Maximum Body Length Research Articles

Context-Dependent Responses of Aquatic Insects to Metals and Metal Mixtures: A Quantitative Analysis Summarizing 24 Yr of Stream Mesocosm Experiments.

Modernizing water quality criteria to predict how contaminants affect natural aquatic communities requires that we utilize data obtained across multiple lines of evidence, including laboratory, mesocosm, and field studies. We report the results of 29 mesocosm experiments conducted from 1994 to 2017 at the Colorado State University Stream Research Laboratory (Fort Collins, CO, USA). The primary goal of the present study was to quantify responses of aquatic insect communities collected from 8 different locations to different combinations of cadmium (Cd), copper (Cu), iron (Fe), and zinc (Zn). Treatments that included Cu or Fe, either alone or in combination with other metals, were especially toxic to aquatic insects. The results showed that effects of metals were context dependent and varied significantly among the 8 sites where communities were collected. In particular, effects on communities from smaller streams were significantly greater than those from larger streams. Our analyses also showed that several morphological (body size, shape, gills, degree of sclerotization) and life history (voltinism) traits were significantly correlated with sensitivity to metals. Across all taxa and experiments, aquatic insects broadly classified as small (maximum body length <8 mm) were significantly more sensitive to metals than medium or large individuals. These findings demonstrate the advantages of integrating results of mesocosm experiments with species traits to develop a mechanistic understanding of biotic and abiotic factors that influence community responses to contaminants. Environ Toxicol Chem 2019;38:2486-2496. © 2019 SETAC.

Larval morphology predicts geographical dispersal range of Eastern Pacific eels

AbstractThe geographical range of many marine species is strongly influenced by the dispersal potential of propagules such as eggs and larvae. Here, we investigate morphological diversity and the effect of body shape on geographical range of leptocephali, the unique, laterally compressed larvae of eels (order Anguilliformes). We used phylogenetically informed analyses to examine the morphological variation of larvae for 17 Eastern Pacific eel species from three adult habitats. We also investigated whether morphological traits of leptocephali could predict larval latitudinal range, hypothesizing that body shape may influence passive dispersal via currents. We found that no two species shared the same multivariate growth trajectories, with the size and scaling of pectoral fin length and snout-to-anus length being particularly variable. Larvae with longer relative predorsal and snout-to-anus lengths at median sizes exhibited wider larval geographical ranges. Body aspect ratio and maximum body length at metamorphosis, two traits we hypothesized to be important for passive transport, were not significant predictors of maximal larval range. We discovered an increase in phylogenetic signal over larval development as eels approach metamorphosis, potentially due to similar selective pressures between related species (such as juvenile habitat or adult morphology). Lastly, we conclude that larval body shape is probably influenced by adult habitat and adult morphology.

Morphometric analysis of Chilean blue whales and implications for their taxonomy

AbstractIn the Southern Hemisphere, blue whales are currently divided into two subspecies, Antarctic blue whales (Balaenoptera musculus intermedia) and pygmy blue whales (B. m. brevicauda), but there is some debate about whether Chilean blue whales should also be considered as a separate subspecies. Here, we provide novel morphometric data to directly address this taxonomic question from a biological survey of 60 blue whales taken during the 1965/1966 Chilean whaling season. The data show that maximum body length and mean body length of both sexually mature females and males for Chilean blue whales are intermediate between pygmy and Antarctic blue whales; and that fluke‐anus lengths of Chilean blue whales are significantly different from pygmy blue whales, but not necessarily from Antarctic blue whales. There is also some support from the data that snout‐eye measurements are different among all three groups. These data provide further confirmation that Chilean blue whales are a distinct population requiring separate management from other blue whale populations, and are also consistent with suggestions that Chilean blue whales are not the same subspecies as pygmy blue whales.

