Meta‐analysis of anthropogenic habitat disturbance effects on animal‐mediated seed dispersal

Fontúrbel, Francisco E.; Candia, Alina B.; Malebrán, Javiera; Salazar, Daniela A.; González-Browne, Catalina; Medel, Rodrigo

doi:10.1111/gcb.13025

Cited by 67 publications

(61 citation statements)

References 65 publications

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Section: Effects Of Human-induced Rapid Environmental Changementioning

confidence: 99%

“…Habitat loss, species extinctions, species introductions, and climate change are all having large impacts on frugivore communities, fruit communities, and, ultimately, seed dispersal (Fontúrbel et al, 2015). Habitat loss and fragmentation can decrease native species richness, increase the distance potential dispersers must travel between patches of fruiting plants, and decrease local fruit abundance within an area (Rey and Alcántara, 2014;Fontúrbel et al, 2015). In addition, the decline or loss of either once-abundant fruiting plant species and/or their vertebrate dispersers can drastically change the structure of a SD network and forest recruitment patterns (Meehan et al, 2002;Wotton and Kelly, 2011;Schleuning et al, 2014;Pejchar, 2015).…”

Section: Effects Of Human-induced Rapid Environmental Changementioning

confidence: 99%

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Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

2017

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Mutualistic interactions between species are crucial for the maintenance and functioning of the community. Current research has shown the importance of not only understanding the structure of these mutualistic interaction networks but also their temporal dynamics. Temporal changes in species abundance, such as those caused by vertebrate resource tracking, may create temporal variability in a network though neighborhood effects and influence the directedness of dispersal. While much research has been done on resource tracking, neighborhood effects, and directed dispersal individually, little research has been done into their interrelationships and, therefore, theory of how resource tracking can influence frugivory and seed dispersal networks remains poorly developed. We use the available literature to show the prevalence of resource tracking by vertebrate frugivores and hypothesize how, through neighborhood effects, resource tracking may influence short-term variation in network properties. We then discuss how resource tracking can influence long-term network properties by altering the dispersal of plant species. Lastly, we use this information to hypothesize how the introductions of new species into a community may alter the influence of resource tracking on frugivory and seed dispersal. While trait matching and links that are not possible between species in a community (i.e., forbidden links) play a large role in determining the structure of a network, temporal change in the abundance of species due to resource tracking may also affect the properties of networks. By increasing our understanding of the role resource tracking has in the temporal variability of frugivory and seed dispersal networks, we can better determine the full extent of species interactions and provide valuable information for the conservation of ecological communities.

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Section: Effects Of Human-induced Rapid Environmental Changementioning

confidence: 99%

Section: Effects Of Human-induced Rapid Environmental Changementioning

confidence: 99%

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

2017

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“…Defaunation, the sustained loss of distinct groups of animals (e.g. top predators, megafauna), is causing added losses of crucial ecosystem functions (Dirzo et al., ; Malhi et al., ; McCauley et al., ; Young, McCauley, Galetti, & Dirzo, ), such as dispersal of seeds for animal‐dependent plants (Fontúrbel et al., ; Markl et al., ). Central ecological consequences of these cascading effects include changes in vegetation structure (Bakker et al., ; Johnson, ), reductions of plant regeneration (Cordeiro & Howe, ; Terborgh et al., ) and carbon storage potential (Bello et al., ; Peres, Emilio, Schietti, Desmoulière, & Levi, ), and altered evolutionary regimes (Galetti et al., ; Valido, ).…”

Section: Introductionmentioning

confidence: 99%

“…Long‐distance dispersal (LDD) assisted by frugivores (Nathan, ) is a crucial ecological process affecting functional connectivity of fleshy‐fruited plant populations at both local and regional scales. Yet, this process is being severely altered by human‐driven disturbances (Fontúrbel et al., ; Markl et al., ), such as anthropogenic defaunation selectively removing large‐bodied vertebrates (Dirzo et al., ; Estes et al., ) which, in turn, are primarily responsible for LDD across landscapes (Jordano, García, Godoy, & García‐Castaño, ). Despite that pollen flow may contribute to genetic exchange among isolated populations, seed dispersal is a crucial process because it moves both maternal and paternal gametic genomes and determines the final establishment of the genotypes, ultimately leading to realized gene flow (e.g.…”

Section: Introductionmentioning

confidence: 99%

Persisting in defaunated landscapes: Reduced plant population connectivity after seed dispersal collapse

