Life History Ecology Research Articles

Community structure of coral microbiomes is dependent on host morphology

BackgroundThe importance of symbiosis has long been recognized on coral reefs, where the photosynthetic dinoflagellates of corals (Symbiodiniaceae) are the primary symbiont. Numerous studies have now shown that a diverse assemblage of prokaryotes also make-up part of the microbiome of corals. A subset of these prokaryotes is capable of fixing nitrogen, known as diazotrophs, and is also present in the microbiome of scleractinian corals where they have been shown to supplement the holobiont nitrogen budget. Here, an analysis of the microbiomes of 16 coral species collected from Australia, Curaçao, and Hawai’i using three different marker genes (16S rRNA, nifH, and ITS2) is presented. These data were used to examine the effects of biogeography, coral traits, and ecological life history characteristics on the composition and diversity of the microbiome in corals and their diazotrophic communities.ResultsThe prokaryotic microbiome community composition (i.e., beta diversity) based on the 16S rRNA gene varied between sites and ecological life history characteristics, but coral morphology was the most significant factor affecting the microbiome of the corals studied. For 15 of the corals studied, only two species Pocillopora acuta and Seriotopora hystrix, both brooders, showed a weak relationship between the 16S rRNA gene community structure and the diazotrophic members of the microbiome using the nifH marker gene, suggesting that many corals support a microbiome with diazotrophic capabilities. The order Rhizobiales, a taxon that contains primarily diazotrophs, are common members of the coral microbiome and were eight times greater in relative abundances in Hawai’i compared to corals from either Curacao or Australia. However, for the diazotrophic component of the coral microbiome, only host species significantly influenced the composition and diversity of the community.ConclusionsThe roles and interactions between members of the coral holobiont are still not well understood, especially critical functions provided by the coral microbiome (e.g., nitrogen fixation), and the variation of these functions across species. The findings presented here show the significant effect of morphology, a coral “super trait,” on the overall community structure of the microbiome in corals and that there is a strong association of the diazotrophic community within the microbiome of corals. However, the underlying coral traits linking the effects of host species on diazotrophic communities remain unknown.2iUFYDy-sBVn2WqgoVCqfbVideo

Stable Isotope Analysis of Ozark Hellbender (Cryptobranchus alleganiensis bishopi) Living and Preserved Museum Tissue Reveals a Shift in Their Generalist Diet Composition

Ozark hellbenders (Cryptobranchus alleganiensis bishopi) have undergone marked population declines across their entire distribution. A variety of ecological life history research has been conducted to determine the cause(s) of the declines. Historically, hellbender diet studies used stomach content examination methods; however, alternative approaches such as less intrusive stable isotope analyses are now options for researchers. The goals of our study were to conduct stable isotope analysis on live and formalin-preserved museum specimen Ozark hellbender tissues to identify diet composition in the Eleven Point and Spring rivers, Arkansas. Also, we used stable isotope analysis to investigate if Spring River hellbender diets have changed over time. We sampled fish, live hellbenders (non-destructively), and formalin-preserved hellbender tissues from museum collections for stable isotope analysis. We sampled crayfish for assemblage composition and stable isotope analysis. The results of our stable isotope study revealed three main findings: (1) there were no statistically significant differences between hellbender δ13C and δ15N values among sites and hellbender stable C and N isotopes were correlated with body length; (2) traditional δ13C versus δ15N bi-plots and trophic discrimination values did not provide complete discernment in hellbender diets; however, Bayesian MixSIAR models revealed hellbenders to be generalists, and (3) the use of δ13C and δ15N values adjusted historic formalin-fixed and ethanol preserved hellbenders matched well with current crayfish and fish stable isotope values based on Bayesian MixSIAR models. These findings provide important diet information and a possible tool to examine dietary patterns from preserved specimens that may be used for hellbender conservation and management.

