ecology (unit 2) Flashcards
what is ecology?
the study of how organisms interact with each other and their environment
what two factors do you look at in ecology?
distribution and abundance
what is a terrestrial biome?
a major ecosystem type that has one dominant type of vegetation
describe the northern coniferous biome?
a terrestrial biome filled with evergreen needles located in upper north America and Asia/Europe
describe the temperate broadleaf biome?
a terrestrial biome filled with deciduous broadleaves with a wet climate located between the polar region and tropical region
describe the tropical forest biome?
terrestrial with evergreen broadleaves in a hot and wet climate in the tropics
describe the temperate grassland biome?
biome in dry climate located in north america and easter europe
describe the savanna biome?
made up of grasses with some trees in a hot climate, located mostly in africa, with some in australia, south america, and india
what are the three types of biomes?
forest biomes, grass biomes, and dry biomes
what are the forest biomes?
northern coniferous, temperate broadleaf, and tropical forest
what are the grass biomes?
temperate grasslands and savanna
what are the dry biomes?
desert and tundra
what are the terrestrial biomes?
northern coniferous, temperate broadleaf, tropical forest, and tundra
what affects distribution?
latitude, temperate, precipitation, and disturbance
what is the definition of distrubance?
an event that removes individuals from a population
what limits the change of distriubtions?
dispersal (the organism doesn’t get there), abiotic factors, or biotic factors
what are some examples of abiotic factors?
temperature, moisture, salinity, oxygen
what are some examples of biotic factors?
resources, predation, competition, disease
explain how coyote populations grew (and distribution changed) in the 90s?
wolfs became extinct in 1990, which made expansion into NS much easier for coyotes, and agriculture led to forest removal, which made rodents and small prey more abundant
what is the exponential growth model?
dN/dt = rN
where:
dN/dt = population change
r = growth rate
N = population size
how do you calculate population growth rate?
r = b - d + i - e
where:
b = birth date
d = death rate
i = immigration rate
e = emigration rate
explain what happened to the desert locusts (from lesson one)?
- population changes quite often, possibly because of rainfall
- more food leads to more locusts, which leads to clumping which leads to crowding which leads to gregarization (high density) which gives the locusts strong colours, swarm flying during daytime (opposed to flying alone at night) this is because mechanical stimulation creates hormone secretion (serotonin) creating a behavioural change in hours and a colour change in months
explain the otters example of population density?
- otters have hisotrically large populations, but have become small and disjointed due to the fur trade (1700s to 1911) leaving 1000/2000 otters left
- went extinct (last otter was on the BC coast in 1929, despite a harvest moratorium to attempt to help the population)
- otters were relocated to Amchitka island in the 50s (which was turned into a wildlife reserve after WW2), but all were killed bu weapons tests in the late 60s/early 70s.
- 89 otters were relocated to van island between 1977 and 1995, causing exponential growth (r = 0.19)
- growth slowed after 1995 (r = 0.08) and stabilized/reached max in 2008-2013 (r = 0.05) with 5200 otters
what is carrying capacity (k)?
the max population an environment can support
what is density dependant/independent?
birth rate is density indepdent
death rate is density dependant
what is equilibrium density?
(if b = d) is if the regulated population is at equilibrium and has more than one density-dependent rate
what is the logistical growth model?
dN/dt = rN(K-N)/K
when N is the growth rate with unlimited resources
what is the relationships between N and K in the logistical growth model?
when N is small, population growth is close to exponential
when N = K population growth is 0
when N > K population growth is negative
what are the reproductive trade-offs?
r-strategy maximizes number of offspring (doesn’t take care of them very well)
K-strategy maximizes offspring survival (less number of offspring)
in what environments/species does the r-strategy work the best?
open/distrubed, temporary, and unprediactable enviornemnts
invading/colonizing species
in what environments/species does K-strategy work the best?
competitive but predictable environments, and crowded/permanent environments
**high survival when young, lower as adults
what are the shapes of age pyramids?
spindle-shaped - boomer bulge and echo (canada)
concave-shaped - high birth rate and high death rate (niger)
convex shape - declining birth rate and low death rate (India)
explain TFR:
total fertility rate, or the average number of children per woman
what is the replacement TFR?
