Ecology Flashcards
What is ecology?
the science of how organisms interact with each other and their environment
Biotic vs. abiotic factors
biotic: living
abiotic: non-living
Ecosystem services
services we can gain from around us
What approaches does modern ecology use?
- observational
- experiments
- data analysis + statistical modelling
- community engagement + diverse knowledge systems
What is distribution and what do ecologists observe about it?
how a population/ species is spatially arranged. Ecologists observe limits to and changes in distributions
How do ecologists examine abundance?
changes in abundance and whether populations are growing or shrinking
Why is ecology important? (NO wrong answer)
to create a sustainable world, to reverse climate change and stop it, to prevent mass extinction and biodiversity loss
How do ecologists address conservation and biodiversity problems?
evaluating effectiveness of conservation strategies
ex: do marine protected areas work?
How do ecologists manage environmental issues?
by evaluating the consequences of human activities
ex: what effect is climate change having on biodiversity?
How are wildlife and resource management problems addressed?
by evaluating the effectiveness of management strategies
ex: when does fishing become overfishing?
What role do ecologists play in pest control?
they create strategies for reducing crop loss
ex: why do some insects get out of control?
How are ecologists involved in human health?
they examine how diseases are spread through animals
ex: what is the role of climate and how will climate change affect pathogen spread?
What are the levels of ecological study? (from smallest to biggest)
- organism
- population
- community
- ecosystem
- landscape/ seascape
- global
What has the most significant influence on the distribution of organisms?
climate
What is climate?
the long-term prevailing weather condition in a given area
What makes up a climate?
- temperature
- precipitation
- sunlight
- wind
- seasonal patterns
What determines climate? (main climate determinants)
- input of solar radiation
- Earth’s movement in space
What determines climate? (climate modifiers)
- large bodies of water
- mountain ranges
- greenhouse gases
How does solar radiation determine climate?
more direct sunlight results in more heat and light (i.e. equator is hotter than the poles)
Why are deserts mostly found at 30 degrees North/South?
descending air from equator heats up again and evaporates moisture resulting in a dry and hot climate
Why does the equator have high precipitation?
solar radiation drives evaporation, the rising moist air cools and releases moisture as precipitation
How do large bodies of water and mountains modify climate?
- cool, moist air flows from offshore onto land
- air warms as it crosses land
- air cools as it travels up mountain and releases moisture as precipitation
- dry air picks up moisture on other side of mountain
How do greenhouse gases modify the climate?
greenhouse gases (e.g., CO2 and methane) trap heat inside the Earth’s atmosphere
What characterizes a biome?
its climatic features and predominant vegetation
What is a climograph?
a representation of annual mean temperature and annual mean precipitation
Northern coniferous forest (boreal forest/taiga)
- largest terrestrial biome
- 30-70 cm annual precipitation
- cold winters, hot summers
- dominated by cone-bearing trees
What drives transitions among forested biome types?
temperature and precipitation
What is disturbance?
an event that removes individuals from a population
What is two examples of disturbance?
- Large animal grazers
- Fire
Both events remove plant life. W/o them, Savannas would be Woodlands
What drives the transition from forested to non-forested biomes?
precipitation and disturbance
What is happening to biomes and ecosystems as temperatures rise?
boundaries are shifting towards the poles (cooler areas)
What are range shifts?
when a species shifts its range to stay within their climatic niche
- generally from equator -> poles
- avg. 17km/decade (terrestrial) and 72km/decade (marine)
- deeper (marine) and higher (mountains)
Why will some species be unable to shift to a more suitable temperature?
- suitable habitat not available
- species may not migrate quick enough to track suitable climate
What limits distributions?
- dispersal: organism didn’t get there
- abiotic factors: temperature, moisture, salinity (oceans), oxygen (oceans)
- biotic factors: resources, predation, competition, disease
Impact of climate on humans
the countries who are contributing the least to climate change are also the most vulnerable
What are some threats to biodiversity?
- habitat destruction
- overexploitation
- pollution
- invasive species
Population
group of individuals of the same species living in the same area sharing similar resources that interact and breed
Population ecology purpose
to measure population size, model population growth, create life history strategies, examine population diversity
What is a census?
measuring ALL individuals in a population
Why is a census disadvantageous?
hard to:
- count a whole population of very small organisms (beetles)
- count individuals in a large area
- count a huge population
What are examples of indirect indicators of population size and why are they more useful?
- # of nests, burrows, tracks
- catch per unit effort (CPUE) -> fisheries
- mark-recapture methods
these methods require less resources, less time, and less money
What was observed in the catch per hundred hooks example?
the number of catches decreased globally as time went on, the region of fishing expanded
red regions -> blue regions -> new red regions -> blue regions
How does the mark-recapture technique work?
a number of organisms from a population are captured and marked (tag, paint, etc.) and then are released. At a later time, another group is captured and researchers count how many organisms are marked out of the group. The number marked in the second group compared to those unmarked is proportional to the total number marked compared to the whole population
What assumptions are made when using mark-recapture?
- marked and unmarked have the same probability of being captured
- marked individuals have completely mixed back in with population (i.e. they aren’t off in their own group)
- no individuals born, die, immigrate/emigrate during sampling interval
What equation is used for mark-recapture?
x/n = s/N
where:
x = total number of individuals marked in second sample
n = number of individuals in second sample
s = number marked and released in first sample
N = estimate of population size
N = s*n/x
What is the exponential growth model?
dN/dt = rN
where:
dN/dt = rate of change in a population
N = current population size
r = growth rate (larger = faster growth)
When does exponential growth occur in a population?
when resources are readily available, not limited
What slows population growth rate?
- limited resources
- food and space
- competition
What is intra-specific competition?
competition for resources among individuals of the same species
Is r (growth rate) dependent on birth and death rates?
Yes, r = b-d
How did population density of sea otters impact birth rate?
Population density did not impact birth rate, therefore birth rate is density independent
Was pup death rate in sea otters density-independent or density-dependent? Why?
Death rate in sea otters was density-dependent because limited food meant mothers were thinner which resulted in a lower survival rate for pups
What is carrying capacity?
represented by K, carrying capacity is the # of individuals of a given population that the environment can support/sustain; birth rate = death rate (intersection of the two lines on graph)
What is the logistic growth model (equation and what it means)?
dN/dt = rN((K-N)/K)
where (K-N)/K reduces the rate at which the population grows as N increases
Briefly summarize the growth model of the lionfish invasion model
- very successful invasive species
- few natural predators, reproduce quickly
- growth originally followed exponential model when resources were abundant, however it eventually followed a logistic growth rate
What is a top-down process?
a given population is regulated by predation from ABOVE them in the food chain
What are the three main variables of life history?
- age of first reproduction
- how often organism reproduces
- how many offspring produced per reproductive episode