Carotenoids of hemipteran insects, from the perspective of chemo-systematic and chemical ecological studies

Carotenoids of 47 species of insects belonging to Hemiptera, including 16 species of Sternorrhyncha (aphids and a whitefly), 11 species of Auchenorrhyncha (planthoppers, leafhoppers, and cicadas), and 20 species of Heteroptera (stink bugs, assassin bugs, water striders, water scorpions, water bugs, and backswimmers), were investigated from the viewpoints of chemo-systematic and chemical ecology. In aphids, carotenoids belonging to the torulene biosynthetic pathway such as β-zeacarotene, β,ψ-carotene, and torulene, and carotenoids with a γ-end group such as β,γ-carotene and γ,γ-carotene were identified. Carotenoids belonging the torulene biosynthetic pathway and with a γ-end group were also present in water striders. On the other hand, β-carotene, β-cryptoxanthin, and lutein, which originated from dietary plants, were present in both stink bugs and leafhoppers. Assassin bugs also accumulated carotenoids from dietary insects. Trace amounts of carotenoids were detected in cicadas. Carotenoids of insects belonging to Hemiptera well-reflect their ecological life histories.

Evolution of Tandem Repeats Is Mirroring Post-polyploid Cladogenesis in Heliophila (Brassicaceae).

The unigeneric tribe Heliophileae encompassing more than 100 Heliophila species is morphologically the most diverse Brassicaceae lineage. The tribe is endemic to southern Africa, confined chiefly to the southwestern South Africa, home of two biodiversity hotspots (Cape Floristic Region and Succulent Karoo). The monospecific Chamira (C. circaeoides), the only crucifer species with persistent cotyledons, is traditionally retrieved as the closest relative of Heliophileae. Our transcriptome analysis revealed a whole-genome duplication (WGD) ∼26.15–29.20 million years ago, presumably preceding the Chamira/Heliophila split. The WGD was then followed by genome-wide diploidization, species radiations, and cladogenesis in Heliophila. The expanded phylogeny based on nuclear ribosomal DNA internal transcribed spacer (ITS) uncovered four major infrageneric clades (A–D) in Heliophila and corroborated the sister relationship between Chamira and Heliophila. Herein, we analyzed how the diploidization process impacted the evolution of repetitive sequences through low-coverage whole-genome sequencing of 15 Heliophila species, representing the four clades, and Chamira. Despite the firmly established infrageneric cladogenesis and different ecological life histories (four perennials vs. 11 annual species), repeatome analysis showed overall comparable evolution of genome sizes (288–484 Mb) and repeat content (25.04–38.90%) across Heliophila species and clades. Among Heliophila species, long terminal repeat (LTR) retrotransposons were the predominant components of the analyzed genomes (11.51–22.42%), whereas tandem repeats had lower abundances (1.03–12.10%). In Chamira, the tandem repeat content (17.92%, 16 diverse tandem repeats) equals the abundance of LTR retrotransposons (16.69%). Among the 108 tandem repeats identified in Heliophila, only 16 repeats were found to be shared among two or more species; no tandem repeats were shared by Chamira and Heliophila genomes. Six “relic” tandem repeats were shared between any two different Heliophila clades by a common descent. Four and six clade-specific repeats shared among clade A and C species, respectively, support the monophyly of these two clades. Three repeats shared by all clade A species corroborate the recent diversification of this clade revealed by plastome-based molecular dating. Phylogenetic analysis based on repeat sequence similarities separated the Heliophila species to three clades [A, C, and (B+D)], mirroring the post-polyploid cladogenesis in Heliophila inferred from rDNA ITS and plastome sequences.

