José Cerca

University of Oslo · Centre for Ecological and Evolutionary Synthesis

Transposable elements (TEs) have been hypothesized to play a pivotal role in driving diversification by facilitating the emergence of novel phenotypes and the accumulation of divergence between species. The rapid speciation and ecological diversification characteristic of adaptive radiations offer a unique opportunity to examine the link between TE...

In the Galápagos Islands, much attention has been devoted to the radiation of iconic species like Darwin's finches, yet the Galápagos Islands offer an overlooked yet equally remarkable opportunity for investigating plant radiations. Using a combination of genomic and phenotypic data, we present evidence of the early stages of a radiation in prickly...

Whole-genome sequencing efforts has during the past decade unveiled the central role of genomic rearrangements - such as chromosomal inversions - in evolutionary processes, including local adaptation in a wide range of taxa. However, employment of reference genomes from distantly or even closely related species for mapping and the subsequent varian...

The ecological and phenotypic diversity observed in oceanic island radiations presents an evolutionary paradox: a high level of genetic variation is typically required for diversification, but species colonizing a new island commonly suffer from founder effects. This reduction in population size leads to lower genetic diversity, which ultimately re...

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...

Premise The lateral membranous expansions of fruits, commonly referred to as wings, have long been theorized to serve only dispersal functions. Alternatively, because winged fruits typically have earlier seed germination than unwinged fruits, we hypothesized that wings could increase the contact surface with water, ultimately triggering earlier ger...

The ecological and phenotypic diversity observed in oceanic island radiations presents an evolutionary paradox: a high level of genetic variation is typically required for diversification, but species colonizing a new island typically suffer from founder effects. This reduction in population size leads to a reduction in genetic diversity, which ult...

The Galapagos Islands are a prime example of a natural laboratory for the study of evolutionary radiations. While much attention has been devoted to iconic species like Darwin's finches, the islands offer an equally unique but often overlooked opportunity for plant radiations. Yet, compared to their animal counterparts, our understanding of the pat...

Anthropogenic impacts on the environment alter speciation processes by affecting both geographical contexts and selection patterns on a worldwide scale. Here we review evidence of these effects. We find that human activities often generate spatial isolation between populations and thereby promote genetic divergence but also frequently cause sudden...

Parallel and convergent evolution offer some of the most compelling evidence for the significance of natural selection in evolution, as the emergence of similar adaptive solutions is unlikely to occur by random chance alone. However, these terms are often employed inconsistently, leading to misinterpretation and confusion, and recently proposed def...

The repeated evolution of phenotypes provides clear evidence for the role of natural selection in driving evolutionary change. However, the evolutionary origin of repeated phenotypes can be difficult to disentangle as it can arise from a combination of factors such as gene flow, shared ancestral polymorphisms or mutation. Here, we investigate the p...

A recurring feature of oceanic archipelagos is the presence of adaptive radiations that generate endemic, species-rich clades that can offer outstanding insight into the links between ecology and evolution. Recent developments in evolutionary genomics have contributed towards solving long-standing questions at this interface. Using a comprehensive...

The repeated evolution of phenotypes is ubiquitous in nature and offers some of the clearest evidence of the role of natural selection in evolution. The genomic basis of repeated phenotypic evolution is often complex and can arise from a combination of gene flow, shared ancestral polymorphism and de novo mutation. Here, we investigate the genomic b...

Cryptic species are organisms which look identical, but which represent distinct evolutionary lineages. They are an emerging trend in organismal biology across all groups, from flatworms, insects, amphibians, primates, to vascular plants. This book critically evaluates the phenomenon of cryptic species and demonstrates how they can play a valuable...

The repeated, rapid and often pronounced patterns of evolutionary divergence observed in insular plants, or the ‘plant island syndrome’, include changes in leaf phenotypes, growth, as well as the acquisition of a perennial lifestyle. Here, we sequence and describe the genome of the critically endangered, Galápagos-endemic species Scalesia atractylo...

The East Greenland-Svalbard-Barents Sea (EGSB) bowhead whale stock (Balaena mysticetus) was hunted to near extinction and remains Endangered on the International Union of Conservation of Nature Red List. The intense, temporally extensive hunting pressure may have left the population vulnerable to other perturbations, such as environmental change. H...

Oceanic archipelagos comprise multiple disparate environments over small geographic areas and are isolated from other biotas. These conditions have led to some of the most spectacular adaptive radiations, which have been key to our understanding of evolution, and offer a unique chance to characterise the genomic basis underlying rapid and pronounce...

Marenzelleria Mesnil, 1896 is a small group of spionid polychaetes comprising five valid species, all of which appear similar to each other. The identification of worms based on morphological features is often confusing, and thus molecular data have been suggested as providing crucial additional diagnostic characters. Here we summarize and map avai...

Spiders (Araneae) have a diverse spectrum of morphologies, behaviours and physiologies. Attempts to understand the genomic-basis of this diversity are often hindered by their large, heterozygous and AT-rich genomes with high repeat content resulting in highly fragmented, poor-quality assemblies. As a result, the key attributes of spider genomes, in...

