Ecology Learning Objectives
Selective pressure resulting in specific life history strategy requires?
(1) Variation in life histories in a population (2) variation is heritable (3) Different life histories result in different fitness
For a given location on the globe, describe the climate you would expect to see there and explain what global, continental, and regional factors would determine that climate.
A combination of global, continental and regional factors determines the climate of a given global location. Global factors include the Earth's tilt and rotation, which determine the amount of sunlight received at different latitudes and seasons. The Earth's atmosphere and oceans also play a role in regulating temperature and precipitation patterns. Continental factors include the distance from the coast, which can affect the temperature and humidity, and the presence of large bodies of water, which can moderate temperature and affect precipitation patterns. Regional factors include topography, such as the presence of mountains, which can create microclimates and affect the amount of rainfall and temperature. Land use, such as the presence of forests or urban areas, can also affect the local climate. For example, if a location is near the equator and close to the ocean, it would likely have a tropical climate with high temperatures and high precipitation. On the other hand, a location in the middle of a continent and far from the coast would likely have a continental climate with large temperature variations and lower precipitation.
Determine if a population is stable, shrinking, or growing based on age structure pyramids.
A population's age structure can provide information about whether it is stable, shrinking, or growing. If a population has a wide base and a narrow top, it typically indicates a growing population with a high birth rate and lower death rate. A population with a narrow base and wide top, on the other hand, indicates an aging population with a low birth rate and high death rate, and potentially a shrinking population. If the population has a relatively uniform structure, it suggests a stable population with a balanced birth and death rate.
Compare how a species can respond to environmental change via adaptation vs. acclimation.
Adaptation refers to genetic changes in a species over time that make it better suited to its environment. These changes are passed on to future generations and can occur over many generations. Acclimation is the change in morphology, physiology, and behavior within an individual's lifetime in response to changing environmental conditions, and it is not passed on to the next generation. Adaptation: - Population-level changes - Occurs over multiple generations FINISH FILLING THIS IN ^^^^^^^^^^^ An example of acclimation is a plant that adjusts its root structure in response to changes in nutrient availability in the soil, as seen in the study by Muller and Schmidt (2004) on Arabidopsis thaliana, where plants developed a more significant number of fine roots with a high surface area to volume ratio when nutrients were in high supply and fewer, but thicker roots with a lower surface area to volume ratio, when nutrients were in low supply to reach deeper layers of soil where nutrients may be more available. In summary, adaptation is a genetic change that occurs over many generations and makes a species better suited to its environment, while acclimation is a process of adjustment that occurs over an individual's lifetime.
Discuss the characteristic relationship between temperature and performance across a range of biological scales from enzymes to species.
At the molecular level, enzymes are biological catalysts that speed up chemical reactions in cells. Enzymes have optimal temperatures at which they function best, and deviations from this optimal temperature can result in decreased performance. As temperature increases, the kinetic energy of the enzyme and substrate molecules also increases, allowing for more collisions and therefore an increase in the rate of the reaction. However, as the temperature continues to rise, enzymes can become denatured or lose their shape, causing a decrease in performance. At the cellular level, the temperature can also have a significant impact on the performance of cells. Many cells have optimal temperatures at which they function best and can adapt to different temperatures through mechanisms such as thermal acclimation. However, extreme temperatures can damage or kill cells, resulting in decreased performance. At the organismal level, the temperature can affect the performance of entire species. Many organisms have adapted to specific temperature ranges and can survive and reproduce in those conditions. However, changes in temperature can shift the distribution of species, causing some to become extinct or migrate to new areas. Additionally, warming temperatures can also affect the phenology (timing of life cycle events) of species, leading to mismatches in the timing of reproduction and food availability.
Explain how the stomata works in CAM, C4 and C3 Photosynthesis.
CAM: Stomata are closed during the day and open at night. C3 plants: Stomata are open during both the day and night, but they close during periods of water stress to reduce water loss. C4 plants: Stomata are usually open during the day and closed at night, in order to optimize the balance between carbon dioxide uptake for photosynthesis and water conservation.
