On the Measurement of Ecological Novelty: Scale-Eating Pupfish Are Separated by 168 my from Other Scale-Eating Fishes

The colonization of new adaptive zones is widely recognized as one of the hallmarks of adaptive radiation. However, the adoption of novel resources during this process is rarely distinguished from phenotypic change because morphology is a common proxy for ecology. How can we quantify ecological novelty independent of phenotype? Our study is split into two parts: we first document a remarkable example of ecological novelty, scale-eating (lepidophagy), within a rapidly-evolving adaptive radiation of Cyprinodon pupfishes on San Salvador Island, Bahamas. This specialized predatory niche is known in several other fish groups, but is not found elsewhere among the 1,500 species of atherinomorphs. Second, we quantify this ecological novelty by measuring the time-calibrated phylogenetic distance in years to the most closely-related species with convergent ecology. We find that scale-eating pupfish are separated by 168 million years of evolution from the nearest scale-eating fish. We apply this approach to a variety of examples and highlight the frequent decoupling of ecological novelty from phenotypic divergence. We observe that novel ecology is not always tightly correlated with rates of phenotypic or species diversification, particularly within recent adaptive radiations, necessitating the use of additional measures of ecological novelty independent of phenotype.     

Origins and evolution of biological novelty

Understanding the origins and impacts of novel traits has been a perennial interest in many realms of ecology and evolutionary biology. Here, we build on previous evolutionary and philosophical treatments of this subject to encompass novelties across biological scales and eco-evolutionary perspectives. By defining novelties as new features at one biological scale that have emergent effects at other biological scales, we incorporate many forms of novelty that have previously been treated in isolation (such as novelty from genetic mutations, new developmental pathways, new morphological features, and new species). Our perspective is based on the fundamental idea that the emergence of a novelty, at any biological scale, depends on its environmental and genetic context. Through this lens, we outline a broad array of generative mechanisms underlying novelty and highlight how genomic tools are transforming our understanding of the origins of novelty. Lastly, we present several case studies to illustrate how novelties across biological scales and systems can be understood based on common mechanisms of change and their environmental and genetic contexts. Specifically, we highlight how gene duplication contributes to the evolution of new complex structures in visual systems; how genetic exchange in symbiosis alters functions of both host and symbiont, resulting in a novel organism; and how hybridisation between species can generate new species with new niches.     

A multidimensional framework for measuring biotic novelty: How novel is a community?

Anthropogenic changes in climate, land use, and disturbance regimes, as well as introductions of non‐native species can lead to the transformation of many ecosystems. The resulting novel ecosystems are usually characterized by species assemblages that have not occurred previously in a given area. Quantifying the ecological novelty of communities (i.e., biotic novelty) would enhance the understanding of environmental change. However, quantification remains challenging since current novelty metrics, such as the number and/or proportion of non‐native species in a community, fall short of considering both functional and evolutionary aspects of biotic novelty. Here, we propose the Biotic Novelty Index (BNI), an intuitive and flexible multidimensional measure that combines (a) functional differences between native and non‐native introduced species with (b) temporal dynamics of species introductions. We show that the BNI is an additive partition of Rao's quadratic entropy, capturing the novel interaction component of the community's functional diversity. Simulations show that the index varies predictably with the relative amount of functional novelty added by recently arrived species, and they illustrate the need to provide an additional standardized version of the index. We present a detailed R code and two applications of the BNI by (a) measuring changes of biotic novelty of dry grassland plant communities along an urbanization gradient in a metropolitan region and (b) determining the biotic novelty of plant species assemblages at a national scale. The results illustrate the applicability of the index across scales and its flexibility in the use of data of different quality. Both case studies revealed strong connections between biotic novelty and increasing urbanization, a measure of abiotic novelty. We conclude that the BNI framework may help building a basis for better understanding the ecological and evolutionary consequences of global change.     

Manihot pachycaulis sp. nov. (Euphorbiaceae) from the Brazilian Cerrado

A new species of Manihot was discovered in the course of revising the taxonomy of some species of the genus occurring in the Midwest Region of Brazil. Its morphology resembles species which belong to different sections of the genus. However, a set of characters related to stem, leaves, inflorescences and flowers serves to differentiate it from the closest species, especially from M. falcata, to which it is most similar. The geographical distribution and conservation status of the new species as well as its flowering and fruiting period are also provided. Additionally, anatomical information about the aerial parts of the stem, a novelty regarding the wild species of the genus, is provided.     

