Exam 2 Review
Exam 2 Review Bio 260
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This 10 page Study Guide was uploaded by Michaela Humby on Tuesday March 8, 2016. The Study Guide belongs to Bio 260 at University of Tennessee - Knoxville taught by Charles Price in Spring 2016. Since its upload, it has received 104 views. For similar materials see Ecology in Biology at University of Tennessee - Knoxville.
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Date Created: 03/08/16
Review for Ecology Exam 2 Ch. 8 Summary An animal’s behavioral decisions play a critical role in activities such as obtaining food, finding mates, avoiding predators. Proximate causes (immediate)—or how the behavior occurs. Ultimate causes—why the behavior occurs; the evolutionary and historical reasons. Behavioral ecologists mostly focus on ultimate causes. natural selection can result in adaptive evolution: • Traits that confer survival or reproductive advantages tend to increase in frequency over time. If energy is in short supply, animals should invest in obtaining the highest-quality food that is the shortest distance away. Optimal foraging theory: Animals will maximize the amount of energy gained per unit of feeding time, and minimize the risks involved. In a study of great tits, proportions of prey types and encounter rates were varied. Trade-offs that affect foraging decisions may be related to predators, environmental conditions, or physiological conditions. Darwin proposed that the extravagant features of some males resulted from sexual selection: • Individuals with certain characteristics gain an advantage over others of the same sex solely with respect to mating success. • Male long-tailed widowbirds have extremely long tail feathers. They establish territories—areas that they defend against intruders. • The handicap hypothesis: a male that can support a costly and unwieldy ornament is likely to be a vigorous individual whose overall genetic quality is high. • The sexy son hypothesis: the female receives indirect genetic benefits through her sons, who will themselves be attractive to females and produce many grandchildren. • Females may benefit from selecting males with long eyestalks because their male offspring will be attractive to the next generation of females, which supports the sexy son hypothesis. • But, eyestalk length in male flies is correlated with overall health and vigor (David et al.1998), supporting the handicap hypothesis. Review for Ecology Exam 2 Mate choice can be altered by factors such as number and locations of potential mates, mate quality, food availability, and presence of predators or competitors. Ecological factors can also influence mating systems: number of mating partners and patterns of parental care. Polygyny can occur if females show a clumped distribution; a male can monopolize them. Monogamy usually occurs in mammalian species where it is difficult for males to defend access to more than one breeding female. Benefits of group living: • Higher reproductive success—especially when males hold high-quality territories. • Group members may share feeding and care of young. • Reduced risk of predation—individuals can band together to prevent attacks; predators may be detected earlier. • Dilution effect: as the number of individuals in a group increases, the chance of being the one attacked by a predator decreases. • Group members may respond to a predator by scattering in different directions, making it difficult for the predator to select a target. • Costs of group living: • As group size increases, the members deplete the available food more rapidly; more time may be spent in moving between feeding sites. • In groups with a dominance hierarchy, subordinate members can spend much time and energy on interacting with group members. The males of many species kill the young of their potential mates— examples include langur monkeys, horses, chimpanzees, bears, and marmots. In some species, females commit infanticide, such as giant water bugs and wattled jacanas. In these species, the males provide most or all of the parental care, and the females have higher reproductive potential. Ch. 9 Summary Distribution: Geographic area where individuals of a species occur. Abundance: Number of individuals in a given area. Review for Ecology Exam 2 Populations are dynamic—distribution and abundance can change over time and space. Genet: a genetic individual from a single fertilization event: e.g Aspen grove. Ramet: an actually or potentially independent member of a genet that may compete with other members for resources, e.g. individual Aspen tree. • Aspen trees produce clones (genetically identical copies) when new plants grow from root buds. A grove of aspens may all be from the same individual. Some species distributions depend on disturbance: Historical Factors Evolutionary history and geologic events affect modern distribution of species. Dispersal limitation can prevent species from reaching areas of suitable habitat. Geographic range—the entire geographic region over which a species is found. • Dispersion: Spatial arrangement of individuals within a population: • Regular—individuals are evenly spaced • Random—individuals scattered randomly • Clumped—the most common pattern • Several methods are used to estimate the actual abundance or absolute population size. Relative population size: Number of individuals in one time period or place relative to the number in another. Area-based counts: individuals in a given area or volume are counted. Quadrats: Sampling areas of specific size, such as 1 m . 