Study Guide for Exam Two: Chapters 8, 9, 11, and 14

Study Guide Exam 2 1. Chapter 8- Group Behaviors a. What are the differences between proximate and ultimate causes/explanations? Which one is more likely to result from genetic inheritance? i. Proximate cause (immediate): HOW the behavior occurs ii. Ultimate causes: WHY the behavior occurs; the evolutionary and historical reasons. 1. this is more likely to occur in genetic inheritance b. Explain that social behaviors have a genetic basis and are therefore subject to natural selection i. Gene locus, or the position where genes are located, play a major part in determining the types of behaviors that animals exhibit, such as domestication vs wild organisms of the same species. c. What is optimal foraging theory and what does it assume about energy gain? i. Optimal foraging theory: animals will MAXIMIZE the amount of energy gained per unit of feeding time, and MINIMIZE the risks involved. ii. This theory assumes that natural selection acts on the foraging behavior of animals to maximize their energy gain. d. What does the profitability of a food item depend on? i. The profitability of a food item (P) depends on how much energy (E) the animals get from the food relative to the amount of time (t) it spends obtaining the food. e. Know the equation P = E/t and be able to explain/apply it i. Profitability equals the amount of energy gained from food divided by the time it took to obtain that food. f. What is the Goldilocks theory relating to the Eurasian oystercatcher? i. The Goldilocks theory explains that easy-to-obtain food may have a small net energy gain, while hard-to-obtain food has more energy to obtain. 1. The Eurasian oystercatchers are a species of birds that feed on oysters, and they primarily pick the “intermediate” oysters that are not too large (more energy spent to find = more energy gained) and are not too small (less energy to find = less energy gained) g. What three kinds of considerations are involved in foraging? 1. Predators: choose less profitable patches to avoid predator risks 2. Environmental conditions: avoid foraging during unfavorable conditions 3. Physiological conditions: more risky behavior when hungry h. Describe three anti-predator behaviors by prey 1. Avoid being seen, hide and forage when predators are gone 2. Detect predators: stay alert 3. Prevent attacks: send signals 4. Escaping attack: play dead, detach body parts i. What is the dilution effect? What benefits does it provide? Dilution effect: the reduced, or diluted, probability of predation to a single animal when it is in a group. j. Describe sexual dimorphism The difference in the phenotype between males and female of the same species (body size, courtship behavior) k. Describe the costs and benefits of living in a group Enhanced foraging efficiency, improved defense against predators, increased reproductive success through cooperative breeding, and sharing of information for better adaptation. However, costs may involve competition for resources, a higher risk of disease transmission, and intra-group conflicts over territory or mating opportunities. l. Explain and provide an example of monogamy, promiscuity, polygyny, polyandry Monogamy refers to a mating system where an individual forms a long-term pair bond with only one partner. An example of monogamy is observed in many bird species, such as the bald eagle, where a male and female form a committed pair and collaborate in raising their offspring together. i. ii. Promiscuity involves individuals mating with multiple partners without forming long-term bonds. An example is found in some insect species like the honeybee, where a queen mates with multiple drones during a single mating event, and each drone mates with multiple queens. Polygyny is a mating system where one male forms long-term bonds with multiple females. In some mammals, such as lions, a dominant male may mate with multiple lionesses within his territory and take on the responsibility of protecting and providing for the pride. Polyandry is a mating system where one female forms long-term bonds with multiple males. This is seen in certain bird species, like the phalaropes, where a female mates with multiple males, and these males collectively contribute to nest-building and raising offspring. m. Define isogamy and anisogamy Isogamy: is the fusion of two motile gametes which are morphologically identical and physiologically different Anisogamy: is the fusion of morphologically dissimilar male and female gametes which can be motile or immotile n. Review mating systems lecture (Yale Ecology Department) 2. Chapter 9- Population and Abundance a. What is a population (according to the biological species concept)? i. Population - a group of individuals of the same species that live in the same area at the same time and interact with each other b. Compare and contrast distribution and abundance- why would ecologists be interested in either one of these things? i. Distribution: geographic area where individuals of a species occur. ii. Abundance: number of individuals in a given area iii. Ecologists try to understand what factors determine the distribution and abundance of species. c. What is a genetic clone and how does it complicate population studies? i. a genetic clone is an exact copy of an individual, this complicates population studies as it is difficult to then distinguish what constitutes an individual. 