Explaining the Paradox of Neophobic Explorers: The Social Information Hypothesis

How animals react to novel food and objects is commonly thought of as a crucial step toward innovations. One would therefore expect innovative species to be attracted to novelty and benefit from a combination of low neophobia and a high motivation to explore. Here we draw attention to the innovation paradox: the most innovative species tend to show neophobic reactions when confronted with novel objects or food, but can use social cues to overcome their initial neophobia. Work on novelty response has highlighted the role of ecological factors as determinants of neophobia and exploration tendency. We examine social influences on novelty response and present the idea that social factors enable some species to maintain the paradoxical combination of high neophobia and high exploration tendency. We compare primates with other species, to assess the extent to which primates are unusual. We review empirical studies that show how intrinsic neophobia is generally overcome by social facilitation and social information, i.e., the presence of experts, especially in species with slow life history, probably because social information reduces risk. We also briefly discuss the role of environmental risk in reducing intrinsic neophobia, in particular its absence in captivity. We draw attention to a strong neophobia-reducing effect of being in captivity, due to humans acting as sources of social information. We propose that species showing the paradoxical combination of strong neophobia and strong exploration tendency use social information to select aspects of the environment worth exploring. The social information hypothesis thus offers an explanation for the paradox of neophobic explorers.     

Characterization of Kudoa monodactyli n. sp. (Myxosporea: Multivalvulida) from the Muscle of Monodactylus argenteus (Teleostei: Monodactylidae) from Moreton Bay, Queensland, Australia

Kudoa monodactyli n. sp. is described from the somatic musculature of Monodactylus argenteus from several localities in southern Queensland, Australia. This is the first record of a myxozoan parasite from the family Monodactylidae. The spores typically have five polar capsules, making this species similar to the four other five-valved Kudoa species (K. neurophila, K. muscularis, K. shulmani, K. cutanea) that have been described to date. However, morphometric measurements particularly of spore length and width make the species from M. argenteus distinct from the other species. Comparison of the small subunit ribosomal DNA sequence of this species with its congeners for which sequence data are available, provides further evidence of novelty. Kudoa monodactyli n. sp. displays 38 (of 1,554) nucleotide differences compared with rDNA sequence of Kudoa neurophila, which on phylogenetic analysis places these species in clades exclusive of each other. Phylogenetic analyses also provide evidence that the number of valves per spore in this genus is an imperfect indicator of relatedness.     

A new species of Prosorhynchoides Dollfus, 1929 (Digenea: Bucephalidae) from Xenentodon cancila Hamilton, 1822 in Mizoram,Northeast India

Prosorhynchoides aspinosus n. sp., a new species of digenean trematode, is described based on morphological, ultrastructural and molecular data from the freshwater fish, Xenentodon cancila Hamilton, 1822, of Tuikum and Tuirial river in Mizoram, Northeast India. It differs from its congeners in the absence of tegumental spines and the length of cirrus sac. These unique morphological characteristics were further supported by the ultrastructural data showing distinct knob-like protrusions in the tegument. Each knob-like protrusion is without cutting plates or spines and appears granulated at higher magnification. The molecular data analyses, along with the sequences of other Prosorhynchoides available in the Genbank, using internal transcribed spacer 2 and 28S rDNA revealed a gap of 4% K2P (Kimura 2 parameter) distance with its closest congener, P. karvei, confirming the novelty of the species, and thus, clearly differentiates the new species from all other valid Prosorhynchoides spp.     

Emergence patterns of novelty in European vegetation assemblages over the past 15 000 years

Plant communities are not stable over time and biological novelty is predicted to emerge due to climate change, the introduction of exotic species and land‐use change. However, the rate at which this novelty may arise over longer time periods has so far received little attention. We reconstruct the emergence of novelty in Europe for a set of baseline conditions over the past 15 000 years to assess past rates of emergence and investigate underlying causes. The emergence of novelty is baseline specific and, during the early‐Holocene, was mitigated by the rapid spread of plant taxa. Although novelty generally increases as a function of time, climate and human‐induced landscape changes contributed to a non‐linear post‐glacial trajectory of novelty with jumps corresponding to periods of rapid changes. Emergence of novelty accelerated during the past 1000 years. Historical cultural landscapes experienced a faster novelty development due to the contribution from anthropogenic land‐cover changes.     

