Rekonstruktion der Zusammensetzung von Inselbiozönosen auf evolutionären Zeitskalen: Ein phylogenetischer Modellierungsansatz
Zusammenfassung der Projektergebnisse
Islands are ideal model systems to study ecology and evolution. They have well-defined borders, are naturally replicated, harbour unique species and processes, and are of high conservation priority. Biodiversity on islands is determined by colonisation, speciation and extinction, and these processes can be studied over evolutionary time scales using phylogenetic trees and modelling. The main objectives of this project were to reconstruct the pattern that island colonisation, speciation and extinction have left behind in the molecular phylogenies of taxa across multiple archipelagos worldwide and from this estimate how island features, historical events, diversity-dependence and anthropogenic extinctions have affected these processes on a global scale. The project aimed to produce a new baseline framework for the study of long-term evolutionary dynamics in isolated environments and deliver much anticipated answers to a topic with wide implications for macroevolution, biodiversity and conservation. The research activities of the project consisted on theoretical model development, implementation of the model in the freely available software package DAISIE (Dynamic Assembly of Islands through Speciation, Immigration and Extinction), molecular phylogenetic reconstructions and statistical and simulation analyses of island biodiversity. The main findings and outcomes of the project were: 1) We confirmed, for the first time, the theory of island biogeography proposed by MacArthur and Wilson in the 1960’s on evolutionary time scales. Using a large new global phylogenetic dataset of birds (produced during this project), we were able to estimate how rates of colonisation, speciation and extinction vary with area and isolation. Using a simple dynamic model of island biogeography developed in this project we were able to accurately reproduce observed numbers of bird species diversity in 41 archipelagos worldwide. 2) We demonstrated for the first time that the number of species of birds in some oceanic islands (north Atlantic, Macaronesia) have achieved an evolutionary equilibrium, so that the number of species remains constant through time as predicted by MacArthur and Wilson. 3) We developed a new metric termed the “evolutionary return time”, which measures how long it would take for island biotas to return to the diversity that was present at the time of human arrival, in other words, a measure of how much evolutionary time was lost due to anthropogenic extinction on islands. Using this metric, we found that 8 million years would be needed to return to pre-human diversity of noctilionoid bats in the Greater Antilles, and that 50 million years would be needed to return to pre-human diversity levels in New Zealand birds. 4) We greatly extended the model DAISIE to be able to study different types of equilibrium or non-equilibrium dynamics on islands, to be able to apply it to different types of islands (oceanic and non-oceanic) and to various types of datasets (e.g. large insular radiations with unknown colonisation times). All new software implementations were made freely available to the scientific community in the R package DAISIE. The research performed in this project was widely featured in the German and international media (four of the publications were featured in international newspapers, magazines and radio interviews). A good example was the study on birds of New Zealand (where we found that humans erased 50 million years of bird evolution in less than 300 years), which was widely reported in the German and international press as an alarming example of the severe impact that human-caused extinctions have had on island biotas. In summary, this project provided important new tests and extensions of the influential theory of island biogeography, developed new software tools for island biologists and provided important new evidence of the macroevolutionary impact of humans on the highly fragile ecosystems of islands.
Projektbezogene Publikationen (Auswahl)
- Mechanistic models in macroecology and biogeography: state-of-art and prospects. (2016) Ecography, 39, 1-14
Cabral JS, Valente L, Hartig F
(Siehe online unter https://doi.org/10.1111/ecog.02480) - Equilibrium bird species diversity in Atlantic islands. (2017) Current Biology, 27, 1660-1666
Valente L, Illera JC, Havenstein K, Pallien T, Etienne RS, Tiedemann R
(Siehe online unter https://doi.org/10.1016/j.cub.2017.04.053) - Recent extinctions disturb path to equilibrium diversity in Caribbean bats (2017) Nature Ecology and Evolution, 1, 26
Valente L, Etienne RS, Dávalos L
(Siehe online unter https://doi.org/10.1038/s41559-016-0026) - Using molecular phylogenies in island biogeography: it’s about time (2018) Ecography, 41, 1684-1686
Valente L, Phillimore AB, Etienne RS
(Siehe online unter https://doi.org/10.1111/ecog.03503) - Deep macroevolutionary impact of humans on New Zealand's unique avifauna (2019) Current Biology, 29, 2563-2569.e4
Valente L, Etienne RS, Garcia-R JC
(Siehe online unter https://doi.org/10.1016/j.cub.2019.06.058) - A simple dynamic model explains island bird diversity worldwide (2020) Nature, 579, 92-96
Valente L, Phillimore AB, Melo M, Warren BH, Clegg SM, Havenstein K, Tiedemann R, Illera JC, Thébaud C, Aschenbach T, Etienne RS
(Siehe online unter https://doi.org/10.1038/s41586-020-2022-5) - Lake expansion elevates equilibrium diversity via increasing colonisation (2020) Journal of Biogeography
Hauffe T, Delicado D, Etienne RS, Valente L
(Siehe online unter https://doi.org/10.1111/jbi.13914)