Explain why cavitation is most likely when the difference between the potential at the top of the plant and the atmosphere is greatest.
Cavitation is most likely to occur when the difference between the potential energy of the fluid at the top of the plant (stomata) and the atmospheric pressure is greatest. This difference in potential energy creates a pressure differential, and if the fluid is flowing fast enough, it can cause a rapid drop in pressure that results in the formation of vapor bubbles. When the fluid slows down or the pressure increases, these vapor bubbles can then collapse, leading to cavitation. The larger the pressure differential, the greater the likelihood of cavitation, as the fluid is subjected to more severe changes in pressure. In other words, when the difference between the potential energy of the fluid at the top of the plant and the atmospheric pressure is greatest, there is a higher chance of the fluid reaching the conditions necessary for cavitation to occur.
Differentiate between climate and weather
Climate refers to the long-term patterns of temperature, precipitation, wind, and other meteorological variables in a specific area over many years. It is the average weather conditions for a region over a long period, typically 30 years or more. Climate can be characterized by various parameters such as temperature, precipitation, wind patterns, and the number of sunny days in a year. Weather, however, refers to the short-term conditions of the atmosphere in a specific area. It is the day-to-day or even hourly conditions of temperature, precipitation, wind, and other meteorological variables. Weather can be described as the state of the atmosphere at a particular time and place. In summary, the climate is the long-term average of weather patterns and conditions, while the weather is the short-term state of the atmosphere in a specific area.
Describe what happens when cavitation occurs.
Death by cavitation refers to the lethal damage caused to plants by the formation of air pockets in their water-conducting vessels, leading to a loss of water pressure and the inability to transport water and nutrients. This phenomenon can be caused by various factors, including drought, extreme temperatures, and herbivore damage, and can have a significant impact on ecosystem dynamics and plant populations.
Explain how evolution by natural selection could allow a population to maintain performance as some aspect of its environment changes.
Evolution by natural selection is the process by which certain traits become more or less common in a population over time based on how well those traits enable the individuals that possess them to survive and reproduce. In the context of environmental change, this process can allow a population to maintain performance by selecting individuals that have traits that are well-suited to the new conditions. For example, if an environment becomes colder, those individuals in a population that has mutations that result in thicker fur will be more likely to survive and reproduce. Over time, as these individuals pass on their thick fur trait to their offspring, the population as a whole will become better suited to the colder environment. Similarly, if a population is subject to a new predator, those individuals that have mutations that result in better camouflage or faster running speeds will be more likely to survive and reproduce, allowing the population to maintain performance in the face of this new threat.
Define fecundity, life history, life-history trait, life-history strategy, and trade-off.
Fecundity: Fecundity refers to an organism's reproductive potential, or its ability to produce offspring. It can refer to the number of eggs or seeds produced or the number of offspring produced over a certain period of time. Life history: A life history refers to the series of events and processes that occur over the course of an organism's life, including growth, development, reproduction, and death. Life-history trait: A life-history trait is a characteristic or feature that influences an organism's life history, such as the age at first reproduction, the number of offspring produced, or the length of time between generations. Life-history strategy: Pattern (sum) of life history traits that have evolved by natural selection in response to biotic and abiotic conditions. Trade-off: A trade-off refers to the relationship between two or more life-history traits, where an increase in investment in one trait results in a decrease in investment in another trait. Trade-offs reflect the limited resources available to an organism, and the need to allocate these resources in a way that maximizes fitness.
Contrast how different life-history strategies may be favored in some but not other environments, using examples of costs, benefits, and trade-offs.
