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NIU / Engineering / BIOS 209 / Desert occur at what latitude?

Desert occur at what latitude?

Desert occur at what latitude?


School: Northern Illinois University
Department: Engineering
Course: Funds of Organismal Biology
Professor: Nicholas barber
Term: Fall 2015
Cost: 50
Name: Exam 4 Study Guide Exam 4
Description: EXAM 4 study guide with tips at the end!
Uploaded: 11/30/2015
23 Pages 169 Views 3 Unlocks

St Sunday, November 29, 2015 Study Guide For Exam 4  

Desert occur at what latitude?

At the end of this study guide there will be tips on how to get a high grade on  exam 4. I have used these same methods to get very high grades this semester  and I highly recommend doing them! Good luck!  

Ecology, Biomes, Global Climate  

(Interactions Between Organisms and Their Environment Include)

-Abiotic environment:



social characteristics e.g., nutrients, texture  

water chemistry e.g., pH, salinity, DO

-Biotic environment:



social groups  

predators, parasites  

competitors, prey  


Why study populations?




social groups  


predators, parasites  


St Sunday, November 29, 2015 competitors, prey  



-interaction between organisms and their environment  We also discuss several other topics like What general pattern describes human heterosexual mating preferences?

-ecologists can focus on different levels of organization  

-Ecology may focus on 1 aspect of interactions  

(Global Climate)  

-determined by the earth’s features and physics  

-Gaseous atmosphere:

size determines the earth’s gravity  

-distance form the sun (93 million miles) determines earth’s average temperature = this means there is a lot of water in liquid form  

What is smallest population that avoids extinction?

-Spherical shape:

amount of solar radiation (heat, light) per surface area, it is greatest near equator and  lower near poles  

-Earth orbits the sun:

once a year  

axis of rotation tilt is constant relative to plane of orbit  If you want to learn more check out What are the roles in animals and serving humans?

weather is tilted toward or away from sun  

this causes vacation is seasons and climate

-Density and water holding capacity of air:

as air warms it expands and rises  

warmest at the equator  

rising air cools (less pressure) and loses water  


St Sunday, November 29, 2015 cool air holds less water- rain  

rising air masses over the equator establish additional circulation cells  because descending air pulls down the air next to it  If you want to learn more check out What factors affect our attributions?

-Ocean currents:

can lead to different temperatures at the same latitude  

-Local Climate:  

is affected by local features  

e.g., a mountain can create rain shadows  

aspect (direction the slope of a mountain or hill faces also affects sunlight and  temperature, influencing the plants and animals that can live there  

-Lake effects:

water has high thermal inertia  

i.e., summers are cooler and winters are warmer near larger bodes of water  precipitation is greater downwind from large bodies of water  


-groupings by similar vegetation structure and look and associated with certain types of  animal;s and abiotic features e.g., desert, tropical rain forest

Which Level…..

fresh water march, estuary= transition zone between river and open ocean), coral reef  

-species composition in a given biome may vary around the world, though paper similar,  e.g., via convergent evolution  If you want to learn more check out What is the importance of family communication?

e.g., cacti in North America and ephors in African desert  

1. Tropical Forest  

-high rainfall year round or had pronounced dry season  

-many vegetation layers  


St Sunday, November 29, 2015 -forest floor: low light  

- biodiversity is high  

-many arboreal animals and epiphytes (grow on another plant non-parasitically)  -soils are low in nutrients  

2. Savanna  

-equatorial and subequatorial  

-seasons: no winter, summer, but wet/dry seasons  

-plants are adapted to regular fires  

(woody plants are sparse, but a lot of grasses and forbs

-fauna (animals) often includes large migratory herbivores  

3. Desert

-occur at what latitude? -30 N and S  

-on West side of continents  

-may be hot or cold  

-key characteristics is little precipitation  

-large herbivores are rare  If you want to learn more check out It is the most common nutrient deficiency, what is it?

