Weak integration allows novel fin shapes and spurs locomotor diversity in reef fishes.

In complex functional systems composed of many traits, selection for specialized function can induce trait evolution by acting directly on individual components within the system, or indirectly through networks of trait integration. However, strong integration can also hinder diversification into regions of trait space that are not aligned with axes of covariation among traits. As a result, non-independence among traits may limit capacity for functional expansion.

Complexity and weak integration promote the diversity of reef fish oral jaws.

Major trade-offs often manifest as axes of diversity in organismal functional systems. Overarching trade-offs may result in high trait integration and restrict the trajectory of diversification to be along a single axis. Here, we explore the diversification of the feeding mechanism in coral reef fishes to establish the role of trade-offs and complexity in a spectacular ecological radiation.

High-latitude ocean habitats are a crucible of fish body shape diversification.

A decline in diversity from the equator to the poles is a common feature of Earth's biodiversity. Here, we examine body shape diversity in marine fishes across latitudes and explore the role of time and evolutionary rate in explaining the diversity gradient. Marine fishes' occupation of upper latitude environments has increased substantially over the last 80 million years.

Replicated Functional Evolution in Cichlid Adaptive Radiations.

AbstractAdaptive radiations highlight the mechanisms by which species and traits diversify and the extent to which these patterns are predictable. We used 1,110 high-speed videos of suction feeding to study functional and morphological diversification in 300 cichlid species from three African Great Lake radiations of varying ages (Victoria, Malawi, and Tanganyika) and an older, spatially dispersed continental radiation in the Neotropics. Among African radiations, standing diversity was reflective of time.

Deep sea evolution: Glowing lures, parasitic males and rapid speciation in anglerfishes.

Anglerfish are creatures of the deep ocean, featuring glowing lures, huge, toothy mouths and parasitic males physically attached to females. A new study finds that genomic degradation of the immune system facilitated the origin of parasitic males as anglerfishes invaded the deep zone where they experienced an adaptive radiation.

Feeding kinematics of a surgeonfish reveal novel functions and relationships to reef substrata.

Biting to obtain attached benthic prey characterizes a large number of fish species on coral reefs, and is a feeding mode that contributes to important ecosystem functions. We use high-speed video to reveal the mechanisms used by a surgeonfish, Acanthurus leucosternon, to detach algae. After gripping algae in its jaws, the species pulls it by ventrally rotating both the head and the closed jaws, in a novel use of the intra-mandibular joint.

The cichlid pharyngeal jaw novelty enhances evolutionary integration in the feeding apparatus.

The modified pharyngeal jaw system of cichlid fishes is widely viewed as a key innovation that substantially facilitated the evolutionary exuberance of this iconic evolutionary radiation. We conduct comparative phylogenetic analyses of integration, disparity, and rate of evolution among feeding-related, skeletal structures in Neotropical cichlids and North American centrarchids, which lack the specialized pharyngeal jaw. Contrasting evolutionary patterns in these two continental radiations, we test a classic decoupling hypothesis.

Alternating regimes of shallow and deep-sea diversification explain a species-richness paradox in marine fishes.

The deep sea contains a surprising diversity of life, including iconic fish groups such as anglerfishes and lanternfishes. Still, >65% of marine teleost fish species are restricted to the photic zone <200 m, which comprises less than 10% of the ocean's total volume. From a macroevolutionary perspective, this paradox may be explained by three hypotheses: 1) shallow water lineages have had more time to diversify than deep-sea lineages, 2) shallow water lineages have faster rates of speciation than deep-sea lineages, or 3) shallow-to-deep sea transition rates limit deep-sea richness.

The rise of biting during the Cenozoic fueled reef fish body shape diversification.

Diversity of feeding mechanisms is a hallmark of reef fishes, but the history of this variation is not fully understood. Here, we explore the emergence and proliferation of a biting mode of feeding, which enables fishes to feed on attached benthic prey. We find that feeding modes other than suction, including biting, ram biting, and an intermediate group that uses both biting and suction, were nearly absent among the lineages of teleost fishes inhabiting reefs prior to the end-Cretaceous mass extinction, but benthic biting has rapidly increased in frequency since then, accounting for about 40% of reef species today.

FishShapes v1: Functionally relevant measurements of teleost shape and size on three dimensions.

Teleost fishes account for 96% of all fish species and exhibit a spectacular variety of body forms. Teleost lineages range from deep bodied to elongate (e.g.

Prolonged morphological expansion of spiny-rayed fishes following the end-Cretaceous.

Spiny-rayed fishes (Acanthomorpha) dominate modern marine habitats and account for more than a quarter of all living vertebrate species. Previous time-calibrated phylogenies and patterns from the fossil record explain this dominance by correlating the origin of major acanthomorph lineages with the Cretaceous-Palaeogene mass extinction. Here we infer a time-calibrated phylogeny using ultraconserved elements that samples 91.

Phylogenomic analysis of Syngnathidae reveals novel relationships, origins of endemic diversity and variable diversification rates.

Background: Seahorses, seadragons, pygmy pipehorses, and pipefishes (Syngnathidae, Syngnathiformes) are among the most recognizable groups of fishes because of their derived morphology, unusual life history, and worldwide distribution. Despite previous phylogenetic studies and recent new species descriptions of syngnathids, the evolutionary relationships among several major groups within this family remain unresolved.

Results: Here, we provide a reconstruction of syngnathid phylogeny based on genome-wide sampling of 1314 ultraconserved elements (UCEs) and expanded taxon sampling to assess the current taxonomy and as a basis for macroevolutionary insights.

A novel intramandibular joint facilitates feeding versatility in the sixbar distichodus.

