Ecology Study Guide for Exam Part 2

Ecology Exam 1 Evolution, Plant & Animal Adaptations Vocabulary Primary Producer: Green plant or chemosynthetic bacterium that converts light or chemical energy into organismal tissue. ! Secondary Producer: Organisms that derive energy from consuming plant or animal tissue and breaking down assimilated carbon compounds. Natural Selection: Differential success (reproductive and survival) of individuals that results in elimination of maladaptive traits from a population. It is the product of two conditions: 1.) Variation occurs among individuals within a population in some heritable characteristic 2.) This variation results in differences among individuals in their survival and reproduction as a result of their interaction with the environment. Fitness: Genetic contribution by an individualÕs descendants to future generations. Darwin wrote, ÒAmong individuals that do reproduce, some will leave more offspring than others. These individuals are considered more fit than the others because they contributed the most to the next generation. Organisms that leave few or no offspring contribute little or nothing to the succeeding generations and are considered less fit.Ó Adaptation: A genetically determined characteristic (behavioral, morphological, physiological) that improves an organismÕs ability to survive and reproduce under prevailing environmental conditions. Evolution: The process of natural selection results in changes in the properties of a population or organisms over the course of generations; this occurs in accordance with fitness - the most fit organisms contribute more offspring which raises the number of organisms with those adaptations. Photosynthesis: Use of light energy by plants to convert carbon dioxide and water into simple sugars. Rubisco: Enzyme in photosynthesis that catalyzes the initial transformation of CO2 into sugar. PEP: Enzyme that catalyzes the fixation of CO2 into four-carbon acids, malate, and aspartate. Net Photosynthesis: Difference between the rate of carbon uptake in photosynthesis and carbon loss in respiration. ! Respiration: Harvesting of energy from the chemical breakdown of simple sugars and other carbohydrates; the oxidation of carbohydrates to generate energy in the form of ATP that takes places exclusively in mitochondria. Light Compensation Point: Depth of water or level of light at which photosynthesis and respiration balance one another. Transpiration: Loss of water vapor fro ma plant to the outside atmosphere. Water Use Efficiency: Ratio of net primary production to transpiration of water by a plant. C3 Plant: Any plant that produces as its first step in photosynthesis the three-carbon compound phosphoglyceric acid. C4 Photosynthetic Pathway: Photosynthetic pathway involving two distinct types of photosynthetic cells: the mesophyll cells and the bundle sheath cells. CO2 initially reacts with PEP to form 4-carbon compounds in the mesophyll cells. These compounds are then transported into the bundle sheath cells where they are converted into CO2 and undergo the C3 photosynthetic pathway (Calvin Cycle). CAM Pathway: Photosynthetic pathway (using the same processes in the C4 pathway) that separates the processes of carbon dioxide uptake and fixation when growing under arid conditions. It takes up gaseous carbon dioxide at night, when the stomata are open, and converts it into simple sugars during the day, when stomata are closed. Stomata: Pores in the leaf or stem of a plant that allow gas exchange between internal tissues and the atmosphere. Acclimation: Reversible phenotypic changes in an individual organism in response to changing environmental conditions Ñ a form of phenotypic plasticity and is a common response in plant and animals involving adjustments relating to biochemical, physiological, morphological and behavioral traits. Seasonal changes in the water on FloridaÕs Gulf Coast results in shifts in enzyme and membrane structure which allows the stingrayÕs physiology to adjust slowly over a period of time influencing heart rate, metabolic rate, neural activity and enzyme reaction rates. Phenotypic Plasticity: Ability to change form under certain environmental conditions resulting in an improvement of individualÕs ability to survive, grow and reproduce under prevailing environmental conditions. These changes are reversible. Trade-Offs: An inescapable compromise between one trait and another that are either incompatible or an increase in one trait might lead to a decrease in another; a negative association between two or more traits (negative association meaning that if one traitÕs presence ! is at the expense of another trait); a special type of constraint which involves links between two or more traits and their cost-benefits considerations. Scaling: Process by which most morphological and physiological features change as a function of body size in a predictable way. Herbivores: Organism that feeds on plants tissue. Carnivores: Organism that feeds on animal tissue. Omnivores: Organism (heterotroph) that feeds on both plant and animal tissue. Detritivores: Organism that feeds on dead organic matter; usually applies to detritus-feeding organisms other than bacteria and fungi. Detritus: Fresh to partly decomposed plant and animal matter. Homeostasis: Maintenance of a nearly constant internal environment in the midst of a varying external environment; more generally, the tendency of a biological system to maintain itself in a state of stable equilibrium. Positive Feedback: Control of a