Ecology 204 2023 TESTBANK-FINAL-1

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Feb 20, 2024

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Ecology 204 2023 TESTBANK SECTION A 1. What are the challenges in defining exactly the “geographic distribution” of a plant or animal? The geographical distribution is constantly changing, which means it's hard to include distribution over a long period. Therefore, they are normally just "snapshots". Some factors that contribute to the change are climate, invasive species, migration, temperature, and natural disasters. 2. What factors could prohibit a species from inhabiting a seemingly viable habitat. Predation, competition, population density, parasites, physical barriers, resource interference, and insufficient time for diffusion are factors that would prevent the occupation of a viable niche. 3. 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. Geological- When continents were connected in Pangea it allowed the pollen of the Antarctic Beech to be found in Australia (over large period the continents separated) Immediate - When ships take in water to help balance themselves and release it in other waters, this can create immediate dispersal and invasive species. This called ballast waters and it is how zebra mussels got introduced to the great lakes. Local - Pinecones are heavy and when they fall, they tend to stay wherever they land. Regional dispersal: wind dispersed seeds such as dandelions can be carried by wind and dispersed at greater distances 4. Provide 5 examples of an invasive species, their origin and how they dispersed.  zebra mussels; eastern Europe origin; ballast water dispersal  Himalayan blackberry; northern Iran/Armenia; originally a crop but spread by seed by birds and people spreading berries and by rooting from stems that touch the ground  Sea lamprey; Atlantic Ocean origin; dispersed by man-made canals  Canadian thistle; Europe/north Asian origin; dispersed by farm seed shipments  Giant hogweed; Asian origin; brought as an ornamental plant but seeds dispersed through streams and roadsides 5. Habitat selection is known to be one of the factors that limit animal distribution. How does habitat selection operate? Factors that affect habitat selection include · Abiotic factors (temperature, moisture, light) · Food resources

· Bioenergetics · Competition: Presence of other conifers (competition within same species/animals that share same niche) · Predation: Presence of other organisms of different species (predators or different species that use the same food source) 6. Habitat selection has rarely been considered in plants. Why might this be the case? Plants do not have control over where they germinate. They rely on other methods of movement to disperse (wind, animal carriers, water flow) once they're in a habitat, they must adapt to it or die. They do not have the option of moving if their environment does not fit their needs. 7. What other organisms may limit the geographic distribution of a particular species. Predators · Prey · Humans · Invasive species · Parasites · And competitive species 8. What two factors limit plant and animal distribution on a global scale? How do these factors act on an organism to limit is distribution? Temperature & moisture There is a biological limit for the combination of both. Organisms need an optimal temperature and moisture level to survive in a certain area. If an area is too hot or too cold or too dry or too wet; the organism cannot survive there and will find a new habitat which effects distribution. 9. 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? The line that is considered the most important climatic demarcation in plants is called the tree line. It is dictated by temperature and moisture. Above the treeline is colder and drier. Plants above treeline: arctic poppy mosses, lichen Plants below treeline: Douglas fir, red cedar, pacific dogwood Climate change will affect the treeline by forcing it upwards due to rising temperatures causing the distribution of trees to occur at higher altitudes. 10. A negative relationship between neotropical forest mammals is found between geographic distribution and abundance. Provide two explanations for this observation. Tropical regions are very competitive. Neotropical forest mammals need to specialize to outcompete good generalists but the more they specialize, the less distribution they have.