Carotenoids of land-locked and sea-run types of masu salmon Oncorhynchus masou ishikawae inhabiting in the Nagara River, Japan, from the perspective of chemical ecological study

Carotenoids of the land-locked type (Amago) and sea-run type (Satsukimasu) of masu salmon Oncorhynchus masou ishikawae inhabiting the Nagara River, Gifu Prefecture, Japan were investigated from the perspective of the chemical ecological point of view. Yellow xanthophylls, 3′-epilutein, lutein, zeaxanthin, and diatoxanthin were major carotenoids in wild Amago. They were also present in the flesh of wild Amago. These carotenoids originated from aquatic insects, which wild Amago fed on. On the other hand, tunaxanthin, zeaxanthin, and salmoxanthin were major carotenoids in the integument of Satsukimasu, which migrated from the Ise Bay to the Nagara River. Astaxanthin was a major carotenoid in the flesh of Satsukimasu. These carotenoids accumulated from marine fish and crustaceans, which Satsukimasu fed on during migration in the sea. Carotenoids of Amago and Satukimasu well-reflect their ecological life history.

Developmental and sexual divergence in the olfactory system of the marine insect Clunio marinus

An animal’s fitness strongly depends on successful feeding, avoidance of predators and reproduction. All of these behaviours commonly involve chemosensation. As a consequence, when species’ ecological niches and life histories differ, their chemosensory abilities need to be adapted accordingly. The intertidal insect Clunio marinus (Diptera: Chironomidae) has tuned its olfactory system to two highly divergent niches. The long-lived larvae forage in a marine environment. During the few hours of terrestrial adult life, males have to find the female pupae floating on the water surface, free the cryptic females from their pupal skin, copulate and carry the females to the oviposition sites. In order to explore the possibility for divergent olfactory adaptations within the same species, we investigated the chemosensory system of C. marinus larvae, adult males and adult females at the morphological and molecular level. The larvae have a well-developed olfactory system, but olfactory gene expression only partially overlaps with that of adults, likely reflecting their marine vs. terrestrial lifestyles. The olfactory system of the short-lived adults is simple, displaying no glomeruli in the antennal lobes. There is strong sexual dimorphism, the female olfactory system being particularly reduced in terms of number of antennal annuli and sensilla, olfactory brain centre size and gene expression. We found hints for a pheromone detection system in males, including large trichoid sensilla and expression of specific olfactory receptors and odorant binding proteins. Taken together, this makes C. marinus an excellent model to study within-species evolution and adaptation of chemosensory systems.

A World of Gorse: Persistence of Ulex europaeus in Managed Landscapes.

Gorse (Ulex europeus L.) is a woody legume and invasive woody weed that has been introduced to temperate pastoral landscapes worldwide. Despite the apparent cosmopolitan distribution of gorse across much of the temperate agroecological landscapes of the world, research and practice pertaining to the management of gorse has been largely constrained to single-treatments, regions, or timeframes. Gorse eradication has been widely attempted, with limited success. Using the PRISMA (preferred reporting items for systematic reviews and meta-analysis) method and a quasi-metanalytical approach, we reviewed the seminal ~299 papers pertaining to gorse management. We identified (i) the ecological characteristics of the species that predispose gorse to behaving invasively, and (ii) the success of management actions (from a plant ecological life history perspective) in reducing weed vigour and impact. A broad ecological niche, high reproductive output, propagule persistence, and low vulnerability to pests allow for rapid landscape exploitation by gorse throughout much the world. Additionally, there are differences in flowering duration and season in the northern and southern hemisphere that make gorse particularly pernicious in the latter, as gorse flowers twice per year. The implications of these life history stages and resistance to environmental sieves after establishment are that activity and efficacy of control is more likely to be favourable in juvenile stages. Common approaches to gorse control, including herbicides, biological controls, and fire have not been ubiquitously successful, and may in fact target the very site resources—sward cover, soil stability, hydrological balance—that, when degraded, facilitate gorse invasion. Ongoing seedling regeneration presents difficulties if eradication is a goal, but facilitated competition may reduce costs via natural suppression. Mechanical methods of gorse removal, though highly successful, induce chronic soil erosion and land degradation and should hence be used sparingly.

Using DNA Barcodes to Aid the Identification of Larval Fishes in Tropical Estuarine Waters (Malacca Straits, Malaysia).

