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22 Cards in this Set
- Front
- Back
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What is a keystone species? |
- disproportionately large effect on its environment relative to its abundance - critical role in maintaining the structure of an ecological community - affected many other organisms in an ecosystem - help determine the types and numbers of other species in the community |
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Describe how lemmings are a keystone species. |
1) work soil which creates niches for plants and insects, weasels. 2) can have major influence on vegetation in peak years 3) abundance controls the rhythm of animal life on the tundra. Important for ermine, arctic foxes, snowy owls, gyrfalcons, and jaegers. Lemmings are the bait of the arctic |
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What are the 2 kinds of lemmings? |
1) Brown lemming: slightly more southern. 2) Collared lemming: farther north, changes to white and dark. |
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What is the lemming range? |
- Matches treeline and continuous permafrost line |
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What are some lemming characteristics? |
- up to 7 offspring per female - can reproduce a few weeks after being born - can breed all year round including under snow - most don't live more than a year in the wild. - somewhat intolerant of other lemmings at higher densities (MEAN) - Egregious, quarrelsome, combative little buggers (HEHE) - conflict, murderous sprees, and cannabilism not uncommon. |
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Describe the Great Disney Fallacy in terms of Lemmings. |
- in a movie they were depicted all jumping off cliffs and committing suicide - this is actually not something they do - Sometimes high population densities migrate over rivers and bays - often lemmings die in the attempt and wash ashore - no evidence that this occurs in north america |
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Describe Lemming population cycles. |
- 4 year cycle - This may be due to stress and confluct which reduces fitness and individuals die off, then build again to 4 year peak. |
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Describe Snowy Owl movements. |
- eruptive movements, - track them, see them go all over the place. - spend alot of time over water/ice, feed on sea ducks and birds |
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Describe Long-tailed Jaeger movements. |
- terrestrial in summer, marine in winter - completely shift their diet (winter = totally marine) |
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Describe Arctic Fox movements. |
- hunt on sea ice in winter - follow bears around - essentially a marine animal in winter |
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Describe the arctic fox harvest. |
- mid 1900s, 10 000 to 80 000 annually harvested for pelts - Key organism in exploration and development of the north - hudsons bay company - barter or money economy for inuit |
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Describe the movement of the Ermine (stoat, short tailed weasel). |
- Found throughout the territory except on ice caps |
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What is the difference between a generalist and a specialist? |
GENERALIST - unpredictable environment variation - more adaptable - arctic - arctic foxes, coyotes SPECIALIST - realiable and abundant resources - fewer competitors - tropics - small niches |
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Describe the relationship between arctic foxes and lemmings. |
- arctic foxes tend to be more marine when lemmings are low - will follow polar bears around more - good for foxes when bears are heavy |
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Describe the relationship between long-tailed jaeger and lemmings. |
- tend to be more of a lemming specialist with 3/4 of their diet consisting of lemming - fewer pellets in 2000 likely meant much poorer reproduction, probably due to low lemming numbers. |
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Describe the relationship between the snowy own and and lemmings. |
- lemming specialist - respond to high lemming years - owl and lemming cycle strongly related, right on top of each other |
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Describe the response of predators when lemming numbers increase. |
- once lemming densities hit certain level, predator numbers jump |
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Describe the relationship between ermine and lemmings. |
- there is a 4 year cycle for both predator and prey - ermine crash is 1 year after the lemming crash - maybe more of a generalist? - mechanism by which they respond must be different than owl. |
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Describe Lemmings in Greenland. |
- cycle disappeared - this had a trickle down affect on other species. |
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Describe the relationship between foxes, geese and lemmings. |
- foxes always breed near the goose colony - litters larger at colony - fox breeding and litter size high in high lemming years - predictable food supply |
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Describe interactions on the tundra. |
- In lemming year, lots of snowy owl are nesting, keep foxes away from them and the snowy geese |
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Describe lemming cycles and snow goose breeding. |
- more owls nests in high lemmings, more foxes, but geese close to owls will protect them. - higher loss of goose eggs 2-3 years after lemming peak - when lots of snowy owls are around sometimes drive away foxes. |