Adaptive radiations have proven important for understanding the mechanisms and processes underlying biological diversity. The convergence of form and function, as well as admixture and adaptive introgression, are common in adaptive radiations. However, distinguishing between these two scenarios remains a challenge for evolutionary research. The Mid...

Morphologically similar species, that is cryptic species, may be similar or quasi-similar owing to the deceleration of morphological evolution and stasis. While the factors underlying the deceleration of morphological evolution or stasis in cryptic species remain unknown, decades of research in the field of paleontology on punctuated equilibrium ha...

The restriction site‐associated DNA (RADseq) family of protocols involves digesting DNA and sequencing the region flanking the cut site, thus providing a cost and time‐efficient way for obtaining thousands of genomic markers. However, when working with non‐model taxa with few genomic resources, optimization of RADseq wet‐lab and bioinformatic tools...

The restriction site-associated DNA (RADseq) family of protocols involves digesting DNA and sequencing the region flanking the cut site, thus providing a cost and time efficient way for obtaining thousands of genomic markers. However, when working with non-model taxa with few genomic resources, optimization of RADseq wet-lab and bioinformatic tools...

Morphological stasis or the absence of morphological change is a well‐known phenomenon in the paleontological record, yet it is poorly integrated with neontological evidence. Recent evidence suggests that cryptic species complexes may remain morphologically identical due to morphological stasis. Here, we describe a case of long‐term stasis in the S...

The recognition of cryptic species concealed in traditionally established species can reveal new biogeographical patterns and alter the understanding of how biodiversity is geographically distributed. This is particularly relevant for marine ecosystems where the incidence of cryptic species is high and where species distribution data are often chal...

Genomic data has revolutionized biology. The vast amount of data produced by High Throughput Sequencing (HTS) technologies have provided solutions to long standing problems; such as long debated positions of taxa in the tree of life, and opened new venues of research in general like the investigation of genome-wide events such as inversions and sup...

PREMISE OF THE STUDY: Ray flowers commonly observed in daisies’ flowering heads are a well-know example of advertising structures for enhancing pollinator attraction. Despite this, ray loss has occurred in multiple lineages, which still rely on pollinators, suggesting that rayless phenotypes could also be adaptive for animal-pollination. Here, we i...

Cryptic species are detected at an ever‐increasing rate, mainly due to the application of molecular data. While the impact of this hidden diversity on macro‐ecology and conversation biology is widely recognized, its evolutionary significance is rarely. In recent years, it became apparent that definitions of cryptic species are too ambiguous to allo...

Many interstitial species were first described as widely distributed, often cosmopolitan or amphi-oceanic. These accounts contrasted descriptions of a sedentary life style and the general absence of pelagic dispersal stages, an inconsistency that became known as the meiofauna paradox. Recent application of genetic data unravelled the occurrence of...

The development and application of DNA sequencing in biology uncovered unrecognized diversity within previously established species – i.e. 'cryptic species'. At first sight, the unveiling of cryptic species suggested the occurrence of taxonomic artefacts and generated a discussion concerning revalidation of taxonomic practices. In this communicatio...

Many interstitial species were first described as widely distributed, often cosmopolitan or amphi-oceanic, contrasting with descriptions of a sedentary life style and the general absence of pelagic dispersal stages. These inconsistencies became known as the “meiofauna paradox”. In this review, we present a literature review investigating these inco...

The development and application of DNA sequencing in systematics uncovered unrecognized diversity within previously established species – i.e. 'cryptic species'. At first sight, the unveiling of cryptic species suggested the occurrence of taxonomic artefacts and generated a discussion focusing on revalidation of taxonomic practices. Nevertheless, a...

Cryptic species could represent a substantial fraction of biodiversity. However, inconsistent definitions and taxonomic treatment of cryptic species prevent informed estimates of their contribution to biodiversity and impede our understanding of their evolutionary and ecological significance. We propose a conceptual framework that recognizes crypti...

The development and application of DNA sequencing in systematics uncovered unrecognized diversity within previously established species – i.e. 'cryptic species'. At first sight, the unveiling of cryptic species suggested the occurrence of taxonomic artefacts and generated a discussion focusing on revalidation of taxonomic practices. Nevertheless, a...

In the last few decades evolutionary biologists have gathered overwhelming evidence of mechanisms which create and maintain biological diversity, e.g. natural selection, genetic drift, genome-wide rearrangements; and their potential synergetic and/or additive effects. Experimental and empirical approaches have demonstrated how fast genetic and morp...

Characterization and identification of interstitial meiofauna is challenging due to its small size, paucity of distinguishing characters, high degree of convergence and spatial patchiness. As a result, a high number of cosmopolitan meiofauna was reported, despite the absence of dispersal stage of these organisms. This phenomenon is known as the mei...

Marine populations were historically perceived as ‘open’ due to the lack of obvious barriers in the sea. Water column and marine currents were thus discussed as dispersal highways for pelagic larvae (e.g., larvae released to the water column), ultimately guaranteeing high genetic connectivity levels among extremely distant populations. In contrast...