Larval descriptions of tropical marine and coastal fishes are very few, and this taxonomic problem is further exacerbated by the high diversity of fish species in these waters. Nonetheless, accurate larval identification in ecological and early life history studies of larval fishes is crucial for fishery management and habitat protection. The present study aimed to evaluate the usefulness of DNA barcodes to support larval fish identification since conventional dichotomous keys based on morphological traits are not efficient due to the lack of larval traits and the rapid morphological changes during ontogeny. Our molecular analysis uncovered a total of 48 taxa (21 families) from the larval samples collected from the Klang Strait waters encompassing both spawning and nursery grounds of marine and estuarine fishes. Thirty-two (67%) of the larval taxa were identified at the species level, two taxa (4%) at the genus level, and 14 taxa (29%) at family level. The relatively low rate of species-level identification is not necessarily due to the DNA barcoding method per se, but a general lack of reference sequences for speciose and non- commercial fish families such as Gobiidae, Blenniidae, and Callionymidae. Larval morphology remains important in species diagnoses when molecular matches are ambiguous. A lower ethanol percentage (50%) for larva preservation is also useful to keep the body of larvae intact for morphological identification, and to preserve DNA for subsequent molecular analyses. The 10% Chelex resin used to extract DNA is also cost- effective for long term monitoring of larval fishes. Hence, the DNA barcoding method is an effective and easy way to aid the identification of estuarine larval fishes at the species level.

Nocturnal torpor by superb fairy-wrens: a key mechanism for reducing winter daily energy expenditure.

Many passerine birds are small and require a high mass-specific rate of resting energy expenditure, especially in the cold. The energetics of thermoregulation is, therefore, an important aspect of their ecology, yet few studies have quantified thermoregulatory patterns in wild passerines. We used miniature telemetry to record the skin temperature ( Tskin) of free-living superb fairy-wrens ( Malurus cyaneus, 8.6 g; n = 6 birds over N = 7-22 days) and determine the importance of controlled reductions in body temperature during resting to their winter energy budgets. Fairy-wrens routinely exhibited large daily fluctuations in Tskin between maxima of 41.9 ± 0.6°C and minima of 30.4 ± 0.7°C, with overall individual minima of 27.4 ± 1.1°C (maximum daily range: 14.7 ± 0.9°C). These results provide strong evidence of nocturnal torpor in this small passerine, which we calculated to provide a 42% reduction in resting metabolic rate at a Ta of 5°C compared to active-phase Tskin. A capacity for energy-saving torpor has important consequences for understanding the behaviour and life-history ecology of superb fairy-wrens. Moreover, our novel field data suggest that torpor could be more widespread and important than previously thought within passerines, the most diverse order of birds.

Fish otoliths: uses of their structural, shape and chemical properties in ichthyology

Event Abstract Back to Event Fish otoliths: uses of their structural, shape and chemical properties in ichthyology Alberto T. Correia1, 2* 1 Centro Interdisciplinar de Investigação Marinha e Ambiental, Portugal 2 Faculdade de Ciências da Saúde da Universidade Fernando Pessoa, Portugal Otoliths are inner ear aragonitic concretions used as hearing and balance organs by teleost fish. These hard structures have unique properties allowing them to have several applications in fish science. Otoliths are classically used to estimate the age of fish by counting daily and/or annual growth increments, particularly important for fisheries management purposes (e.g. determination of age at first maturity). Moreover, the tracking of some microstructural checks under visual microscope observation allow us to identify some key ecological life history fish events (e.g. settlement age). At present, the use of otolith morphology (e.g. landmarks and shape contour) is also contributing to assess the population structure of commercially important fish stocks. Recently, the use of high precision analytical methodologies permitted that the microchemistry (e.g. elemental and isotopic signatures) of otoliths had a remarkable growing in the last few years. At present, otoliths could complement, or even replace, other natural tags, such as the common genetic tools (e.g. mt-DNA and usat-DNA), in the study of the population structure, movement patterns and habitat connectivity in fish. Several published examples of the current applications and methodological pre-requisites of the use of fish otoliths will be shortly explored during this presentation. Moreover, future challenges of the otolith science will be also pinpointed. Acknowledgements This research was partially supported by the Strategic Funding UID/Multi/ 04423/2019 through national funds provided by Foundation for Science and Technology (FCT) and European Regional Development Fund (ERDF) in the framework of the programme PT2020. Keywords: fish, Natural tags, otoliths, Applications & Properties and Structure, Life-cycle Conference: XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019. Presentation Type: Key-note Presentation Topic: OTOLITHS AS A TOOL TO STUDY FISH LIFE CYCLES Citation: Correia AT (2019). Fish otoliths: uses of their structural, shape and chemical properties in ichthyology. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00001 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Jun 2019; Published Online: 14 Aug 2019. * Correspondence: Prof. Alberto T Correia, Centro Interdisciplinar de Investigação Marinha e Ambiental, Matosinhos, Portugal, atcorreia.ciimar@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Alberto T Correia Google Alberto T Correia Google Scholar Alberto T Correia PubMed Alberto T Correia Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Torpor reduces predation risk by compensating for the energetic cost of antipredator foraging behaviours.

