Final

Question 1

What factors could prohibit a species from inhabiting a seemingly viable habitat.

Answer 1

because of various biotic and abiotic factors

Ex: soil, temp, pH, minerals, predators, physical features of environment (ex: mountain ranges), etc…

Question 2

Dispersal can happen on several time scales from the geological to immediate and on many spatial scales from local to region. Provide an example for each.

Answer 2

• Geological (occurs over millions of years): ex: ice age, breaking up of pangea, etc…
• Immediate: human introduction of invasive species into new environments
• Local: highway getting put through the middle of a habitat
• Regional: boats bringing foreign algae species to new marine habitats through bildges

Question 3

Habitat selection is known to be one of the factors that limit animal distribution. How does habitat selection operate?

Answer 3

The species will get pushed towards a specific area due to one of the modes of dispersal. Then the abiotic and biotic factors of the ecosystem will determine whether or not the species can thrive. This could be depending on the species a lack of food, not enough/too much moisture, too hot/cold of a climate, too much competition, too many predators, etc…. If the habitat does not meet the species’ needs they will either move on or die off

Question 4

Habitat selection has rarely been considered in plants. Why might this be the case?

Answer 4

Plants cannot move freely and consciously choose their habitat, as their methods of dispersal are the result of environmental conditions and are often quite random. Even if predation, soil pH, moisture levels, climate, are not ideal are harming the plant they cannot leave and will instead just die

Question 5

Provide three examples where chemical interactions have affected the distribution of marine organisms.

Answer 5

1. Algae blooms: are the result of chemical runoff ( of excess phosphorus and nitrogen) causes algae to growth and ultimately algae blooms which result in less free oxygen in the water and a loss of habitat
2. Ocean acidification: As a result of climate change CO2 is being absorbed by the ocean resulting in it becoming acidified. This results in coral bleaching killing off corals which are the homes to many species forcing them to find new homes or die
3. Salinity: most freshwater fish are restricted to saltwater, most saltwater fish are restricted to salt water. Their bodies’ concentration gradients are adapted to specific salinities, and if in water of a different salinity they will either gain or loose too much water

Question 6

What other organisms may limit the geographic distribution of a particular species

Answer 6

Predators may limit the geographic distribution of certain species, as well as the ones it competes with for resources, and the availability of prey

Question 7

What two factors limit plant and animal distribution on a global scale? How do these factors act on an organism to limit its distribution?

Answer 7

Temp and moisture
These define specific biomes with specific climates and characteristics that only some species are adapted for. This limits distribution since the ones who are not adapted for that particular habita will be unable to live there

Question 8

Provide 5 examples of an invasive species, their origin and how they dispersed.

Answer 8

Cane toads: Were brought into Australia to control pests and protect crops. They are very hardy and can live in hot climates with little water so they did well in Australia. They have incredibly high reproduction rates and quickly spread over much of Australia. They are also quite toxic and kill many native species, and have even caused the local extinction of native species.
Burmese python in florida: Many people bought them as pets and when they didn’t want them anymore they released them into the everglades, this happened enough to create a large breeding population. They did quite well since they have no predators and are well adapted to the floridian climate. They have become apex and have significantly decreased the biodiversity in their inhabited areas
Rabbits in australia: In the 1800s british settlers wanted rabbits to hunt so they brought them over from england. Though they had incredibly fast reproduction rates and no natural predators and are very adaptable so they quickly spread. This lead to overgrazing which resulted in limited resources for other native herbivores as well as caused a lot of soil erosion greatly threatening native species
Zebra mussels: were brought to north america by way of ship’s ballast water. They reproduce very quickly and have taken over aquatic habitats. Because of their large numbers when they filter feed on plankton they eat too much of it resulting in their not being enough food for fish and other native species
Northern pacific sea stars: brought to australia by way of ships’s ballasts. They are very adaptable and reproduce very fast so they quickly took over many coastal habitats. This is a major problem since they eat almost anything they can find, taking away resources from native species, even causing the spotted handfish to become endangered

Question 9

What is population density and what does this metric integrate?

