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Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae./
Author:	Anstett, Daniel.
Description:	1 online resource (349 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
Contained By:	Dissertation Abstracts International79-04B(E).
Subject:	Ecology. -
Online resource:	click for full text (PQDT)
ISBN:	9780355531220

Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae.
Anstett, Daniel.

Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae. - 1 online resource (349 pages)

Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

Herbivory is predicted to increase at lower latitudes, leading to the evolution of increased plant defence towards the tropics. These ideas are known as the Latitudinal Herbivory-Defence Hypothesis (LHDH). While initial empirical tests supported this hypothesis, it has been challenged by new studies leading to controversy. I tested LHDH at the micro- and macroevolutionary scale, through a series of well-replicated studies. At the microevolutionary scale I surveyed common evening primrose (Oenothera biennis), which has a well characterized herbivory community, and diverse and abundant ellagitannins. First, I sampled herbivory across 79 populations of O. biennis in Eastern North America. Latitudinal gradients in herbivory varied depending on herbivore guild and degree of specialization. In particular damage by specialist seed predators was greater at higher latitudes. To explain these patterns, I then studied genetically based latitudinal clines in plant defences across 137 populations of O. biennis by growing them in a common garden. Populations from lower latitudes showed greater resistance to all herbivores. Increased chemical defences best predicted this resistance. A subsequent growth chamber experiment then examined latitudinal gradients in constitutive versus induced defences. Genotypes from lower latitudes were less damaged by a generalist caterpillar, although there was no pattern by a specialist weevil. Total phenolics were greater at lower latitudes when measuring constitutive defences, but were greater at higher latitudes in induced plants. These results suggest there might be increased herbivory at higher latitudes because of relatively low constitutive defences, but that induced defences may be used to prevent additional damage.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355531220Subjects--Topical Terms:

575279
Ecology.
Index Terms--Genre/Form:

554714
Electronic books.

Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae.
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245 1 0 $a Latitudinal Gradients in Herbivory and Plant Defence Across the Onagraceae.
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300 $a 1 online resource (349 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
500 $a Includes supplementary digital materials.
500 $a Adviser: Marc TJ Johnson.
502 $a Thesis (Ph.D.) $c University of Toronto (Canada) $d 2017.
504 $a Includes bibliographical references
520 $a Herbivory is predicted to increase at lower latitudes, leading to the evolution of increased plant defence towards the tropics. These ideas are known as the Latitudinal Herbivory-Defence Hypothesis (LHDH). While initial empirical tests supported this hypothesis, it has been challenged by new studies leading to controversy. I tested LHDH at the micro- and macroevolutionary scale, through a series of well-replicated studies. At the microevolutionary scale I surveyed common evening primrose (Oenothera biennis), which has a well characterized herbivory community, and diverse and abundant ellagitannins. First, I sampled herbivory across 79 populations of O. biennis in Eastern North America. Latitudinal gradients in herbivory varied depending on herbivore guild and degree of specialization. In particular damage by specialist seed predators was greater at higher latitudes. To explain these patterns, I then studied genetically based latitudinal clines in plant defences across 137 populations of O. biennis by growing them in a common garden. Populations from lower latitudes showed greater resistance to all herbivores. Increased chemical defences best predicted this resistance. A subsequent growth chamber experiment then examined latitudinal gradients in constitutive versus induced defences. Genotypes from lower latitudes were less damaged by a generalist caterpillar, although there was no pattern by a specialist weevil. Total phenolics were greater at lower latitudes when measuring constitutive defences, but were greater at higher latitudes in induced plants. These results suggest there might be increased herbivory at higher latitudes because of relatively low constitutive defences, but that induced defences may be used to prevent additional damage.
520 $a At the macroevolutionary scale, gradients in chemical defences were assessed across 80 species of Onagraceae. Latitude did not predict defence patterns. Instead colder climates, temperature variability, and hemisphere of origin were associated with greater levels of defence. These results challenge the validity of LHDH at the macroevolutionary scale.
520 $a The utility of LHDH varies across different scales. This generates the need for more robust theory that can incorporate these scales into predictions. I advance new lines of inquiry that should be explored, by analyzing the assumptions used in LHDH through a critical review. I also recommend increased rigor and consistency in chemical and herbivory metrics. I apply some of these recommendations throughout my work, including confirming the effect of phenolics and ellagitannins on herbivore performance.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Ecology. $3 575279
650 4 $a Biology. $3 599573
650 4 $a Botany. $3 599558
655 7 $a Electronic books. $2 local $3 554714
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710 2 $a University of Toronto (Canada). $b Ecology and Evolutionary Biology. $3 1179765
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