Biology subjects

Emanuel A. Fronhofer

Publications and source records attributed to Emanuel A. Fronhofer.

5 recordsLinked to original sources

bioRxiv2016

Information use shapes range expansion dynamics into environmental gradients

Globally, geographic distributions of species are dynamic and strongly influenced by dispersal. Vice versa, range dynamics feed back and may select for increased dispersal. This interplay almost universally happens across environmental gradients which can directly impact the fitness of organisms, but also provide individuals with information on the environmental changes. However, the organisms; ability to subsequently adjust dispersal decisions plastically has been largely ignored and the (macro)ecological consequences remain unclear. Using modeling and controlled experiments in replicated microcosm landscapes, we show that information on environmental gradients severely impacted range dynamics and inverted the spatial distribution of population densities in comparison to controls where this information was not provided. Additionally, information use prevented evolutionary changes in dispersal and an acceleration of range expansions. We demonstrate the strong impact of informed dispersal and subsequent behavioral changes on range dynamics in environmental gradients and spatial dynamics in general.

Evolutionary Biology↗

bioRxiv2015

Classical metapopulation dynamics and eco-evolutionary feedbacks in dendritic networks

Eco-evolutionary dynamics are now recognized to be highly relevant for population and community dynamics. However, the impact of evolutionary dynamics on spatial patterns, such as the occurrence of classical metapopulation dynamics, is less well appreciated. Here, we analyse the evolutionary consequences of spatial network connectivity and topology for dispersal strategies and quantify the eco-evolutionary feedback in terms of altered classical metapopulation dynamics. We find that network properties, such as topology and connectivity, lead to predictable spatio-temporal correlations in fitness expectations. These spatio-temporally stable fitness patterns heavily impact evolutionarily stable dispersal strategies and lead to eco-evolutionary feedbacks on landscape level metrics, such as the number of occupied patches, the number of extinctions and recolonizations as well as metapopulation extinction risk and genetic structure. Our model predicts that classical metapopulation dynamics are more likely to occur in dendritic networks, and especially in riverine systems, compared to other types of landscape configurations. As it remains debated whether classical metapopulation dynamics are likely to occur in nature at all, our work provides an important conceptual advance for understanding the occurrence of classical metapopulation dynamics which has implications for conservation and management of spatially structured populations.

Ecology↗

bioRxiv2015

Environmental DNA reveals that rivers are conveyer belts of biodiversity information

DNA sampled from the environment (eDNA) is becoming a game changer for uncovering biodiversity patterns. By combining a conceptual model and empirical data, we test whether eDNA transported in river networks can be used as an integrative way to assess eukaryotic biodiversity for broad spatial scales and across the land-water interface. Using an eDNA metabarcode approach we detected 296 families of eukaryotes, spanning 19 phyla across the catchment of a river. We show for a subset of these families that eDNA samples overcome spatial autocorrelation biases associated with classical community assessments by integrating biodiversity information over space. Additionally, we demonstrate that many terrestrial species can be detected; thus revealing that eDNA in river-water also incorporates biodiversity information across terrestrial and aquatic biomes. Environmental DNA transported in river networks offers a novel and spatially integrated way to assess total biodiversity for whole landscapes and will transform biodiversity data acquisition in ecology.\n\n\"Eventually, all things merge into one, 32 and a river runs through it.\" -- Norman Maclean

Ecology↗

bioRxiv2015

Informed movement and dispersal in experimental metacommunities

Dispersal, and the underlying movement behaviour, are processes of pivotal importance for understanding and predicting metapopulation and metacommunity dynamics. Generally, dispersal decisions are non-random and rely on information, such as the presence of conspecifics. However, studies on metacommunities that include interspecific interactions generally disregard information use. Therefore, it remains unclear whether and how dispersal in metacommunities is informed and whether rules derived from single-species contexts can be scaled up to (meta-)communities. Using experimental protist metacommunities, we show how dispersal and movement are informed and adjusted by the strength of inter-specific interactions. We found that predicting informed movement and dispersal in metacommunities requires knowledge on behavioural responses to intra- and inter-specific interaction strength. Consequently, metacommunity dynamics inferred directly from single-species metapopulations without taking inter-specific interactions into account are likely flawed. Our work identifies the significance of information use for understanding metacommunity dynamics, stability and the coexistence and distribution of species.\n\nAuthor contributionsAll authors designed the study. EAF and JK performed the experiments and analysed the data. EAF wrote the manuscript and all authors contributed substantially to revisions.

Ecology↗

bioRxiv2014

The downward spiral: eco-evolutionary feedback loops lead to the emergence of ‘elastic’ ranges

In times of severe environmental changes and resulting shifts in the geographical distribution of animal and plant species it is crucial to unravel the mechanisms responsible for the dynamics of species ranges. Without such a mechanistic understanding reliable projections of future species distributions are difficult to derive. Species ranges may be highly dynamic and subject to elastic behavior, i.e. a range contraction following a period of range expansion as a consequence of eco-evolutionary feedbacks due to (rapid) dispersal evolution. It has been proposed that this phenomenon occurs in habitat gradients, which are characterized by a negative cline in selection for dispersal from the range core towards the margin, as one may find with increasing patch isolation, for example. Using individual-based simulations we show in this study that the presence of Allee effects is a necessary condition for ranges to exhibit elastic behavior. A pronounced source/sink-structure at the range margin caused by Allee effects, leads to selection for decreased dispersal and subsequently to lowered colonization rates and increased local extinction risk. In addition, the nature of the gradient is crucial, as gradients which do not select for lower dispersal at the margin than in the core (patch size, growth rate, demographic stochasticity, extinction rate) did not lead to elastic range behavior.\n\nThus, we argue that range contractions are likely to occur after periods of expansion for species living in gradients of increasing patch isolation, which suffer from Allee effects.

Ecology↗