Answer 9

Population density is the number of organisms per unit area/volume
This integrates births, deaths, immigration and emigration
Gives us important info to help us determine the health and abundance of a species

Question 10

How does unitary organism differ from modular organism and provide an example of each

Answer 10

Modular organisms consist of several connected branches and each are genetically identical
Ex: fungi
Unitary: individuals are genetically unique and can live independent of other members of their species
Ex:humans

Question 11

What is the difference between an r versus a K select species?

Answer 11

R select have a type 3 survivorship curve, produce large amounts of quantities of offspring, but put little energy into raising them
Ex: mice
K select are type are type 1 or 2 curve, live longer and put more energy into raising their offspring
Ex: humans

Question 12

How is the logistic growth curve applied to study competition between species? Provide an example in your answer.

Answer 12

You can compare their logistic growth curves before and after they experienced competition and then look at how things such as carrying capacity have changed since you can see what species is dominant by what one has a larger one. An example could be competing species such as cheetahs and lions whose populations change as a result of the competition

Question 13

What does competition accomplish on an evolutionary time scale?

Answer 13

Competition drives new adaptations and speciation events. If species are competing for the same resource they will need to adapt to be able to co-exist or out last the other one. As species become more adapted to their niches and gain protective or offensive traits to ward off competition new traits arise eventually leading to new species

Question 14

How does herbivory on seeds and fruits differ from herbivory on leaves and stems of plants?

Answer 14

Seeds and fruits are specifically adapted to attract herbivores as for many plants this is how they disperse seeds. While leaves which are necessary for photosynthesis for the plant, and branches are necessary for the plants structure, so if they are eaten it causes damage to the plant so they often are are adapted for protecting the plant from herbivores, ex: thorns or thicker outer layers

Question 15

Community ecologists discuss the “health” of a community. How would you measure the biological health of a community?

Answer 15

Health of a community can be measured in species richness, species diversity, abundance, alpha and beta diversity, biodiversity
The biodiversity of a population as well as population numbers indicate population health. This includes whether or not the numbers of a population are steady. If they have decreased or fluctuated in any way it may mean the population is unhealthy.

Question 16

What determines optimum growth within a population?

Answer 16

no predation, no competition, unlimited resources, unlimited space to establish new population

Question 17

Complete competitors cannot coexist. Is this a true statement? Why or why not?

Answer 17

Complete competitors cannot coexist
Because they would have the same niche and be trying to exploit the same resources. One will be better adapted to the niche and/or warding off the other one and as a result one will be less successful in exploiting the resource and will dwindle as a result

Question 18

How does phosphorus cycle through ecosystems?

Answer 18

• rain and weathering cause rocks to release phosphate ions into soil and water
• Plants take up phosphate from the soil
• Once in the plant (or animal after consuming the plant/or plant eating animal) it is incorporated in organic molecules in the organism
• When it dies as it decomposes the phosphate is returned to the soil
• Bacteria break down the organic matter so it is in a form that can be absorbed by plants
• Phosphorus in soils can eventually end up in waterways or oceans where it gets incorporated into sediment

Question 19

How is carbon cycled through ecosystems?

Answer 19

Primary producers (plants and phytoplankton) absorb carbon from the atmosphere as part of photosynthesis 
As animals eat plants and each other carbon travels through the food web
When they die and are decomposed of carbon is released back into the soil and in time the atmosphere as well

Question 20

What are the major nutrient cycles?

Answer 20

Nitrogen, carbon, phosphorus
They repeatedly go through a pathway from the environment through organisms in an ecosystem and then return to the environment

Question 21

What are some of the classical predator prey relationships that exist in nature?

Answer 21

Cat and mouse, lion and gazelle, snake and mouse, great white sharks and seals, etc..

Question 22

A major controversy is the culling of the wolf population to protect declining caribou populations. Why is this controversy?

Answer 22

People want to kill wolves since their prey is the caribou which is endangered
Though this is only a temporary fix not a permanent solution
Human activity is more to blame for their population decline than wolves

Question 23

How can radioisotopes be used to identify levels within a food chain?

Answer 23

Isotopes of carbon 13 and nitrogen 15 can be tracked through the composition/density of each substance in organisms and can then be tracked to figure out which ones consumed which ones allowing them to figure out a food chain

Question 24

Who are the main players in all ecosystems?