For example, consider the life-history strategies of two species of birds: one is a migratory bird and the other is a sedentary bird. The migratory bird may have a strategy that prioritizes reproduction over survival, as it is able to migrate to a warmer and more hospitable environment during the winter months, where it can find ample food and avoid harsh weather conditions. This strategy allows the migratory bird to produce more offspring, increasing the chances of its genetic material being passed on to future generations. However, this strategy also comes with costs, such as the energy expenditure required for migration and the potential risks associated with traveling long distances. On the other hand, the sedentary bird may have a strategy that prioritizes survival over reproduction. It stays in the same location year-round and is adapted to survive in its environment, even during harsh winter months. This strategy may result in fewer offspring, as the bird's resources are focused on survival rather than reproduction. However, the benefits of this strategy include a lower risk of death and greater chances of survival, which can increase the bird's overall lifetime reproductive success. In this example, the migratory bird's strategy may be favored in environments with relatively mild and predictable winter conditions, where the benefits of migration outweigh the costs. On the other hand, the sedentary bird's strategy may be favored in environments with harsh and unpredictable winter conditions, where survival is more important than reproduction.
How are global and regional precipitation patterns produced? Describe what happens as the sun heats the air at the equator and why this leads to high precipitation in the tropics. Describe the "rain shadow" effect and how it comes about.
Global and regional precipitation patterns are produced by the movement of air masses and the formation of weather systems. As the sun heats the air at the equator, it causes the air to rise and cool, forming large areas of low pressure known as the Intertropical Convergence Zone (ITCZ). As the air rises, it cools, and the water vapor condenses to form clouds and precipitation. This process is known as convection, the primary driver of precipitation in the tropics. The tropics are known for their high precipitation and frequent thunderstorms. As air masses move away from the equator and towards the poles, they begin to cool and sink, forming high-pressure areas. This sinking air is dry and stable, suppressing the formation of clouds and precipitation. This is why regions near the poles tend to be dry and have low precipitation. The "rain shadow" effect occurs when a mountain range blocks the movement of moist air masses, causing the air to rise and cool on the windward side of the mountain. As the air cools, it releases its moisture as precipitation, leading to a wet and lush environment on the windward side of the mountain. The air sinks and warms on the leeward side of the mountain, leading to a dry environment. This is why many mountain ranges have a "rain shadow" desert on their leeward side.
Analyze the ability of an individual to modify their water budget to maintain homeostasis.
H2O balance = Wd + Wf + Wa - We - Ws Wd = Ingestion: The process of taking in water through the mouth. Wf = Metabolism: The process by which the body converts food into energy and produces metabolic water. Wa = Absorption: The process by which water is taken up by the body's cells and tissues. We = Evaporation: The process by which water is lost through the skin and respiratory system. Ws = Secretion: The process by which the body eliminates waste products and excess water. The water balance in living organisms is important for maintaining proper fluid balance and overall health. When the water intake is not equal to the water output, it can result in dehydration or overhydration, which can have serious consequences for health.
Identify environmental factors that contribute to body temperature.
Hnet = Har + Hmet - Hrr ± Hcond ± Hconv - He Hnet = body temperature Har = absorbed radiation (heat gained by the system due to a heat source) Hmet = heat generated by metabolism Hrr = re-radiated heat (heat lost due to radiation) Hcond = heat transfer due to conduction Hconv = heat transfer due to convection He = evaporative heat loss
Using what you know about biome classification, explain why you think the biomes shift the way they do (for one of your chosen biomes and each model scenario).
Light, temperature, and precipitation are the primary factors determining the distribution of different biomes on Earth. Each biome is characterized by a unique combination of these factors, which shape the types of plants and animals that can survive and thrive in that area. Light is an important factor because different types of plants have varying light requirements. For example, tropical rainforests typically receive a high amount of light, while temperate rainforests typically receive less light. As a result, tropical rainforests are characterized by tall, dense canopies of vegetation, while shorter, more diffuse canopies characterize temperate rainforests. Temperature is another key factor that determines the distribution of biomes. Different biomes are adapted to different temperature ranges, and temperature changes can cause these biomes to shift. For example, tropical biomes may expand into previously too-cool areas to survive as temperatures rise, while temperate biomes may shrink. Precipitation is also an important factor in determining the distribution of biomes. Different biomes are adapted to different precipitation levels, and precipitation changes can cause these biomes to shift. For example, as precipitation decreases, desert biomes may expand into previously too wet areas for them to survive, while tropical and temperate rainforests may shrink. Overall, changes in light, temperature, and precipitation can cause biomes to shift in response to changes in climate and land use. These shifts can significantly impact the plants and animals that depend on these biomes for survival and on human populations that rely on them for resources such as food, water, and timber.