1. in order to combat this ecologists came up with two new terms for distinguishing clones a. Genet: a genetic individual resulting from a single fertilization event (asexually reproduced), a genet may consist of multiple genetically identical parts that have the potential to function as an independent unit. (aspen tree) b. Ramets: an actual or potential physiologically independent member of a genet that may compete with other members for resources (strawberries are an example) d. Explain population size vs. density i. Density: number of individuals per unit of area ii. population size: total number of individuals in an area 1. Example: On a 20-hectare island there are 2,500 lizards a. population size: 2,500 b. population density: 125/hectare (2,500 / 20) e. What pattern do you expect to observe how the size of organisms changes with increased density? i. The density of a population is negatively correlated with the body size of a species 1. example: in herbivorous animals, the smallest-bodied species (mice) live at the highest densities, whereas the f. g. h. i. j. k. l. largest-bodied species (elephants) live at the smallest densities. What factors contribute to habitat suitability? Provide examples of both abiotic and biotic features that might influence habitat suitability i. Abiotic factors: moisture temperature, pH, sunlight, nutrients, etc 1. some species are able to tolerate broad ranges of physical conditions, while others cannot. ii. Biotic factors: species distributions are affected by herbivores, predators, competitors, parasites, and pathogens. Why do the creosote bush and the saguaro cactus have such different distributions if they are both drought tolerant? Are the limiting factors biotic or abiotic? i. The creosote bush is able to tolerate dry conditions as well as cold (thus having a large distribution range), while the saguaro cactus can only tolerate dry conditions (thus having a much narrower range) Explain the relationship between Opuntia stricta and Cactoblastis cactorum in Australia i. In Australia, the species Opuntia stricta was introduced and quickly became invasive, spreading over vast areas and destroying natural habitats. In response, the species Cactoblastis cactorum (a moth) was introduced to feed on said invasive cactus species as a method of controlling it. 1. this is a form of biological control. What is biological control? What are some of the risks we discussed regarding this management strategy? i. biological control can backfire as it can damage native species as well (if the moths began to eat native species as well) What is dispersal? How might humans help increase plant dispersal? i. Dispersal: the movement of individuals from one area to another. 1. humans are able to manually disperse plant and animal species that otherwise would not have occurred What is dispersal limitation? How is habitat fragmentation related to this concept? i. Dispersal limitation: the absence of a population from suitable;e habitats because of barriers to dispersal 1. barriers can include large expanses of inhospitable land that an organism cannot cross. ii. Habitat fragmentation: humans have created barriers for dispersal (road, forest clearings) which prevent dispersal of many species. What is a wildlife corridor? Provide an example. i. Habitat corridor: connections across the landscape that link up areas of habitat m. n. o. p. q. r. 1. Creating a landscape bridge over a highway that allows animals to cross the highway without risk of injury from vehicles. What is a geographic range? i. A geographic range includes all the areas a species might occupy throughout its entire life 1. an example would be the large-scale migration that Monarch Butterflies make. What is migration? Why would animals migrate seasonally? i. Migration: the seasonal movement of individuals back and forth between habitats. 1. some species migrate back and forth between summer and winter habitats, while others migrate to move to breeding grounds Compare and contrast dispersion and dispersal. i. Dispersal: the movement of individuals from one area to another ii. Dispersion: spatial arrangement of individuals within a population What are the three main patterns of population dispersion found in nature? When would each occur? i. Regular: individuals are evenly spaced 1. bird species that have large nesting grounds (penguins) ii. Random: individuals are scattered randomly 1. dandelions or other plant species that rely on wind dispersal iii. Clumped: individuals occur in clumps or clusters 1. Species that travel in herds (elephants, wildebeest, etc) When would you use an area-based method to estimate population size? When might you use a distance measure/transect? i. Area-based counts: individuals in a given area or volume are counted. 1. most often used to estimate the abundance of immobile organisms. What is a quadrat? How large is one hectare in meters squared? i. 2 Quadrat: sampling areas of a specific size, such as 1 𝑚 1. 