Biology subjects

Florian Altermatt

Publications and source records attributed to Florian Altermatt.

6 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↗

bioRxiv2016

Demographic stochasticity and resource autocorrelation control biological invasions in heterogeneous landscapes

Classical models of biological invasions assess species spread in homogeneous landscapes by assuming constant growth rates and random local movement. Mounting evidence suggests, however, that demographic stochasticity, environmental heterogeneity and non-random movement of individuals affect considerably the spread dynamics. Here, we show that the dynamics of biological invasions are controlled by the spatial heterogeneity of the resource distribution. We show theoretically that increasing the landscape resource autocorrelation length causes a reduction in the average speed of species spread. Demographic stochasticity plays a key role in the slowdown, which is streghtened when individuals can actively move towards resources. The reduction in the front propagation speed is verified in laboratory microcosm experiments with the flagellated protist Euglena gracilis by comparing spread in habitats characterized by different resource heterogeneity. Our theoretical and experimental findings highlight the need to account for the intrinsic stochasticity of population dynamics to describe spread in spatially extended landscapes, which are inevitably characterized by heterogeneous spatial distributions of resources controlling vital rates. Our work identifies the resource autocorrelation length as a key modulator and a simple measure of landscape susceptibility to biological invasions, with implications for predicting the characters of biological invasions within naturally heterogeneous environmental corridors.

Ecology↗

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↗

bioRxiv2015

The Ecological Forecast Horizon, and examples of its uses and determinants

1Forecasts of ecological dynamics in changing environments are increasingly important, and are available for a plethora of variables, such as species abundance and distribution, community structure, and ecosystem processes. There is, however, a general absence of knowledge about how far into the future, or other dimensions (space, temperature, phylogenetic distance), useful ecological forecasts can be made, and about how features of ecological systems relate to these distances. The ecological forecast horizon is the dimensional distance for which useful forecasts can be made. Five case studies illustrate the influence of various sources of uncertainty (e.g. parameter uncertainty, environmental , and demographic stochasticity, evolution), level of ecological organisation (e.g. population or community), organismal properties (e.g. body size or number of trophic links) on temporal, spatial, and phylogenetic forecast horizons. Insights from these case studies demonstrate that the ecological forecast horizon is a flexible and powerful tool for researching and communicating ecological predictability. It also has potential for motivating and guiding agenda setting for ecological forecasting research and development.

Ecology↗