-plants and animals have adaptations to water scarcity  

E.g., Desert Darkling Beetle Namibia

4. Chaparral

-midlatitude coasts  

-summers: hot dry  

-winters: mild/wet  


St Sunday, November 29, 2015 -plants include lots of: woody shrubs  

-includes fire adapted plants: resist burning, resprout from underground plants,  germination triggered by high heat  

5. Temperate Grassland  

-seasonal droughts and occasional or regular fire

-fauna includes large herbivores, e.g., bison  

-soil: deep, fertile  

-this means that there is A LOT of agriculture  

6. Temperate Broadleaf Forest  

-large trees are mostly deciduous (lose leaves every winter)  

-vegetation layers: fewer, simpler, than tropics  

-soil: dep, fertile  

-animals adapted for cold winters (hibernation, migration)  

-Ecotone: where two biomes and blend into each other  

*much of Illinois is forest-praise ecotone  

-forest areas were historically dominated by oaks, so much of the area is described as  oak savanna  

7. Northern Coniferous Forest  

-high latitude or elevation  

-short summers,, long cold winters  

-large areas dominated by single species  If you want to learn more check out It is one of three emperors between 1662­-1799?

-cone-bearing trees (pines, firs, spruces)  


St Sunday, November 29, 2015

8. Tundra  

-arcticic alpine (mountain tops)  

-temperature: cold all year  

-deep soil is permanently frozen = permafrost  

-vegetation low, with no trees  

-Aquatic Biomes:

-cover the majority of the earth’s surface  

-mostly open ocean (75%)  

-U.S-Canadian Great Lakes Contain -1/5 of world’s fresh water  

-Aquatic Biomes Zones:  

photic zone: sufficient light for photosynthesis  

aphotic: insuffiecient  

benthic zone: bottom  

*ocean specific terms:

intertidal zone= influenced by tides  

abyssal zone= extremely deep ocean bottom  


mixes oxygenated water from surface with nutrient rich water from bottom where (dead  stuff) sinks to  

-Species Distributions:

global and local climate influence what species live in an area  

interactions with environment and with other organisms determine the distribution  (where it lives) of a species

*Abundance can vary across the species’ distribution usually highest where conditions  ideal and resources are also abundant  


St Sunday, November 29, 2015

Why doesn't a particular species live in an area?

1. Can it get to that area, or is its range limited by dispersal? (movement of individuals,  seeds, etc.) EX: We don't have European Hedgehogs here  

2. If it can get there, will it find the right kind of habitat? EX: We also don't have Puffins,  even though they could fly here  

3. If it can get there and the right general habitat is present, it might still be limited by  biotic and abiotic factors

*abiotic factors that can limit the distribution of a species are Temperature and water  availability  

-for aquatic animals, salinity affects ability to regulate water balance = limited to fish or  salt water  

-plants too: more or less tolerant of salt water  

-abiotic factors can limit the distribution of a species:  

soil conditions:  



physical structures  


1. what plants can grow in a location  

2. what crops can be grown in a location  

-Overcoming Dispersal Limitations:

long distance dispersal can have big effects:

# add a new member to a biological community  

# adaptive radiations resulting in evolution of new species  


St Sunday, November 29, 2015 …..humans can accidentally or purposely introduce species to new places  

> this can result in serious and expensive problems if they become invasive species  -Community ecology: focuses on multiple species  

-Population ecology: focuses on one species  

-Ecology: interaction between organisms and their environment  

ecologists can focus of different levels of organization  


same species  

live in same area  

rely on the same resources  

interact and breed with each other  


may be natural  

(e.g., an island) or arbitrary)  

(e.g., DeKalb County)

1. Why study populations?

-manage animals  

-control pests  

-Epidemiology study of diseases in populations  

-consevation of rare and endangered species  

Population Size  

-increases in 2 ways:  


-decreases in 2 ways  


St Sunday, November 29, 2015 DEATHS AND EMIGRATION  

2. Estimating Population Size  

-mark-recapture method  


1. Capture  

2. Mark and release number marked  

3. Recapture = proportion of population marked  

Estimating Population Sixe  


1. Capture qo snakes, mark and release them  

2. wait a little bit  

3. capture 10 more snakes. If 1 of these is marked, then :

