The conservation physiology of seed dispersal

Abstract

At a time when plant species are experiencing increasing challenges from climate change, land-use change, harvesting and invasive species, dispersal has become a very important aspect of plant conservation. Seed dispersal by animals is particularly important because some animals disperse seeds to suitable sites in a directed fashion. Our review has two aims: (i) to highlight the various ways plant dispersal by animals can be affected by current anthropogenic change and (ii) to show the important role of plant and (particularly) animal physiology in shaping seed -dispersal interactions. We argue that large-bodied seed dispersers may be particularly important for plant conservation because seed dispersal of large-seeded plants is often more specialized and because large-bodied animals are targeted by human exploitation and have smaller population sizes. We further argue that more specialized seed-dispersal systems on island ecosystems might be particularly at risk from climate change both owing to small population sizes involved but also owing to the likely thermal specialization, particularly on tropical islands. More generally, the inherent vulnerability of seed-dispersal mutualisms to disruption driven by environmental change (as well as their ubiquity) demands that we continue to improve our understanding of their conservation physiology.

Assessing the effect of roads on impala (Aepyceros melampus) stress levels using faecal glucocorticoid metabolites

“…Physiological tools have previously proven successful in addressing conservation issues related to both plants and animals. Pywell et al (2003) used physiological traits to assess the performance of plants in ecological restoration, Ruxton and Schaefer (2012) described how plant and animal physiology affects seed dispersal interactions and Tingvold et al (2013) showed how African elephants (Loxodonta africana) have lower stress hormone levels inside protected parks compared to individuals outside. Conservation physiology can thus be used to understand and potentially solve a wide variety of conservation related problems.…”

Determining environmental causes of biological effects: the need for a mechanistic physiological dimension in conservation biology

“…These interactions may be nested within the effect of abiotic drivers as in the example above where energetic needs for thermoregulation change in different environmental contexts. Nutrition, with respect to both energetic and macronutrient requirements, in particular determines interactions between organisms [32,33]. At a quantitative level, density of prey will determine predator numbers [34], but this relationship will change with environmentally driven changes in energy requirements, such as for thermoregulation.…”

“…For example, temperature affects the relative macronutrient requirements in trout, and fish at warm temperatures require relatively more protein than at cooler temperatures [35]. As a result, foraging behaviour must be adjusted to meet intake targets, and predation pressures shift to different prey species, potentially leading to a change in community structure and interactions [33].…”

Ecophysiology of avian migration in the face of current global hazards

“…These impacts on migrants may also have ecological ramifications at community and ecosystem scales, because migratory birds provide many ecosystem functions and services, such as pest control, assistance in dispersal of other organisms, pollination and nutrient cycling [7][8][9]. There is also increasing interest in how migratory birds may affect the abundance and distribution of diseases that threaten humans, such as highly pathogenic avian influenza virus H5N1 originating in Southeast Asia, and West Nile virus in the Americas [10].…”