The presence of cryptic species in some organismal groups is not by any means surprising. Interstitial taxa (i.e. organisms living between sand grains in marine sediments) are characterized by their small size, paucity of distinguishing characters and a high degree of convergence. As a result, many interstitial species have been regarded as cosmopo...

Hunting for deciduous azalea in the panhandle of Florida.

Success in hybridization native Northern American deciduous azaleas is greatly aided by knowing the ploidy level of both parents. We recommend hybridizers of deciduous azaleas desiring pest and disease resistance deciduous azaleas concentrate on tetraploid X tetraploid using the tetraploid North American species unless the goal is late bloom then c...

The advent of sequencing technologies enabled the discovery of hidden species lineages with considerable genetic diversity within originally described species (cryptic species). Considering the prominent role of species delimitation in biological sciences, failing to recognize these can result in misleading ecological and evolutionary conclusions....

This presentation on polyploids shows images of Rhododendrons and deciduous azaleas that have been tested for ploidy using flow cytometry. These images include information on a polyploid Rhododendron garden established in France, polyploid deciduous azaleas hybridized in New England, fertile triploid and pentaploid deciduous azaleas, and ploidy lev...

This presentation on polyploids shows images of Rhododendrons including Ledums and Menzesias that have been tested for ploidy using flow cytometry. These images include information on ploidy level and illustrate how in interploidy crosses the higher ploidy parent often dominates.

An exceptional model for understanding the selective mechanism underlying the great diversity of floral traits is provided by the floral polymorphism within the sunflower family (Asteraceae). Rayed capitula usually attract a larger number of pollinators, guaranteeing higher outcrossing rates while, on the other hand, rayless plants avoid costs of p...

Rhododendron enthusiasts may not know it, but they love polyploid hybrid elepidotes. Check any flower show bench and look at the finalists for awards. Mention Rhododendron ‘Cynthia’, ‘Gomer Waterer’, ‘Grace Seabrook’, ‘Horizon Monarch’, ‘Marinus Koster’, ‘Pink Pearl’, ‘Phyllis Korn’, ‘Point Defiance’, ‘Taurus’, or ‘Trude Webster’, and gardeners qui...

Since 1814 hybridization of elepidote Rhododendron subgenera Hymenanthes has involved exclusively starting with diploid species resulting in more than 20,000 named diploid hybrids. The first polyploid hybrid elepidote most likely appeared in 1840 when a triploid English hybrid named 'Broughtonii' resulted from the crossing of 2 diploid species. The...

The family tree for the elepidote Rhododendron cultivar 'The Duchess' shows a sixth generation polyploid that developed from diploid ancestor species but has 23 non-distinctive polyploids in its ancestry including 4 distinct triploids and 4 distinct tetraploids. This family tree, which spans nearly 150 years (1840 to 1986) of human hybridization of...

Most plants rely on pollinators for their reproductive success. To attract pollinators, plants display conspicuous structures such as rays in Asteraceae. Rayed plants usually attract more pollinators than rayless plants, however several independent reversals towards rayless capitula occurred in the evolutionary history, suggesting that rayless capi...

Premise of the study: In heterocarpy, fruits with different morphologies have been associated with alternative strategies of dispersal, germination, dormancy, and seedling competitive ability. In heterocarpic species, it is common to find fruits with competitive or dispersal syndromes. The competitive advantage of nondispersing fruits has been freq...

Rhododendron-Begeisterte wissen es vielleicht nicht, aber sie lieben polyploide, elepidote (nicht beschuppte) Hybriden. Sie müssen nur die Tische einer beliebigen Rhododendron-Schau prüfen und einen Blick auf die Finalisten für die Prämierungen werfen. Erwähnen Sie Rhododendron 'Cynthia', Rh. 'Gomer Waterer', Rh. 'Grace Seabrook', Rh. 'Horizon Mona...

The interest to study genome evolution, in particular genome size variation and polyploid incidence, has increased in recent years. Still, only a few studies have been focused at a community level. Of particular interest are high mountain species, because of the high frequency of narrow endemics and their higher susceptibility to extinction due to...

Hybridization can create natural hybrid zones where two related species mate and produce (some) viable hybrids. These areas are natural laboratories to investigate evolutionary processes and mechanisms operating in the organisms integrating them, especially gene flow and selective pressures on phenotypic traits. For example, hybrid zones often pres...

As dozens more rhododendrons with larger than normal ploidy levels are revealed below, we hope that gardeners begin to see the connection with characteristics of thickness in the leaf and firmness in flower substance. indeed, remarkable vigor and substance overall, coupled with outstanding floral performance at a young age, starts to make sense. ev...

Polyploidy plays an important role in plant evolution and diversification, contributing to reproductive isolation, increased heterozygosity, novel gene combinations and ultimately in divergence and speciation. For plant breeders, information on the ploidy level of individuals is fundamental as it can influence male and female fertility, cross ferti...