system that reinforces a process to continue in the same direction. Negative Feedback: When a system deviates from the normal or desired state (known as the set point), mechanisms function to restore the system to that state. Three Components: Receptor: Measures the internal environment for the variable and transfers the information to the integrator. Integrator: Evaluates the information from the receptor, comparing it to the set point, and determines whether action must be taken by the effector. Effector: Modifies the internal environment in reference to the monitored variable. Endotherms: Organism which is capable of the regulation of body temperature by internal heat production; allows maintenance of appreciable difference between body temperature and external temperature; warm-blooded. Homeotherms: Animal with a fairly constant body temperature. Ectothermy: Determination of body temperature primarily by external thermal conditions. Poikilotherms: Organism whose body temperature varies with the temperature of its surroundings. ! Torpor: Temporary great reduction in an animalÕs respiration, with loss of motion and feeling; reduces energy expenditure in response to some unfavorable environmental condition, such as heat or cold. Hibernation: Winter dormancy in animals, characterized by a great decrease in metabolism. Biological Clock: An innate mechanism that controls the physiological activities of an organism that change on a daily, seasonal, yearly, or other regular cycle. Circadian Rhythm: A cycle that tells our bodies when to sleep, rise, eat Ñ regulation of many physiological processes; affected by environmental cues, like sunlight and temperature. Learning Objectives/Important Ideas All organisms must solve three basic functions: ! Assimilation: Acquire energy and matter from the environment to synthesize new tissue. Reproduction: Survive long enough and allocate resources to produce new life. Respond to External Stimuli: Deal with heat, humidity, salinity or avoid predators. What lets organisms succeed in a given habitat/environment? Their physiology, morphology, behavior, and life history which reflects adaptations to the environment that enable survival, growth and reproduction. Each habitat presents a unique set of constraints due to different combinations of resources and conditions. Identify the assumptions of evolution by natural selection 5 Key Assumptions 1.) Variation: Organisms within a population exhibit individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand some traits show little to no variation among individuals such as number of eyes on a vertebrate. 2.) Heritability: The variation in the trait is heritable and passed from the parent to the offspring. 3.) Growth Potential: Most populations have more offspring each year than local resources can support leading to a struggle for resources. Each generation experiences substantial mortality. 4.) Differential Success: (Differential survival and reproduction) Individuals possessing traits well suited for the struggle for local resources will contribute more offspring to the next generation than those who donÕt. 5.) Environment: Fitness depends on interaction between traits and the environment; adaptations enable an organism to function in the prevailing environment as well as limiting them from functioning in other environments. ! Explain why trade-offs are essential to understanding ecological and evolutionary processes There is no ÒSuper-PhenotypeÓ existing for any organism; you simply canÕt have it all. The same organisms maybe living in different locations/environments which cause natural selection to select for different traits or promote one trait over another in each environment, only the most helpful adaptation to that organismÕs survival in that environment can be developed over time. DarwinÕs finches show a trade-off between morphology and diet. The bill size in the finch is associated with the size of seed it can eat. A larger bill allows them to eat small and large seeds but requires a change in overall morphology in the finch. Provide an example of a plant based adaptive trade-off In terrestrial plants, in order to carry out photosynthesis the plant must open the stomata to take up CO2. When the stomata are open, the plant loses water. The loss of water must be replaced by the uptake of water by the roots. If the roots have limited access to water, the plant must find a way to balance the opening and closing of the stomata in order to minimize water loss through transpiration. Contrast the adaptive significance of the C3, C4, and CAM photosynthetic pathways -Each pathway is optimized to distinct environmental conditions resulting in differences in their growth and distribution. Photorespiration: The result of the enzyme Rubisco oxygenating the molecule RuBP which causes the loss of some energy produced by the photosynthesis cycle and the rate is increased in warm, arid/dry environments. -C3 pathway allows photorespiration to occur which results in 25% reduction in efficiency. The C3 pathway also has a lower water use efficiency. -Most plants utilize this pathway/environmentally widespread. -Abundant in cool, wet, temperate environments -Works in low-light, cool areas -C4 pathway minimizes photorespiration spatially by separating the processes of initial CO2 fixation and the C3 cycle into two different different cell types. This pathway is more Carbon efficient and has medium water use efficiency. -Most productive in high-light, warm and wet climates (tropic/subtropic) -Perform