Paradigms for parasite conservation

Abstract

Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite‐inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid‐20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host‐density threshold and cost‐benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host–parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of an uncertain environmental future.

Parasite component community of smalltooth sawfish off Florida: diversity, conservation concerns, and research applications

“…The summer−fall decline in D. pristidis populations corresponds with the rainy season in south Florida (June to November), a period during which marked drops in salinity can influence the movements of smalltooth sawfish within the nursery, but they remain within it (Poulakis et al 2011(Poulakis et al , 2013. Parasites have been called ecological puppeteers because their impacts on individual hosts' health and behavior can be profound at the ecosystem (collective) level (Dougherty et al 2016), and the possibility that infection by D. pristidis could influence host movements in the Charlotte Harbor estuarine system is intriguing. Poulakis et al (2011) suggested that the tendency for juvenile smalltooth sawfish to remain in place during periods of high freshwater flow might be an adaptive strategy for avoiding predators and competitors, but they did not consider whether low salinity might have a prophylactic effect on ectoparasites.…”

“…Attention to parasites has largely focused on their role as agents of disease, but a full understanding of their complex ecological function requires broader consideration (Wood & Johnson 2015). They are, in fact, an integral component of a healthy ecosystem and can serve as biological indicators of host and environmental health (Marcogliese 2005, Dougherty et al 2016. Some may reduce transmission rates of more pathogenic species (Johnson et al 2013), act as contaminant sinks (Sures 2003), indicate host ancestry, or serve as biological tags (Whiteman & Parker 2005).…”

Pythons, parasites, and pests: anthropogenic impacts on Sarcocystis (Sarcocystidae) transmission in a multi‐host system

“…, Gómez & Nichols , Dougherty et al . ). However, parasite–host interactions are often studied as discrete topics from (or analogs to) predator–prey interactions rather than dynamic parts of an integrated system (Raffel et al .…”

“…THE ROLE OF PARASITES IN ECOSYSTEMS HAS HISTORICALLY BEEN CONSIDERED TRIVIAL (Marcogliese 2004, Hudson et al 2006, until developments in the past few decades revealed the significant control that parasites have over their hosts' densities and population cycles (Hansson 1987, Hudson et al 1998, Klemola et al 2003, and how they shape community structure (Mouritsen & Poulin 2005, Wood et al 2007, Kuris et al 2008. A growing body of evidence also suggests that ecosystem function and resilience improve with increased parasite diversity (Hudson et al 2006, G omez & Nichols 2013, Dougherty et al 2016). However, parasite-host interactions are often studied as discrete topics from (or analogs to) predator-prey interactions rather than dynamic parts of an integrated system (Raffel et al 2008).…”

Biosecurity, Bibliometrics, and Conservation Biology

“…In these books, the reader would look in vain for a chapter advocating a paradigm shift in how we consider pests and pathogens, as was recently the case in this journal for animal parasites (Dougherty et al. ). We try to preserve threatened animals and plants, but what about endangered pests and pathogens (Ingram )?…”