Lecture 30 - Ecology (part 1) Flashcards
Ecology
is the rigorous study of climate and interactions with other species in understanding how these influence the distribution and abundance of organism
Organismal Ecology
how does an organism’s structure, physiology, and behaviour affect its SURVIVAL in the environment
• Ex. How do flamingos mate?
Population Ecology
analyses factors that effect POPULATION SIZE and how it CHANGES through time
• Ex. What environmental factors affect the reproductive rate of flamingos?
Community Ecology
examines how interactions between species, such as predation and competition, affect COMMUNITY STRUCTURE AND ORGANIZATION
• Ex. What factors influence the diversity of species that interact within an area?
Ecosystem Ecology
emphasises energy flow and chemical cycling BETWEEN ORGANISMS and their environments
• Ex. What factors control photosynthetic productivity in this aquatic ecosystem?
Landscape Ecology
focuses on factors controlling exchanges of energy, materials, and organisms ACROSS MULTIPLE ECOSYSTEMS
• Ex. To what extent do nutrients from terrestrial ecosystems affect organisms in this lake?
Global Ecology
examines how the regional exchange of energy and materials influences the functioning and distribution or organisms ACROSS the biosphere
• Ex. How do global patterns of air circulation affect global distribution of species?
Earth’s climate varies by…
latitude & season & is changing very rapidly!
What is the main driver of organismal distribution?
climate
Climate
the long term prevailing weather conditions in an area
Climate is determined by a wide variety of factors:
- Solar energy
- Seasonality
- Water Bodies
- Mountains
Solar energy
- Insolation
- Higher temps in the tropics evaporate more water, causing warm air masses to flow to the poles
- As they move over tropics, condense and release moisture (rain)
- Dry air creates deserts (~30°N/S)
Insolation
is the intensity of sunlight (energy) in a given area during a period of time
Seasonality
- The Earth’s tilt toward the sun and annual rotation around the sun causes strong seasonal variations in middle to high latitudes
- Changes day length, solar radiation, temperature
- Can cause seasonal shifts in rainfall amounts, wind patterns, ocean currents
Water Bodies
- Ocean currents affect climate by heating and cooling overlying air masses
- Coastal regions are also generally wetter than intercontinental areas
- Supports huge diversity of coniferous rainforests (Giant redwoods and Sitka spruces along West Coast), or fog forests of Newfoundland
- The specific heat capacity of water means water moderates local climates
On hot days…
land is warmer than water and warmer air masses draw in cooler air masses from water to land
At night…
water cools more slowly than land, drawing cooler air from the land away and warming it with the warmer air from water
Mountains
- When warm air meets a mountain, the air rises and cools
- The windward side receives abundant rainfall as the air moves up the mountains
- On the leeward side, air is now cooler and descends, picking up moisture and resulting in a “rain shadow” (drier)
- Produces the world’s deserts and also Alberta Chinooks
- Also affect sunlight
South-facing slopes in the N. hemisphere…
receive more sunlight than north-facing slopes, and are thus warmer and drier
Spruce and conifers grow on the…
&
Drought-resistant plants grow on the…
cooler north-face and shrubby
south-face
Every 1000m increase in elevation drops the temperature by…
~6°C
At a smaller scale…
microclimate can develop
Microclimate
Very fine, localised patterns in climatic conditions
What factors can microclimates be caused by?
