Ecology, Biology 216 Todd Livdahl Requirements
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Ecology, Biology 216 Requirements Essays (3) 20% Lab exercises 20% Quizzes (3) 30% Final Exam (comp) 20% Essays Lab Exercises Interpret ecological data Clarify relationship between field observations and central concepts Develop skills in computation and analysis Quizzes and Final 3 Quizzes, equal weight Full class in length Concept-driven Qualitative Substitution Final = 2 x (quiz) If Final/2 > (lowest quiz), then Final/2 will be substituted for the lowest quiz score Example: Quizzes-- 25 27 19 (out of 30) Final-- 44 (out of 60), 44/2 > 19 lowest quiz score (19) is replaced by (22) NO MAKEUP QUIZZES First Essay Due Jan. 28 Description of problem Justification as a problem Solution strategies possible or solution strategies attempted Problems arising from solutions 3-4 pages should suffice Borneo The Borneo Cat Crisis The Coconut Leaf-mining Beetle Crisis, Fiji 1850-1880 Early development, plantations 1880-1900 Intensive cultivation and shipping 1900-1920 Gradual increase in impact of beetle 1920 Outbreaks threaten Fiji economy Natural Coconut Community Intensive Cultivation: Container-breeding Mosquitoes Natural examples Treeholes Bromeliads Pitcher plants Bamboo stems Leaf axils Crab holes Snail shells Snow-melt pools Water-filled hoof prints Domestic examples (short list) Bird baths Cemetery urns Discarded junk Bottle caps to Bath tubs Downspouts, eave troughs Cisterns Trash barrels Tires Meetings of interest (from AMCA Newsletter): Aedes albopictus and the New Globalism Distribution: 1983: tropical and temperate Asia, Pacific Islands 1984, 1985: Memphis, Tennessee Houston, Texas-- the most abundant mosquito in a pile of used tires First discovery of Aedes albopictus in Western Hemisphere Aedes albopictus since 1985 Numerous US localities South America, esp. Brazil Central America, Mexico Europe (Italy, Albania) Caribbean Bermuda From countries in the range of albopictus From countries outside albopictus range Used Tires Imported (millions) Potential Habitats Potential Habitats Treehole Long-range Prospects for Invasion Depend on: Adaptations to physical challenges Success in dealing with native community Competition with native species Other interactions with native species (predation, hatch inhibition, parasitism) Origin from temperate Asia KEY ADAPTATION: Winter Diapause Difference (%H, Long - %H, Short days) Potential interactions with resident species North: Competition with treehole mosquitoes in treeholes and tires South: Competition with Aedes aegypti in open tire habitats Competition with treehole mosquitoes in forested tires and treeholes Predation Parasitism Topics, 2nd & 3rd Lecture 2nd Lecture Origins of Ecology Influence of Evolution Determining Inheritance 3rd Lecture Reasons to study Evolution Criteria for Natural Selection Forms of Selection A sample of calculations involved in predicting changes in allele frequencies. The initial frequency of the a allele (p) is 0.4. Genotype aa ab bb Total Number of zygotes 30 20 50 100 at time 0 Survival fraction 0.5 0.8 0.9 Number of adults 0.5x30 = 15 16 45 76 Number of successful 10 5 2 gametes per adult Number of 10x15=150 80 90 320 successful gametes produced Fitness 0.5x10/2=2.5 2.0 0.9 New allele p=(150+80/2)/320=0.59 q=0.41 frequencies Next fraction 0.592^2=0.35 2x0.59x0.41=0.48 0.402^2=0.17 1 of zygotes Number of 0.35*320/2=56.4 77.2 26.4 147.8 zygotes at time 1 Figure 1. Changes in the frequency of allele a through time. Selection in this case is against allele b. For both cases, Waa = 1 and Wbb=0.5. For curve 1, Wab=0.5; for curve 2, Wab=1. Selection against allele b Creating ecological islands Mainland Orange environment Population is all orange p = 0 Inheritance: aa: blue ab: orange bb: orange OR: aa: blue ab: blue bb: orange Dispersal from Mainland to Island: fixed fraction of individuals on island (I) have been born on the mainland Changes in the frequency of allele a through time for different fractions of immigrants to an island population. Selection in this case is against a dominant allele (b). I denotes the fraction of immigrant individuals arriving into the population with each generation. The initial frequency of the a allele in the island population is 0.2; mainland frequency=0. Fitness values are: Waa=1, Wab=0.5, Wbb=0.5. Changes in the frequency of allele a through time for different fractions of