Foraging activity is needed for energy intake but increases the risk of predation, and antipredator behavioural responses, such as reduced activity, generally reduce energy intake. Hence, the mortality and indirect effects of predation risk are dependent on the energy requirements of prey. Torpor, a controlled reduction in resting metabolism and body temperature, is a common energy-saving mechanism of small mammals that enhances their resistance to starvation. Here we test the hypothesis that torpor could also reduce predation risk by compensating for the energetic cost of antipredator behaviours. We measured the foraging behaviour and body temperature of house mice in response to manipulation of perceived predation risk by adjusting levels of ground cover and starvation risk by 24 h food withdrawal every third day. We found that a voluntary reduction in daily food intake in response to lower cover (high predation risk) was matched by the extent of a daily reduction in body temperature. Our study provides the first experimental evidence of a close link between energy-saving torpor responses to starvation risk and behavioural responses to perceived predation risk. By reducing the risk of starvation, torpor can facilitate stronger antipredator behaviours. These results highlight the interplay between the capacity for reducing metabolic energy expenditure, optimal decisions about foraging behaviour and the life-history ecology of prey.

Population structure and genomic variation of ecological life history diversity in wild-caught Lake Superior brook trout, Salvelinus fontinalis

Delineating patterns of extant genetic diversity is crucial for understanding the evolutionary history of populations and how they can be conserved. Brook trout (Salvelinus fontinalis; n = 173) were sampled from 11 locations in Nipigon Bay, Lake Superior to evaluate genetic differentiation between migratory (coaster) and non-migratory (resident) individuals. Stable isotope data were used to classify the trophic ecology of individuals, rather than relying on size or capture location and timing to classify ecotypes. Genome-wide association analysis of 4676 single nucleotide polymorphism (SNP) markers was conducted to test if phenotypic and behavioral differences within and among populations of brook trout were linked to allelic variation in the genome. Population genetic structure was also evaluated to determine the source of migratory coasters based on multilocus genotypes from a subset of 906 SNP markers. Significant population genetic structure was revealed among the sampled tributaries, and the population genetic structure suggests that a single, larger stream in the study area, Cypress River, was the primary source of migratory brook trout in Nipigon Bay. There was little evidence of genetic differentiation between sympatric migrant and stream-resident brook trout; across the genome only 11 SNP loci (<1%) were significantly associated with life history type. Our findings suggest that coaster brook trout are an ecotype derived from resident populations, rather than a distinct genetic form. Raw RADseq is deposited in the NCBI Genbank Sequence Read Archive (PRJNA486545). Biological metadata and processed genotypes are found in the Electronic Supplementary Material (ESM).