2017

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Defaunation of large‐bodied frugivores could be causing severe losses of crucial ecosystem functions such as seed dispersal. The immediate ecological consequences may include alteration or even collapse of seed‐mediated gene flow affecting plant population connectivity, with impacts on the regional scale distribution of genetic variation. Yet, these far‐reaching consequences of defaunation remain understudied. Here, we tested whether human‐induced defaunation of the Canarian frugivorous lizards (Gallotia, Lacertidae) altered within‐island population connectivity and the amount and large‐scale distribution of genetic variation of Neochamaelea pulverulenta (Rutaceae), which relies exclusively on these lizards for seed dispersal. Our study system defines a lizard downsizing gradient with three contrasted ecological scenarios (islands) with relatively optimal (Gran Canaria; large‐sized lizards), suboptimal (Tenerife; medium) and collapsed seed dispersal processes (La Gomera; small). We extensively sampled individual plant genotypes from 80 populations spanning the full geographical range of the plant to examine their genetic diversity, population‐genetic network topologies, and the patterns of isolation both by distance (IBD) and resistance (IBR) across these three ecological scenarios. Plant genetic diversity appeared unaffected by defaunation‐mediated downsizing of frugivorous lizards. However, we found a reduced overall plant population connectivity together with an increased isolation by distance within the most defaunated islands (La Gomera and, to a lesser extent, Tenerife) when compared with the scenario preserving the functionality of lizard‐mediated seed dispersal (Gran Canaria). The results, with a significant effect of lizard downsizing, were robust when controlling for biotic/abiotic differences among the three islands by means of isolation by resistance models (IBR). Synthesis. Our results provide valuable insights into the far‐reaching consequences of the deterioration of mutualisms on plant population dynamics over very large spatial scales. Conservation of large‐bodied frugivores is, thus, essential because their irreplaceable mutualistic dispersal services maintain an extensive movement of seeds across the landscape, crucial for maintaining the genetic cohesiveness of metapopulations and the adaptive potential of plant species across their entire geographical range.

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“…Forest degradation and fragmentation can result in a loss of fruiteating species, in particular of old-growth forest specialists, and the consequent decrease in their seed dispersal service (Luck and Daily, 2003;Markl et al, 2012;Albrecht et al, 2013;Fontúrbel et al, 2015). However, secondary forests in Los Toldos showed increased SDE compared to old-growth forests dominated by P. parlatorei.…”

Section: Implications For Conservationmentioning

confidence: 99%

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

Blendinger

2017

Front. Ecol. Evol.

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Most fleshy-fruited plants establish strong local interactions with a few fruit-eating species across their distribution range, which can differ among sites and have a major impact for the plant population dynamics. In turn, human disturbances alter both the original animal assemblage with which plants interact and the outcome of the mutualistic interaction. Negative consequences of human disturbances can be weakened when different seed dispersers exert similar effects on plant populations, being functionally equivalent. To understand the consequences of variability in seed dispersers on the recruitment of a long-lived tree species, I assessed changes in the assemblages of avian dispersers of Podocarpus parlatorei in subtropical Andean cloud-forests, and how these changes affect the outcome of the interaction at different spatial scales. The seed dispersal effectiveness (SDE) concept, defined as the likelihood of a seed removed by a fruit-eating bird to be dispersed to a suitable site for seed survival and germination, provides the framework to compare the contributions of different birds to seed dispersal. I compared the SDE in two old-growth forests dominated by P. parlatorei and a human disturbed forest, and in the main habitat types of these sites. In all sites, highest SDE values were provided by "gulpers" that swallow the whole fleshy cone ("fruit"), predominantly Elaenia and Turdus species. SDE was highest in forest edges and secondary forests, and negligible in other habitats. Equivalence in SDE was relatively low both within and between forest sites. Human forest disturbance modified the functional equivalence, the generalization in mutualistic interactions and the strength of SDE. Secondary forests showed the higher SDE and the greater richness of dispersers high in SDE; as a consequence, the ecological equivalence increased in the most suitable habitat for recruitment. This could lead to greater resilience of plant populations to local extinctions of dispersers, and allows the recovery of human disturbed forests. This study shows that in the replacement of functional equivalent species, the outcomes of the interactions are strongly affected by disperser abundance and habitat use, at the expense of dispersers' trait redundancy on plant population dynamics and community structure.

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Meta‐analysis of anthropogenic habitat disturbance effects on animal‐mediated seed dispersal

Cited by 67 publications

References 65 publications

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

Persisting in defaunated landscapes: Reduced plant population connectivity after seed dispersal collapse

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

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