-10% of the snakes in the population are marked  

-you marked 10 snakes  

-these 10 marked snakes represent 10% of total population  

-the total population size 100  

Mark -recapture calculations  



N= population size (unknown)  

M= #marked in 1st capture  

n= #captured in 2nd census  

R= # marked recaptures in 2nd census  


St Sunday, November 29, 2015


pattern of spacing individuals in a population  



e.g., via territoriality  

defense of a space against other individuals  


position of each individual is independent of other individuals  

-occurs in absence of strong attractions or repulsion  

Life Tables- follow the survival patterns of a population  

-Follows Cohort (same-aged group) from brith until everybody’s dead  

Projecting further population size  

Who cares  

1. Zoos:  

What is smallest population that avoids extinction?

2. Conversation  

3. Bioindustry: farmers, fisheries, microbial industry:

what is the maximum harvest?

4. Pest management:

At what size does control need to be applied?

Projecting Future Population Size


St Sunday, November 29, 2015 -by using models  

-it helps us think about complex reality  

e.g., by simplifying, by picking out most influential variables  

mathematical models are used in many field like:

engineering, science, weather  

don’t have to be 100 % accurate to be useful  

Base Model:

with unlimited resources, populations tend to exhibit exponential growth  This gives a J-shaped form for N verses t

Note: #added per unit time per capita is constant= r  

#added per time is accelerating  

Where can we expect exponential growth?

-populations in new or unfilled environments  

e.g., following extreme population decline  

e.g., in highly seasonal environments  

e.g., spring insects here  

(Kruger National Park, S. Africa, after hunting was banned)

Change in population = birds-deaths  

r = b - m  

-b > m, then more births than deaths and population grows  

-b < m, then fewer births than deaths and population shrink  

-b=m, then same number of births and deaths and population constant  11

St Sunday, November 29, 2015 if r=0, then zero population growth i.e., constant N  

Population Ecology:  

-in the real world populations cannot grow forever: eventually, various factors limit population  growth  

-Limited population growth:  

populations do not grow indefinitely  

e.g., like Reindeer on an island off Alaska  

-Exponential population growth assumes unlimited resources  

-when resources start to become limited, pop. growth slows  

-Carrying Capacity:  

“K” of the population’s environment  

-Logistic Growth:  

“S”- shaped population growth = logistic growth (occurs when a resource in the environment is  limited)  

REMEMBER- Logistic model starts with exponential model but adds an expression that reduces  per capita rate of increase (r) as N approached K, which in the example is 1500  -logistic assumes that resources are NOT limitless, rather that growth slows down as approaches  K  

*In which is per capita growth rate constant?  

exponential growth dependent on N and the environment? -Logistic growth  -K depends on which resource is MOST limiting  


St Sunday, November 29, 2015

-What limits populations?  

populations do not grow indefinitely  

…..a limiting factor may be  

(1) density independent  

-often true of severe weather event e.g., tsunami, cold winter  

(2) density dependent  

-often true of competition, contagious diseases, toxic waste  

-in logistic growth model, r is density dependent, birth or death rates depend on the population’s  size  

*In drought, plants with exposed roots often die; density-independent mortality  *when a population gets large, more nutrients in sand get used up, and reproduction declines:  density-dependent birth rate e.g., Dune Fescue (a costal grass in the UK), often grows alongside  golf courses  

-Factors that influence populations:

competition with other organisms (infraspecific or interspecific)  

*predation = mortality  

*disease parasites = morality or reduced reproduction  



St Sunday, November 29, 2015 patterns of reproduction + survival in a species  

-Producing Offspring:  

1. Semelparity- one sensational birth e.g., century plant flowers grows for 10-30 years, flowers  once then dies, eg., Salmon  

2. Iteroparity- repeated throughout lifetime  

e.g., eastern cottontail breeds 3-4 times a year  

Species can sometime be described as r- or K- selected”  

1. r-selected= rapid reproduction, large number of small offspring, little parental care (in  animals)  

2. K-selected= fewer offspring, well-provisioned or cared for, increase competitive ability  

Why does variation in life history traits exists?  

