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Distribution of a plant parasite on its host:
Distribution of a plant parasite on its host:

Distribution of a plant parasite on its host: - PowerPoint Presentation

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Distribution of a plant parasite on its host: - Description

gall distribution on the flowering dogwood Cornus florida Purpose To determine the distribution of midge galls on dogwood trees and to investigate some environmental factors that might influence distribution ID: 541822 Download Presentation

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galls dogwood trees distribution dogwood galls distribution trees tree leaf bud scars number midge branch identification nearest parasites distance

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Presentation on theme: "Distribution of a plant parasite on its host:"— Presentation transcript

Slide1

Distribution of a plant parasite on its host: gall distribution on the flowering dogwood, Cornus floridaSlide2

PurposeTo determine the distribution of midge galls on dogwood trees and to investigate some environmental factors that might influence distribution.

Questions

1) How are the galls distributed spatially?

Random vs. clumped vs. uniform

2)

Number or

distribution of galls influenced by:Size/age of the plant? Nearest neighbor distance? Sunny versus shady microhabitat?Slide3

Midge fly, Resseliella clavulaSlide4

Random DistributionParasites are randomly distributed within the environment. If midges flew until they “hit” a dogwood haphazardly …Predict:

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Even Distribution“Regular”: Organisms are evenly spaced in the environment. Then every tree would have the same number of galls. This would suggest that the parasites are competing for the trees.Predict:

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Clumped DistributionMost trees have few parasites, and some a lot.Typically associated with:disease outbreaks, tree densities (“contagious”), agePredict:

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Tree sizeOlder and infirm trees might be more likely to be attacked by the midge parasite.Distance to nearest neighbor

If trees are close together, they might be more likely to attract

galls.

Collect gall data in two habitats

Some microhabitats might be better for galls than others.

Environmental Factors We are MeasuringSlide8

Dogwood (Cornus florida) IdentificationSlide9

Dogwood IdentificationFlowers: white, four petals (spring)

Fruit: bright red, in clusters (late summer, fall)

Leaves: opposite, veins curvedSlide10

Dogwood Identification (Winter)Flower buds(reproductive)

Leaf bud(somatic)

BothSlide11

Bark: dark brown with squarish, scaly blocks.Young trees will be smooth and not as distinctive. Slide12

Terminal BudsExamples of different numbers of bud scales Dogwood with two bud scales.

Twigs are slender, green or purple.Slide13

Leaf ScarsDogwood leaf scars are opposite, small, and encircle twig. Example of alternate leaf scars

Opposite leaf scars

Terminal budSlide14

MethodsGroups of 4Go to 2 sites and survey 20 trees each1) Record how many galls on 100 branch nodes per tree

2)

Measure the DBH (cm) of each tree trunk

DBH = “Diameter at breast height”

3)

Measure the distance (m) of the three closest dogwood neighbors (

DNN = nearest neighbor dist.)Slide15

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Dogwood Branch

Galls

…so this branch is good for 13 out of the 100 counts you need for each tree, and the number of galls is 2