Define homeostasis
Maintaining relatively constant internal conditions that keep the organism within its range of physiological tolerance.
Identify the role of models in enhancing our understanding of ecological patterns.
Models can help us better understand the underlying mechanisms that drive ecological patterns and make more informed decisions about the conservation and management of ecosystems.
Define physiological tolerance
Physiological tolerance refers to the decrease in an organism's response to a drug or other substance over time, such that higher doses are required to produce the same effect. This can happen as the body adapts to the presence of the substance, and can lead to dependence or addiction.
Distinguish among poikilotherm, homeotherm, ectotherm, and endotherm
Poikilotherm: an organism whose body temperature varies significantly and is dependent on the environment. (EX: Frog & Chameleon) Homeotherm: an organism that maintains a stable body temperature regardless of external conditions. (EX: Ostrich & Capybara) Ectotherm: an organism that regulates its body temperature mainly through external sources such as sunlight or ambient temperature. (EX: Frog & Chameleon) Endotherm: an organism that generates heat internally to regulate its body temperature, independent of external conditions. (EX: Ostrich & Capybara)
Explain how constraints limit resource allocation and thus establish the trade-offs that shape life-history strategies.
Resource allocation refers to the way in which organisms allocate their limited resources, such as energy and nutrients, to different functions or activities. Constraints refer to the limitations that restrict an organism's ability to allocate resources as they would like, due to various factors such as genetic, environmental, and physiological conditions. These constraints limit the number of resources available for each function and thus establish trade-offs between different life-history strategies. For example, an organism may need to allocate a large number of resources to growth or reproduction, but this means there may be less available for long-term maintenance and survival. In order to maximize fitness, organisms must make trade-off decisions that balance the allocation of resources to different functions. These trade-offs shape life-history strategies by determining the priority of different functions and influencing the timing, frequency, and intensity of resource allocation. For example, a young organism may prioritize growth over reproduction, while an older organism may prioritize reproduction overgrowth. The life-history strategy that an organism adopts will depend on the specific constraints and trade-offs that it faces, and will play a critical role in determining its survival, growth, and reproductive success.
What causes seasonality? Explain why different parts of the earth experience seasons, how those seasonal differences change with latitude, and how seasonality affects the large-scale climate patterns created by the global atmospheric circulation cells.
Seasonality is caused by the tilt of the Earth's axis relative to its orbit around the sun. As the Earth orbits the sun, different parts of the planet receive different amounts of sunlight due to the tilt of the axis. This results in the familiar seasons of winter, spring, summer, and fall. The seasonal differences experienced by different parts of the earth change with latitude. Closer to the equator, the seasonal differences are less pronounced, while areas closer to the poles experience more extreme seasonal changes. This is because the amount of sunlight a location receives is directly related to its distance from the equator. Seasonality also affects the large-scale climate patterns created by the global atmospheric circulation cells, including the Hadley, Ferrel, and Polar cells. The changes in temperature and solar radiation caused by seasonality drive the global atmospheric circulation patterns, leading to the movement of heat and moisture from the equator to the poles. This, in turn, affects the formation of weather systems, such as monsoons and hurricanes, and can lead to changes in precipitation patterns and the severity of droughts and floods in different regions.
Discuss selective pressures that could favor the evolution of semelparity versus iteroparity.