well in saline and dry environments -Higher Nitrogen efficiency which allows them to flourish in low-nutrient environments -CAM pathway minimizes photorespiration temporally by separating the processes of initial CO2 fixation and the C3 cycle between night and day, respectively while the processes occur in the same cells like in C3. This pathway is more Carbon efficient and has the ! -Highest water use efficiency/highest transpiration efficiency of the three paths -Found in arid/dry, desert, hot environments -Low photosynthetic capacity, slow growth, low competitive abilities (limited by need for vacuolar storage and greater ATP cost) -Many CAM plants can switch to a C3 mode with their stomata open during the day when water is available, thus increasing photosynthetic capacity and growth Reduced photorespiration in C4 and CAM is advantageous in areas that photorespiration is typically high such as areas with low CO2 concentrations (causing lower rates of stomata opening resulting in decrease in transpiration) and/or high temperatures. Describe above ground - below ground tissue trade-off Allocating carbon to the production of leaves and stems increases the plantÕs access to the resources of light and CO2 but is at the expense of allocating carbon to the production of roots. Allocating carbon to the production of roots increases access to water and soil nutrients but limits carbon allocation to the production of leaves. Decrease in the amount of water available results in higher allocation of carbon / growth in the roots enabling them to explore a larger volume and depth of soil for extracting water which also means a decrease in the production of leaves, reducing the amount of light interception and leaf area and reduction of leaf area means less stomata which means less transpiration and higher retention of water within the plant. Decrease in nutrient availability results in higher allocation of carbon to root growth at the expense of shoot growth as well as decreased allocation of carbon to leaf growth and decreased photosynthesis inevitably leading to reduction in the growth rate. Explain key adaptive differences between terrestrial and aquatic plants Lack of stomata in submerged aquatic plants means the plant does not get CO2 from the atmosphere, instead the CO2 is diffused directly across the cell membrane. Some aquatic species can also use bicarbonate as a carbon source but have to convert it to carbon dioxide first. The CO2 in the atmosphere diffuses into the water and reacts with the water to form Bicarbonate. The Bicarbonate and CO2/H+ have a dynamic equilibrium which means that in the absence of CO2, Bicarbonate will dissociate and the equation will shift to make it equal again. Identify key processes common to all animals -Acquisition and digestion of food -Absorption of oxygen -Maintenance of body temperature -Maintenance of water balance -Adaptation to systemic variations in light and temperature (Eat, breathe, No Fever/Freeze, Hydrate or DIE-drate, homeostasis in changing places) ! Explain why scaling is a fundamental constraint on the evolution of organisms The relationship between surface area an volume tells us that smaller bodies have a larger surface area relative to their volume and larger bodies have a smaller surface area relative to their volume. This presents issues with physiologic processes of metabolism due to its need for materials and energy to transfer between the organismÕs interior and exterior environments. Adaptations function to increase the surface area and enable adequate exchange of energy and materials between inner cells and the external environment including altering the shape by creating more complex form can allow objects with the same volume to have different surface areas. Explain why positive and negative feedbacks are core concepts in ecology and provide and example of each Negative Feedback Loop: Homeostasis (maintaining the internal environment factors such as temperature, water, pH, salinity) is regulated by a negative feedback in organisms which is essential to their existence. Example: Thermostat in the house. If it is set to a desired specific temperature and the house falls below this temperature, it is prompted to turn on the heat. When the desired temperature is reached again, the thermostat shuts off. If it didnÕt shut off it would overheat the house either causing a fire or mechanical shut down. Positive Feedback Loop: Encourages the continuation of an initial stimulus/change due to the change the stimulus has caused. Will go on until a negative feedback is triggered. Plays a role in blood clotting and coagulation as well as breast milk production. Example: Exponential population growth. When there is a surplus of resources available or lack of predators in an environment, this allows a plant or animal population to grow without limit. The increase in population leads to an increase in births and more births leads to an increase in population which starts the cycle over again creating an intensified effect compared to when the whole thing started. *Negative feedback resists change; Positive feedback promotes change. Two categories of how animals respond to variations in the external environment: Conformer: Change in the environmental conditions induce internal changes in the body that parallel the external conditions. Such animals are unable to maintain consistent internal conditions such as body temperature, fluid salinity, or levels of tissue oxygen. Their chance of survival depends greatly on the