14. Ecology +

Question 1

Age Structure

Answer 1

• 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.

Question 2

Survivorship Curves

Answer 2

• 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.

Question 3

Carrying Capacity

Answer 3

• maximum number of individuals that a habitat can sustain.

Question 4

Biotic Potential

Answer 4

• maximum growth rate of a population under ideal conditions w/ unlimited resources and without restrictions.

Question 5

Population growth

Answer 5

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.

Question 6

General Patterns of population growth:

Answer 6

1. Exponential growth - J shaped curve

2. Logistic Growth - limiting factors restrict population to carrying capacity. S shaped or sigmoid curve

Question 7

2 Kinds of life history strategies:

Answer 7

1. 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.
2. 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.

Question 8

Interspecific Competition

Answer 8

• competition between different species.

Question 9

Various ways competiton is resolved:

Answer 9

1. competitive exclusion principle - no 2 species can coexist
2. resource partitioning - competitors pursue slightly different resources.
3. Character displacement - divergence of features resulting from resource partitioning. ex. beak difference
4. 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.

Question 10

Symbiosis

Answer 10

1. Mutualism. both species benefit. ex. lichen, symbiosis of fungi and algae.
2. Commensalism. one specis benefits, other not helped or harmed.
3. parasitism, parasite benefits, host harmed.

Question 11

Aposematic coloration

Answer 11

• warning coloration

Question 12

Mullerian vs. Batesian mimicry

Answer 12

• Mullerian - animals with same defense share colors

- Batesian - animal with no defense mimics color of another with defense.

Question 13

Climax community

Answer 13

• final successional stage of constant species compostion. The climax community persists relatively unchanged until destroyed by some catastrophic event.

Question 14

Pioneer species

Answer 14

• 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.

Question 15

Two kinds of succession:

Answer 15

1. primary succession - occurs on substrate that never previously supported living things. ex. volcanic islands.
2. secondary succession - occurs on habitats where communities were entirely or partially destroyed. ex. forest fire, floods, overgrazing. Substrate already bear soil

Question 16

Detritivores

Answer 16

• consumers that obtain energy by consuming dead plants and animals (detritus)
• smallest detritivores, called decomposers, include fungi and bacteria.

Question 17

Nitrogen fixation

Answer 17

N2 –> NH4+

by

nitrogen fixing prokaryotes

Question 18

Nitrification

Answer 18

NH4+ —> NO2- and NO2- —> NO3- by various nitrifying bacteria.

Question 19

Denitrification

Answer 19

NO3- —> N2

Question 20

Ammonification

Answer 20

• organic compound –> NH4+

Question 21

Tropical rain forests

Answer 21

• 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.

Question 22

Savannas

Answer 22

• grasslands w/ scattered trees. Receive less water than rain forests.

Question 23

Temperate grasslands

Answer 23

• receive less water and are subject to lower temp than savannas

Question 24

Temperate deciduous forests

Answer 24

• occupy regions that have warm summers, cold winters and moderate precipition. deciduous trees shed their leaves in winter.

Question 25

Deserts

Answer 25

• hot and dry

Question 26

Taigas

Answer 26

• coniferous forests. winters are cold, precip is in form of snow

Question 27

Tundras

Answer 27

• harsh winter, where ground freezes. During summer, upper topsoil thaws but deeper soil, the permafrost, remains permanently frozen.

Question 28

Fresh water biomes

Answer 28

• bonds, lakes, streams, and river

Question 29

Marine biomes

Answer 29

• estuaries (ocean meets river), Intertidal zone (ocean meet land), pelagic ocean (deep ocean)

Question 30

Ozone

Answer 30

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.

Question 31

Acid rain

Answer 31

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.

Question 32

Desertification

Answer 32

Overgrazing of grasslands that border deserts transform grasslands into deserts. Agriculture output decreases as a result.

Question 33

Deforestation

Answer 33

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.

Question 34

Biological magnification

Answer 34

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

Question 35

Eutrophication

Answer 35

. Process of nutrient enrichment in lakes and subsequent increase in biomass is called eutrophication.

Question 36

7. Reduction in species diversity

Answer 36

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.