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Lecture 11

BIO120H1 Lecture Notes - Lecture 11: Soil, Erythronium, Elaiosome

Course Code
James Thomson

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Lecture 11 species interactions in subalpine meadows
Distribution and abundance
Glacier lily flowering plants seem to do best where the soil surface is very rocky. Something about rock
that favors glacier lily. Life history: iteroparous, long resource accumulation phase in an underground
corm. Seeds stage primary seed dispersal distance. Results modal dispersal distance about 20cm
Secondary dispersal by ants, present in other Erythronium species elaiosome, full of elaios acid that is
attractive for ant because of protein, then they through it out with seeds, which is better dispersal and a
lot of nutrients in the soil in the ants garbage that favors the growth of the lily
Seed germination experiment
What factors about soil may influence on success of seeds. Deeper soil areas will contain more moisture
compared to the rocky. Buried in organic soil made it, others not.
Results of experiment suggest the opposite of what we saw: should find more plants away from thin soil
around rock outcrops
Should find most seedlings near flowering plants
- Flowering plants
- Vegetative plants
- Seedlings
- Soil moisture
- Rockiness
- Predation risk, pocket gopher
How to quantify gopher activity leave cores of soil in the spring
Flower vs vegetation vs seedlings
Rockiness vs soil moisture
Rockiness vs gopher activity
- Most seeds are produced in rocky areas and fall there but most die
- Few seeds that reach moist, deep-soil area are more likely to survive and produce seedlings
- But seedlings that get established in deep-soil have a risk to be under predation of gopher
- Rock-refuge hypothesis
- Desiccation due to abiotic conditions and stress, cant happen a lot, because flowers are there
- Delayed interoparity brings vulnerability
- Predation species interactions
- Lily realized niche
- Why no elaisome dispersal is a disadvantage
Cantor, Whitham: pocket gophers as an influence to the aspen trees. Trapping gophers at aspen-
meadow interface allows aspen to invade the meadow. Removed gophers -> a lot of new stems in those
areas without gophers, when gophers are moving through the soil are cutting the roots influencing
aspens growing
- Aspen grow better in deep-soil areas but only if protected from gophers
- Aspen clones are centered on rock outcrops; outward expansion is limited by gophers cutting
roots, rock-refuge effect again
- Gophers have a profound effect on the habitat it leaves in, are keystone species in the aspen-
meadow mosaic; direct effect on the lilies, - effect on the aspen -> + effect on lilies
Climate change
- Co2 and methane: atmosphere is warming and can hold more water
- Hadley cells get stronger and larger, contain more water: desert belts shifting poleward beyond
30 degrees
- Local climate changes are affecting organisms
- Geographical ranges are shifting to match ranges of tolerance, a lot of animals migrate from
Eg. Polar bear is endangered species, because arctic snows melt fast, migrate to south -> hybridize with
grizzly bears
Eg 2 Pika adapted to cold mountain tops, death zone for pika is in the lower part of the mountain
Extirpation local extinction