Yiğitler Deresi’nde (Nif Çayı, İzmir) dağılım gösteren Gammarus izmirensis (Amphipoda) türünün populasyon yapısı

Yiğitler Brook, one of the branches of Nif Stream, has a regular flow regime throughout the year. The brook is one of the important aquatic habitats in terms of biological diversity by having relatively unpolluted water. The main objective of the present study is to get information about the population structure of Gammarus izmirensis Özbek, 2007 whose type locality is Yiğitler Brook. There is no information about the species in literature except its original description paper. Gammarus specimens were sampled in monthly intervals between October 2015 and November 2016. Samplings were performed at one locality. During the study, a total of 1938 G. izmirensis specimens were investigated. Of them; 850 were females, 586 were males and 502 were juveniles. The maximum body length was 14.5 mm in males and 14.0 mm in females. The number of juveniles is higher in March and August. The species has a multivoltine life cycle with two generations (spring and summer) throughout the year.

The relationship between geographic range extent, sea surface temperature and adult traits in coastal temperate fishes

AbstractAimWe use publicly available data to assess the influence of ocean basin, various biological traits and sea surface temperature on biogeographic range extent for temperate, continental shelf fish species spanning 141 families.LocationCoastal waters of the temperate Northern Hemisphere.TaxonTeleost Fishes (Infraclass Teleostei).MethodsWe assess the relationship between species range extent and depth range, maximum body length, schooling behaviour and use of multiple habitats for 1,251 species of northern, temperate, continental shelf fishes in different basins (Atlantic vs. Pacific) and margins (east vs. west) using linear mixed‐effect models with family and genus as nested random effects. We further assess the relationship between species range endpoint distribution and latitudinal temperature gradient using generalized linear models.ResultsWe found strong positive relationships between the number of species northern range endpoints and the steepness of the latitudinal sea surface temperature gradient on the western margins of the Atlantic and Pacific Oceans, but no relationship on the eastern margins of these ocean basins. The strongest predictors of range extent in our global model are ocean basin/margin and depth range. Maximum body length, schooling behaviour and use of multiple habitats are also significant predictors of range extent in the global model. The factors influencing range extent differ by basin and margin.Main conclusionsThere are broad differences in patterns of species range extent and distribution of species ranges among basins/margins. These differences appear to be driven in part by variation in latitudinal water temperature gradient between basin margins. Our data suggest that sharp latitudinal temperature gradients may pose a barrier to dispersal and range expansion along the western margins of the Atlantic and Pacific Oceans, but not necessarily on the eastern margins. Our work also suggests that several post‐settlement traits may be associated with range extent either globally or in some temperate basins.

Length–weight relations for 20 fish species (Actinopterygii) from the southern Ionian Sea, Greece

Length&ndash;weight relations are presented for 20 fish species caught by small-scale fishery from the southern Ionian Sea (Greece) including a marine protected area from 2013 to 2017. The following species were studied: Spicara maena (Linnaeus, 1758); Labrus merula Linnaeus, 1758; Symphodus tinca (Linnaeus, 1758); Xyrichtys novacula (Linnaeus, 1758); Mullus surmuletus Linnaeus, 1758; Phycis phycis (Linnaeus, 1766); Sparisoma cretense (Linnaeus, 1758); Scorpaena scrofa Linnaeus, 1758; Serranus scriba (Linnaeus, 1758); Siganus luridus (R&uuml;ppell, 1829); Diplodus sargus (Linnaeus, 1758); Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817); Pagellus acarne (Risso, 1827); Pagellus erythrinus (Linnaeus, 1758); Pagrus pagrus (Linnaeus, 1758); Spondyliosoma cantharus (Linnaeus, 1758); Dentex dentex (Linnaeus, 1758); Synodus saurus (Linnaeus, 1758); Trachinus radiatus Cuvier, 1829; Uranoscopus scaber Linnaeus, 1758. The main fishing gears that were involved in the data collection were trammel nets and longlines that were set in the sea during all seasons of the year. A total of 3510 specimens belonging to 12 families were examined. For two species (Labrus merula and Xyrichtys novacula) the maximum total body length reported in our study was higher than the one reported in the literature. To our knowledge, the length&ndash;weight relations for all the 20 fish species are the first to be reported from this area. Thus this contribution can serve as a baseline for monitoring, conservation and management efforts in this region, which is well known for its prime ecological importance.&nbsp

