Ontogenetic diversity buffers communities against consequences of species loss

Abstract

Biodiversity can be measured at multiple organizational scales. While traditional studies have focused at taxonomic diversity, recent studies have emphasized the ecological importance of diversity within populations. However, it is unclear how these different scales of diversity interact to determine the consequence of species loss. Here we asked how predator diversity and presence of ontogenetic diversity within predator populations influences community structure. Ontogenetic diversity arises from shifts in the traits and ecology of individuals during ontogeny and it is one of the biggest sources of intraspecific diversity. However, whether it dampens or strengthens the negative consequences of with species loss is poorly understood. To study the interaction of species diversity and ontogenetic diversity, we experimentally manipulated predator species diversity and diversity of developmental stages within focal predator species and analysed their joint effect on predator and prey survival, biomass and prey community structure in experimental pond systems. While individual effects of ontogenetic diversity were often species specific, losing predator species from the community often had a much smaller or no effect on prey survival, biomass or community structure when all predator populations had high ontogenetic diversity. Thus, ontogenetic diversity within populations buffered against some of the consequences of biodiversity loss at higher organizational levels. Because the experiment controlled mean per capita size and biomass across structured versus unstructured populations, this pattern was not driven by differences in biomass of predators. Instead, results suggest that effects were driven by changes in the functional roles and indirect interactions across and within species. This indicates that even if all environmental conditions are similar, differences in the intrinsic structure of populations can modify the consequences of biodiversity loss. Together, these results revealed the importance of ontogenetic diversity within species for strengthening the resilience of natural communities to consequences of biodiversity loss and emphasize the need to integrate biodiversity patterns across organizational scales.

Why body size matters: how larger fish ontogeny shapes ecological network topology

“…3). These differences are expected as ontogenetic diversity has been shown to increase network complexity and the potential for indirect interactions (Rudolf and Eveland 2021). One prominent difference between the adult and stage-structured graphlet correlation matrix-11s is the relationship of a four-node chain external position (orbit 4) with other external node positions.…”

“…Most species interaction networks treat individuals as identical (Losapio et al 2018) with few studies exploring empirically how intraspecific variation influences network topology (Clegg et al 2018). One of the largest sources of intraspecific variation is ontogenetic variation, which arises due to changes in species' traits or ecology during development (Rudolf and Eveland 2021). As the presence of diet or habitat changes occurring throughout development can modify conditions for species coexistence (Miller and Rudolf 2011) as well as indirectly or directly regulate the dynamics of communities (Osenberg et al 1992), investigating networks that incorporate ontogenetic variation is useful from both a theoretical and conservation perspective.…”

Complex life cycles drive community assembly through immigration and adaptive diversification

“…The consequences of complex life cycles and ontogentic niche shift for community richness are potentially significant (for reviews see Miller & Rudolf, 2011;Moran, 1994;Nakazawa, 2015;Wilbur, 1980), and interest in investigating these ideas is seemingly increasing. From an ecological perspective, recent research focused on the potential role of ontogentic niche shift in species coexistence in plant communities (Lasky et al, 2015), freshwater invertebrates (Rudolf & Eveland, 2021), and fish (Anaya-Rojas et al, 2021). From an evolutionary perspective, several authors provide evidence that complex life cycles could drive high speciation rates in amphibians (Bossuyt & Milinkovitch, 2000) and insects (Mayhew, 2007;Rainford et al, 2014;Yang, 2001).…”

Exploring temporal patterns in fish feeding ecology: Are ontogenetic dietary shifts stable over time?

“…Ontogenetic dietary niche shifts are common in nature, particularly in insects, amphibians, and fishes, and are essential for understanding ecological processes that function at the individual, population, and community levels (e.g., Werner and Gilliam 1984;Nakazawa 2015;Sánchez-Hernández et al 2019a;Rudolf and Eveland 2021). Such shifts are beneficial for consumers, enhancing growth and lifetime fecundity, and reducing mortality risk (e.g., Olson 1996;Post 2003;Trakimas et al 2011).…”

“…Moreover, ontogenetic dietary shifts may have important implications for higher trophic levels and the overall community dynamics (e.g., de Roos and Persson 2013; Rudolf and Rasmussen 2013;Reichstein et al 2015) by influencing energy pathways and food-web structures (e.g., Miller and Rudolf 2011;Nakazawa 2015;Sánchez-Hernández 2016). Several predators feeding on the same food resource can strongly destabilise a system, while ontogenetic dietary shifts may enhance community stability by facilitating coexistence among sympatric species through resource partitioning (Schellekens et al 2010;Klecka and Boukal 2012;Wollrab et al 2013;Nilsson et al 2018;Rudolf and Eveland 2021). Hence, ontogenetic dietary shifts generally seem to balance consumer-resource dynamics and increase population and community resilience by reducing inter-and/or intraspecific competition (reviewed in Nakazawa 2015 andSánchez-Hernández et al 2019a).…”