Early life history ecology for five commercially and ecologically important fish species in the eastern and western Gulf of Alaska

The Gulf of Alaska Integrated Ecosystem Research Program is a multi-disciplinary study examining interactions between physical and biological oceanography to understand how the environment influences the survival and recruitment of early life stages of select commercially and ecologically important groundfish species. Biological and oceanographic surveys in the eastern and western Gulf of Alaska were conducted during spring and summer of 2011 and 2013; we present a synthesis of ichthyoplankton data. The results describe seasonal (spring vs. summer), regional (eastern vs. western Gulf of Alaska), and interannual (2011 vs. 2013) variation in distribution, abundance, and larval sizes of the focal species. In spring, Pacific Cod (Gadus macrocephalus) larvae were more abundant in 2013 than 2011 and occurred primarily in the western Gulf of Alaska near Kodiak Island, over the shelf, and over the continental slope. Walleye Pollock (Gadus chalcogrammus) larvae were also more abundant in the western Gulf of Alaska, with substantially higher abundance in 2013. Larval rockfish (predominantly Pacific Ocean Perch; Sebastes alutus) were collected in deep water or were associated with the slope, troughs and canyons intersecting the slope, and the outer shelf. Rockfish larvae were collected throughout the study region in spring, with no significant differences in abundance between regions or years. In summer, rockfish (predominantly species other than Pacific Ocean Perch) were more widely distributed over the shelf and were more abundant in the eastern Gulf of Alaska both within and across years, indicating species-specific spawning events. Sablefish (Anoplopoma fimbria) larvae, however, were more abundant in the eastern Gulf of Alaska and in 2011 and were predominantly collected near areas of deep water such as Yakutat Canyon. In 2011, Arrowtooth Flounder (Atheresthes stomias) abundances of larvae were higher in the western Gulf of Alaska, whereas in 2013 abundances were higher in the eastern Gulf of Alaska. Arrowtooth Flounder larvae were collected primarily along the slope and near canyons and troughs. The results from individual years presented here can be used in individual-based model validation of connectivity matrices, delineating transport patterns to suitable nursery habitat, and evaluating recruitment bottlenecks for these focal species in the Gulf of Alaska. Future research will examine patterns of community structure and assemblage diversity using the comprehensive ichthyoplankton dataset. The observed ecological patterns provide insight into how environmental forcing may influence early life history aspects of recruitment.

Density-Dependent Selection Revisited: Mechanisms Linking Explanantia and Explananda

Interest in the most general theory of the evolutionary ecology of life histories ever proposed—that of density-independent (r) versus density-dependent (K) selection—peaked in the 1980s and 1990s respectively but declined somewhat thereafter because of arguments over its theoretical coherence and some empirical failures; although as is shown here, not so much as is commonly supposed. In this article, some conceptual analyses and clarification of terms in the conditions for its application (density relative to resources as a variable with spatial, temporal, and niche boundaries fixed), and in the explanantia of the theory (costs and frequencies, stability and instability within and among growing and declining populations, multiple levels of selection, and ultimately homogeneous and patchy environments) are presented. These make intelligible plausible mechanisms (consumption and digestion, production, and reproduction) linking the explanantia and the explananda of the theory that are both theoretically coherent and clarify what predictions it does not and does make including about senescence.

Fish metacommunity dynamics in the patchy heterogeneous habitats of varzea lakes, turbid river channels and transparent clear and black water bodies in the Amazonian Lowlands of Bolivia

The causes of fish community organization in a system of habitat patches with different environmental conditions were described using a data set of 65 sites sampled during the dry season. Incorporating the patchy heterogeneous structure, variation partitioning allowed us to specifically evaluate the fine-scale neutral processes produced by spatial autocorrelation within habitat patches, and the broad-scale dispersal limitations between patches. Only the second subset of spatial variables was significant; dispersal limitation was relatively low between habitat patches of varzea lakes. An analysis of functional ecology allowed an empirical description of the functional mechanisms of alpha and beta niche differentiation, and an assessment of the phylogenetic signal. The trait-convergence assembly pattern among habitat patches indicated that fish in turbid river channels were better adapted to low light than fish in transparent black and clear water bodies. Also, fish in varzea lakes had a wider ecological range; this association indicated phylogenetic niche conservatism. The trait-divergence assembly pattern was almost expressed by body weight and was prominent in varzea lakes; combined with ecological range and sensory adaptation, this association indicated a marginal phylogenetic signal. These results suggest the radiation of species-rich clades with a high degree of sensory adaptation may have occurred in the seasonal environment of varzea lakes. This resulted in larger ecological distribution and innovative life histories tightly synchronized with periodic flooding. The lineage-specific sensory adaptation and subsequent landscape and evolutional history of habitat specialization were also found to actually contribute to the fish metacommunity dynamic in the Bolivian Amazonian lowland.

