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Ecology, Biology 216 Todd Livdahl Requirements • • • • Essays (3) Lab exercises Quizzes (3) Final Exam (comp) 20% 20% 30% 20% Essays 1. Practical ecological problem 2. Population study 3. Species interaction (2 spp or more) 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 Mosquitoes Malaria Wasps Caterpillars Roof Thatching The Borneo Cat Crisis Housefly control Cats Geckos Houseflies Rats 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 Mite 4 Mite 3 Mite 2 Ants Beetle: Mite 1 Egg Ants Larva Lizards Pupa Coconut Adult Birds Intensive Cultivation: Mite 5 Mite 4 Mite 3 Mite 2 Ants Beetle: Mite 1 Egg Ants Larva Lizards Pupa Coconut Adult Birds Container-breeding Mosquitoes Adults Pupae Eggs Larvae Container habitat Container Habitats 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 Used Tires Imported (millions) 3 From countries in the range of albopictus From countries outside albopictus range 2 1 0 1970 1975 1980 Year Used Tire Importation 1985 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) Difference (%H, Long - %H, Short days) 100 U.S. Beijing Asian 80 Korea Tokyo Kyoto 60 Nagasaki Shanghai 40 20 0 0 10 20 30 40 50 Latitude Origin from temperate Asia KEY ADAPTATION: Winter Diapause 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 Forest type (% recapt) Polluted Unpolluted Dark 34.1 6.3 Light 16.0 12.5 Genes, Alleles, and Allele Frequencies Chromosome pair Locus: location on chromosome that influences a particular trait Locus Alleles: variations of genes that occur at a particular locus Type a Genotype ab Type b Chromosome pair with 2 alleles at a single locus: a Heterozygote for that locus Type a Genotype aa Type a Chromosome pair with the same allele on both chromosomes at the locus: a Homozygote Type b Genotype bb Type b Chromosome pair with the same allele on both chromosomes at the locus: a Homozygote Allele Frequency: the fraction of all genes at a locus that are of a particular type Genotype allele aa ab bb Number 10 5 35 Number of a allele Number of b 20 0 5 5 0 70 Totals: 25 75 Frequency of the a allele = p = 25 25+75 = 0.25 Frequency of the b allele = q = 75 25+75 = 0.75 = 1-p Our experimental population: Basic Life cycle Eggs Juveniles Hatch Mortality Pool of Gametes Uniting at random Life Cycle with Genetic Variation: aa E A Juv. ab bb Pool of Gametes Uniting at random Adults Gamete production aa E A Juv. ab bb Pool of Gametes Uniting at random Rules for joining gametes: 1. Randomness. Gametes fuse with other gametes without regard to genotype. 2. Many, many gametes. These rules permit us to calculate the number of eggs for each new generation for each genotype: Male gametes p Allele a Allele b q Allele a p 2 p pq Allele b q pq 2 q Female Gametes 2 Fractions of eggs produced = p (aa) 2pq (ab) and q (bb) 2 aa E A Juv. ab bb Pool of Gametes Uniting at random Survival: For each Genotype, The number of adults produced Reproduction: For each Genotype, = Number of eggs Genotype X survival fraction The number Number of successful = of adults gametes Fitness: Fraction Surviving x #Offspring for each genotype Genotype X fertility rate A sample of calculations involved in predicting changes in allele frequencies. The initial frequency of the Genotype aa ab bb Total Number of zygotes at time 0 30 20 50 100 Survival fraction 0.5 0.8 0.9 Number of adults 0.5x30 = 15 16 45 Number of successful gametes per adult 10 5 2 Number of successful gametes produced 10x15=150 80 90 2.0 0.9 Fitness 0.5x10/2=2.5 76 320 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 of zygotes Number of 0.35*320/2=56.4 zygotes at time 1 77.2 26.4 1 147.8 a allele (p) is 0.4. Selection against allele b 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. Creating ecological islands Warwickshire, England Costa Rica U.S. 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 Island Blue environment Blue individuals (initially rare) survive at higher rate 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 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) Island Low initial fraction wingless (aa) Some fraction of winged individuals disperse away from the island Low I High I Low I High I Genetic Drift N=10 N=20 N=20 N=100 Drift Chance deviations in frequency result in loss of genetic variation, especially in small populations N=1000 Measuring Genetic Variation Gel electrophoresis Alleles: 1 2 Pgm 3 Genotypes: Etc… Do this for many individuals Heterozygotes Do this for many loci Heterozygosity: fraction heterozygous/locus 12 22 23 24 12 Genetic Variation 18 16 Heterozygosity 14 Finnish Spittlebugs 12 10 8 6 4 2 0 0 5 10 15 20 Distance Index 18 16 Heterozygosity 14 12 10 8 6 4 2 0 0 5000 10000 15000 20000 Population Size 25000 30000 35000 Oropendula colony, Ecuador Oropendula Giant Cowbird Oropendula egg mimetic non-mimetic Cowbird eggs 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: Fledgling success (fraction of Oropendula leaving nest) Oropendula Cowbird Discriminator Nondiscriminator 2 0 0.53 0.19 3 0 0.55 0.19 2 1 0.28 0.53 2 2 0.20 0.43 Discriminators do best without cowbirds Nondiscriminators do best with cowbirds Attributes of discriminator and nondiscriminator Oropendula colonies Discriminator Nondiscriminator Wasp nests Present Absent Bot flies Slight or absent Heavy Cowbird effects Disadvantage Advantage Cowbird eggs Mimetic Non-mimetic Foreign objects in nest Cowbird behavior Rejected Accepted Timid Aggressive Nesting season Late Early 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 Acclimatory Developmental Evolutionary Physiological/behavioral Physiological/behavioral Developmental/behavioral Genetic/ecological <<1 generation <1 generation ~1 generation >1 generation Reversible Reversible Irreversible 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) Success of response 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 A B Ecological-- set of places with suitable conditions C Ecological > Geographic Reasons why involve most topics of interest to ecologists Explaining an Absence Species does not occur because: 1) It can’t reach it 2) It doesn’t choose to (habitat selection) 3) Physical or chemical conditions not favorable 4) Other organisms in the area prevent establishment (competition, predation, parasitism) or a key species (food, mutualist) is missing 5) Chance Transplant experiments Remove suspected dispersal barrier 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 Starling Gypsy moth A albopictus Rabbits to Australia Failed introductions: Fish stocking Seeds in wool Chestnut Blight Dutch Elm Disease Hessian Fly Norway maple