14. Ecology + Flashcards
Age Structure
- description of abundance of individuals of each age.
- rapidly growing population is indicated when a large proportion of the population is young.
- pyramid-shaped age diagrams indicate rapidly growing populations.
Survivorship Curves
- describe difference in mortality of a species during its lifetime
- Type I - most survive to middle age at which mortality is high. ex. humans
- Type II - survivorship random. Mortality same at all ages. ex. rodents
- Type III - most die young. ex. oysters and other species that produce free-swimming larvae.
Carrying Capacity
- maximum number of individuals that a habitat can sustain.
Biotic Potential
- maximum growth rate of a population under ideal conditions w/ unlimited resources and without restrictions.
Population growth
r = (births - deaths) / N
- when r is maximum (biotic potential), it is called intrinsic rate of growth.
- When deaths exceed births, r will be negative, and population size will decrease.
General Patterns of population growth:
- Exponential growth - J shaped curve
2. Logistic Growth - limiting factors restrict population to carrying capacity. S shaped or sigmoid curve
2 Kinds of life history strategies:
- r-selected species: rapid growth, J-shaped curve. Opportunistic species, such as grasses and many insects that quickly invade a habitat, quickly reproduce and then die.
- k-selected species: population size remains relatively constant (at carrying capacity), produce small number of relatively large offspring that require extensive care. Reproduction occurs repeatedly during lifetime. ex. humans.
Interspecific Competition
- competition between different species.
Various ways competiton is resolved:
- competitive exclusion principle - no 2 species can coexist
- resource partitioning - competitors pursue slightly different resources.
- Character displacement - divergence of features resulting from resource partitioning. ex. beak difference
- Realized niche. in absence of competing species, the niche an organism occupies is fundamental niche. in presence of competing species, each occupies a realized niche, where there is no overlap.
Symbiosis
- Mutualism. both species benefit. ex. lichen, symbiosis of fungi and algae.
- Commensalism. one specis benefits, other not helped or harmed.
- parasitism, parasite benefits, host harmed.
Aposematic coloration
- warning coloration
Mullerian vs. Batesian mimicry
- Mullerian - animals with same defense share colors
- Batesian - animal with no defense mimics color of another with defense.
Climax community
- final successional stage of constant species compostion. The climax community persists relatively unchanged until destroyed by some catastrophic event.
Pioneer species
- plants and animals that are first to colonize a newly exposed habitat. Typically opporunistic, r-selected species.
- as conditions change, r-selected species gradually replaced by k-selected species.
Two kinds of succession:
- primary succession - occurs on substrate that never previously supported living things. ex. volcanic islands.
- secondary succession - occurs on habitats where communities were entirely or partially destroyed. ex. forest fire, floods, overgrazing. Substrate already bear soil
Detritivores
- consumers that obtain energy by consuming dead plants and animals (detritus)
- smallest detritivores, called decomposers, include fungi and bacteria.
Nitrogen fixation
N2 –> NH4+
by
nitrogen fixing prokaryotes
Nitrification
NH4+ —> NO2- and NO2- —> NO3- by various nitrifying bacteria.
Denitrification
NO3- —> N2
Ammonification
- organic compound –> NH4+
Tropical rain forests
- mostly tall trees forming a spreading canopy that allows little light to reach forest floor.
- Epiphytes - plants that live commensally on other plants.
- little growth on floor.
Savannas
- grasslands w/ scattered trees. Receive less water than rain forests.
Temperate grasslands
- receive less water and are subject to lower temp than savannas
Temperate deciduous forests
- occupy regions that have warm summers, cold winters and moderate precipition. deciduous trees shed their leaves in winter.
Deserts
- hot and dry
Taigas
- coniferous forests. winters are cold, precip is in form of snow
Tundras
- harsh winter, where ground freezes. During summer, upper topsoil thaws but deeper soil, the permafrost, remains permanently frozen.
Fresh water biomes
- bonds, lakes, streams, and river
Marine biomes
- estuaries (ocean meets river), Intertidal zone (ocean meet land), pelagic ocean (deep ocean)
Ozone
UV + O2 —> O3
ozone absorbs UV and prevents it from damaging DNA of plants and animals
- chlorofluorocarons (CFC) enter upper atmosphere and break down ozone —> ozone holes over antarctica, arctic.
Acid rain
Burning of fossil fuels release pollutants that contain SO2 and NO2. These react w/ H2O, producing sulfuric acid and nitric acid. These return to earth (rain/snow), and kill plants and animals.
Desertification
Overgrazing of grasslands that border deserts transform grasslands into deserts. Agriculture output decreases as a result.
Deforestation
Causes erosion, flooding, and changes in weather patterns. Slash-and-burn method of clearing tropical rain forests for agriculture increases atmospheric CO2 -> greenhouse effect. Most nutrients are stored in the vegetation, therefore burning destroys the vegetation.
Biological magnification
Air pollution, water pollution, and land pollution contaminate the materials essential to life. Some toxins concentrate in plants and animals. As one organism eats another, the toxin becomes more and more concentrated, a process called biological magnification
Eutrophication
. Process of nutrient enrichment in lakes and subsequent increase in biomass is called eutrophication.
- Reduction in species diversity
Destruction of tropical rain forests and other habitats, plants and animals becoming more extinct at a faster rate than the planet has ever previously experienced. Disappearing plants could be useful to humans as medicines, food.