Early life history pelagic exposure profiles of selected commercially important fish species in the Gulf of Alaska

A synthesis of nearly four decades of ichthyoplankton survey data from the Gulf of Alaska was undertaken to provide the most comprehensive information available on the early life history ecology of five focal species: Pacific Cod (Gadus macrocephalus), Walleye Pollock (Gadus chalcogrammus), Pacific Ocean Perch (Sebastes alutus), Sablefish (Anoplopoma fimbria), and Arrowtooth Flounder (Atheresthes stomias). This analysis of historical data, along with information from published studies, is presented here in the form of ecological reviews of the species during their planktonic phase. The reviews include descriptions of temporal and spatial patterns of exposure to the environment, and interpretation regarding associated sensitivities to environmental forcing. On a temporal scale, patterns in abundance of eggs and larvae are synthesized that characterize seasonal exposure to the pelagic environment, and interannual variation that is presumed to incorporate responses to long-term environmental forcing. Spatial patterns are synthesized to identify horizontal and vertical extent of egg and larval distributions, delineate areas of primary larval habitat, and illuminate egg and larval drift pathways. The observed patterns are discussed with respect to characterizing species early life history strategies, identifying long-term adaptations to the Gulf of Alaska environment, and associated resilience and vulnerability factors that may modulate early life responses to environmental forcing in this region. For each species, gaps in knowledge are identified and are concerned primarily with the period of transition between the larval and juvenile stage, and feeding habits and ecology across seasons, habitats and sub-intervals of early ontogeny. These early life history reviews advance our ecological understanding of the pelagic phase, and fine-tune our focus for the investigation of potential response mechanisms to environmental forcing at appropriate, species-specific temporal and spatial scales.

Assessing variation in the potential susceptibility of fish to pharmaceuticals, considering evolutionary differences in their physiology and ecology.

Fish represent the planet's most diverse group of vertebrates and they can be exposed to a wide range of pharmaceuticals. For practical reasons, extrapolation of pharmaceutical effects from 'model' species to other fish species is adopted in risk assessment. Here, we critically assess this approach. First, we show that between 65% and 86% of human drug targets are evolutionarily conserved in 12 diverse fish species. Focusing on nuclear steroid hormone receptors, we further show that the sequence of the ligand binding domain that plays a key role in drug potency is highly conserved, but there is variation between species. This variation for the oestrogen receptor, however, does not obviously account for observed differences in receptor activation. Taking the synthetic oestrogen ethinyloestradiol as a test case, and using life-table-response experiments, we demonstrate significant reductions in population growth in fathead minnow and medaka, but not zebrafish, for environmentally relevant exposures. This finding contrasts with zebrafish being ranked as more ecologically susceptible, according to two independent life-history analyses. We conclude that while most drug targets are conserved in fish, evolutionary divergence in drug-target activation, physiology, behaviour and ecological life history make it difficult to predict population-level effects. This justifies the conventional use of at least a 10× assessment factor in pharmaceutical risk assessment, to account for differences in species susceptibility.

