KW - Plant defense guild hypothesis

The second factor is the value of protection: would the plant be lessable to survive and reproduce after removal of part of its structureby a herbivore? Not all plant parts are of equal evolutionary value,thus valuable parts contain more defenses. A plant’s stage ofdevelopment at the time of feeding also affects the resulting changein fitness. Experimentally, the fitness value of a plant structure isdetermined by removing that part of the plant and observing theeffect. In general, reproductive parts are not as easily replaced asvegetative parts, terminal leaves have greater value than basalleaves, and the loss of plant parts mid-season has a greater negativeeffect on fitness than removal at the beginning or end of the season. Seeds in particular tend to be very well protected. For example, theseeds of many edible fruits and nuts contain cyanogenic glycosidessuch as amygdalin . This results from the need to balance the effortneeded to make the fruit attractive to animal dispersers whileensuring that the seeds are not destroyed by the animal.

Plant defense against herbivory ..

According to this hypothesis, apparent plants are the most collected and used by humans.
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This is also related to the plant apparency hypothesis, ..

A recent test of this model involved a reciprocal transplants ofseedlings of 20 species of trees between clay soils (nutrient rich)and white sand (nutrient poor) to determine whether trade-offs betweengrowth rate and defenses restrict species to one habitat. When plantedin white sand and protected from herbivores, seedlings originatingfrom clay outgrew those originating from the nutrient-poor sand, butin the presence of herbivores the seedlings originating from whitesand performed better, likely due to their higher levels ofconstitutive carbon-based defenses. These finding suggest thatdefensive strategies limit the habitats of some plants.

Plant Apparency and Chemical Defense | Request PDF

The growth rate hypothesis, also known as the _resource availabilityhypothesis_, states that defense strategies are determined by theinherent growth rate of the plant, which is in turn determined by theresources available to the plant. A major assumption is that availableresources are the limiting factor in determining the maximum growthrate of a plant species. This model predicts that the level of defenseinvestment will increase as the potential of growth decreases. Additionally, plants in resource-poor areas, with inherentlyslow-growth rates, tend to have long-lived leaves and twigs, and theloss of plant appendages may result in a loss of scarce and valuablenutrients.

The thorns on the stem of this raspberry plant, serve as amechanical defense against herbivory.
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Out Of The Quagmire Of Plant Defense Hypotheses

The second factor is the value of protection: would the plant be less able to survive and reproduce after removal of part of its structure by a herbivore? Not all plant parts are of equal evolutionary value, thus valuable parts contain more defenses. A plant’s stage of development at the time of feeding also affects the resulting change in fitness. Experimentally, the fitness value of a plant structure is determined by removing that part of the plant and observing the effect. In general, parts are not as easily replaced as parts, terminal leaves have greater value than leaves, and the loss of plant parts mid-season has a greater negative effect on fitness than removal at the beginning or end of the season. Seeds in particular tend to be very well protected. For example, the seeds of many edible fruits and nuts contain cyanogenic glycosides such as . This results from the need to balance the effort needed to make the fruit attractive to animal dispersers while ensuring that the seeds are not destroyed by the animal.

Macroevolution of plant defense strategies - ScienceDirect

In a phylogenetic reanalysis of Ehrlich and Raven's [] study on butterfly and plant coevolution, Janz & Nylin [] found strong effects of both plant phylogeny and growth form on patterns of host use among butterflies. An overwhelming majority of host shifts occurred while feeding on trees, giving support for Feeny's "plant apparency" hypothesis. Trees appeared to serve as a "bridge" that could facilitate host shifts between distantly related plants.

What is the plant apparency hypothesis?..

Our understanding of herbivory in geological time comes from threesources: fossilized plants, which may preserve evidence of defense(such as spines), or herbivory-related damage; the observation ofplant debris in fossilised animal faeces ; and the construction ofherbivore mouthparts.