Dataset Information

Tolerance to seed predation mediated by seed size increases at lower latitudes in a Mediterranean oak.

ABSTRACT:

Background and aims

The ability of plants to allocate energy to resistance against herbivores changes with abiotic conditions and thus may vary along geographical clines, with important consequences for plant communities. Seed size is a plant trait potentially influencing plant tolerance to endoparasites, and seed size often varies across latitude. Consequently, plant tolerance to endoparasites may change across geographical clines.

Methods

The interaction between Quercus ilex (holm oak) and seed-predating Curculio spp. (weevils) was explored along most of the latitudinal range of Q. ilex. This included quantification of variation in seed size, survival likelihood of infested seeds, multi-infestation of acorns and community composition of Curculio weevils in acorns.

Key results

Larger seeds had a higher probability of surviving weevil attack (i.e. embryo not predated). Southern populations of oak produced on average four times larger seeds than those of northern populations. Consequently, the probability of survival of infested acorns decreased with latitude. The community composition of Curculio varied, with large weevils (C. elephas) dominating in southern populations and small weevils (C. glandium) dominating in northern populations. However, damage tolerance was robust against this turnover in predator functional traits. Furthermore, we did not detect any change in multi-infestation of acorns along the geographical gradient.

Conclusions

Quercus ilex tolerance to seed predation by Curculio weevils increases toward the southern end of its distribution. Generally, studies on geographical variation in plant defence against enemies largely ignore seed attributes or they focus on seed physical barriers. Thus, this research suggests another dimension in which geographical trends in plant defences should be considered, i.e. geographical variation in tolerance to seed predators mediated by seed size.

SUBMITTER: Bogdziewicz M

PROVIDER: S-EPMC6417470 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Publications

Tolerance to seed predation mediated by seed size increases at lower latitudes in a Mediterranean oak.

Bogdziewicz Michał M Espelta Josep Maria JM Bonal Raul R

Annals of botany 20190301 4

<h4>Background and aims</h4>The ability of plants to allocate energy to resistance against herbivores changes with abiotic conditions and thus may vary along geographical clines, with important consequences for plant communities. Seed size is a plant trait potentially influencing plant tolerance to endoparasites, and seed size often varies across latitude. Consequently, plant tolerance to endoparasites may change across geographical clines.<h4>Methods</h4>The interaction between Quercus ilex (ho ...[more]

PMID: 30452531

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Project description:Background and aimsClassic theory on geographical gradients in plant-herbivore interactions assumes that herbivore pressure and plant defences increase towards warmer and more stable climates found at lower latitudes. However, the generality of these expectations has been recently called into question by conflicting empirical evidence. One possible explanation for this ambiguity is that most studies have reported on patterns of either herbivory or plant defences whereas few have measured both, thus preventing a full understanding of the implications of observed patterns for plant-herbivore interactions. In addition, studies have typically not measured climatic factors affecting plant-herbivore interactions, despite their expected influence on plant and herbivore traits.MethodsHere we tested for latitudinal variation in insect seed predation and seed traits putatively associated with insect attack across 36 Quercus robur populations distributed along a 20° latitudinal gradient. We then further investigated the associations between climatic factors, seed traits and seed predation to test for climate-based mechanisms of latitudinal variation in seed predation.Key resultsWe found strong but contrasting latitudinal clines in seed predation and seed traits, whereby seed predation increased whereas seed phenolics and phosphorus decreased towards lower latitudes. We also found a strong direct association between temperature and seed predation, with the latter increasing towards warmer climates. In addition, temperature was negatively associated with seed traits, with populations at warmer sites having lower levels of total phenolics and phosphorus. In turn, these negative associations between temperature and seed traits led to a positive indirect association between temperature and seed predation.ConclusionsThese results help unravel how plant-herbivore interactions play out along latitudinal gradients and expose the role of climate in driving these outcomes through its dual effects on plant defences and herbivores. Accordingly, this emphasizes the need to account for abiotic variation while testing concurrently for latitudinal variation in plant traits and herbivore pressure.

Project description:The process of seed dispersal of many animal-dispersed plants is frequently mediated by a small set of biotic agents. However, the contribution that each of these dispersers makes to the overall recruitment may differ largely, with important ecological and management implications for the population viability and dynamics of the species implied in these interactions. In this paper, we compared the relative contribution of two local guilds of scatter-hoarding animals with contrasting metabolic requirements and foraging behaviours (rodents and dung beetles) to the overall recruitment of two Quercus species co-occurring in the forests of southern Spain. For this purpose, we considered not only the quantity of dispersed seeds but also the quality of the seed dispersal process. The suitability for recruitment of the microhabitats where the seeds were deposited was evaluated in a multi-stage demographic approach. The highest rates of seed handling and predation occurred in those microhabitats located under shrubs, mostly due to the foraging activity of rodents. However, the probability of a seed being successfully cached was higher in microhabitats located beneath a tree canopy as a result of the feeding behaviour of beetles. Rodents and beetles showed remarkable differences in their effectiveness as local acorn dispersers. Quantitatively, rodents were much more important than beetles because they dispersed the vast majority of acorns. However, they were qualitatively less effective because they consumed a high proportion of them (over 95%), and seeds were mostly dispersed under shrubs, a less suitable microhabitat for short-term recruitment of the two oak species. Our findings demonstrate that certain species of dung beetles (such as Thorectes lusitanicus), despite being quantitatively less important than rodents, can act as effective local seed dispersers of Mediterranean oak species. Changes in the abundance of beetle populations could thus have profound implications for oak recruitment and community dynamics.

Dataset Information

Tolerance to seed predation mediated by seed size increases at lower latitudes in a Mediterranean oak.

Background and aims

Methods

Key results

Conclusions

Publications

Tolerance to seed predation mediated by seed size increases at lower latitudes in a Mediterranean oak.

Similar Datasets

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