2 Distance methods: Distances of individuals from a line or point are converted into estimates of abundance. • Mark–recapture studies: • Used for mobile organisms. • A subset of individuals is captured and marked or tagged, then released. • At a later date, individuals are captured again, and the ratio of marked to unmarked individuals is used to estimate population size. Ch. 10 Summary Review for Ecology Exam 2 A life table is a summary of how survival and reproductive rates vary with age. Cohort life table: follows the fate of a group of individuals all born at the same time (a cohort). Mostly used for sessile organisms. Organisms that are highly mobile or have long life spans are difficult to track. Static life table: Survival and reproduction of individuals of different ages during a single time period. Survivorship curve: Plot of the number of individuals from a hypothetical cohort that will survive to reach different ages. Type I: Most individuals survive to old age (Dall sheep, humans). Type II: The chance of surviving remains constant throughout the lifetime (some birds). Type III: High death rates for young; those that reach adulthood survive well (species that produce a lot of offspring Age structure: Proportion of the population in different age classes. Geometric growth: When a population reproduces in synchrony at discrete time periods and growth rate does not change. The population increases by a constant proportion: The number of individuals added is larger with each time period. The logarithm of a number is the exponent to which another fixed value, the base, must be raised to produce that number. Log (10010 = 3 3 because 10 = 1000 Exponential growth: When individuals reproduce continuously and generations can overlap and the population changes in size by a constant proportion at each instant in time. Doubling time (t ):dNumber of years it will take a population to double in size: Net reproductive rate (R ): M0an number of offspring produced by an individual during its lifetime: Density-independent factors: Effects on birth and death rates are independent of the number of individuals in the population. Weather conditions, such as temperature and precipitation. Catastrophes, such as floods or hurricanes Density-dependent factors: Birth, death, and dispersal rates change as the density of the population changes. As density increases, birth rates often decrease, death rates increase, and dispersal (emigration) increases, all of which tend to decrease population size. Population regulation: Density-dependent factors cause population to increase when density is low and decrease when density is high. Review for Ecology Exam 2 Logistic growth: Population increases rapidly, then stabilizes at the carrying capacity (maximum population size that can be supported indefinitely by the environment). Ecological footprint: Total area of productive ecosystem required to support a population. This method uses data on agricultural productivity, production of goods, resource use, population size, and pollution. Ch. 11 Summary Exponential Growth Population increases by a constant proportion at each point in time. When conditions are favorable, such as good weather, a population can increase exponentially for a limited time. When a species reaches a new area, exponential growth can occur if conditions are favorable. The population may grow exponentially until density-dependent factors regulate its numbers. Species such as the cattle egret colonize new regions by long-distance or jump dispersal events. Logistic Growth Some populations reach a stable size (equilibrium) that changes little over time. Population Fluctuation In all populations, numbers rise and fall over time. Fluctuations can be erratic deviations from an overall mean value. • Population Cycles • Some populations have alternating periods of high and low abundance at regular intervals. • Populations of small rodents, such as lemmings and voles, typically reach a peak every 3–5 years. Delayed density dependence: Delays in the effect that density has on population size. Demographic stochasticity—chance events affect survival and reproduction of individuals. Allee effects: Growth rate decreases as population density decreases. Environmental stochasticity: Unpredictable changes in the environment that can cause extinction of small populations. Metapopulation: A set of spatially isolated populations linked by dispersal of individuals or gametes; Metapopulations are characterized by repeated extinctions and colonizations of the small individual populations, but the metapopulation persists. Habitat fragmentation: Large tracts of habitat are converted to isolated patches, resulting in a metapopulation structure. • Isolation by distance—when patches are too far apart. Review for Ecology Exam 2 • Effect of patch size—small patches may be hard to find and have high extinction rates. • Rescue effect: High rates of immigration that protect a population from extinction. Ch. 12 Summary Competition: An interaction between individuals in which each is harmed by their shared use of a limiting resource. Resources: Features of the environment required for growth, survival, or reproduction, and that can be consumed to the point of depletion. Exploitation competition: Species compete indirectly; individuals reduce the availability of a resource as they use it. Interference competition: Species compete directly for access to a resource. The effects of competition are often unequal, or asymmetrical, and one species is harmed more than the other. • The ends of this continuum represent amensalism: –/0 interactions; individuals of one species are harmed while individuals of the other species are not affected at all. A “natural experiment” is a situation in nature that is similar in effect to a controlled removal experiment. If the ecological requirements of competing species—the ecological niches—are very similar, the superior competitor may drive the other species to extinction. Competitive exclusion principle: Two species that use a limiting resource in the same way cannot coexist indefinitely. Resource partitioning: Species using a limited resource in different ways. Environmental conditions can result in competitive reversal—the inferior competitor in one habitat becomes the superior competitor in another. fugitive species must disperse from one place to another as conditions change. Natural selection can influence the morphology of competing species and result in character displacement. Ch. 13 Summary exploitation (+/– interaction)—individuals of one species benefit by feeding on, and directly harming, individuals of another species. Herbivore—eats tissues of living plants or algae. Predator—kills and eats other organisms, referred to as prey. Parasite—lives in or on another organism (its host), feeding on parts of it. Usually does not kill the host. Some parasites (pathogens) cause