Macrogeographic variation of a pond predator's top‐down effects in a common garden environment

Abstract

Geographic variation in species behavior and life history has been well documented in biology. Species with wide geographic distributions (i.e., across a continent) but small home ranges (i.e., <1 km2) likely experience wide variability in abiotic environments across the entirety of their range, possibly exhibiting strong local adaptation. Understanding variation across a large geographic scale is especially important when considering species that have strong ecological importance, such as keystone species. Yet, few studies have compared the potential cascading ecological effects of a predator with a keystone role in at least part of its range. To understand how keystone ability in pond food webs can vary across a large geographic range, we conducted an artificial pond experiment with a known keystone predator in at least part of its range, the marbled salamander (Ambystoma opacum). To do so, we collected size‐matched salamander larvae from three geographically distant populations (>650 km apart) in Ohio, Mississippi, and North Carolina and placed them in mesocosms with a suite of spring breeding amphibian prey species. We observed differential survival of some prey species leading to differences in spring‐breeding amphibian diversity among the three predator populations, indicating that keystone predation may vary at a geographic scale. Prey diversity was lowest with predators from northern (Ohio) populations of salamanders. Further understanding of large‐scale variability in ecologically important predators and the potential effects of translocating wide‐ranging ambystomatid species is needed to direct future conservation efforts and preserve biodiversity.

Limited population and community effects of hatching asynchrony in a pond‐breeding salamander

“…Larvae overwinter in ponds prior to undergoing metamorphosis in late spring to early summer. Larval diet primarily consists of zooplankton, other invertebrates, and larvae of other amphibians (Branch & Altig, 1981; Petranka & Petranka, 1980; Stemp et al, 2021). Larvae are also known to be highly aggressive and cannibalistic on conspecifics, especially if size variation among individuals exists (Mott & Maret, 2011; Smith, 1990; Walls & Blaustein, 1995).…”

“…Larvae are also known to be highly aggressive and cannibalistic on conspecifics, especially if size variation among individuals exists (Mott & Maret, 2011; Smith, 1990; Walls & Blaustein, 1995). Larval A. opacum are top predators in fishless ponds, influencing both amphibian and invertebrate communities (Davenport & Chalcraft, 2012; Morin, 1995; Stemp et al, 2021; Urban, 2013). Recent evidence in South Carolina has shown that the median breeding date for A. opacum has also shifted to 15 days later than the historical median date (Todd et al, 2011), suggesting larvae would have a smaller body size in the spring and a reduced role as a top predator (Urban, 2007) unless compensatory growth occurs.…”

“…The goal of this study was to assess how egg hatching synchrony of a top predator influenced its life history traits and whether such effects were transmitted to other trophic levels. We addressed this goal using Ambystoma opacum (marbled salamander), a pond‐breeding species known for initiating strong top‐down effects in aquatic food webs during its larval stage (Davenport & Chalcraft, 2012; Morin, 1995; Stemp et al, 2021; Urban, 2013). We specifically addressed two questions: (1) How does variation in hatching synchrony affect intraspecific interactions in a top predator?…”

Intraspecific variation in a predator changes intertidal community through effects on a foundation species

“…Intraspecific trait variation can have important ecological effects, altering interactions and reshaping communities and ecosystems (Albert, 2015; Bolnick et al, 2011; Des Roches et al, 2018; Hairston et al, 2005; Harmon et al, 2009; Hughes et al, 2008; Palkovacs et al, 2012; Raffard et al, 2019). Much evidence for the community effects of intraspecific trait variation focuses on predators directly altering prey communities (Butler, 1989; Des Roches et al, 2013; Hughes et al, 2015; Katano, 2011; Matthews et al, 2016; Palkovacs & Post, 2009; Stemp et al, 2020; Wood et al, 2019) and genetic variation in foundation species (Bangert et al, 2008; Hays et al, 2021; Hughes et al, 2008; Whitham et al, 1999). However, predators of foundation species can have indirect effects on communities by altering habitat structure, both through nonconsumptive (Catalán et al, 2021) and consumptive effects (Hughes et al, 2015; Navarrete, 1996; Paine, 1966).…”