degree of tolerance of their body tissues to the internal changes brought upon them by the external environment. -Low energy cost but results in reduced activity, growth and reproduction Regulator: Use a variety of biochemical, physiological, morphological, and behavioral mechanisms to regulate their internal environments over a broad range of external environmental conditions. Behavioral is usually the initial response. -High energy cost but results in higher level of performance and a greater range of environmental conditions over which activity can be maintained. " ! Population Properties Vocabulary Population Properties: How we characterize a biological population. -Structure: Abundance, density -Distribution: Geographic range, dispersion -Age distribution -Sex ratio -Dynamics: A pattern of continuous change through time that results from birth, death, and movement of individuals. Questions to consider when looking at population properties: 1.) How do we empirically measure or estimate the value of the property? That is, is there a pattern? 2.) What ecological factors (physical, chemical, biological) influence or determine the property? That is, what causes the pattern? 3.) What are the ecological consequences of specific property values? That is, how does the pattern matter? Ecological Population: A group of individuals of the same species living in a given area at a given time. (Statistical/general: All members of a group under investigation) Abundance: The number of individuals of a species in a given area. Population Density: The number of individuals in a population per unit area. Affected by how individuals are distributed within a population. (See Distribution) Unitary Organism: An organism, such as an arthropod or vertebrate, whose growth to adult form follows a determinate pathway, unlike modular organisms whose growth involves indeterminate repetition of units of structure. -Distinct individuals, a genetic unit. -Examples include humans, dogs, cats, red maple trees Modular Organism: Organism that grows by repeated iteration of parts, such as branches or shoots of a plant; some parts may separate and become physically and physiologically independent. -The organism grows into genetically identical modules that may or may not be physically connected. -Examples include most plants, aspen trees, shoal grass, coral, sea sponges Genet: A genetic individual that arises from a single fertilized egg. -Individual arising from sexual reproduction. Ramet: An individual member of a plant clone. -Modules arising from asexual reproduction. ! Statistical Population: Set of objects about which inferences can be drawn. Sample: That part of a population that is selected for observation by an investigator (a subset of the total population). Multiple samples allows the description of observations and characterization of populations. What issues to consider when sampling: -What sampling method to use -How to select sampling locations -How to maximize accuracy while minimizing cost (number of samples, time, effort) Sampling Sedentary Organisms: Used when characterizing the population density or population variation or dispersion. Plot Based Sampling: Using either a quadrat or belt transect to divide the area evenly and then counting the individuals in that area. Plot-less Sampling: Using string to identify the organisms that will be counted or defining an area and splitting it up into four squares then the individual closest to the point in each quadrant is identified and counted. (Usually faster/use less equipment) Mark-Recapture: Most common technique in estimating animal population size/density. Based on trapping, marking and releasing a known number of marked individuals into the population. After giving the marked individuals an appropriate period of time to mix with the rest of the population, some individuals are recaptured from the population and counted as either recaptured individuals or not. Assumptions: -Sampling is random and each individual has an equal probability of being captured ! -Marked individuals distribute themselves randomly back into the population -Ratio of marked and unmarked individuals must not change between sampling periods that is, marked individuals do not die or emigrate -Marks are not lost -During sampling emigration and births are equal to immigration and birth rates in the unmarked population Application of the following formula will give the population size estimate: N1 = M1n2 / M12 N1 = Original Population Size M1 = Number of marked individuals released into the population n2 = Number of individuals taken in the second sample M12 = Number of individuals in the second sample that were marked Simple Random Sample: Each individual has an equal chance of being selected from the population such as drawing names from a hat. Stratified Random Sample: The population is divided into separate groups called strata then a simple random sample is drawn from each group. ! Systematic Sample: Sampling data at chosen fixed intervals within the population which provides a random sample but does not afford all individuals equal chance of selection. Quadrat: Each of number of small areas of habitat, typically one square meter, selected at random to act as samples for assessing the local distribution of plants and animals. Distribution: The spatial location or area occupied by a population; based on presence and absence of individuals. The spatial boundary within which all individuals in a population reside. How individuals are distributed within a population - in other words, their spatial positioning relative to one another - has an important bearing on density. With regard to density, it is measured by dividing the population into equal parts and calculating how many individuals out of the total population live in that area. These numbers can be skewed due to random and clumped distribution and whereas uniform distribution can give accurate data. Distributions are categorized as follows: Random Distribution: If each individualÕs position is independent of the position of others. Example: Plants with wind-dispersed seeds such as dandelions. ! Uniform Distribution: Individuals are more or less evenly spaced resulting from some form of negative interaction among the individuals, such as competition, which functions to maintain some minimum distance among members of the population. Common in animal populations where they defend an area for their own personal use (being territorial) and common in plant populations where severe competition for below ground resources exists. Example: Plants which inhibit growth of nearby individuals. ! Clumped Distribution: (Most Common) Individuals occur in groups resulting from a variety of factors such as suitable habitats or other resources only being available in distinct patches over the larger landscape; species which form social groups like schools of fish or flocks of birds; asexual reproducing plants form clumps; humans form clumps due to social behavior, geography, economics, urban development. Example: Elephants which travel in groups. ! Geographic Range: The distribution described by all the individuals of a species encompassed in a defined area. How does the geographic range relate to the niche: Influenced by numerous factors such as the range of abiotic environmental and resource conditions under which a species can survive, grow and reproduce and geographic barriers such as the ocean, mountains; anything that restricts the dispersal/spread of the organism. Habitat Suitability: occurrence of a suitable environmental and resource conditions. Ubiquitous: A species with a widespread geographic distribution. Endemic: A species with a distribution that is restricted to a particular locality or localized habitat which usually have specialized habitat requirements. Spatial Scales: Show distribution of a population at different from its global geographic range which shows every individual in a species, to the location of an individual population of the species. Worldwide > Continental > Regional > Physiographic Area > Cluster > Locality > Colonies > Clump of Individuals Spatial/Environmental Heterogeneity: Refers to the uneven distribution of various concentrations of each species within an area. Subpopulation: Result of environmental heterogeneity; most populations are divided into subpopulations each occupying suitable habitat patches of various sizes and shapes within the larger landscape of the parts of the area which is an unsuitable habitat. Metapopulation: A population broken into sets of subpopulations held together by dispersal or movements of individuals among them. The collective of local subpopulations. Although spatially separated, these local populations are connected through the movement of individuals among them. Dispersal: Leaving an area of birth or activity for another area. Emigration: When individuals move out of a subpopulation. Immigration: When an individual moves from another location into a subpopulation. Migration: Intentional, directional, usually seasonal movement of animals between two regions or habitats; involves departure and return of the same individual; a round-trip movement. ! Invasive Species: Nonnative/nonindigenous plants and animals which have been introduced to places they have never occurred or that are considered outside of their geographic range and are able to flourish in their new environments due to being freed from the constraints of their native competitors, predators, and parasites allowing them to establish themselves and spread. Introduction can be harmless or can negatively affect native plant and animal species and the ecosystem. -Within recent centuries, dispersal by humans has become a new source of long-distance dispersal leading to the redistribution of species at a global scale. Learning Objectives Distinguish between unitary and modular organisms Unitary organisms are genetically distinct units arising from sexual reproduction which makes them Genets. Modular organisms are cloned modules of the organism arising from asexual reproduction which makes them Ramets. Use common properties of populations to describe their state (condition) Devise sampling protocols to estimate the abundance of organisms Plot based, non plot based random sampling or Mark-Recapture sampling. Explain the consequences of population structure (spatial, age, sex, etc) Larger spatial environments allow for larger population growth Populations with younger individuals will grow more rapidly Smaller generation time results in increased population growth Fewer females slows the rate of population growth Describe possible effects of invasive species Negative Effects: New predator introduced into the environment Larger competition for resources May exploit a resource which the native species cannot use Destruction of the new habitat Large cause of species extinction Positive Effects: New food source introduced into the environment Could enhance the environment for the native organisms Could become a predator of an organism that harms the environment " !