disease. Review for Ecology Exam 2 Parasitoids are insects that lay eggs on or in another insect host. After hatching, larvae remain in the host, which they eat and usually kill. Some predators forage throughout their habitat in search of food, such as wolves. Others are sit-and-wait predators, remaining in one place and attacking prey that move within striking distance. Warning coloration (aposematic): Predators learn not to eat organisms that have toxins. Crypsis: The prey is camouflaged, or resembles its background. Mimicry: The prey resembles another organism that is toxic or very fierce. Compensation: Removal of plant tissue stimulates new growth. induced defenses—produced in response to herbivore attack. Secondary compounds—toxic chemicals to reduce herbivory A variety of factors can prevent predators from driving prey to extinction: • Habitat complexity and limited predator dispersal (as in Huffaker’s mites) • Prey switching in predators • Spatial refuges (where predators cannot hunt effectively) • Evolutionary changes in prey populations Ch. 14 Summary Symbionts: Organisms that live in or on other organisms. More than half of Earth’s species are symbionts. Our own bodies can be a home to many other species. EXAMPLE: Bacteria living in the human body Used to think it was antagonistic but it is actually an important component of health A parasite consumes the tissues or body fluids of the organism on which it lives (the host). Pathogens are parasites that cause diseases. Unlike predators, parasites usually have a higher reproductive rate than their hosts. Parasites typically harm, but do not immediately kill, the organisms they eat. Macroparasites: Large species such as arthropods and worms. Microparasites: Microscopic, such as bacteria. Parasites can include herbivores such as aphids or nematodes that feed on one or a few host plants. Parasitoids: Insects whose larvae feed on a single host and almost always kill Review for Ecology Exam 2 Ectoparasites live on the outer body surface of the host; can disperse more easily than endoparasites; are more exposed to predators, parasites, and parasitoids. Endoparasites live inside their hosts, within cells or tissues or in the alimentary canal; have evolved various mechanisms for dispersal, including complex life cycles and enslavement of hosts; are protected from the external environment and have easy access to food. Host age may affect likelihood of infection. There can be a latent period in which an individual is infected but cannot spread the disease. Vertical transmission—disease is passed from mother to newborn. A simple model shows that a disease will spread only if the density of susceptible hosts exceeds a critical threshold density. EXAM 2 REVIEW Sexual selection- handicap vs. sexy son Mutually exclusive? No both are probably operating Why are females choosier than males? Spend more time with the offspring and they put more resources; female gametes are so much bigger than male gametes so they are choosier to make sure the fertilized gamete survives; increased investment of care of offspring; Polygyny: one male with multiple females clumped distribution because it’s easier to monopolize it Polyandry- one female many males Monogamy- on male and female Under what types of conditions would we see polygamy in respect to distribution of females? If the females are clusters so it’s easier for the men to make the territory What are some of the advantages for living in groups? Highly specialized One member looks out for predators while others find food Review for Ecology Exam 2 Easier to stay safe from predators Shared care; higher reproductive success Better forage in Easier to mate Why do other male lions kill? Other male lions cubs because so the female becomes receptive reproductive faster Dilution effect Red box around the equations we need to know Population density is number of individuals per area Genet and a ramit- gene (ex: Aspin trees) all the trees were identical and ramit is one tree competing for the resources; we are looking at the ramit What limits distribution and abundance? Historical factors, dispersal, habitat suitability; competition; Dispersion patterns: clumped, regular, and random Competition leads to a regular distribution Resources lead to a clumped (which is most common) What process leads to regular dispersion pattern: organisms that are competing for resources (competition) What leads to clumped distribution? Polygamy, resources Which one is most common? Clumped Density dependence and density independence As density increases, more factors affected; Logistic growth is flattens out at the top meaning there is a carrying capacity Exponential growth is not realistic because there is not a carrying capacity Metapopulation is population of populations; species with loss of patches like gaps in a forest; all of those populations together; lake is a good system for metapopulation Skipper butterfly population (examples) what influenced whether or not a patch would be colonized or not? How close it is to a colonized patch and the size of the nearest patch affected the other patches Competition definition: competing for limited resource; both have to be harmed for competition Review for Ecology Exam 2 What is the difference between exploitation and interference; Exploitation competition: Species compete indirectly; individuals reduce the availability of a resource as they use it. Interference competition: Species compete directly for access to a resource. The effects of competition are often unequal, or asymmetrical, and one species is harmed more than the other. Definition of ammensilism: Competitive exclusion principle: If 2 species use resources in different ways is called resource partitioning Are insects more specialists or generalists; they are more specialists What are adaptations to avoid being eaten; mimicry; camouflage What is masting? - Lots of acorns being produced because you cant eat them all Red queen hypothesis; must keep up with everything that is moving evolutionary What happened with Robert…. Moved starfish from the intertidal zone? The muscle increased and diversity decreased and that illustrates; example of wolves in Yellowstone
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