- Abiotic
* Biotic
Abiotic
non-living
• Chemical and physical attributes
• Temperature, light levels, water, nutrients
Biotic
living
• Forest trees moderate climate below them by casting shade, reducing wind, reducing surface evaporation
• Creates a cooler, humid microclimate
Global climate change can affect the…
interactions of life all around Earth (biosphere)
Climate change
The burning of fossil fuels and deforestation have dramatically changed the Earth’s climate in a directional shift from Earth’s normal climate
• The burning question becomes then if current global species will be able to adapt to these climatic shifts
Interactions…
limit the distribution of species
Physical location of the land…
can affect distribution
• Kangaroos in Australia are found no where else on Earth
Ecologists…
ask not only where are organisms found, but also why
- can use molecular evidence to unravel evolutionary pasts and historic dispersal routes
As climate warms…
natural range expansion can occur, however abiotic factors can limit how much they expand their ranges
- Range expansions can have huge affects
- Coyotes expand into new territories, reducing deer populations
- Reduced deer populations affect tick populations and reduce the prevalence of Lyme-disease (if humans don’t control coyote populations)
- Coyotes can also hybridise with wolve “coy-wolf”, ie Eastern coyote
Abiotic factors can affect…
dispersal
Abiotic factors that can affect dispersal:
- Temperatures
- salinity
- water levels
- sunlight
- soil nutrients/composition can also prevent organisms from tolerating and surviving in new environments
Fundamental niche
the abiotic factors that permits an organism to survive in an area
Main abiotic factors limiting dispersal are…
temperature and moisture
Fundamental niche affects…
biological processes
• Cells can rupture if water they contain freeze
• Proteins denature in high temperatures
Temperature sets northern limit for many…
Northern Hemisphere species
Northern Hemisphere species
- These have evolved adaptations to survive with temperature fluctuations
- Ecotherms have evolved behaviours to adapt to these changes (ie burrowing in mud during the winter)
Ectotherms
have evolved behaviours to adapt to these changes (temp fluctuations) (ie burrowing in mud during the winter)
Biotic factors also affect…
dispersal (are other species responsible for limiting dispersal?)
Biotic factors that also affect dispersal:
- Negative interactions with predators or herbivores can restrict an organism’s ability to survive and reproduce
- Absence of food sources or plant pollinators
- Presence of pathogens, parasites, or other competing species
- Humans
Biological process affect…
population dynamics
Populations
are a group of individuals from the species inhabiting the same general area
Populations rely on what?
Rely on the same resources, are influenced by the same environmental factors, and are likely to interaction and interbreed with each other
Populations described via…
boundaries and size (ie # individuals in an area)
Density
is the # individuals per unit area or volume
Density use a variety of methods to determine density:
- mark-recapture
- counting a subset per unit area and extrapolating
- counting proxies (tracks, fecal piles, number of nests, etc)
Individuals can be:
added or removed from populations
• Additions from births or removals from deaths
Immigration
influx of new individuals from another population
Emigration
movement of individuals out of a population to other locations
Dispersion
is the pattern of spacing among individuals
3 types of dispersion:
- Clumped
- Uniform
- Random
Clumped
aggregate in patches (ie plants and fungi due to soil conditions)
Uniform
evenly spaced (ie territorial animals, flocks of birds)
Random
spacing is independent of other individuals (ie dandelions)
Demography
is the study of vital statistics of populations and how they change over time
Demographics…
Can construction life tables, summarising the survival and reproductive rates of individuals in specific age-groups in populations
Birth rates
frequency of live offspring born in a population
Death rates
frequency of deaths in a population (ie Mortality rate) during a given timeframe
Life tables usually just look at…
females since only females physically produce offspring
Demographics can represent the survival data as a…
survivorship curve
Survivorship curve
Plot of the proportion of individuals in a cohort still alive at each age
Type I (Survivorship curve)
flat at start, low death rates early on
• Typical of large mammals that produce few offspring but high investment in
parental care
Type II (Survivorship curve)
intermediate, constant death over lifespan
• Typical of ground squirrels and small animals
Type III (Survivorship curve)
sharp death rate at start, declines as aging increases
• Typical of organisms that produce abundant young (fish, plants, etc),and do not provide much for parental care
Reproductive rates
Reproductive output varies with age in females
What do Reproductive rates estimate via & with?
• Estimate via direct counts, mark-recapture method
• Estimate with molecular tools
- Skin samples from mother and amplify DNA using genetic markers using PCR
- Then sample young to see how many match the genetic profile of the mother