Second, human disturbances are a huge issue in neotropical environments so species with larger distributions are more likely to be hunted or killed by deforestation/human activity. Which leads to a species with high distribution but low abundance. 11. Why is the relationship between distribution and abundance important in conservation biology? Distribution and abundance are positively related, meaning species that have a greater distribution also have a greater abundance. Since species in more restricted distribution are less abundant, their habitats are more at risk. Species with larger distribution are more abundant meaning that their habitat could be analyzed to find the key to conservation of the species and what is working in that specific environment/species. For the survival of a species, it is important to ensure there is an abundant number of organisms who will survive and reproduce, this is more likely with a wide distribution and larger populations which is why conservation biologists must understand and study this relationship. SECTION B 12. What is population density and what does this metric integrate? Population density is a measure of the number of individuals of a species per unit area or volume in a given habitat or region. population density integrates the number of individuals, their spatial distribution, and their interactions with the environment 13. How does unitary organism differ from modular organism and provide an example of each. A unitary organism refers to a type of organism where the individual is a distinct, separate entity A modular organism is characterized by having repeated, relatively independent structural units or modules. Each module in a modular organism can function somewhat independently, and the organism can exhibit a degree of modularity in its development 14. What are some of the methods applied to determine population size ? Ecologists often estimate the size and density of populations using quadrats (number of small areas of habitat, typically of one square meter, selected at random to act as samples for assessing the local distribution of plants or animals.) and the mark-recapture method (capture a small number of individuals, put a harmless mark on them, and release them back into the population. Later, you catch another small group, and record how many have a mark). Relative density: the density of one population relative to another population incomplete count - quadrats and mark-recapture method (like the Galapagos Island) complete count - all members of population with aerial photography indirect count - section area and sign of the animal

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15. What is the intrinsic capacity for increase and how is it determined? The intrinsic rate of natural increase is the fraction by which a particular population is growing at each instant in time # birth- # deaths per generation time 16. With respect to population growth how do organisms with discrete generations differ from organisms with overlapping generations? Organisms with discrete generation have breeding generation that only last one season. Bees or insects Organism with overlapping generation have more than one breeding generation present at a time. Population growth is expected to be much higher because more organisms from various generations can interbreed with potential to produce more offspring ex. human or octopus 17. What model can be applied to describe the growth of a population with overlapping generations? Leslie matrix model. Takes into account the age or stage structure of a population. 18. What is the difference between an r versus a K select species? R-selected species are those that produce many offspring and contribute few resources to each individual offspring. They often offer little to no parental care, have high offspring mortality, short life spans, and small body sizes. Ex insects K selected species possess relatively stable populations fluctuating near the carrying capacity of the environment. These species are characterized by having only a few offspring but investing high amounts of parental care. Elephants, humans, and bison are all k-selected species 19. What determines optimum growth within a population?  Adequate access to resources/food  Optimal climate for species  Lack of competition  Population abundance  Adequate habitat size 20. 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. Past events in an environment determine  Current breeding populations  A past introduction of invasive species that could compete with the population growth

 Food sources  Terrain seasonality  Climate change in an environment including temperature and moisture levels changing  Ecological degradation  Overhunting in the past can cause disruptions in food chain 21. How is the logistic growth curve applied to study competition between species? Provide an example in your answer. The logistic growth curve portrays that population growth decreases as resources become scarce. Introducing competition between species would limit the resources available to a species which would cause the curve to plateau. 22. What factors are key to understanding the effects that competition has on populations? Provide examples in your answer. The factors that are key to understanding the effects competition has on populations are changes in species distribution in a certain area. Competition between species can cause species to distribute themselves so that competing species inhabit a different area of their ecosystem or consume a slightly different prey. An example is the warbler bird which has 2 species that consume the same pray and cannot live together so different variations of warbler inhabit different height zones in the forest canopy which minimizes interspecific interactions & resource competition between them. 23. What are some of the classical predator prey relationships that exist in nature? 1. Lion and gazelle 2. Bear and fish 3. Fox and rabbit 24. A major controversy is the culling of the wolf population to protect declining caribou populations. Why is this controversy? This is not a humane way to protect declining caribou populations as they perform arial shooting killings on wolves and has not been scientifically proven to be a solution to declining caribou populations. 25. That the world is green implies that herbivory is limited. How is this so? Herbivory, or the consumption of plants by animals, is a natural and widespread ecological process. Ecosystems are typically capable of supporting a balance between herbivores and the vegetation they consume.