1 hectare equals 10,000 meters squared (multiple given area by 10,000) s. When would you use Mark recapture (MRR) methods to measure population size? i. mark-recapture method: used for mobile spieces 1. Capture individual(s), mark or track them, then release them. At a later date, individuals are captured again, and the ratio of marked to unmarked individuals is used to estimate population size. t. Use the equation provided in your notes to estimate population size based on MRR methods i. Example: 23 salmon are captured and marked (M). Later, 15 salmon are captured (C), 4 of them marked (R, for recaptured). To estimate the total population size (M) use: M / N = R / C or N = (M x C) / R. 3. Chapter 11 - Population growth and regulation a. Why are ecologists interested in human population growth? i. As the human population quadrupled, we increased energy consumption by 93-fold. (3 billion in 1960 → 7.7 billion in 2019) b. When did the human population first reach 1 billion people? i. 1850 (from crash course video on Canvas) c. How many people are now being added to the planet every 13 years? What is today’s population? i. As of 2021, the current world population is 7.888 Billion. Around 1 billion people are added to the world population every 12-13 years. d. Which two countries have the largest populations in the world according to the world figures in our notes? i. India and China have the largest populations out of all countries (1.409 billion and 1.416 billion, respectively) 1. compare this to the United States (3rd most populous country) with 336 million. e. What was the effect of the Industrial Revolution on human population size? (see Fig 10.2) i. The industrial revolution brought large-scale changes to the way that Humans lived, via machines, medicine, and crop growth. The Industrial Revolution causes our population to grow faster (less death and more babies) f. Ecological Maxim from Ch 1: No population can grow forever; Ecologists study what regulates population growth/declines- how does this relate to endangered species? i. Every population has its carrying capacity (the max population size that can be supported indefinitely by the environment), once this limit is reached the population will not have enough resources to survive and may experience a sharper decline in population (due to starvation, disease, etc) g. What is plotted on a survivorship curve? Describe a Type I, II, and III survivorship curve and provide an organism that is representative of each i. Survivorship curve: a graph that shows the proportion of a population that survives from one age to the next 1. Type I (humans): a high rate of surviving through childhood and adulthood, typically dies once the individual is elderly. 2. Type II (birds): Equal chance of dying throughout the entire lifespan (straight line with a negative slope) 3. Type III (trees): low chance of surviving until adulthood, but once there the individual can live for quite some time. h. What is the population age structure? How does age structure influence how fast a population will grow? i. i. j. k. l. m. n. o. p. q. r. s. t. u. Proportional Age Structure: the distribution of people in different age groups in a population over a set period of time What is the most important aspect of age structure that affects the rate of population increase? i. The most important parts of an age structure are ages 0-14 (future generation) and age 15-44 (reproductive age) Explain why Nigeria and Japan have such different outcomes for the Projected population in 2050 in Figure 10.7 in your text? i. Nigeria and Japan have such different outcomes due to the birth rates in the country. Nigeria has a very high birth rate (around 4 children per woman) while Japan has a very low birth rate (around 1 child per woman). This may cause long-term problems with the age structure of the population, as it may cause the population to be primarily composed of individuals past reproductive age. Define geometric growth and exponential growth and explain how they are similar i. Geometric growth is discrete (A fixed number is multiplied to x. For example, the sequence (1, 3, 9, 27, 81, ...) is a geometric sequence) ii. Exponential growth is continuous (A fixed number is raised to the x) iii. Both are similar in the sense that they are consistently growing. How are geometric growth and exponential growth different? i. see the previous question What type of curve is produced from exponential growth? i. results in a J-shaped curve pattern Describe the equations for geometric and exponential growth and what the variables are i. Geometric Growth: Nt+1 = λ Nt ii. Exponential Growth: dN / dt = rN What is λ and what is r? i. λ is the geometric pop growth rate, r is the exponential pop growth rat When λ = 1 or r = 0, the population stays the same size. When λ < 1 or r < 0, the population size will decrease. When λ > 1 or r > 0, the population grows geometrically or exponentially. Be able to recognize graphs of the above patterns Compare and contrast density-dependent and density-independent factors i. Density-independent factors: independent of the size or growth rate of the population (weather, climate