Ecology Week 3 Notes
Ecology Week 3 Notes BIOSC 0370
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This 2 page Class Notes was uploaded by Shannon Kiss on Tuesday January 27, 2015. The Class Notes belongs to BIOSC 0370 at University of Pittsburgh taught by Anthony Bledsoe in Winter2015. Since its upload, it has received 148 views. For similar materials see Ecology in Biology at University of Pittsburgh.
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Date Created: 01/27/15
Ecology 116 1 Natural selection Ecology Week 3 Notes Definition see lecture Requirements Natural selection CANNOT operate if one or more of these is not in place 1 Trait variation often expressed graphically 2 Trait heritability 3 Consistent relationship between trait form and survival reproduction Ex ebola gt immunity trait will dominate Ex bubonic plague in Northern Europe immunity allele very present there Populations NOT individuals evolve Natural selection does not generate variation can maintain Sources of trait variation 1 Mutation 2 Recombination Outcomes 3 Stabilizing Selection does not yield evolutionary change 4 Directional Selection 5 Disruptive Selection Examples 0 Peppered moth Biston betularia Britain Dark and light moths Initially dark were rare and light were abundant Nocturnal so slept on trees during day Dark were more visible to predators During Industrial Revolution sut and dirt went on the trees making the white moths more noticeable than the dark moths After revolution light were rare and dark were abundant because they camo aughed better to predators quotIndustrial melanismquot Consistent relationship between color and survival First wellworked example of natural selection Directional Selection 0 Galapogos finches Archaepalago peninsula Ecuador Studied the medium ground finch on the Daphne Major island Rosemary and Peter Grant mid 1970s In 1976 18 monthlong drought with little rain Left only hardshelled seeds Only birds with big finches could crack the seeds The bigger the beak size the more birds that survived Directional Selection 0 Birth weight in humans Infants around the mean trait value have the highest birth rate 68 pounds Low birth weight babies often have respiratory problems High birth weight babies have complications with delivery There have been improvement on both ends with new medical advancements Asymmetric because it is more likely that a high birth weight baby will survive instead of a low birth still highest for mean Stabilizing Selection 0 Snow Geese Snow geese have a hatching synchrony where most clutches hatch on the same day of breeding season Say day 0 Some clutches can hatch up to six days before or after day 0 The young that hatch on days other than day 0 have a higher rate of mortality because there is less of them to be hunted down by predators snowy owl arctic foxes yagers Day 0 hatch have safety in numbersquot and a selective advantage Stabilizing Selection 0 African Swallowtails Papilio dardanus 3 sets of identical mothsquot mimics of each other