
Ole SeehausenUniversität Bern + Eawag Swiss Federal Institute for Aquatic Science and Technology
Ole Seehausen
PhD
About
561
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Introduction
I study the ecology, genetics and evolution of species diversity, mostly - but not exclusively - in fish. I seek understanding of causes of variation between evolutionary lineages in rates and mechanisms of diversification, in their current diversity, and in the rates of loss of diversity. I use methods from ecology, behaviour, morphology, population and phylogenetics and genomics.
Additional affiliations
June 2001 - August 2001
June 2004 - present
January 2001 - May 2004
Publications
Publications (561)
Human pressures, particularly urbanisation and agricultural expansion, profoundly affect biodiversity by reshaping species and functional trait distributions, with critical consequences for ecosystem resilience and multifunctionality. Yet, the extent and strength of these impacts across diverse taxa and ecosystems remain poorly understood. Here, we...
Ring species provide a valuable framework for studying intermediate steps of speciation resulting in two new species. Classic examples of ring species have involved large spatial and temporal scales-and this is partly why few idealised cases exist. In contrast, we focus on two species complexes of cichlid fishes from Southern Lake Victoria that evo...
It remains unknown how species’ populations across their geographic range are constrained by multiple coincident natural and anthropogenic environmental gradients. Conservation actions are likely undermined without this knowledge because the relative importance of the multiple anthropogenic threats is not set within the context of the natural deter...
A genomic database of all Earth’s eukaryotic species could contribute to many scientific discoveries; however, only a tiny fraction of species have genomic information available. In 2018, scientists across the world united under the Earth BioGenome Project (EBP), aiming to produce a database of high-quality reference genomes containing all ~1.5 mil...
Gerade in Seen und Gewässern nimmt die Biodiversität mit einer beispiellosen Geschwindigkeit ab. Bei den Bemühungen, diesen Verlust zu stoppen, werden die Wichtigkeit fundierter Artenkenntnisse und die Beschreibung unbekannter Arten häufig unterschätzt. Dies, obwohl sie die Grundlage sind für das Verständnis der vorhandenen Biodiversität, ihrer geo...
African cichlids are model systems for evolutionary studies and host-parasite interactions, because of their adaptive radiations and because they harbour many species of monogenean parasites with high host-specificity. Five locations were sampled in southern Lake Victoria: gill-infecting monogeneans were surveyed from 18 cichlid species belonging t...
River habitats are fragmented by barriers which impede the movement and dispersal of aquatic organisms. Restoring habitat connectivity is a primary objective of nature conservation plans with multiple efforts to strategically restore connectivity at local, regional, and global scales. However, current approaches to prioritize connectivity restorati...
Reciprocal effects of adaptive radiations on the evolution of interspecific interactions, like parasitism, remain barely explored. We test whether the recent radiations of European whitefish (Coregonus spp.) across and within perialpine and subarctic lakes promote its parasite Proteocephalus fallax (Platyhelminthes: Cestoda) to undergo host reperto...
Discerning ecosystem change and food web dynamics underlying anthropogenic eutrophication and the introduction of non-native species is necessary for ensuring the long-term sustainability of fisheries and lake biodiversity. Previous studies of eutrophication in Lake Victoria, eastern Africa, have focused on the loss of endemic fish biodiversity ove...
Understanding the processes that drive phenotypic diversification and underpin speciation is key to elucidating how biodiversity has evolved. Although these processes have been studied across a wide array of clades, adaptive radiations (ARs), which are systems with multiple closely related species and broad phenotypic diversity, have been particula...
River habitats are fragmented by barriers which impede the movement and dispersal of aquatic organisms. Restoring habitat connectivity is a primary objective of nature conservation plans with multiple efforts to strategically restore connectivity at local, regional, and global scales. However, current approaches to prioritize connectivity restorati...
Damselfishes (Pomacentridae) are one of the most behaviourally diverse, colourful and species-rich reef fish families. One remarkable characteristic of damselfishes is their communication in ultraviolet (UV) light. Not only are they sensitive to UV, they are also prone to have UV-reflective colours and patterns enabling social signalling. Using mor...
The Lake Victoria ecosystem is emblematic of the catastrophic effects that human activities, particularly cultural eutrophication, can have on freshwater biodiversity. However, little is known about the long-term spatial and temporal pattern of aquatic primary paleo-production (PPaq) and producer communities in Lake Victoria and how these patterns...