Evidence of Repeated and Independent Saltational Evolution in a Peculiar Genus of Sphinx Moths (Proserpinus: Sphingidae)

Background

Saltational evolution in which a particular lineage undergoes relatively rapid, significant, and unparalleled change as compared with its closest relatives is rarely invoked as an alternative model to the dominant paradigm of gradualistic evolution. Identifying saltational events is an important first-step in assessing the importance of this discontinuous model in generating evolutionary novelty. We offer evidence for three independent instances of saltational evolution in a charismatic moth genus with only eight species.

Methodology/Principal Findings

Maximum parsimony, maximum likelihood and Bayesian search criteria offered congruent, well supported phylogenies based on 1,965 base pairs of DNA sequence using the mitochondrial gene cytochrome oxidase subunit I, and the nuclear genes elongation factor-1 alpha and wingless. Using a comparative methods approach, we examined three taxa exhibiting novelty in the form of Batesian mimicry, host plant shift, and dramatic physiological differences in light of the phylogenetic data. All three traits appear to have evolved relatively rapidly and independently in three different species of Proserpinus. Each saltational species exhibits a markedly different and discrete example of discontinuous trait evolution while remaining canalized for other typical traits shared by the rest of the genus. All three saltational taxa show insignificantly different levels of overall genetic change as compared with their congeners, implying that their divergence is targeted to particular traits and not genome-wide.

Conclusions/Significance

Such rapid evolution of novel traits in individual species suggests that the pace of evolution can be quick, dramatic, and isolated—even on the species level. These results may be applicable to other groups in which specific taxa have generated pronounced evolutionary novelty. Genetic mechanisms and methods for assessing such relatively rapid changes are postulated.     

Vannella epipetala n. sp. isolated from the leaf surface of Spondias mombin (Anacardiaceae) growing in the dry forest of Costa Rica

As part of a Microbial Observatory of Caterpillars located in the Area de Conservacíon Guanacaste (ACG) in northwestern Costa Rica, we isolated a novel species of the genus Vannella associated with the food of the caterpillars of the saturniid moth Rothschildia lebeau, namely the leaves of the dry forest deciduous tree Spondias mombin (Anacardiaceae). The new species can be distinguished from other described species of the genus by the presence of a plasmalemma coated with a thickened, osmiophilic lamina containing glycostyles, and by its unusual habitat, the leaf surfaces or phylosphere of S. mombin. We further established the novelty of our isolate by sequencing its nuclear small-subunit (SSU) rRNA gene and inferring its phylogenetic position among all other currently sequenced members of the genera Vannella and Platyamoeba. Our results reveal that our isolate shares most recent common ancestry with three strains of Platyamoeba placida, the type species of the genus Platyamoeba. Despite this placement, the isolate clearly possesses glycostyles that are the hallmark of the genus Vannella. In addition to the cultured isolate, we also present a closely related sequence from a SSU rRNA gene clone library constructed from a DNA extract of leaf-wash of S. mombin with sterile water.     

A sauropodomorph tooth increases the diversity of dental morphotypes in the Cañadón Asfalto Formation (Early – Middle Jurassic) of Patagonia

This communication aims to describe an isolated sauropodomorph tooth (MPEF-PV 10860) from the Cañadón Asfalto Formation and test its phylogenetic relationships with other sauropodomophs. The novelty of this specimen implies a combination of features present in non-sauropod sauropodomorphs (coarse denticles at 45° with respect to the margin, absent marginal grooves and lingual concavity) and others previously referred to as synapomorphic of Sauropoda and subgroups of this lineage (D-shaped cross section, enamel-wrinkling). A comparison with formerly defined sauropod tooth morphotypes from Cañadón Asfalto highlights major differences in enamel-wrinkling, having a simpler and more homogeneous pattern. The crown proportions, compared with other sauropodomorph teeth, retrieve MPEF-PV 10860 within the morphospace of sauropods in two different age-ratio scatterplots, and the phylogenetic analysis depicts this specimen in multiple positions within Sauropodiforms but outside Eusauropoda, indicating the presence of both eusauropods and non-eusauropods in the Cañadón Asfalto Formation, and of a putative new species.     