Selective pressures that could favor the evolution of semelparity (also known as "big-bang" reproduction) versus iteroparity (repeated reproduction) include: Semelparity: High mortality: if there is a high risk of death, organisms may reproduce once and then die, maximizing the number of offspring they produce. Scarcity of resources: if resources are scarce or unpredictable, organisms may reproduce once and allocate all their resources to their offspring to ensure their survival. Predation: if there is a high risk of predation, organisms may reproduce once and invest all their energy in a few offspring to increase their chances of survival. Iteroparity: Abundance of resources: if resources are abundant and predictable, organisms may be able to reproduce multiple times, increasing their overall reproductive success. Low mortality: if there is a low risk of death, organisms may be able to survive long enough to reproduce multiple times. Avoidance of predators: if there is a low risk of predation, organisms may be able to survive long enough to reproduce multiple times.
Explain how an organism's surface-to-volume ratio affects its heat budget.
The surface-to-volume ratio of an organism affects its heat budget because it determines the balance between heat loss and heat retention. A high surface-to-volume ratio means that a large surface area relative to the volume is available for heat exchange with the environment, which results in a greater rate of heat loss. On the other hand, a low surface-to-volume ratio means that a smaller surface area relative to the volume is available for heat exchange, which results in a lower rate of heat loss and increased heat retention. Therefore, an organism with a high surface-to-volume ratio must consume more energy to maintain its body temperature and avoid heat loss, whereas an organism with a low surface-to-volume ratio is more energy efficient in retaining heat. This principle applies to both endothermic (warm-blooded) and ectothermic (cold-blooded) organisms, although in different ways. Endothermic organisms regulate their body temperature internally by generating heat, and their surface-to-volume ratio affects how much energy they need to maintain their temperature. Ectothermic organisms regulate their body temperature by absorbing heat from the environment, and their surface-to-volume ratio affects how effectively they can absorb and retain heat.
Describe the three-cell model (northern and southern hemispheres) of global atmospheric circulation patterns (wind), including the factors that drive the cycles, and the resulting latitudinal differences in climate.
The three-cell model of global atmospheric circulation patterns is a conceptual model that helps to explain the large-scale wind patterns in the Earth's atmosphere. This model is based on the idea that the atmosphere can be divided into three large-scale circulation cells: the Hadley cell, the Ferrel cell, and the Polar cell. In the northern hemisphere, the Hadley cell is located near the equator, where warm, moist air rises and then cools and sinks at higher latitudes. This creates a low-pressure area near the equator and a high-pressure area near the poles. The trade winds, which blow toward the equator, are driven by this circulation pattern. The Ferrel cell is located in the middle latitudes, between the Hadley and Polar cells. In this cell, the atmosphere is characterized by a west-to-east flow of air, known as the westerlies. This flow is driven by the temperature difference between the poles and the equator, which creates a pressure gradient that forces air to move from west to east. The Polar cell is located in the high latitudes, near the poles. In this cell, cold, dry air sinks and flows towards the equator, creating the polar easterlies. The cold temperatures drive this circulation pattern at the poles, which causes the air to become denser and sink. The pattern is similar but inverted; the Hadley cell is located in the southern hemisphere, with the trade winds blowing towards the south pole and the westerlies blowing towards the east. These circulation patterns result in latitudinal differences in climate. The equatorial regions in the Hadley cell tend to be warm and humid, while the middle latitudes in the Ferrel cell tend to be mild and changeable. The polar regions in the Polar cell tend to be cold and dry. Overall, the three-cell model of global atmospheric circulation patterns is driven by the temperature differences between the poles and the equator, which are caused by the Earth's rotation and the distribution of solar energy. This creates large-scale wind patterns that result in latitudinal differences in climate.
Explain how the trade-off between water loss and evaporative cooling link an organism's water and heat budgets.
The trade-off between water loss and evaporative cooling is a crucial link between an organism's water and heat budgets. Evaporative cooling is a key mechanism for regulating body temperature in many organisms, including both endothermic (warm-blooded) and ectothermic (cold-blooded) species. When an organism sweats, the evaporation of the sweat from the surface of the skin cools the body, reducing the internal temperature and helping to regulate heat balance. However, this evaporative cooling comes at a cost. By losing water through sweating, the organism also loses a critical resource that it needs to maintain water balance and avoid dehydration. As a result, the trade-off between water loss and evaporative cooling requires an organism to carefully balance its water and heat budgets, conserving water while also regulating heat. In endothermic species, such as mammals, the ability to regulate body temperature through evaporative cooling is particularly important, as they need to maintain a relatively constant internal temperature to support their metabolic processes. For ectothermic species, such as reptiles, evaporative cooling is also important, as it helps to regulate body temperature and avoid overheating, especially in warm environments.