Lake Victoria is well known for its high diversity of endemic fish species and provides livelihoods for millions of people. The lake garnered widespread attention during the twentieth century as major environmental and ecological changes modified the fish community with the extinction of approximately 40% of endemic cichlid species by the 1980s. Su...
Hybridization, or interbreeding between different taxa, was traditionally considered to be rare and to have a largely detrimental impact on biodiversity, sometimes leading to the breakdown of reproductive isolation and even to the reversal of speciation. However, modern genomic and analytical methods have shown that hybridization is common in some...
Rising temperatures are leading to increased prevalence of warm-affinity species in ecosystems, known as thermophilisation. However, factors influencing variation in thermophilisation rates among taxa and ecosystems, particularly freshwater communities with high diversity and high population decline, remain unclear. We analysed compositional change...
Intrinsic postzygotic hybrid incompatibilities are usually due to negative epistatic interactions between alleles from different parental genomes. While such incompatibilities are thought to be uncommon in speciation with gene flow, they may be important if such speciation results from a hybrid population. Here we aimed to test this idea in the end...
Developmental shifts in gene regulation underlying key innovations remain largely uncharacterised at short evolutionary timescales. Here we investigate the gene expression and alternative splicing landscape of trophic innovations in the fastest vertebrate adaptive radiation: cichlid fishes from Lake Victoria. Using whole-transcriptomes of the oral...
Divergent ecological character displacement (ECD) is the competition-driven divergence in resource use-related phenotypic traits between coexisting species. It is considered one of the primary drivers of ecological diversification and adaptive radiation. We analyzed phenotypic and ecological variation in two African annual killifish species of the...
Across the globe, the spatial distribution of species and of biodiversity is driven by multiple geographically overlapping environmental gradients. Underpinning this variation is the fact that a species occurs only in certain locations, but not others.
It remains unknown how species’ populations across their geographic range are constrained by mul...
Work on the Lake Victoria cichlids Pundamilia nyererei (red dorsum males, deeper water), Pundamilia pundamilia (blue males, shallower water) and related species pairs has provided insights into processes of speciation. Here, we investigate female mating behaviour of five Pundamilia species and four of their F1-hybrids through mate choice trials and...
Genomic diversity is associated with the adaptive potential of a population and thereby impacts the extinction risk of a species during environmental change. However, empirical data on genomic diversity of populations before environmental perturbations are rare and hence our understanding of the impact of perturbation on diversity is often limited....
Lake Tanganyika’s pelagic fish sustain the second largest inland fishery in Africa and are under pressure from heavy fishing and global warming related increases in stratification. The strength of water column stratification varies regionally, with a more stratified north and an upwelling-driven, biologically more productive south. Only little is k...
Reconstructing hydrological variability is critical for understanding Lake Victoria's ecosystem history, the evolution of its diverse endemic fish community, the dynamics of vegetation in the catchment, and the dispersal of aquatic and terrestrial fauna in the East African Rift system during Latest Pleistocene and Holocene times. Whereas consensus...
Im Rahmen des Projekts LANAT-3 wollen Forschende der Universität Bern und der Eawag zusammen mit dem Schweizerischen Kompetenzzentrum Fischerei evidenz-basierte Ansätze für
ein integrales Gewässermanagement entwickeln mit dem Ziel, die Biodiversität der Gewässer zu
erhalten, wiederherzustellen und deren Resilienz gegenüber Klimaveränderungen zu stä...
Tropical freshwater lakes are well known for their high biodiversity, and particularly the East African Great Lakes are renowned for their adaptive radiation of cichlid fishes. While comparative phylogenetic analyses of extant species flocks have revealed patterns and processes of their diversification, little is known about evolutionary trajectori...
Adaptive radiations have been instrumental in generating a considerable amount of life’s diversity. Ecological opportunity is thought to be a prerequisite for adaptive radiation ¹ , but little is known about the relative importance of species’ ecological versatility versus effects of arrival order in determining which lineage radiates ² . Palaeonto...
Although some lineages of animals and plants have made impressive adaptive radiations when provided with ecological opportunity, the propensities to radiate vary profoundly among lineages for unknown reasons. In Africa’s Lake Victoria region, one cichlid lineage radiated in every lake, with the largest radiation taking place in a lake less than 16,...
Intrinsic postzygotic hybrid incompatibilities are usually due to negative epistatic interactions between alleles from different parental genomes. While such incompatibilities are thought to be uncommon in speciation with gene flow, they may be important if such speciation results from a hybrid population. Here we aimed to test this idea in the end...