1. organisms energy for life functions is finite  

2. Thus, energy used for one function may not be available for other functions  -there are trade-offs in maintaining body, growing, and producing offspring  *Human population growth has been exponential  

Current human population = 7.3 billion  

b= .020 births per individual per year  

m= .008 deaths per individual per year  

r=b-m = .020-.008 = .012 per individual per year  

*if r stayed constant, doubling time would be 58 years  


St Sunday, November 29, 2015 Serious questions that have to be asked:  

-can world food production continue to increase?  

-is there enough fresh water?  

-are resources (many of which are being used more rapidly today) going to run out?  -Population Projections:

Recently, there has been a Decrease in population growth rate  

So population size is not growing as fast, but it is still growing  

-Reproductive Decisions and r:  

U.S. family size has decreased in past century  

this is typical when shift from agricultural in industrial economy  

b decrease is usually associated with a decrease in m via improvements in education, nutrition,  and medical care  

*growth is affected not only by family size, but also by age structure: more young people, father  growth  

So what do we do if we don’t want to run out of resources?  

-smaller family size  

-greater delay of reproduction  

-Another option:  

population size matters relative to K  


St Sunday, November 29, 2015 ……which may be limited by water, food, habitable space, nonrenewable resources, buildup of  


-we could increase K if resources used per person went down  

-Ecological Footprint:

area if resources used per person  

*many people could lower theirs and still have a high quality of life  

1. Community = all the different species in ONE place  

-Many different types of interactions, e.g., competition, symbiosis, mutualism, predation,  parasitism, herbivory  

2. Competition = when > 2 organisms use same resource and the resource is limited (in short  supply)  

-there are TWO ways to compete  

1. Fights, territoriality, or via chemicals  

2. Use resource 1st. before competitor, before competitor  

*negative effect on both organisms’ fitness  

Competition with whom?  

1. Interspecific = different species  

2. infraspecific = same species  

*population growth models considered just 1 species, but competition is one factor that can lead  to logistic growth  


St Sunday, November 29, 2015 -Niche:  

all the biotic and abiotic resources an organism uses in its environment  


what it eats  

where it seeks shelter  

abiotic factors it can withstand (temp. rain)  

time of day and year it is active or reproduces  

-Niche Overlap:

determines the strength of competition between species  

-Fundamental Niche:

the range of conditions a species has the potential to live  

-Realized Niche:

the portion of those conditions that is actually occupied  


babe jointed legs and are closely related to pillbugs and shrimp  

Phylum: Arthropoda  

Class: Crustacea  

-Competitive Exclusion:  

is a short term outcome of competition  

(Long-term (evolutionary) outcomes of interspecific competition  

1. Selection may favor use of resource for which there is less competition  -niche shifts = resource partitioning  


St Sunday, November 29, 2015 2. expect such selection to be STRONGER in sympatry than in allopatry  

-if it is shift in trait, e.g., in beak depth, is called character displacement  

3. Predation, Parasitism, and Herbivory  

-predation: prey is killed and consumed  

-Parasitism: obtain resources from host but don’t always kill it  

-Herbivory: plant is consumed partly or entirely  

-Ecological time: effects in short term e.g.,  

*changes in population size for both prey and predators  

*reduced fitness and thus population size or parasite’s host  

*reduced seed production in plants that suffer herbivory  

(Effects In Evolutionary Times)  

1. adaptation, including coevolution  

eg., the newt’s skin contains an unusual toxin, not usually seen in newts  

for most predators, lethal or paralysis because toxin backs sodium channels in cell membrane’s  lipid bilayer —— often allows newt to escape  

*but some garter snakes are tolerate to the toxin- they have few amino acid differences in their  sodium channel proteins  

-Other adaptations against predators:  

Aposematic coloration ….in frogs  

increases fitness because predators’ associative learning is quicker if signal is strong  *cryptic coloration  