Describe how the type of biome found in an area varies with average temperature and precipitation
The type of biome found in an area is directly influenced by the average temperature and precipitation levels. Warmer climates, such as tropical regions, tend to have biomes characterized by dense vegetation, such as rainforests and jungles. These areas receive high levels of precipitation throughout the year. In contrast, colder climates, such as the Arctic, have biomes characterized by limited vegetation and low levels of precipitation, such as tundra. Temperate regions, which have a more moderate climate, can have a variety of biomes depending on the level of precipitation. For example, regions with higher levels of precipitation tend to have biomes such as temperate rainforests and deciduous forests, while regions with lower levels of precipitation tend to have biomes such as grasslands and chaparral.
Explain what Ton, Tpeak, and Toff mean.
Ton, Tpeak, and Toff refer to the specific timing characteristics of the response of Heat Shock Proteins to changes in temperature in the marine snail species of the Chlorostoma genus. Ton: the time it takes for Heat Shock Proteins expression to increase after a temperature increase, representing the snails' response to the thermal stress. Tpeak: the time at which the highest expression level of Heat Shock Proteins is reached, representing the snails' ability to cope with the thermal stress. Toff: the time it takes for Heat Shock Protein expression to decrease after a temperature decrease, representing the snails' recovery from the thermal stress.
Distinguish among Type I, II, and III survivorship curves
Type I, II, and III survivorship curves are graphical representations of the probability of survival for individuals in a population as they age. Type I survivorship curve: This type of curve describes a population with high survival rates at all ages. Examples of organisms with Type I survivorship curves are humans, whales, and elephants. Type II survivorship curve: This type of curve describes a population with a constant rate of mortality. Examples of organisms with Type II survivorship curves are birds, reptiles, and many fish species. Type III survivorship curve: This type of curve describes a population with high mortality rates early in life. Examples of organisms with Type III survivorship curves are insects, annual plants, and some species of fish and mammals.
Determine from a population's per capita growth rate whether the population is stable, shrinking, or growing.
r > 0 --> growing r < 0 --> shrinking r = 0 --> stable The first equation, b = births / t * Navg, calculates the number of births per capita over a given time period t. Navg represents the average population size during that time period. The second equation, d = deaths / t * Navg, calculates the number of deaths per capita over a given time period t. Navg represents the average population size during that time period. The third equation, (births - deaths) / t * Navg = r, calculates the net change in population size (births minus deaths) per capita over a given time period t. Navg represents the average population size during that time period and r is the growth rate (or net reproduction rate) of the population.
Define life cycle
the series of stages that a species goes through from birth to death. This can include the early developmental stages, growth, reproduction, aging, and eventual death. The life cycle of an organism can vary greatly between species and can also be influenced by environmental factors such as temperature, food availability, and predation pressure. Understanding the life cycle of a species is important in ecology because it provides insight into its reproductive potential, population dynamics, and the role it plays in the ecosystem. The life cycle of a species is also a key factor in determining its susceptibility to various threats and its ability to adapt to changing conditions. Human Life Cycle: 1. Eggs/Sperm 2. Juvenile phase 3. Adulthood 4. Reproduce & Repeat Turtle Life Cycle: 1. Gametes 2. Hatching and juvenile stage 3. Adulthood 4. Reproduce & Repeat Butterfly Life Cycle: 1. Egg/sperm 2. Larval (caterpillar) stage 3. Pupation (chrysalis) stage 4. Adult 5. Reproduce & Repeat Adult annual lifecycle of a migrating bird 1. reproduce 2. molt (shedding old feathers) 3. migrate 4. winter 5. molt (shedding old feathers) 6. migrate 7. Repeat