Speedy Sue, driving at 30.0 m/s, enters a one-lane tunnel. She then observes a slow-moving van 155 m ahead traveling at 5.00 m/s. Sue applies her brakes but can accelerate only at 2.00 m/s2 because the road is wet. Will there be a collision? State how you decide. If yes, determine how far into the tunnel and at what time the collision occurs. If no, determine the distance of closest approach between Sues car and the van.
Exam I Locations for Monday 15 February 8:00—10:00pm Last/Surname begins with O—Z Go to WTHR 200 PLUS those with accommodations that are NOT going to the DRC to take the test Last/Surname begins with A—N Go to EE 129 You MUST show your student ID when you turn in your exam! Bring a Calculator (You may NOT use your phone) Bring a pencil! About the Exam: 50 multiple choice questions Covers up through today’s lecture HOWEVER: math from Tuesday’s lecture will be found on Exam II. Still need to study terms and definitions from that day Fair game: Lecture slides, readings on BB, podcast, textbook chapters About the Exam: Show up ON TIME --Early is ON Time --On time is late Read questions carefully and read all choices carefully Choose the most appropriate answer iClicker Which of the following curves most closely describes the mortality curve (or survivorship) of humans A A) A B) B C) C B C iClicker The phenotype of an individual is a manifestation of: A) natural selection B) meiosis C) genotype D) reproductive ability E) anything it wants to be Both Born February 12, 1809 (207 years ago) Life Histories An Introduction Life cycle Life cycle Reproduction (reproductive cycle) Individual Organism’s maintenance Search of nest sites Courtship Nest building Egg-laying Chick hatching Parental care Molt Migration (some species) Development Life history How organisms allocate energy and time to growth, survivorship and reproduction, and what are the consequences Acquiring energy Allocating energy Foraging Life history Allocating energy What do we measure (Phenotypic traits) Body size Fecundity (offspring production) Age of first breeding Growth rate Mortality Longevity Trade-offs Trade-off occur when individuals allocate resources to one trait reducing the expression of other trait Resources are finite • Survival vs. reproduction • Current vs. future reproduction • Quality and quantity of offspring • Offspring number vs size Trade-offs How to detect trade offs • Measure two traits and see how they correlate • Manipulate experimentally one trait and analyze what happens to the other trait Adult survivorship Adult survivorship 1 5 # eggs Think about humans Or Kestrels... Artificially large clutch Adult survivorship drops because parents work so hard feeding kids that it is difficult for them to store enough mass for themselves to survive the winter. + parents can’t provision offspring adequately despite increased effort -> juvenile mortality increases Molt during the breeding period Not a good idea... Manipulation of broods to overlap experimentally reproduction and molt. Non-molting Male feeding rate Molting Non-molting Molting Offspring number vs. quality in mites Sometimes trade-off cannot be detected: why Are resources always finite or scarce Acquisition of resources Trait 1: ex Fecundity R Trait 2: ex Offspring survival Trait 1: ex Fecundity R Trait 2: ex Offspring survival • When resources are abundant some trade-offs cannot be detected • Individuals can be able to allocate a higher amount of resources to several traits • Traits no longer “compete” for resources (“relax”) Offspring survival Fecundity Offspring survival or Constraints Ecological constraints : not every organism can exploit all resources that generally are finite Example: Temperature, predators, altitude, food availability, etc. Constraints Physiological constraints : internal processes Example Hummingbirds feeding on fructose and sucrose flowers, they lack specific enzymes to digest different sugar types. Constraints Phylogenetic constraints: evolutionary history Constraints that previously evolved in and now characterize a linage The direction of evolutionary change depends on past changes Mammals Arthropods Microorganisms Generation time Body mass Optimization – Resource allocation principle Natural Selection favors individuals that optimally allocate resources “Better” resource Greater fitness allocation Fitness Ex. Environment: predation, offspring competition, food availability, etc. Trait Ex. Fecundity (# eggs) Life histories along elevational gradients and different predation pressures Lower fecundity Higher parental care Lower investment in fecundity and greater investment in parental care at higher elevations Strategy changed Offspring number Offspring quality (reduce fecundity) (increase parental care) Elevation: changes in temperature, food. Reduces time that eggs and chicks are exposed to predators Faster incubation and parental care periods with predation pressure However , there is great variation/dispersion in the data!!! Slow – fast life histories (r vs. K) MacArthur & Wilson 1967 R-strategists Maximize intrinsic K strategists Maximize carrying growth rate capacity of environment • Short lifespan • Long life span • Fast growth • Slow growth • Early maturity • Delayed maturity • High parental investment • Low parental investment • Exponential growth of their populations – • Logistic growth of their unstable environments populations – stable environments The problem is that they are trying to explain all the diversity in life histories in one dimension r-k For mammals r-K explains 48% of the total diversity in life histories Differences in reproductive traits Egg weight between populations in Brown Trout Small geographical scale Fecundity Waterfalls separate different regions Gonad weight Variation between species • Age of first breeding: 1 year • Age of first breeding: 4-5 years • Several broods of 3-4 eggs/year • One brood of 1 egg/year • Lifespan: 3-4 years • Lifespan: 30-40 years Development mode influences life history strategies, how Precocial development Altricial development Continuum • Leave the nest very quickly • They stay in the nest • Down feathers • No down feathers • Depend on parents for • Depend on parents for thermoregulation and feeding thermoregulation and feeding • Open eyes • Closed eyes • Females acquire energy prior to • Increase energy acquisition hatching to produce high quality during parental care eggs. • Nest should be hidden to • Chicks can actively escape from avoid predation (high predators vulnerability) GOOD LUCK ON THE EXAM ON MONDA Y!