The intramandibular joint (IMJ) is a secondary point of movement between the two major bones of the lower jaw. It has independently evolved in several groups of teleost fishes, each time representing a departure from related species in which the mandible functions as a single structure rotating only at the quadratomandibular joint (QMJ). In this study, we examine kinematic consequences of the IMJ novelty in a freshwater characiform fish, the herbivorous Distichodus sexfasciatus.

Divergent Processes Drive Parallel Evolution in Marine and Freshwater Fishes.

Evolutionary comparisons between major environmental divides, such as between marine and freshwater systems, can reveal the fundamental processes governing diversification dynamics. Although processes may differ due to the different scales of their biogeographic barriers, freshwater and marine environments nevertheless offer similar opportunities for diversification in benthic, demersal, and pelagic habitats. Here, we compare the evolutionary patterns and processes shaping teleost diversity in each of these three habitats and between marine and freshwater systems.

The Effect of Locomotion Mode on Body Shape Evolution in Teleost Fishes.

Teleost fishes vary in their reliance on median and paired fins (MPF) or undulation of the body (BCF) to generate thrust during straight-line, steady swimming. Previous work indicates that swimming mode is associated with different body shapes, though this has never been empirically demonstrated across the diversity of fishes. As the body does not play as active a mechanical role in steady swimming by MPF swimmers, this may relax constraints and spur higher rates of body shape diversification.

Constraints on the Ecomorphological Convergence of Zooplanktivorous Butterflyfishes.

Whether distantly related organisms evolve similar strategies to meet the demands of a shared ecological niche depends on their evolutionary history and the nature of form-function relationships. In fishes, the visual identification and consumption of microscopic zooplankters, selective zooplanktivory, is a distinct type of foraging often associated with a suite of morphological specializations. Previous work has identified inconsistencies in the trajectory and magnitude of morphological change following transitions to selective zooplanktivory, alluding to the diversity and importance of ancestral effects.

The deep sea is a hot spot of fish body shape evolution.

Deep-sea fishes have long captured our imagination with striking adaptations to life in the mysterious abyss, raising the possibility that this cold, dark ocean region may be a key hub for physiological and functional diversification. We explore this idea through an analysis of body shape evolution across ocean depth zones in over 3000 species of marine teleost fishes. We find that the deep ocean contains twice the body shape disparity of shallow waters, driven by elevated rates of evolution in traits associated with locomotion.

Driving quality improvement with a massive open online course (MOOC).

Background: Quality improvement (QI) is a priority for national regulatory bodies in health and care in the UK. However, many health and care staff do not know where to go for support in gaining the required skills and knowledge in QI. This paper reviews Improvement Fundamentals, a massive open online course (MOOC), designed to address this gap, run by an improvement team in the national regulatory body.

Anatomical basis of diverse jaw protrusion directionality in ponyfishes (Family Leiognathidae).

Protrusion of the oral jaws is a key morphological innovation that enhances feeding performance in fishes. The mechanisms of protrusion and the basis of variation in its magnitude are well studied, but little attention has been paid to the functional morphology of protrusion directionality, despite wide variation among teleost species from slightly dorsal to strongly ventral. Ponyfishes (Leiognathidae) comprise a group of 52 species that exhibit striking diversity in the directionality of jaw protrusion, providing a promising system for exploring its underlying basis in a single clade.

A Multifunction Trade-Off has Contrasting Effects on the Evolution of Form and Function.

Trade-offs caused by the use of an anatomical apparatus for more than one function are thought to be an important constraint on evolution. However, whether multifunctionality suppresses diversification of biomechanical systems is challenged by recent literature showing that traits more closely tied to trade-offs evolve more rapidly. We contrast the evolutionary dynamics of feeding mechanics and morphology between fishes that exclusively capture prey with suction and multifunctional species that augment this mechanism with biting behaviors to remove attached benthic prey.

Do key innovations unlock diversification? A case-study on the morphological and ecological impact of pharyngognathy in acanthomorph fishes.

Key innovations may allow lineages access to new resources and facilitate the invasion of new adaptive zones, potentially influencing diversification patterns. Many studies have focused on the impact of key innovations on speciation rates, but far less is known about how they influence phenotypic rates and patterns of ecomorphological diversification. We use the repeated evolution of pharyngognathy within acanthomorph fishes, a commonly cited key innovation, as a case study to explore the predictions of key innovation theory.

Body shape diversification along the benthic-pelagic axis in marine fishes.

Colonization of novel habitats can result in marked phenotypic responses to the new environment that include changes in body shape and opportunities for further morphological diversification. Fishes have repeatedly transitioned along the benthic-pelagic axis, with varying degrees of association with the substrate. Previous work focusing on individual lineages shows that these transitions are accompanied by highly predictable changes in body form.

Correlated Evolution of Sex Allocation and Mating System in Wrasses and Parrotfishes.

In accordance with predictions of the size-advantage model, comparative evidence confirms that protogynous sex change is lost when mating behavior is characterized by weak size advantage. However, we lack comparative evidence supporting the adaptive significance of sex change. Specifically, it remains unclear whether increasing male size advantage induces transitions to protogynous sex change across species, as it can within species.

Decoupled jaws promote trophic diversity in cichlid fishes.

Functional decoupling of oral and pharyngeal jaws is widely considered to have expanded the ecological repertoire of cichlid fishes. But, the degree to which the evolution of these jaw systems is decoupled and whether decoupling has impacted trophic diversification remains unknown. Focusing on the large Neotropical radiation of cichlids, we ask whether oral and pharyngeal jaw evolution is correlated and how their evolutionary rates respond to feeding ecology.