Midterm 1.2 Flashcards
Epigenetics
Study of heritable changes in gene expression
Involves phenotype: no changes in actual dna sequence
Anthropocene
Human era today
Damage to earth by human activity
Our impact: higher conc of greenhouse gases
Altered climate, etc
Carbon cycle
Organisms, volcanoes, natural processes pump CO2 in air
But humans adding a lot more to atm
Routes that C atoms take through env
Carbon placement
What phase/chemical bond #or carbon stays same
Carbon cycle problems with human int
Rate at which we extract carbon is exceeding natures capacity to return it/ absorb it
Dissolves in water, causes impacts
Phosphorus cycle
Phosphate is need for plants to grow
Agriculture: demand for phosphorus inc fast
Mining of phosphate rock for agr and fertilizers
Problem of human int of phosphorus cycle
Phosphates from fertilizers leak into our waterways and cause eutrophication
Boasts algae growth
Eutrophication
Excess phosphorus/nitrogen to soil drains into waterways and inc algae growth
Ex. Lake Winnipeg
Nitrogen cycle
Nitrogen passes from air (through lightning or bacteria) to NH4 that can be used by plants and animals
Industrial nitrogren fixation
The process of converting n2 from air to nh4 by haber process to make liquid ammonia which is a compound in fertilizers
Nitrogen cycle problems with human int
Fertilizers runoff and excess nitrogen boosts growth of plants and algae
Results in hypoxia and eutrophication, robbing the other organisms of oxygen
Implications of human modifications to cycles
Rate of modification is exceeding natures capacity
Disrupting cycles that are billions of years old
Ethical debate: we must feed and power ourselves too
Externalizing costs
A cost/ benefits that impacts something other than the buyer/seller.
Ex. Harm to citizens from water pollution, air pollution, etc.
We are externalizing costs to the environment
Interdependance of species example- wolves
Wolves brought dear pop down by hunting- also changed beh of deer who no longer went in the open prairies to graze all the grass- vegetation started to grow back- made habitats for other species- number of species increased (beavers, otters, ducks, mice, invertibraes)- more food for species and so on…rivers: less erosion with regenerating forests
Possible causes of extinction
Disease Habitat destruction Exploitation Pollution Pesticide use Alien species Uv radiation
Changes in pop
of organisms not stable
Fluctuations with env
Shifts may be dramatic
J curve
Exponential growth:
Env conditions
Little competition
Exceeds carrying capacity
Over grazes and crashes due to starvation
S curve
Pop increases but stabilizes around carrying capacity
Pop held in balance despite small fluctuations
Logistic curve
Biotic potential
Capacity for a species to increase its numbers
Given optimum conditions, reproduction, expansion of habitat, etc
Environmental resistance
Sum of factors that limit biotic potential
Geographically and biologically
Water, space, food, predators, disease
Carrying capacity
Upper limit of # of organisms an ecosystem can support
Over long term
Includes both biotic pot and env resistance
Critical number
Lowest number of org required to ensure that a pop may reproduce and continue
Factors that influence pop #s
Available habitat Availability of forage or prey (food) Predation - capacity to kill prey Disease Parasites
Keystone species
Species that has a large effect on community
Critical to functioning of ecosys
Disproportionately large effect relative to its abundance
On lower trophic levels or high ones
Keep things in check
When u remove, one pop may boom and the other may decline
Regime shift
Disturbance exceeds limit of ecosystem resilience
Sudden
Ex. Coral reef to algae reef
Tropical forest to grassland
Forest fires
Crucial to some ecosys
Serotinous cones: seeds are only released when heated