A large collection of cichlids (N = 133) from Lake Victoria in Africa, with total lengths ranging from 6 to 18 cm was nondestructively imaged using micro-computed tomography. We present a method to efficiently obtain three-dimensional tomographic datasets of the oral and pharyngeal jaws and the whole skull of these fishes to accurately describe the...
The Adriatic brook lamprey, Lampetra zanandreai Vladykov 1955, was described from northeastern Italy. Its distribution is thought to include left tributaries of the River Po and the river basins of the Adriatic Sea from the River Po to the River Isonzo/Soča in Italy, Switzerland and Slovenia. It also shows a geographically isolated distribution in...
Hosts often harbour multiple parasite species, that may interact and thus modify each other’s effects on host fitness. These interspecific interactions between parasites may result in parasites occupying different niches within hosts (niche segregation). The within-host distribution of different parasite taxa may constitute an important axis of inf...
Global change alters the stability of biological communities by affecting species richness and how species covary through time (i.e., synchrony). There are few large-scale empirical tests of stability-diversity-synchrony relationships and those mostly focus on the terrestrial realm. Moreover, the effect of synchrony is largely unknown when species...
Hybridization following secondary contact of genetically divergent populations can influence the range expansion of invasive species, though specific outcomes depend on the environmental dependence of hybrid fitness. Here, using two genetically and ecologically divergent threespine stickleback lineages that differ in their history of freshwater col...
Because of potentially strong eco-evolutionary interactions with their hosts, parasites may initiate or enhance host diversification. The adaptive radiation of cichlid fish in Lake Victoria provides a good system to study the role of parasites at different stages of host speciation. We analysed the macroparasite infection of four replicates of symp...
Hybridization can rapidly generate novel genetic variation, which can promote ecological speciation by creating novel adaptive phenotypes. However, it remains unclear how hybridization, creating novel mating phenotypes (e.g., mating season, genitalia shapes, sexual displays, mate preferences), affects speciation especially when the phenotypes do no...
Tropical freshwater lakes are well-known for their high biodiversity, and the East African Great Lakes in particular are renowned for their endemic cichlid fish adaptive radiations. While comparative phylogenetic analyses of extant species flocks have revealed patterns and processes of their diversification, evolutionary trajectories within lineage...
A large collection of cichlids from Lake Victoria in Africa spanning a length range of 6 to 18 cm was nondestructively imaged using micro-computed tomography. We describe our method to efficiently obtain three-dimensional tomographic datasets of the oral and pharyngeal jaws and the whole skull of these fishes for accurately describing their morphol...
The taxonomy of the endemic whitefish of the lakes of the Reuss River system (Lucerne, Sarnen, Zug) and Lake Sempach, Switzerland, is reviewed and revised. Lake Lucerne harbours five species. Coregonus intermundia sp. nov. and C. suspensus sp. nov. , are described. Coregonus nobilis Haack, 1882, C. suidteri Fatio, 1885, and C. zugensis Nüsslin, 188...
Fire regimes differ across tropical and subtropical biomes depending on multiple parameters whose interactions and levels of importance are poorly understood, particularly at multidecadal and longer time scales. In the catchment of Lake Victoria, savanna, rainforest, and Afromontane vegetation have interspersed over the last 17,000 years, which may...
Most of the 500+ cichlid species of Lake Victoria evolved very rapidly in the wake of an adaptive radiation within the last 15’000 years. All 500 species have evolved from just one out of five old cichlid lineages that colonized the lake. Endemic to the Lake Victoria region, Astatoreochromis alluaudi is a member of an old haplochromine lineage that...
Studying phenotypic and genetic differentiation between very young species can be very informative with regard to learning about processes of speciation. Identifying and characterizing genetic species structure and distinguishing it from spatial genetic structure within a species is a prerequisite for this and is often not given sufficient attentio...
Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrativ...
Metabarcoding of environmental DNA (eDNA) is a powerful tool for describing biodiversity, such as finding keystone species or detecting invasive species in environmental samples. Continuous improvements in the method and the advances in sequencing platforms over the last decade have meant this approach is now widely used in biodiversity sciences an...
Lineages with independent evolutionary histories often differ in both their morphology and diet. Experimental work has improved our understanding of the links between the biomechanics of morphological traits and foraging performance (trait utility). However, because the expression of foraging-relevant traits and their utility can be highly context-...