Herbivores and plants often engage in a dynamic balance known as coevolution. Plants develop various strategies to defend themselves against herbivores, such as chemical compounds, thorns, or other physical structures. Meanwhile, herbivores develop mechanisms to overcome these defenses, such as specialized digestive systems or behaviors that minimize the impact of plant defenses. 26. What are some of the advantages and disadvantages of physical versus chemical defenses in plants? Advantages of chemical: chemical defenses can be highly diverse and complex, some chemicals attract predators/parasites of herbivores which provides indirect defense, and it is a flexible response as plants can produce chemicals in response to specific threats Disadvantages of chemical: energetically costly, some chemical defenses may not be highly specific to herbivores and impact other beneficials organisms in ecosystem, & herbivores may evolve mechanisms to resist or tolerate plant chemicals. Advantages of chemical and physical: prevents predation & overconsumption Disadvantages of chemical and physical: herbivores/pathogens can always come up with ways to get around plant defences (eating while leaves are less firm, thicker protective tissue around the mouth) Advantages of physical: can make it more obvious to predators that the plant is dangerous and offer immediate protection, mechanical deterrence, and reduced energy cost as once developed physical defences can require less ongoing energy expenditure. Disadvantages of physical: limited effectiveness as some herbivores may adapt to physical defences over time, and physical defences can exert selective pressure on herbivores to develop counter adaptations which can lead to an evolutionary arms race 27. How does the biology of plant-plant pathogens systems differ from animal host-parasite systems? The key differences between plant-plant pathogen system and host-parasite systems are:  Cell wall vs no cell wall: plants cells are surrounded by a rigid cell wall which makes it more challenging for pathogens to penetrate the cell

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 Mobility: plants are sessile and cannot move away from pathogens and rely on local/systematic responses to fend off pathogens while animals are mobile, and parasites have evolved mechanisms to exploit mobility for transmission to new hosts  Immune systems: plants lack an adaptative immune system but have an innate that relies on pattern recognition receptors to detect pathogens while animals have both innate and adaptive immune systems which allows for a more specific response  Responses to infection: plants exhibit localized responses to infection such as programmed cell dead at infection site while animal hosts may have inflammatory responses and produce antibodies  Metabolism: plants photosynthesize, and pathogens may interfere with this process while animals consume other organisms and parasites may exploit the hosts nutrients.  SECTION C Community: a community is a group or association of populations of two or more different species occupying the same geographical area at the same time 28. How can we simply approach the study of communities? We can simply approach the study of ecological communities by  defining the study area,  identifying key species present in the community such as dominant plants, keystone species, and indicator species  studying species interactions: Look for signs of competition, predation, mutualism, and other ecological relationships  assessing biodiversity  examining abiotic factors  studying trophic levels 29. Community ecologists discuss the “health” of a community. How would you measure the biological health of a community? The biological health of a community can be measured by looking at factors such as:  Biodiversity metrics such as species richness and evenness  Habitat quality  Presence of indicator species (species that are particularly sensitive to environmental changes)  Functional diversity such as feeding strategies, reproductive methods, and resource utilization  Ecosystem function: measure the rate at which energy and biomass are produced *healthy communities have higher levels of productivity & assess the efficiency of nutrient cycling  Monitor Population sizes & age structure 30. What is succession and how does it proceed? Ecological succession is the process by which the mix of species and habitat in an area change over time There is primary and secondary succession.

Primary succession: begins in area devoid of soil and pioneer species (first species) colonize the area. Over time soil develops as pioneer species die and decompose. From this soil nutrient levels increase, and more diverse and complex plants can live there. The community begins to change, and new species replace the pioneers. Process continues until a stable, mature, diverse ecosystem is reach which is the climax community. Secondary succession: occurs in an area where an existing community has been disturbed. Soil is already present. It follows same process as primary, but it is faster as the soil already has organic material and nutrients present for the pioneer species to build off of. 31. How can the adaptive strategies of species in early and late stages of succession be explained in terms of r and K select species? In general, communities in early succession will be dominated by fast-growing, well- dispersed species (opportunist, fugitive, or r-selected life histories) as environmental conditions are often harsh, and resources are relatively abundant. r-selected species are adapted to exploit these temporary and unpredictable environments. As succession proceeds, these species will tend to be replaced by more competitive (K- selected) species because as succession progresses and the environment becomes more stable, resource competition increases, and conditions become more predictable. K-selected species are adapted to these stable environments 32. How is biodiversity defined and with this definition how does biodiversity vary on a global scale? Biodiversity refers to the variety of life on Earth at all levels of biological organization, including the diversity of species, ecosystems, and genetic diversity within species. The concept encompasses the totality of living organisms, their interactions, and the ecological and evolutionary processes that sustain them. Biodiversity varies on a global scale because there are many different habitats and ecosystems with different abiotic factors that affect the variety of life present. Latitude, topography, climate, historical factors, human influence, isolation, and environmental stability all affect biodiversity. 33. What are the eight factors that act to enhance species richness in communities?  Habitat diversity that allows niches for different species  Favorable climate conditions  Spatial diversity: both the physical arrangement of habitats and the connectivity between them  Moderate levels of disturbance such as fire, flooding, and grazing can enhance species richness by preventing dominance by a few competitive species  Evolutionary history: areas with a long and stable evolutionary history may have a greater diversity of species over time  Predation & herbivory: the presence of these factors can regulate populations and prevent dominance of a certain species which creates a more balances and diverse community structure

