused by a spirochaete (bacteria) -- pathogen can cause fever, joint pain, arthritis, bulls-eye rash

Question 33

how do yuo getnthe lyme pathogen

Answer 33

tick bites. -- from black-legged tick (also known as deer tick) -- they enlarge during feeding

Question 34

when do ticks bite humans

Answer 34

when theyre adults

Question 35

transmission

Answer 35

pathogens much move between hosts. there is direct and indirect

Question 36

direct transmission

Answer 36

pathogens move from one host to the next

Question 37

indirect transmission

Answer 37

pathogens use another organism (vector) to help them move -- tick is a vector

Question 38

hiow many blood meals do ticks take from hosts

Answer 38

3

Question 39

which life span of tick would not have lyme

Answer 39

newly hatched larva, they have to pick it up from an animl theyre getting blood from

Question 40

basic run down of how the lyme transmission goes

Answer 40

ticks get the pathogen by feeding on an infected hiost. when the tick feeds again, it may pass the pathogen on to a new host. humans are hust accidental hosts.

Question 41

lyme disease historically

Answer 41

lyme disease when europeans first colonzied north america was very common -- then declined dramatically during 1800s -- increased again in late 1900s

Question 42

wht happened that the ticks increased again

Answer 42

pre-1700s -- forest and deer were abundant 1830 -- peak forest clearing (25%) left 1850 -- farm abandonment 1910 -- abandoned fields 1930 -- forest recovering 1960s-- 75% of forest bacxk increase in the habitat, forest, increased number of deer, which increased ticks because deer is their preferred food source.

Question 43

small mammals limit tick abundance

Answer 43

more mice -- more infected ticks -- more lyme diseasef

Question 44

factors that influence white footed mouse abundance affect incidence of lyme disease

Answer 44

coyotes vs foxes -- foxes eat mice but coyotes eat foxes. because of huge exapansion, more coyotes present -- therefore coyotes have negative impact on foxes, which increases abundance iin mice.

Question 45

howq does lyme disease spread `

Answer 45

migratory birds move ticks to new locations

Question 46

climate change and lyme disease

Answer 46

climate must be warm enough for tick survival and reproduction -- as climate warms , black legged tick range is predicted to expand