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

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

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