change, hunting) ii. Density-dependent factors: dependent on the size and growth rate of the population (food, habitat, mates) What is logistic growth? What is meant by carrying capacity? i. Logistic growth: a model for population growth that takes into account limited resources 1. Carrying capacity is the the max population size that can be supported indefinitely by the environment v. What shape curve is produced by logistic population growth? i. S-shaped curve w. Describe the equation for logistic growth and what the variables are 𝑑𝑁 𝑁 i. = 𝑟𝑁 (1 − 𝐾 ) 𝑑𝑡 1. dN / dt is the rate of change in population size as time (t), N is the population density (also at time t), r is the (per capita) intrinsic rate of increase under ideal conditions, and K is the density at which the population stops increasing in size. x. What is K? How does it affect population growth? i. see above question y. Is the world population following logistic growth? Why or why not? i. The human population has NOT been following the expected growth pattern, we are growing faster than logistic growth without reaching the expected carrying capacity. z. The human population is projected to be between 8-11 billion by 2050what will this look like? i. 4. Chapter 14 Competition a. Why are some plants carnivorous? i. Some plants are carnivorous due to the lack of nutrition that is found in the environment (such as Venus flytraps) b. What is the definition of a resource? What is a good definition of competition? i. Resource: anything an organism consumes or uses that causes an increase in population growth rate when it becomes more available c. Describe intraspecific competition vs. interspecific competition i. Intraspecific competition: between members of the same species 1. competition for mates, niches, territory ii. Interspecific competition: between members of different species 1. predator vs prey competition d. Explain the competitive exclusion principle and how Tillman and Gause demonstrated the competitive exclusion and competitive co-existence principles i. Competitive exclusion: The dominant species prevents another species from using the same essential resources; the inferior species may become locally extinct. ii. Competitive coexistence: the ability to coexist despite sharing limiting resources e. Explain Tansley’s experiment with heath and white bedstraw and how its results relate to natural selection i. an experiment done with 2 diatom species showed that when both species were grown alone, the population was stable, but when f. g. h. i. j. k. l. grown together they competed for the same resource (silica) and one species drove the other to extinction. Compare and contrast fundamental and realized niches i. Fundamental niche: the full set of resources, plus other biotic and abiotic requirements of species ii. Realized Niche: the restricted set of resources a species is limited to, due to species interactions iii. Competition forces species into their realized niche. Describe resource partitioning and character displacement and provide examples i. Resource partitioning: species using a limited resource in different ways. 1. both rodents in ants compete for seeds in the desert, but ants tend to consume a much smaller quantity of seeds compared to rodents. ii. Character displacement: competition causes the phenotypes of competing species to evolve to become different over time, facilitating resource partitioning. Describe the example of interspecific competition between ants and rodents in deserts i. See above question (g) Describe the competition experiment involving Goldenrod and the Goldenrod-eating beetle- what was done and what were the results? i. Every 5-15 years, a species of beetle (goldenrod-eating beetle) achieves incredibly high densities and consumes vast amounts of Goldenrod. Researchers sprayed some fields with an insecticide that killed the beetles and left the other fields unsprayed. In sprayed plots, goldenrod continued to dominate, in unsprayed plots competitors became much more abundant. Provide several examples of exploitative competition i. Exploitation competition: individuals reduce the supply of a resource as they use it. 1. one species of plant in an area consumes all of the nitrogen, leaving other species nitrogen-starved. Define interference competition and allelopathy- give examples of each i. Interference competition: one species directly interferes with the ability of its competitors to use a limiting resource. 1. when carnivores fight with one another over animal prey. ii. Allelopathy: a type of interference competition that occurs when organisms use chemicals to harm their competitors. 1. many trees protect their roots from other plants; Eucalyptus trees use harmful chemicals to ward off bacteria from their roots. Explain the example of interference competition involving nest-plugging with red harvester ants and long-legged ants in New Mexican deserts and how they partition resources temporally (according to time) instead of spatially. i. In the desert of New Mexico, long-legged ants an red harvester ants compete for seeds and insects they can subdue. In the early morning, long-legged ants plug the entrance of harvester ants with stones and soil.