An overview of ichthyosaurian remains from the Cretaceous of Texas, USA

The clade nominal Ophthalmosauridae encompasses all currently recognized ichthyosaurian taxa from the mid-Cretaceous (Albian–Cenomanian) time interval in North America. These would have inhabited what is today known as the Western Interior Seaway. The remains represent mid to large-sized (up to around 5 m in maximum body length) ichthyosaurians that are mainly based upon isolated teeth and vertebrae, although some partial skeletons have been recovered from both the USA and Canada. Most of these fossils have taxonomic affinities with platypterygiines, such as the ubiquitous ‘form genus’ Platypterygius. This taxon has historically been the default identification for most North American Cretaceous ichthyosaur specimens. However, in comparison with remains from elsewhere, the ichthyosaurian fossils from Texas have been relatively understudied. Here, I review the existing records and present a concise list of all Cretaceous ichthyosaurian material currently held in public museum collections across the state. I have recognized 11 Cretaceous ichthyosaurian occurrences from Texas, including an indeterminate tooth, numerous vertebral centra, and some fragmentary skeletal remains attributable to Platypterygius. Ichthyosaurians therefore demonstrably occupied the Cretaceous epeiric seas of Texas from at least the Albian to middle Cenomanian, a distribution that traverses both the western and eastern coastlines of the Western Interior Seaway during its early phase of southern epicontinental incursion.

GROUP GROWTH, NATURAL MORTALITY, AGE OF MATURATION, AND COMMERCIAL SIZE OF WHITE AMUR BREAM PARABRAMIS PEKINENSIS (BASILEWSKY, 1855) IN THE AMUR RIVER

Linear and weight growth of amur white bream are considered on the basis of von Bertalanffy and Schmalhausen growth equations using the data collected in the Amur River (from Nizhneleninskoe village to the mouth) in 1958–2011. Age was determined for 1703 specimens (672 females and 699 males, sex not defined for others). The main feature of the amur white bream growth is a sexual dimorphism, primarily in the specific growth rate. Generally, females live longer than males. Another important feature is a compensatory growth, that maintains the size of all individuals around the mean level in the age of their pubertation. Mean age of females maturation is 5+...6+ years, when their body length is 27 cm on average. Males mature earlier, in the age of 4+...5+ years. Commercial size of amur white bream is determined as 27 cm that corresponds with the size in the age of mass maturation and the highest biomass of females. The minimum natural mortality coefficient (φM) is determined as 0.249 for females and 0.320 for males, on average. The maximum body length of amur white bream, both in the model and real observations, is 50 cm, the maximum body weight is 2 kg, and the maximum age is 17 years. So, the reports about findings of amur white bream with the length up to 55 cm and weight up to 4.1 kg are doubtful.

Trophic specialization drives morphological evolution in sea snakes.

Viviparous sea snakes are the most rapidly speciating reptiles known, yet the ecological factors underlying this radiation are poorly understood. Here, we reconstructed dated trees for 75% of sea snake species and quantified body shape (forebody relative to hindbody girth), maximum body length and trophic diversity to examine how dietary specialization has influenced morphological diversification in this rapid radiation. We show that sea snake body shape and size are strongly correlated with the proportion of burrowing prey in the diet. Specialist predators of burrowing eels have convergently evolved a ‘microcephalic’ morphotype with dramatically reduced forebody relative to hindbody girth and intermediate body length. By comparison, snakes that predominantly feed on burrowing gobies are generally short-bodied and small-headed, but there is no evidence of convergent evolution. The eel specialists also exhibit faster rates of size and shape evolution compared to all other sea snakes, including those that feed on gobies. Our results suggest that trophic specialization to particular burrowing prey (eels) has invoked strong selective pressures that manifest as predictable and rapid morphological changes. Further studies are needed to examine the genetic and developmental mechanisms underlying these dramatic morphological changes and assess their role in sea snake speciation.

Do functional groups of planktonic copepods differ in their ecological niches?