Exotesta morphology of the Gardenieae — Gardeniinae (Rubiaceae)

Persson, C. 1995. Exotesta morphology of the Gardenieae-Gardeniinae (Rubiaceae). -Nord. J. Bot. 15: 285–300. CGpenhagen. ISSN 0107–055X.
Exotesta morphology of 68 species in 59 genera of the Gardeniinae were examined with the aid of scanning and light microscopy. The shape of the exotesta cells in surface is either isodiametrical or elongate and both shapes occur among New World and Old World genera. All genera, except for Monosalpinx, Posoqueria and Macrosphyra , are provided with secondary thickenings in the cell walls of the exotesta. The majority of the genera has a thickened radial wall. In the Asian genera Catunaregam, Deccania, Tamilnadia and the mainly Pacific genera, Atractocarpus and Trukia thickenings of the radial wall are very low or absent. In nearly half the genera the inner tangential wall is provided with thickenings, usually in the shape of a continuous plate. However, in four African genera, Atractogyne, Didymosalpinx, Mitriostigma and Sherbournia , the wall is provided with elongate anastomosing ribs. Atractocarpus differs markedly from the rest of the Gardeniinae by its ring-like thickenings in the inner tangential wall. Thickenings, in the shape of a continuous plate, in the outer tangential wall is restricted to three neotropical genera, Alibertia, Amaioua and Borojoa . Presence of distinct knobs is common in palaeotropical genera, whereas in neotropical genera this feature is only present in Casasia and Kotchubaea . It is concluded that data on exotesta morphology alone does not support any of the previously proposed informal groups, but may still be an important character to deduce phylogenetic relationships, primarily on a level just above the genus.     

Behavioral responses of weakly electric fish to complex impedances

Summary Members of the family of African electric fish, Mormyridae, exhibit a novelty response, consisting of an acceleration in the rate of electric organ discharges (EODs), when faced with changes in feedback arising from their EODs. In this study, the novelty responses of three different species of mormyrids to shunts with different electrical characteristics were noted. The three species differed in the frequency contents of their EODs: two species had relatively high spectral frequencies in their EODs (>10 kHz), while the third species had only lower spectral frequencies (< 10 kHz). Primarily resistive shunts elicited novelty response accelerations in all three species, and the magnitudes of these responses, when normalized to the responses obtained for a shunt with no introduced resistance, were comparable for all three species. For primarily capacitive shunts, however, the magnitudes of the normalized responses were different for the three species: the two species with high spectral frequencies in their EODs showed larger normalized responses than the third species which had only low EOD spectral frequencies.The differences in species responses for capacitive shunts, and the similarities in species responses for resistive shunts, suggest that electric fish detect the complex impedance of objects in their near field environment: a circuit model consisting of a fish emitting discharges into the surrounding water, which can be shunted by a variable complex impedance, conforms well to the data. Thus, electrolocation is a frequency dependent sensory process, and this frequency dependency should be considered in any speculation about the adaptive value of different EOD waveforms.Abbreviation EOD electric organ discharge     

Eco‐evolutionary experience in novel species interactions

A better understanding of how ecological novelty influences interactions in new combinations of species is key for predicting interaction outcomes, and can help focus conservation and management efforts on preventing the introduction of novel organisms or species (including invasive species, GMOs, synthetic organisms, resurrected species and emerging pathogens) that seem particularly ‘risky’ for resident species. Here, we consider the implications of different degrees of eco‐evolutionary experience of interacting resident and non‐resident species, define four qualitative risk categories for estimating the probability of successful establishment and impact of novel species and discuss how the effects of novelty change over time. Focusing then on novel predator–prey interactions, we argue that novelty entails density‐dependent advantages for non‐resident species, with their largest effects often being at low prey densities. This is illustrated by a comparison of predator functional responses and prey predation risk curves between novel species and ecologically similar resident species, and raises important issues for the conservation of endangered resident prey species.     

On the extent and origins of genic novelty in the phylum Nematoda

Background

The phylum Nematoda is biologically diverse, including parasites of plants and animals as well as free-living taxa. Underpinning this diversity will be commensurate diversity in expressed genes, including gene sets associated specifically with evolution of parasitism.

Methods and Findings

Here we have analyzed the extensive expressed sequence tag data (available for 37 nematode species, most of which are parasites) and define over 120,000 distinct putative genes from which we have derived robust protein translations. Combined with the complete proteomes of Caenorhabditis elegans and Caenorhabditis briggsae, these proteins have been grouped into 65,000 protein families that in turn contain 40,000 distinct protein domains. We have mapped the occurrence of domains and families across the Nematoda and compared the nematode data to that available for other phyla. Gene loss is common, and in particular we identify nearly 5,000 genes that may have been lost from the lineage leading to the model nematode C. elegans. We find a preponderance of novelty, including 56,000 nematode-restricted protein families and 26,000 nematode-restricted domains. Mapping of the latest time-of-origin of these new families and domains across the nematode phylogeny revealed ongoing evolution of novelty. A number of genes from parasitic species had signatures of horizontal transfer from their host organisms, and parasitic species had a greater proportion of novel, secreted proteins than did free-living ones.