The Implications of Temperature-Mediated Plasticity in Larval Instar Number for Development within a Marine Invertebrate, the Shrimp Palaemonetes varians

Variations in larval instar number are common among arthropods. Here, we assess the implications of temperature-mediated variations in larval instar number for larval development time, larval growth rates, and juvenile dry weight within the palaemonid shrimp, Palaemonetes varians. In contrast with previous literature, which focuses on terrestrial arthropods, particularly model and pest species often of laboratory lines, we use wild shrimp, which differ in their life history from previous models. Newly-hatched P. varians larvae were first reared at 5, 10, 17, 25, and 30°C to assess their thermal scope for development. Larvae developed at 17, 25, and 30°C. At higher temperatures, larvae developed through fewer larval instars. Two dominant developmental pathways were observed; a short pathway of four instars and a long pathway of five instars. Longer developmental pathways of six to seven instars were rarely observed (mostly at lower temperatures) and consisted of additional instars as ‘repeat’ instars; i.e. little developmental advance over the preceding instar. To assess the implications of temperature-mediated variation in larval instar number, newly-hatched larvae were then reared at 15, 20, and 25°C. Again, the proportion of larvae developing through four instars increased with temperature. At all temperatures, larval development time and juvenile dry weight were greater for larvae developing through five instars. Importantly, because of the increasing proportion of larvae developing through four instars with increasing temperature, larval traits associated with this pathway (reduced development time and juvenile dry weight) became more dominant. As a consequence of increasing growth rate with temperature, and the shift in the proportion of larvae developing through four instars, juvenile dry weight was greatest at intermediate temperatures (20°C). We conclude that at settlement P. varians juveniles do not follow the temperature-size rule; this is of importance for life-history ecology in response to environmental change, as well as for aquaculture applications.

Diet and habitat use by age-0 deepwater sculpins in northern Lake Huron, Michigan and the Detroit River

Deepwater sculpins (Myoxocephalus thompsonii) are an important link in deepwater benthic foodwebs of the Great Lakes. Little information exists about deepwater sculpin spawning habits and early life history ecology due to difficulty in sampling deep offshore habitats. Larval and age-0 deepwater sculpins collected in northern Lake Huron and the Detroit River during 2007 were used to improve our understanding of their habitat use, diet, age, and growth. Peak larval density reached 8.4/1000m3 in the Detroit River during April and was higher than that in Lake Huron. Offshore bottom trawls at DeTour and Hammond Bay first collected benthic age-0 deepwater sculpins in early September when fish were ≥25mm TL. Otolith analysis revealed that hatch dates for pelagic larvae occurred during late March and larvae remained pelagic for 40 to 60days. Diet of pelagic larvae (10–21mm TL) was dominated by calanoid copepods at all sample locations. Diets of benthic age-0 fish varied by location and depth: Mysis and chironomids were prevalent in fish from Hammond Bay and the 91m site at DeTour, but only chironomids were found in fish from the 37m DeTour site. This work showed that nearshore epilimnetic sites were important for pelagic larvae and an ontogenetic shift from pelagic planktivore to benthivore occurred at about 25mm TL in late summer. Age analysis showed that larvae remained pelagic long enough to be transported through the St. Clair–Detroit River system, Lake Erie, and the Niagara River, potentially contributing to populations in Lake Ontario.

“Variation and selective retention” as an evolutionary epistemology: were Donald Campbell's life histories sufficient?

Campbell's “evolutionary epistemology” is used more frequently to refer to extensions of Darwinism than other phrases, and his description of it as “variation and selective retention” is highly cited. However, we can still ask whether it is sufficient. The evidence from his classic essay is that he understood it to include somatic maintenance and reproductive growth, but omitted somatic growth and reproductive maintenance. We describe some of the complexity of the evolutionary ecology of life histories, including ecological and ecological versus social density-dependence and scale-dependence, and find that, interestingly, understood as a distinction between spending and investing, the traditional r versus K density-dependence distinction yields the same pattern of expected life history traits as does scale-dependence (although there should be other ways of distinguishing them). We then use this to fill in the missing somatic growth and offspring maintenance of Campbell's model of sociocultural evolution. In concluding, we emphasize the degree to which not only the evolutionary ecology of life histories but also the logic of population genetics and tree-building have been found relevant to the social sciences. Donald Campbell and David Hull, both now deceased, will be remembered as early modern pioneers of the theory of Darwinian sociocultural evolution.