Coral reef fishes are diverse in ecology and behaviour and show remarkable colour variability. Investigating the visual pigment gene (opsin) expression in these fishes makes it possible to associate their visual genotype and phenotype (spectral sensitivities) to visual tasks, such as feeding strategy or conspecific detection. By studying all major...
Anthropogenic disturbances of ecosystems are causing a loss of biodiversity at an unprecedented rate. Species extinctions often leave ecological niches underutilized, and their colonization by other species may require new adaptation. In Lake Constance, an endemic profundal whitefish species went extinct during a period of anthropogenic eutrophicat...
While aquatic (blue) and terrestrial (green) food webs are parts of the same landscape, it remains unclear whether they respond similarly to shared environmental gradients. We use empirical community data from hundreds of sites across Switzerland and a synthesis of interaction information in the form of a metaweb to show that inferred blue and gree...
Quaternary climate fluctuations can affect speciation in regional biodiversity assembly in two non-mutually exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation in underused adaptive zones during ice-free periods. We detected biogeographic and genetic signatures associa...
Adaptive radiations represent some of the most remarkable explosions of diversification across the tree of life. However, the constraints to rapid diversification and how they are sometimes overcome, particularly the relative roles of genetic architecture and hybridization, remain unclear. Here, we address these questions in the Alpine whitefish ra...
Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with even greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integ...
Evolution of trophic diversity is a hallmark of adaptive radiation. Yet, transitions between carnivory and herbivory are rare in young adaptive radiations. Haplochromine cichlid fish of the African Great Lakes are exceptional in this regard. Lake Victoria was colonized by an insectivorous generalist and in less than 20 000 years, several clades of...
Ecosystem degradation and biodiversity loss are major global challenges. When reproductive isolation between species is contingent on the interaction of intrinsic lineage traits with features of the environment, environmental change can weaken reproductive isolation and result in extinction through hybridization. By this process called speciation r...
Ontogenetic diet shifts, where individuals change their resource use during development, are the rule rather than the exception in the animal world. Here, we aim to understand how such changes in diet during development affect the conditions for an adaptive radiation in the presence of ecological opportunity. We use a size-structured consumer–resou...
Build a major genomics resource on the continent to help breeders and conservationists.
Intraspecific colour polymorphisms (CPs) present unique opportunities to study fundamental evolutionary questions, such as the link between ecology and phenotype, mechanisms maintaining genetic diversity and their putative role in speciation. Wrasses are highly diverse in ecology and morphology and harbour a variety of colour-polymorphic species. I...
Adaptive radiations represent some of the most remarkable explosions of diversification across the tree of life. However, the constraints to rapid diversification and how they are sometimes overcome, particularly the relative roles of genetic architecture and hybridization, remain unclear. Here, we address these questions in the Alpine whitefish ra...
The cover image is based on the Viewpoint A global agenda for advancing freshwater biodiversity research by Alain Maasri et al., https://doi.org/10.1111/ele.13931. Image Credit: Solvin Zankl. image
The field of paleolimnology has made tremendous progress in reconstructing past biotic and abiotic environmental conditions of aquatic ecosystems based on sediment records. This, together with the rapid development of molecular technologies, provides new opportunities for studying evolutionary processes affecting lacustrine communities over multice...
Progress in genome sequencing now enables the large-scale generation of reference genomes. Various international initiatives aim to generate reference genomes representing global biodiversity. These genomes provide unique insights into genomic diversity and architecture, thereby enabling comprehensive analyses of population and functional genomics,...
Adaptive radiations are known for rapid niche diversification in response to ecological opportunity. While most resources usually exist prior to adaptive radiation, novel niches associated with novel resources can be created as a clade diversifies. For example, in African lake cichlid radiations some species prey upon other species of the clade (in...
While aquatic (blue) and terrestrial (green) food webs are parts of the same landscape, it remains unclear whether they respond similarly to shared environmental gradients. We use empirical community data from hundreds of sites across Switzerland, and show that blue and green food webs have different structural and ecological properties along eleva...
Quaternary climate fluctuations can affect biodiversity assembly through speciation in two non-mutually-exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation during ice-free periods. Here we detected biogeographic and genetic signatures associated with both mechanisms in...
Understanding genetic connectivity plays a crucial role in species conservation decisions, and genetic connectivity is an important component of modern fisheries management. In this study, we investigated the population genetics of four endemic Lates species of Lake Tanganyika (Lates stappersii, L. microlepis, L. mariae and L. angustifrons) using r...