immigrants to an island population. Selection in this case is against a recessive allele (b). I denotes the fraction of immigrant individuals arriving into the population with each generation. The initial frequency of the a allele in the island population is 0.2; mainland frequency=0. Fitness values are: Waa=1, Wab=1, Wbb=0.5. Mainland Population is all winged p = 0 Island Low initial fraction wingless (aa) Some fraction of winged individuals disperse away from the island Inheritance: aa: wingless ab: winged bb: winged OR: aa: wingless ab: wingless bb: winged Genotypes have same fitness Dispersal from Mainland to Island: fixed fraction of individuals on island (I) have been born on the mainland (all winged, all bb) Chance deviations in frequency result in loss of genetic variation, especially in small populations Do this for many individuals Do this for many loci Heterozygosity: fraction heterozygous/locus Genetic Variation Finnish Spittlebugs Oropendula colony, Ecuador Number of nestling Oropendula in nests With Cowbirds Without Cowbirds With Bot-fly parasites 57 382 Without Bot-flies 619 42 Fledgling success of oropendulas in discriminator and nondiscriminator colonies relates to the presence or absence of cowbirds: Attributes of discriminator and nondiscriminator Oropendula colonies Nonevolutionary Responses to Environmental Change Organisms can change to perform better in different conditions, without a change in population genetic makeup Time scales, mechanisms, flexibility Regulatory Physiological/behavioral <<1 generation Reversible Acclimatory Physiological/behavioral <1 generation Reversible Developmental Developmental/behavioral ~1 generation Irreversible Evolutionary Genetic/ecological >1 generation Reversible Regulatory Responses No morphological change required, involves physiology or behavior Modified activity to maintain favorable body conditions Examples: Sweating, panting, shivering, altered kidney filtration, altered heart rate, drinking, basking Objective: homeostasis-- buffer the internal environment of an individual, or to modify the immediate external environment. Acclimatory Responses Change in physiology, behavior, or morphology, in response to environmental changes, especially seasonal changes Examples: Fur growth Color change Foliage loss Flowering Mating coloration Antler growth Mating rituals Feeding patterns Responses to environmental cues (e.g. change in day length) Developmental Responses (Phenotypic Plasticity) Differences in body form or behavior depending on environmental conditions Induced defenses and cyclomorphosis Nonevolutionary responses are not adaptations, but they are adaptive Response itself is done without genetic change, but the ABILITY to make the response has very likely evolved through adaptation (i.e. natural selection) Survival and Reproduction Establishment and Maintenance of population Distributions Summarize the locations where a species has been successful Do not tell us about locations where they could be successful Do not tell us about places where a species has failed Understanding distributions relies on knowing what factors prevent species from occupying a particular location or region Ranges Geographic-- set of places actually occupied Ecological-- set of places with suitable conditions Ecological > Geographic Reasons why involve most topics of interest to ecologists Explaining an Absence Species does not occur because: It can’t reach it It doesn’t choose to (habitat selection) Physical or chemical conditions not favorable Other organisms in the area prevent establishment (competition, predation, parasitism) or a key species (food, mutualist) is missing Chance Success: transplanted populations grow Reject: physical/chemical factors Reject: species interactions Support: dispersal barrier Failure: transplanted populations dwindle Reject: dispersal barrier Consistent with species interactions or physical/ chemical factors Problem: ethical considerations of transplantation Solutions: Compare occupied and unoccupied environments What major factors differ? --> hypotheses Duplicate differences in laboratory setting “Transplant” occurs in lab; hypotheses tested limitation: lab setting Conduct transplants in field under highly controlled conditions Catch species in the act of invasion Lessons from Invasions and Introductions 1>1> Failed introductions: Fish stocking Seeds in wool
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