Answer 24

The main players in an ecosystem vary depending on the characteristics of each individual ecosystem, but are often predators. They often define and control the population. They define the ecosystem. An example being lions

Question 25

How energy efficient are trophic levels? Provide examples from one trophic level to the next

Answer 25

Generally 90% of the energy is lost at each trophic level. Primary producers only pass 10% of their energy to primary consumers

Question 26

What are the predictors of terrestrial primary productivity?

Answer 26

The greatest predictor for it is light availability This is because primary producers convert sunlight into biomass. So the more sun the more primary production can be done Closer to the equator productivity increases as there is more sun

Question 27

Provide an example for each of the consequences of altering the natural geochemical cycles of carbon, nitrogen and phosphorus.

Answer 27

- Too much runoff from artificial nitrogen from fertilizers can cause large destructive algae blooms - Too much co2 emissions by humans have lead to the ocean to take absorb more of it causes the oceans to acidify causing issues to many organisms such as coral bleaching - The industrial waste contains large amounts of phosphorus causing eutrophication in lakes

Question 28

When is a community not in “equilibrium”?

Answer 28

When succession has yet to reach a climax. In these environments small disturbances can result in any species becoming the dominant species in an ecosystem. Community is highly variable and species come and go. Sensitive to disturbances and is unstable

Question 29

What are the two general models of community organization and how do they differ?

Answer 29

- Equilibrium model: views ecological communities as relatively constant in composition and resilient to disturbances - Non-equilibrium model: view ecological communities and not constant in their compositions since they are always recovering from abiotic and biotic disturbances, and therefore never reaching equilibrium

Question 30

What is the best predictor of biodiversity within both marine and terrestrial ecosystems? Why is this so?

Answer 30

Light availability and climatic conditions They determine the amount of resources and energy in an ecosystem and the more of them you have the more complex the environments become like coral reefs and tropical rainforests. This allows for more niches and species that can coexist

Question 31

How is biodiversity defined and with this definition how does biodiversity vary on a global scale?

Answer 31

Biodiversity is the variety and variable of species, and is measured by the amount of different species that inhabit a particular area. Varies on a global scale since the closer to the equator the higher the biodiversity as there are more resources available due to the high temp and moisture levels

