Abstract
The accelerating rate of vertebrate extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes such as animal seed dispersal. The study of highly specialized mutualistic interactions is crucial to predict the consequences of population declines and extinctions. Islands offer unique opportunities to study highly specialized interactions, as they often have naturally depauperated faunas and are experiencing high rates of human-driven extinctions. In this study, we assess the effect of seed dispersal on seedling recruitment of Ephedra fragilis (Ephedraceae) on a Mediterranean island ecosystem. We used field data and stochastic simulation modeling to estimate seed fate and recruitment patterns of this pioneer shrub typical of arid and semiarid areas, and to estimate the dependence of recruitment on the lizard Podarcis lilfordi (Lacertidae), its only known seed disperser. Ephedra fragilis recruitment highly depended on lizards: lizards produced 3.8 times more newly-emerged seedlings than non-dispersed seeds and no seedlings from undispersed seeds survived the study period. Seed dispersal by lizards was mostly to open sites, which was key for the increased success observed, while undispersed seeds, falling under mother plants, suffered higher predation and lower seedling emergence and survival. The ability of this pioneer shrub to get established in open ground is crucial for vegetation colonization and restoration, especially on degraded lands affected by desertification, where they act as nurse plants for other species. Lizards are key in this process, which has important consequences for community structure and ecosystem functioning.
Highlights
The accelerating rate of wildlife extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes [1]
In diverse communities, seed dispersers typically feed on the fruits of many different plant species, and seeds of a particular plant species are usually dispersed by many different animals
Functional redundancy attenuates the impact of the extinction or severe decline of particular species, which can be replaced in their role by their functional equivalents [5]
Summary
The accelerating rate of wildlife extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes [1]. Plant recruitment is a crucial process that, in many plant species, depends on the services provided by animals for seed dispersal [2]. In diverse communities, seed dispersers typically feed on the fruits of many different plant species, and seeds of a particular plant species are usually dispersed by many different animals. This makes these interactions diffuse, with low interdependence between plant and animal partners, which reduce the vulnerability of the community to co-extinctions and cascade effects Functional redundancy attenuates the impact of the extinction or severe decline of particular species, which can be replaced in their role by their functional equivalents [5]
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