Population Ecology and Ch. 40
Population Ecology and Ch. 40 012
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This 7 page Class Notes was uploaded by Amanda Notetaker on Saturday April 9, 2016. The Class Notes belongs to 012 at University of Vermont taught by Dr. Hill in Fall 2016. Since its upload, it has received 25 views. For similar materials see Exploring Biology in Biomedical Engineering at University of Vermont.
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Date Created: 04/09/16
Population Ecology Ecology: The study of… - Ernest Haeckel (1869) came up with the word “ecology” o Oikos – house/home; “study of the household” - Vick’s definition: Economics of nature - Textbook: study of the relationships of organisms to their environment and one another The Economics of Nature: - Based on distribution/abundance of organisms o Individual organisms o Populations of organisms o Communities of organisms Ecology vs. Evolution Ecologists & Evolutionary Ecologists: look to understand/explain processes that determine the distribution, diversity, and abundance of organisms Ecologists: Evolutionary Ecologists: Look for proximate answers for diversity, Look for ultimate answers for diversity, distribution, and abundance of organisms distribution, and abundance of organisms Ex: Why did the chicken cross the road? A: To get away from a predator, find food, A: migration pattern of the chicken went or find a mate across the road, appendages carry it across the road, inclination to cross roads Ex: Colorado Potato Beetle is a pest in America (lg. population), not Mexico (sm. population) Proximate Causes: Ultimate Causes: - Pest Status: based on food - Pest Status: evolved to process availability, predation potatoes or endure cold conditions - Population Size: large amt of food - Population Size: evolved to live in increases population; potatoes less regions where natural enemies defended cannot survive Ecology: Changes in numbers of individuals or populations in ecosystems over a few Evolution: (Macroevolution) generations Changes in traits in populations - Scope: Populations or individuals over many generations within habitats - Scope: Traits within populations - Timescale: Days/Years - Timescale: Larger time frames Ecology Evolution Evolutionary change changes in ecology evolves abilities to survive differently Invasive Species: dispersal limitation Factors limiting Geographic Distribution - Dispersal - Behavior (Habitat selection) - Biotic factors (Other species, predation, competition, disease) - Abiotic factors (Chemical/physical) Density: number of individuals per unit area or volume - Often impractical/impossible to count all individuals in a population - Sampling techniques used to estimate densities/total population size MarkRecapture Method: scientists capture, tag, and release random sample of individuals (m) in a population - Marked individuals are given time to mix back into the population - Scientists capture second sample of individuals (n) and note how many of them are marked (x) - Population size (N) is estimated by: N = mn / x because m / N = x / n - Ex: Scientist marked 180 dolphins and waited a few days to mix them. He observed 44 dolphins the second time, 7 of which were marked. m = 180 So N = (180) (44) / 7 = 1131 n = 44 x = 7 Density is the results of interplay between processes that add individuals to a population and those that remove individuals Immigration: influx of new individuals from other areas Emigration: movement of individuals out of a population Dispersion: pattern of spacing among individuals within the boundaries of a population (clumped, uniform, random) Exponential Growth: (growth without limits) N: Population size d N d T r N R: Intrinsic rate of natural increase (= birth rate – death rate) dN/dT: Rate of change in population size Logistic Growth: (growth with limited resources) dN (K−N) =rN K: Carrying capacity dt K CH. 40 Behavior Behavior: Response to a stimulus Environmental Change Stimulus - Adjustments of behavior are often the most visible responses to environmental change - Ex: Many migratory animals change timing of migrations in response to climate change 40.1: Behavior is Controlled by the Nervous System but is Not Necessarily Deterministic An animal’s nervous system activates/coordinates behaviors: - Fixed Action Patterns: highly stereotyped animal behaviors that are expressed without prior learning; often resistant to modification by learning o Ex: begging behavior of gull chicks peck at red dot on bills; spiders’ web spinning - Ex: The ultimate cause of what the male threespined stickleback attacks other males entering his nesting territory is to increase their reproductive ability - Behaviors evolve: Natural selection favors the alleles that produce more adaptive behaviors than others o Many studies show that genes exert important effects on behavior o Ex: In Drosophila mutants for gene per altered circadian rhythms o - Biological Determinism: behaviors of animals are hardwired by genetics; individual’s genes change neural properties in fixed ways that affect behavior o Behavior is more flexible than any other biological trait b/c learning modifies behavior o Epigenetic effects on behavior lifelong influences; can be transmitted to next generation o Ex: Clams are inflexible in many of their responses to their environment 40.2: Behavior is Influenced by Development and Learning Learning: ability of individual to modify its behaviors as a consequence of individual experiences - Ex: Experiments with mice show that they learn layout/hiding places of their environment, learning that helps them escape predation by screech owls. - Learning is taught through patterns of recognition, whereas fixed action pattern is not Behavioral Imprinting: type of learning that is taught; takes place within a narrow window of time early in postnatal life and after is inflexible - Can have lifelong consequences - Examples o Geese imprint on their true parents and species to establish a strong attraction; o Speciesspecific songs of Darwin’s finches used to attract females; o Hungry adult offspring of “lowcaring” mothers wait longer than those of “high caring” mothers to go to food and spend less time eating food - Key regulatory genes in stressresponse biochemical/hormonal pathways are tagged with epigenetic marks early on in life permanently altering their stress responses - Malnutrition/abandonment early on in life affects epigenetic tagging in rats 40.3: Behavior is Integrated with the Rest of Function - Pronghorn have the highest sustained speeds in running animals o Can deliver O2 to muscles at high rates o Use O2 at high rates to make ATP in muscle cells o Use ATP at high rates to perform intense muscular work o Exceptionally large lungs/skeletal muscles, and muscle cells are tightly packed with mitochondria - Escape behavior is dependent upon ATP synthesis o Aerobic ATP is slow and resists fatigue o Anaerobic ATP is fast but subject to fast fatigue o Ex: Toads evolved enzymes for aerobic ATP production in legs whereas frogs evolved them for anaerobic ATP production, and therefore, leap away faster - Behaviors are dependent upon body size/growth o Ex: Tonal frequencies of insects’ songs vary based on body size; larger body low frequency song o Some species must grow to adult size before developing reproductive behaviors 40.4: Moving through Space Presents Distinctive Challenges Navigation: act of moving toward a destination or along a course - Trail following o Pheromone: chemical compound/mix of compounds emitted into outside environment by individuals of a species and elicits behavioral responses from other members of same species o Can use pheromones to attract members of opposite sex - Path Integration o Monitors length/compass direction of each segment and integrates the information about segment lengths/directions to determine where it is relative to its nest Orientation: adopting a position or path of locomotion relative to an environmental cue such as the sun - Sun Compass: determine where N, S, E, W are by observing sun o Ex: Pigeons observe position of the sun and also know the time of day to calculate direction using circadian clock; on cloudy days they detect Earth’s magnetic field to orient to - Many insects determine compass direction by detecting patterns of polarized light in sky o Depends on photoreceptors - Honey bee workers’ “Waggle Dance” o When worker bee finds flowers it returns to hive to communicate the path using the dance based on measurements taken of distance and direction to the flowers o Measures distance by monitoring rate flying past landmarks o Measures direction by monitoring the angle of flight relative to the compass position of the sun o If cloudy, they use atmospheric polarization patterns to determine position of sun - Migration: move periodically from one location to another to remain for a substantial period of time and later return from o Ex: Sea turtles use Earth’s magnetic field to orient themselves 40.5: Social Behavior is Widespread Society: group of individuals of a single species organized to some degree in a cooperative manner Social Behavior: behaviors of individuals that integrate them into societies and the group behaviors of entire societies - Disadvantages o Grouping makes animals more visible o diseases spread more rapidly o resources are depleted more rapidly - Advantages of Equal Status o Enhanced awareness of environment (Ex: Goshawk’s success in capturing pigeons decreases as number of pigeons in flock increase) o Discover preferred environments more efficiently - Advantages of Differing Statuses o Dominates: “wins” oneonone behavioral contests with others; has greatest chance of mating with adult females in group o Reasons above o Process of becoming dominant serves as a test of male’s strength, endurance, properties for success therefore females that mate with it ensure that their offspring are genetically well developed - Eusociality: social structure in which some members of social group are non reproductive and assist reproduction of fertile members of group, usually mother o Mostly in insects o Exemplify Altruism: any characteristic of an individual that imposes a cost on that individual while aiding another 40.6: Behavior Helps Structure Ecological Communities and Processes - Behavior helps maintain species - Behaviorally partition space into territories o Territory: region occupied by an individual that actively keeps others of same species out o Home Range: other individuals aren’t excluded o Provide familiarity (escape route, resources, etc) CostBenefit Approach: Assumes an animal has only a limited amount of time/energy and therefore cannot afford to engage in behaviors that cost more to perform than they bring benefits
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