AbstractAimTo assess the degree of overlap between the environmental niches of marine planktonic copepods and test if the distribution of copepod functional groups differs across environmental gradients.LocationThe Mediterranean Sea.MethodsFunctional groups were defined based on clustering of functional traits in 106 marine copepod species using a multivariate ordination analysis. Functional traits included maximum body length, feeding mode, spawning strategy and trophic group. Simultaneously, the global distribution of the species was used to model their environmental niches with six environmental variables. For each of these predictors, four niche parameters were derived from the univariate response curve of each species to summarise their environmental preferences and ordinate the species in niche space through a PCA. Finally, the differences in the position in niche space of functional groups were tested with variance analysis.ResultsWe identified seven copepod functional groups with different distributions along the environmental gradients covered by our study. While carnivorous functional groups were affiliated with oligotrophic and tropical conditions, large and small current‐feeding herbivores are associated with colder, more seasonally varying and productive conditions. Small cruising detritivores and other small current‐feeding herbivores were not affiliated with specific conditions as their constituting species were scattered in niche space.Main conclusionsSince copepod functional groups occupy distinct ecological niches, ecosystem processes related to these groups are expected to vary across environmental gradients. Conditions favouring large current‐feeding herbivores should allow for enhanced fluxes of energy and nutrients through Mediterranean Sea ecosystems, while such fluxes should be weakened where large carnivores and small passive ambush‐feeding copepods dominate. Our study supports the development of trait‐based zooplankton functional groups in marine ecosystem models.

Length-weight relationships of six fish species from the headstream region of the Dongjiang River, China

Dongjiang River, a main tributary of the Pearl River, is geographically situated in South China. The present study describes the length–weight relationships (LWRs) of six fish species (Acrossocheilus paradoxus, Barbodes semifasciolatus, Onychostoma elongatum, Microphysogobio fukiensis, Microphysogobio kiatingensis, Metzia lineata) from the headstream region of the river including five Chinese endemic species (A. paradoxus, B. semifasciolatu, O. elongatum, Mi. fukiensis, Mi. kiatingensis). Fish species of five genera of the same family were collected quarterly from April 2012 to October 2014 by using non-selective fishing gears: drag nets (5 m, mesh-size 3 cm), drift gillnets (30 × 15 m, mesh-size 5 mm), fish cages (4 m, mouth opening 40 × 40 cm), scoop nets (mesh-size 0.5-1 cm), and electro-fishing (12V, 200 Hz). The parameter a and b in the LWR equations (W = a Lb) ranged from 0.0014 to 0.0228, and 2.89 to 3.18, respectively. Compared with FishBase, this study provides the first LWR records for four cyprinids (A. paradoxus, B. semifasciolatu, O. elongatum, Me. lineata) and a new record of maximum body length for O. elongatum.

Growth-related changes in non-essential and essential metals in the liver of star-spotted smooth-hounds (dogfish) Mustelus manazo from the northern region of Japan

We analyzed Cd, Hg, Zn, Cu, Mn and Fe concentrations in liver samples from male and female star-spotted smooth-hounds at various life stages. Male sharks of this species are known to reach their maximum body length (BL) more quickly than females, while females are known to mature later and live longer than males. Hepatic Cd and Hg concentrations in males and females markedly increased after maturation, but these increases proceeded earlier in males than in females. Hepatic Zn and Cu concentrations decreased during the growth stage of males and females, and thereafter increased concomitantly with increases of Cd and Hg burdens, forming a U-shaped curve over their lifespan, and the BL at which the lowest concentrations of Zn and Cu were observed was smaller in males than in females. These gender-related differences in those metals could reflect the faster growth and earlier cessation of growth in males.

Body growth and life history in wild mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda.

Great apes show considerable diversity in socioecology and life history, but knowledge of their physical growth in natural settings is scarce. We characterized linear body size growth in wild mountain gorillas from Volcanoes National Park, Rwanda, a population distinguished by its extreme folivory and accelerated life histories. In 131 individuals (0.09-35.26 years), we used non-invasive parallel laser photogrammetry to measure body length, back width, arm length and two head dimensions. Nonparametric LOESS regression was used to characterize cross-sectional distance and velocity growth curves for males and females, and consider links with key life history milestones. Sex differences became evident between 8.5 and 10.0 years of age. Thereafter, female growth velocities declined, while males showed increased growth velocities until 10.0-14.5 years across dimensions. Body dimensions varied in growth; females and males reached 98% of maximum body length at 11.7 and 13.1 years, respectively. Females attained 95.3% of maximum body length by mean age at first birth. Neonates were 31% of maternal size, and doubled in size by mean weaning age. Males reached maximum body and arm length and back width before emigration, but experienced continued growth in head dimensions. While comparable data are scarce, our findings provide preliminary support for the prediction that mountain gorillas reach maximum body size at earlier ages compared to more frugivorous western gorillas. Data from other wild populations are needed to better understand comparative great ape development, and investigate links between trajectories of physical, behavioral, and reproductive maturation.