 Higher resource availability such as nutrients and sunlight can support a larger number of species  Positive biotic interactions such as mutualism can enhance species richness by promoting coexistence 34. What is the best predictor of biodiversity within both marine and terrestrial ecosystems? Why is this so? The best predictor of biodiversity is ambient energy. An increase in light abundance allows for the primary producers to obtain the maximum 1% of sunlight. The most biodiversity is found within the equatorial region since there is more ambient energy for plants to obtain. When there are more resources in an area. It makes sense that more species could live within that area. 35. What is primary productivity and how is it measured? Primary productivity the rate at which biomass is produced by organisms that convert inorganic substrates into complex organic substances. It is usually measured by the uptake of carbon dioxide or the output of oxygen. 36. What are the limiting factors of primary productivity in aquatic ecosystems? The phosphate and nitrate are the two most important limiting factors for the aquatic productivity 37. What are the predictors of terrestrial primary productivity? Primary productivity varies by -solar radiation -temperature -moisture -nutrients (especially nitrogen and phosphorus) -co2 concentration -disturbances such as fires -topography such as slope, and aspect can affect solar radiation and water availability 38. What is secondary productivity and how is it measured? What limits secondary productivity? Secondary productivity refers to the rate at which consumers (heterotrophs), such as herbivores, carnivores, and decomposers, convert organic matter into biomass. The factors that limit sec productivity include:  Primary productivity: the availability of primary producers influences the amount of energy available for consumers  Nutrient availability: specifically, nitrogen and phosphorous  Temperature influences metabolic rates, extreme temperatures can limit the activities of consumers  Availability of prey or food resources  Top-down control: the presence of predators or herbivores can regulate the population sizes of consumers and limit their impact on primary producers  Availability of shelter and habitat

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 Presence of competitors 39. How energy efficient are trophic levels? Provide examples from one tropic level to the next. The efficiency of energy transfer between trophic levels in an ecosystem is typically low, and it is the trophic pyramid. only about 10% of the energy stored as biomass in one trophic level—e.g., primary producers —gets stored as biomass in the next trophic level—e.g., primary consumers. Put another way, net productivity usually drops by a factor of ten from one trophic level to the next ex: primary producers produce 100% of energy and secondary consumers only have 10% of that energy and secondary consumers have 1% while tertiary consumers have 0.1% 40. Provide an example for each of the consequences of altering the natural geochemical cycles of carbon, nitrogen and phosphorous. Consequences of altering the Carbon cycle: an increase in carbon results in increasing temperatures and helps plants on land grow more. excess carbon in the ocean makes the water more acidic Consequences of altering the Nitrogen cycle: eutrophication and nitrous oxide emissions. Excessive use of nitrogen-based fertilizers in agriculture can lead to nitrogen runoff into water bodies. This nutrient enrichment causes eutrophication, a process where excessive nutrients stimulate the growth of algae and other aquatic plants. Algae feed on the nutrients, growing, spreading, and turning the water green. Algae blooms can smell bad, block sunlight, and even release toxins in some cases. Consequences of altering the phosphorous cycle: water pollution & ecosystem disturbance: The excessive use of phosphorus-based fertilizers in agriculture and runoff from sewage can lead to phosphorus enrichment in aquatic ecosystems. This can result in water pollution and contribute to the eutrophication of lakes and rivers.

Ecology 204 2023 TESTBANK-FINAL-1

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