Conclusions

These classes of genes may underpin parasitic phenotypes, and thus may be targets for development of effective control measures.     

Secondary contact seeds phenotypic novelty in cichlid fishes

Theory proposes that genomic admixture between formerly reproductively isolated populations can generate phenotypic novelty for selection to act upon. Secondary contact may therefore be a significant promoter of phenotypic novelty that allows species to overcome environmental challenges and adapt to novel environments, including during adaptive radiation. To date, this has largely been considered from the perspective of interspecific hybridization at contact zones. However, it is also possible that this process occurs more commonly between natural populations of a single species, and thus its importance in adaptive evolution may have been underestimated. In this study, we tested the consequences of genomic introgression during apparent secondary contact between phenotypically similar lineages of the riverine cichlid fish Astatotilapia calliptera. We provide population genetic evidence of a secondary contact zone in the wild, and then demonstrate using mate-choice experiments that both lineages can reproduce together successfully in laboratory conditions. Finally, we show that genomically admixed individuals display extreme phenotypes not observed in the parental lineages. Collectively, the evidence shows that secondary contact can drive the evolution of phenotypic novelty, suggesting that pulses of secondary contact may repeatedly seed genetic novelty, which when coupled with ecological opportunity could promote rapid adaptive evolution in natural circumstances.     

Transformational restoration: novel ecosystems in Denmark

Restoring the estimated 1 billion hectares of degraded forests must consider future climate accompanied by novel ecosystems. Transformational restoration can play a key role in adaptation to climate change but it is conceptually the most divergent from contemporary approaches favoring native species and natural disturbance regimes. Here, we review concepts of novelty in ecosystems with examples of emergent/neo-native and designed novel ecosystems, with application to transformational restoration. Danish forests have a high degree of novelty and provide a realistic context for discussing assisted migration, one method of transformational adaptation. Deforestation and impacts of past land use created a highly degraded landscape dominated by heathland in western Denmark. Restoration with non-native species began 150 years ago because the native broadleaves could not establish on the heathlands. Danish forestry continues to rely extensively on non-native species. Preparing for transformational adaptation requires risky research today to prepare for events in the future and refugia from the last glaciation may provide genetic material better adapted to future climate. A new project will test whether species and provenances from the Caspian forests in Iran possess greater genetic diversity and superior resistance (physiological adaptability) and resilience (evolutionary adaptability) and possibly a gene pool for future adaptation.     

Differential Responsiveness of Great Tit Nestlings,Parus major,to Natural Auditory Stimuli

In one field and two laboratory experiments, wild, wild-captured and partly laboratory-raised 16 to 18-day old great tit nestlings were subjected to repeated presentations of auditory stimuli of varying biological significance. The frequency of occurrence of the stimuli in the study area was censused. — All nestlings showed strong aversive reactions to the ‘seeet’ alarm-call of the species. It is concluded that a selective responsiveness to this call develops independently of previous exposure to it. A functional interpretation of this reaction is derived from its presumed adaptive value. Three hypothetical interpretations are suggested to explain its emergence in the individual nestling; The ‘seeet’-call elicits aversive reactions because of, 1) its novelty, 2) its intensity in terms of relative concentration of energy over its frequency range and 3) its contrasting acoustic structure compared to the nestlings' begging-call which has become strongly associated with approach behavior.     

Striatal activity underlies novelty-based choice in humans

The desire to seek new and unfamiliar experiences is a fundamental behavioral tendency in humans and other species. In economic decision making, novelty seeking is often rational, insofar as uncertain options may prove valuable and advantageous in the long run. Here, we show that, even when the degree of perceptual familiarity of an option is unrelated to choice outcome, novelty nevertheless drives choice behavior. Using functional magnetic resonance imaging (fMRI), we show that this behavior is specifically associated with striatal activity, in a manner consistent with computational accounts of decision making under uncertainty. Furthermore, this activity predicts interindividual differences in susceptibility to novelty. These data indicate that the brain uses perceptual novelty to approximate choice uncertainty in decision making, which in certain contexts gives rise to a newly identified and quantifiable source of human irrationality.