TY  - JOUR
A1  - Rolshausen, Gregor
A1  - Hallman, Uwe
A1  - Dal Grande, Francesco
A1  - Otte, Jürgen
A1  - Knudsen, Kerry
A1  - Schmitt, Imke
T1  - Expanding the mutualistic niche: parallel symbiont turnover along climatic gradients
T2  - Proceedings of the Royal Society of London. Series B, Biological sciences
N2  - Keystone mutualisms, such as corals, lichens or mycorrhizae, sustain fundamental ecosystem functions. Range dynamics of these symbioses are, however, inherently difficult to predict because host species may switch between different symbiont partners in different environments, thereby altering the range of the mutualism as a functional unit. Biogeographic models of mutualisms thus have to consider both the ecological amplitudes of various symbiont partners and the abiotic conditions that trigger symbiont replacement. To address this challenge, we here investigate 'symbiont turnover zones'--defined as demarcated regions where symbiont replacement is most likely to occur, as indicated by overlapping abundances of symbiont ecotypes. Mapping the distribution of algal symbionts from two species of lichen-forming fungi along four independent altitudinal gradients, we detected an abrupt and consistent β-diversity turnover suggesting parallel niche partitioning. Modelling contrasting environmental response functions obtained from latitudinal distributions of algal ecotypes consistently predicted a confined altitudinal turnover zone. In all gradients this symbiont turnover zone is characterized by approximately 12°C average annual temperature and approximately 5°C mean temperature of the coldest quarter, marking the transition from Mediterranean to cool temperate bioregions. Integrating the conditions of symbiont turnover into biogeographic models of mutualisms is an important step towards a comprehensive understanding of biodiversity dynamics under ongoing environmental change.
KW  - altitude-for-latitude
KW  - beta-diversity turnover
KW  - facilitation
KW  - lichen symbiosis
KW  - mutualist-mediated effects
KW  - range predictions
Y1  - 2020
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/82545
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-825456
VL  - 287
IS  - 20192311
PB  - The Royal Society
CY  - London
ER  -