Integrating experimental and distribution data to predict future species patterns

Abstract

Predictive species distribution models are mostly based on statistical dependence between environmental and distributional data and therefore may fail to account for physiological limits and biological interactions that are fundamental when modelling species distributions under future climate conditions. Here, we developed a state-of-the-art method integrating biological theory with survey and experimental data in a way that allows us to explicitly model both physical tolerance limits of species and inherent natural variability in regional conditions and thereby improve the reliability of species distribution predictions under future climate conditions. By using a macroalga-herbivore association (Fucus vesiculosus - Idotea balthica) as a case study, we illustrated how salinity reduction and temperature increase under future climate conditions may significantly reduce the occurrence and biomass of these important coastal species. Moreover, we showed that the reduction of herbivore occurrence is linked to reduction of their host macroalgae. Spatial predictive modelling and experimental biology have been traditionally seen as separate fields but stronger interlinkages between these disciplines can improve species distribution projections under climate change. Experiments enable qualitative prior knowledge to be defined and identify cause-effect relationships, and thereby better foresee alterations in ecosystem structure and functioning under future climate conditions that are not necessarily seen in projections based on non-causal statistical relationships alone.

Additive Multivariate Gaussian Processes for Joint Species Distribution Modeling with Heterogeneous Data

“…Hence, in extrapolation tasks stationary covariance functions may not be the optimal choice (Vanhatalo et al, 2012;Kallasvuo et al, 2017) and combining the multivariate GP models with functional constraints (e.g. Kotta et al, 2019) could improve their predictive performance further.…”

“…Even though this approach allows flexible modeling by describing the randomness of response variables with different probabilistic models (Nelder and Wedderburn, 1972), it is still limited by its parametric assumptions. Hence, it may fail to accurately describe a species' response to environmental conditions (Vanhatalo et al, 2012;Kotta et al, 2019). Here, we propose a semi-parametric JSDM model represented with multivariate Gaussian processes (GPs).…”

Exploratory and confirmatory research in the open science era

“…Such natural experiments provide researchers with the opportunity for a real‐world test of a hypothesis, and can be seen as ‘conceptual’ replications where different systems and approaches are used to test the same theory. A complementary approach is to integrate findings from small‐scale manipulative experiments into analysis of large‐scale observational data (Kotta et al, ). Such integration will necessitate closer collaboration between ecologists working at different spatial scales, and between experimentalists and modellers (Heuschele, Ekvall, Mariani, & Lindemann, ).…”

Geographic variation in fitness‐related traits of the bladderwrack Fucus vesiculosus along the Baltic Sea‐North Sea salinity gradient

“…active photosynthetic system of algae growing under favorable environmental conditions increases the synthesis of carbohydrates and other nutritious compounds, and therefore the palatability of F. vesiculosus for herbivores. This may be due to the inability of our bioassays to reliably detect the influences of highly watersoluble compounds(Jormalainen, Honkanen, Vesakoski, & Koivikko, 2005) or the less important role of phlorotannins in affecting the palatability of F. vesiculosus for I. balthica.The climate-induced desalination predicted for the end of the century is expected to produce a 30% contraction of the distribution of F. vesiculosus in the Baltic Sea(Jonsson et al, 2018;Kotta et al, 2019). Carbohydrates and mannitol in particular, are used by I. balthica and other crustaceans as feeding cues inthe assessment of the quality of different food items.…”

“…The higher concentration of phlorotannins (suggested as anti-grazing compounds,Koivikko et al, 2005) did not affect the palatability of high-salinity individuals. This may be due to the inability of our bioassays to reliably detect the influences of highly watersoluble compounds(Jormalainen, Honkanen, Vesakoski, & Koivikko, 2005) or the less important role of phlorotannins in affecting the palatability of F. vesiculosus for I. balthica.The climate-induced desalination predicted for the end of the century is expected to produce a 30% contraction of the distribution of F. vesiculosus in the Baltic Sea(Jonsson et al, 2018;Kotta et al, 2019). The rapid southward and westward expansions of low salinity conditions (with maximum velocities exceeding 100 km per decade)…”