Question 32

What are the eight factors that act to enhance species richness in communities

Answer 32

``` History Climate Predation Competition Spatial heterogeneity latitude productivity (related to producers) immigration/emigration ```

Question 33

What are the challenges in defining exactly the “geographic distribution” of a plant or animal?

Answer 33

Not constant, distribution changes over time Hard to control variables with transplant experiments Could take a long time since some animals take awhile to reproduce Hard to find sufficient data

Question 34

What is a community?

Answer 34

An interacting group of species in a common location

Question 35

How can the adaptive strategies of species in early and late stages of succession be explained in terms of r and K select species?

Answer 35

Early succession tends to have more r select species as they can colonize the area rapidly by producing a lot of offspring. Late stage succession become stable enough to support k select species

Question 36

What is succession and how does it proceed?

Answer 36

It is the process of how a biological community changes over time and there are two types Primary succession: occurs in essentially lifeless areas where the soil cannot support life. Often happens after major natural events such as lava flowing, rocks appearing from a glacier melting Secondary succession: occurs in areas where a community that previously existed there was removed, usually happens from smaller scale disturbances that don’t eliminate all life and resources Certain species have adapted to exploit certain aspects of each type of succession. These slowly make the environment more livable and more and more organisms become able to live there and then further the livability of the ecosystem

Question 37

What are the ways in which species can interact during succession?

Answer 37

Facilitation: Existing plants help other new plant species to exist Inhibition: existing plants inhibit other plants from establishing (ex: ferns blocking sun) Tolerance: Plants tolerante each other and can coexist, but dont particularly help each other Random colonization: no relationship between species

Question 38

How can we simply approach the study of communities?

Answer 38

We can study them by observing the interactions between members of a community in their natural environments as well as comparing the interactions to that of a different community

Question 39

Can a population persist without regulation and how could you determine if a population was persisting without regulation?

Answer 39

A population cannot persist without regulation continuously. Eventually the resources will run out. A population with exponential growth would be one without regulation

Question 40

What are some of the biotic and abiotic factors that can regulate populations?

Answer 40

Biotic: predator, prey, plants for animals to eat, pathogens Abiotic: climate, water, space, pH of soil and water, sunlight

Question 41

It has been postulated that the growth of many plant populations will be close to logistic. If so then why? If not then why?

Answer 41

Logistic growth occurs when as there is a carrying capacity where a limit is placed on population growth. With plant growth resources become limited as the population grows, and areas of soil with a lot of nutrients of patches with a lot light are competed for, resulting in a limit to how many plants can live in that area

Question 42

That the world is green implies that herbivory is limited. How is this so?

Answer 42

The green world hypothesis claims that the balance between predators and herbivores prevents destruction of plant life If there were no predators, or not enough of them to meet the increase of the herbivore population, the population would increase rapidly. To meet the incraeseing demands more and more plants would have to be eaten eventually killing all of them. This is seen on smaller scales in areas with too many herbivores such as rabbits in some parts of australia. They eat all the plants and leave it almost barren

Question 43

What are some of the methods applied to determine population size?

Answer 43

One method is the mark recapture technique to estimate the size of a population when its impractical to count every individual You capture a small amount of individuals and mark them somehow then release them, and then another day you capture individuals and count how many have/dont have a mark Quadrant method: used to count fixed in place individuals by counting all of the individuals or percentage of coverage inside of a square and then using that to estimate the amounts over a larger area

Question 44

What “line” is considered the most important of all climatic demarcation in plants”? Provide three examples of plant species on either side of this line. What anthropogenic impact will affect this “line” and what possibly consequences with respect of plant distribution may happen?

Answer 44

Tree Line Beyond tree line: arctic heather, arctic moss, bearberry Below tree line: arbutus, daisy, douglas fir Climate change will affect this line, as the earth heats the line will move further up, making it so plants such as trees will begin to distribute one the other side of what was previously the tree line, and species that already lived on the other side may be forced further up or could struggle with competing with trees and other newer species to the area

Question 45

What model can be applied to describe the growth of a population with overlapping generations?

Answer 45

Continuous time models since overlapping generations reproduce year round and therefore it continuously changing

Question 46

With respect to population growth how do organisms with discrete generations differ from organisms with overlapping generations?

Answer 46

discrete generations: breeding generation lasts just one breeding season so growth only occurs at specific intervals Overlapping generations: more than one breeding generation is present at any time so their population growth is continuous. It is also faster since they can respond to population increases immediately instead of waiting a generation to gain the reproductive benefits

Question 47

A negative relationship between neotropical forest mammals is found between geographic distribution and abundance. Provide two explanations for this observation.

Answer 47

-Generalists: have broad range, lower abundance Less specialized adaptations allowing them to live in a wide arrange of environments, but not adapted enough to a specific area’s niche to huge abundance since other species are better adapted to the specific characteristics of the environment Ex: raccoons -Specialists: high abundance narrow range This would be because they are more adapted to the unique characteristics of a particular environment meaning that their distribution is small since they are only adapted to live in a small area. But they would be much more adapted to the environment than generalists so they thrive more in the habitat - ex koala

Question 48

What are the models that attempt to describe the strength of the connections between species within a community?

Answer 48