2.1 (zero population growth - births exactly replace death)
what are the main features of aquatic biomes?
they vary in salinity, range from freshwater to estuaries to marine
what does depth affect in aquatic biomes?
light, temperature, places to attach, and pressure
what is stratification?
the formation of zones that form a thermocline (zone of rapid temp change)
what are the two zones of lake stratification?
the photic zone (warm, oxygen rich, nutrient poor) and the bottom zone (cool, oxygen poor, nutrient rich)
when do the stratification zones of lakes mix?
during turnover seasons (spring and fall)
what are the layers of ocean stratifcation?
eutrophic (high nutrients and productivity) and oligotrophic (low nutrients and productivity)
what are some examples of shallow water marine biomes?
kelp forests, coral reefs, and intertidal biomes
what are the main types of species interactions?
competition (loss for both), mutualism (gain for both), parasitism (gain/loss) or commensalism (gain/neutral)
*gain/loss is on growth rates
what is the ecosystem of the rocky intertidal like?
- the rocky intertidal has four zones that have typical/common organisms
- splash zone with periwinkle snail
- high intertidal with barnacles
- mid intertidal with mussels
- low intertidal with sea stars
explain the competition in the rocky intertidal?
barnacles and algae are competing for space (interspecific comp)
there was a experiment in Scotland that showed that the small (chthamalus) and large (balanus) barnacles don’t overlap
realized that balanus excludes chthamalus from lower shore and that they cannot live on upper shore because of desiccation (physical barrier)
and that they live on different niches
what are the different types of niches?
realized niche is observed in nature
fundamental nice is theoretical good conditions for the species
what are the main features of coral reefs?
they have high diversity (corals, fish, invertebrates) and exist in shallow water between 18 to 30 degrees (tropics and subtropics)
explain the mutualism in the coral reefs?
coral polyps are small nutrient poor colony animals that live in abundant light, zooxanthellae (polysynthetic eukaryotes) live symbiotically in coral polyps by producing carbs (and giving up 90% to the polyps) and receiving safety and nutrients (CO2 and N) for photosynthesis (mutualism)
explain the competition in the coral reefs?
coral cover is being replaced by macroalgae (50% coral cover in the Caribbean in the 1970s, which was reduced to 10% in the 2000s)
this was caused by disturbance (increased coral death) and settlement (more macroalgae) - so depends on settlement rate and growth rate) and is due to a decline in large herbivorous fish (parrotfish populations were replaced by sea urchin) that ate macroalgae, a massive die-off of diadema (in 1983) and warm temps causing coral bleaching and sewage/agriculture run-off causing high nutrient leaks which killed off the coral
what are trophic interactions?
species interactions that are related to food (and are shown on food webs)
what are the important species in food webs?
those that have high biomass - dominant species
those that alter the environment - ecosystem engineers
those that are important but have low biomass/abundance - keystone species
what are trophic cascades?
top -> down control causing cascades (more predators -> less herbivores -> more plants)
what is an example of cascades (sea otters)?
otters returned to BC which caused less sea urchins and starfish, which caused more kelp (which affects productivity, physical structure, and richness of fish species) this is because kelp is harmed by urchin barrens (caused by overfishing wolfish cod in Alaska in the 90s)
what is an example of a regime shift?
urchin barrens and kelp beds to alternate (because of urchin disease) - this
what is lyme disease caused by?
spirochaete bacteria
what are the symptoms of lyme disease?
fever, joint pain, arthritis, and a bulls-eye rash
how is lyme disease communicated?
indirectly through pathogens infecting vectors (black legged (deer) ticks) which then infect a victim
what are the recent changes in lyme disease?
has been around for over 60,000 years, and on ticks for over 10,000, but cases and spread are increasing rapidly
what is the history of the prevalence of lyme disease?
it was common pre -1700s but declined in 1800s due to deforestation and agriculture, but increased again in the 1900s when the forests recovered
in connecticut there were 12 deer in 1896 and over 150,000 now
in mohegan island (maine) there are now no deer and no lyme disease
therefore: small mammals cause more ticks (migratory birds spread lyme - first found in NS on a bird in 1999)
climate change benefits also benefits ticks and lyme