St Sunday, November 29, 2015 -Batesian Mimicry:  

it is BS e.g., fly and bee  

-Mullerian Mimicry:  

it is mutual e.g., Cuckoo bee + Yellow jacket  

*Cryptic coloration can work for predators too!  


both species’ fitness is increased by the interaction  

EX: ants get shelter in the thorns and food  

Acacia tree gets protection  

*both get benefits  

-widespread mutualism includes pollination and seed dispersal  

-speech richness (number of species in a community) + relative abundance (some species are  numerous, some are rare) = species diversity  

*Higher diversity communities tend to be more stable  

 -they are also less affected by disturbances like drought  

 -less likely to be invaded by a non-native species  

-Tropic Structure:  

feeding relationships  

Food Chains:  

about 10 % transfer energy as from 1 trophic level to the one above, thus usually < 5 trophic  levels  

*Food web = diagram of feeding (trophic) relationships in a community  


St Sunday, November 29, 2015

(Control of Community Structure)  

-Top-Down: controls go from HIGHER to LOWER trophic levels  

-Bottom-Up: controls goes from LOWER to HIGHER trophic levels  

*remember that both differ  

*communities are not always at equilibrium =stays the same  

 -ecological succession  

-Secondary Succession:

where solid and some species remain after a disturbance  

EX: forest fire  

*Also ecological succession in our mouth  

-Pathogens: can play important in ecological communities  

-Zoonotic Pathogens:  

when spread from animals to humans  


= community and abiotic  

1. Transfer of energy and materials through trophic levels  

-energy flows (not cycles) through ecosystems  

-Energy flow:

follows 1st and 2nd laws of thermodynamics:  

-energy can’t be created or destroyed  

-BUT can change form  


St Sunday, November 29, 2015 e.g., light E to chemical bond E to heat E  

-any transfer of energy are not 100 % efficient  

-Primary Producers:  

sun’s light energy stored in chemical bonds by primary producers  

*primary producers are autotrophs -(secondary producers)  

*the amount of energy in this chemical form that is available to consumers is NET PRIMARY  PRODUCTIVITY  

^ expressed per area per time  

*primary production is LOW in oceans and HIGH in tropical forests  

2. Water, Carbon and Nitrogen Cycles  

-Biogeochemical cycles: movement of chemicals through ecosystems (including through  organisms)  

*organisms assimilate (take in) chemical elements  


water loss from plants  


-99 % of earth’s water is IN THE GROUND  

-lots of earth’s carbon is stored in fossil fuels, as a side note CO2 is released when humans burn  them for energy  

-Nitrogen Cycle:  

air nitrogen (N2) not available to organisms except after fixed by certain bacteria  21

St Sunday, November 29, 2015 -N in all organisms’ nucleic acids and proteins  

-nitrogen cycle is affected by human activities like industrial fixation to make fertilizer  REMEMBER:  

-Hubbard Brook New Hampshire  

3. Human impacts that are good  


using plants, bacteria, or other organisms to clean up polluted ecosystems  -organisms may break down pollutants on their own  

-or concentrate them (e.g. in leaves and stems) so they can be easily harvested and disposed of  safely  

 -Restoration Ecology:

re-establishing ecosystems that have been lost or heavily degraded  

e.g., poorly-managed farm - diverse tall grass prairie  

e.g., management or removal of livestock to avoid overgrazing  

-Combining bioremediation and restoration:

constructing wet lands that also function in sewage treatment  

-use biotic and abiotic components of biogeochemical cycles  

-inexpensively treat sewage  

-provide habitat for wildlife  


St Sunday, November 29, 2015 TIPS  

1. Don’t stress about reading the book, your better off skimming it or not reading it at all.  Focus on the slides and the little details in this study guide and my notes that I make  available to you  

2. Remember names and places where important things occurred  

3. don’t over study, read over this study guide or the lecture notes four or five times a day  4. Know how to do the math problems because they WILL be on the test  5. R-E-l-A-X, don’t build this test up, go into prepared and confident and you’ll be just fine  ……… feel free to E-mail me with any questions, good luck!  


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