Food web models describe the various relationships between all the species in a community. It shows which ones are eaten and which ones. What ones are predators, prey, herbivores, carnivores, omnivores, and producers, and how the energy flows through the ecosystem through these connections. -We can see the strength of their connections through how direct or indirect their connections are

Question 49

For both plants and animals provide 6 reasons why the assumption that population growth at a given point in time depends only on conditions at that time and not on past events might be incorrect.

Answer 49

1. Previous generations have to produce enough females to support population growth 2. Previous seasons with unusually extreme weather can affect the amount resources available for future individuals, or when certain resources are available 3. Previous increases/decreases in amounts of predators/prey affect how many breeding individuals their currently are 4. Previous alterations to habitats such as highways through them that cause some of the population to disperse lowering the amount of individuals available to reproduce 5. If a disease or parasite has been building up in a population from previous generations 6. Previous natural disaster can affect the future populations as they can change the layout of the environment as well as decrease the population significantly

Question 50

How does the biology of plant-plant pathogens systems differ from animal host-parasite systems?

Answer 50

That plants don't have an adaptive immune system like animals have, so how they fight off a pathogen/parasite would be different Animals pathogens/parasites would usually be more transmissible than plant ones since they are able to move around and affect a wider area of hosts

Question 51

Forest ecologists usually measure the size structure of a forest and less often make use of the annual rings of temperate-zone trees to get the age structure of the forest. What might we learn from determining age structure in addition to size structure in a forest stand? Why only temperate-zone trees?

Answer 51

Only temperate zones since seasons affect growth Focus on size not rings since trees grow at different rates and it matters more for the environment its size not its age. If we use rings to determine the age structure we can learn about the past conditions in the area, such as how moisture levels and soil have changed, and how harsh certain seasons have been in the area

Question 52

Why is the relationship between distribution and abundance important in conservation biology?

Answer 52

The distribution and abundance in a specific region affect the carrying capacity. More diverse ecosystems create more complex food webs Also knowing a species abundance and distribution can help with conservation If species have very low abundances in the environments they inhabit they could be at risk of extinction and measures should be taken to protect the remaining ones and increase the population If a species has a very small distribution, and only lives in a few environments (like koalas, orangutans, etc..) measures should be taken to preserve these habitats

Question 53

What is the intrinsic capacity for increase and how is it determined?

Answer 53

Measures of the rate of increase of a population and is determined by birth rate minus death rate in a generation time

Question 54

What factors are key to understanding the effects that competition has on populations? Provide examples in your answer.

Answer 54

Lotka volterra equations Graphs how two species interact with each other when competing Factors: K (carrying capacity), r (the intrinsic rate of natural increase in population size), alpha (competition coefficient, indicating effecting one of the species has on the growth of the other one) Beta (per capita reduction in carrying capacity of one of the species caused competition with the other one) Ex: lions and cheetahs since they feed on similar prey, meaning the presence of one negatively affects the other since they will have less food available, or water buffalos and zebras competing for limited water at waterholes

Question 55

What are some of the advantages and disadvantages of physical versus chemical defenses in plants?

Answer 55

Physical: pro: can make it harder for an animal to eat parts of it such as leaves, some defense mechanisms such as waxy cuticle can prevent water loss Cons: energy expenditure to make them Chemical: Pros: Many animals will learn the harmful effects and avoid it in the future Cons: for some poisons to work they must first be ingested meaning that some of the plant would be taken off. energy expenditure to make them

Question 56

What is a “guild”? What is a “keystone” species? What is a “dominant” species? Provide examples of how these terms are used to describe a community.

Answer 56

Guild: a group of species that exploit the same resources in a community Ex: Lions and cheetahs would be in the same guild as they have very similar diets Keystone species: a species that the other species in an ecosystem that largely depend on and whose removal would be change the ecosystem drastically Ex: sea otters are keystone species since without them eating sea urchins preventing them from destroying kelp forests which are home to a wide array of marine species Dominant species: most abundant species in ecosystem, largest biomass Ex: kangaroos are a dominant species in many Australian environments as they are the most abundant of any other species in these environments

Question 57

What is primary productivity and how is it measured?

Answer 57

Primary productivity is the process whereby organic compounds are synthesized from atmospheric or aqueous carbon dioxide. It mainly occurs through the process of photosynthesis, which uses light as its source of energy: You can measure primary productivity through: 1. The amount of carbon dioxide used. 2. The rate of sugar formation. 3. The rate of oxygen source production Generally Net Primary Production (NPP) is how primary productivity is measured

Question 58

What are the limiting factors of primary productivity in aquatic ecosystems?

Answer 58

Primary production is limited by nitrogen and iron in the ocean and phosphorus in lakes

Question 59

What is secondary productivity and how is it measured? What limits secondary productivity?

Answer 59

Secondary productivity is the The rate at which these consumers convert the chemical energy of their food into their own biomass. It depends on how much food is available and how efficient the organism is at converting it towards biomass It is measured in gross secondary production (mass of food intake - mass of waste) or net secondary production (gross secondary production - respiratory loss).

Question 60

How is nitrogen cycled through ecosystems?

Answer 60

fixation: bacteria change nitrogen into ammonium Nitrification: ammonium gets changed into nitrates by bacteria. Nitrates are what the plants can then absorb. Assimilation: plants absorb nitrates from soil into their roots Ammonification: when plant/animal dies decomposers turn nitrogen back into ammonium denitrification: extra nitrogen in soil gets put back out into the air Can then fall as dust or can be fixed again by bacteria