Morphological Indicators of Skilled Single and Pair Kayak and Canoe Rowers who Participate in Events of Different Distances

In the foreign and native books on rowing it focuses more on investigation of body build, physical and special preparation of sportsmen. These parameters limit the passing time of a competitive distance, so they are used as qualification criteria for specialization and team batching. Methods and investigation design. Canoeists and rowers on kayaks participate in the research. The characteristics of group are: age– 19–26 years, both male and female, high sport qualification, group sizes 160 rowers of both sexes. The complex investigation includes the anthropometric measuring of total body sizes (length and body weight, chest circumference, absolute surface of the body). Conclusions. In the research the biggest length is found in Merited Sports Masters (MSM), each of male and female; the smallest – in Sports masters (SM). The similar trend was noted in parameters of body weight, in exception of single-canoe sportsmen. In this case International Masters of Sports (IMS) show the highest values. In kayaks and canoes, in teams of kayaks pairs at a distance of 200 m, the highest length and body weight were recorded in highly qualified athletes (MSM). The only exception is the body weight of female athletes-canoeists, where this figure is higher for IMS (р&gt;0,05). Among singles at a distance of 500 m the MSM canoeists and rowers on kayaks have the best values of length and bodyweight, MS rowers have the worst results., the only exception is the maximum body length of ISM (р&gt;0,05)/ the female ISM rowers have the highest parameters (р&gt;0,05). The similar trend was found for kayak pairs rowers at a distance of 500 m. At a distance of 1000 m the female and male MSM rowers were superior to IMS’ and SM” in their classes, for canoe the maximum parameters of length and body weight wee noted at ISM. In teams of kayaks pairs at a distance of 1000m the size parametersof MSM are higher then ISM’ and SM’ ones.

Growth and Reproductive Activity of a Captive Female Harbour Porpoise (Phocoena phocoena) from Japanese Water

This report describes growth and annual reproductive cycle of female harbour porpoise (Phocoena phocoena) rescued from Japanese water in 2007. The maximum body length was 179 cm and body weight was 69.8 kg. The average daily food consumption was 7.0 kg (ranging 3.7 - 9.9 kg), 11.8% of the body weight. In this report, the porpoise was kept in 17 °C water annually and the blubber thicknesses showed almost constant throughout the year (average 18 mm, range 13 - 22 mm). Therefore, we added new evidence to this hypothesis by showing that body weight and the blubber thickness do not fluctuate seasonally in fixed water temperature. Serum progesterone level of the female showed five peaks from September to November, and each cycle lasted the average of 20.5 days. Such result indicates that harbour porpoise exhibits seasonal polyestrous activity.

Microarchicotylus ochroleucus gen. et sp. n. (Plathelminthes, Tricladida, Paludicola): A new genus and species of dwarf planarians in Lake Baikal

This paper gives an illustrated description of a new genus and species of endemic Baikal planarians, Microarchicotylus ochroleucus gen. et sp. n. The morphological similarity in the structure of the pharynx, male copulative organs, and external features allowed the authors to include two more species, M. stringulatus (Korotneff 1912) and M. elegans (Porfiriev et Timoshkin 2009), formerly belonging to a poorly investigated genus Archicotylus, into the new genus. Microarchicotylus gen. et sp. n. planarians are attributed to dwarf forms, since their maximal body length does not exceed 5–6 mm. One more distinctive external feature of these Microarchicotylus species is a bright and uneven coloration of the dorsal part of the body, sometimes being dark brown, light brown, or ochreous with distinct white transverse strokes or without them. The anterior part of the body is bright orange or blackish, its color always being different from the remaining body, separated by a white transverse collar behind the pair of eyes. The pharynx is either short cylindrical barrelshaped (length-to-width ratio of ~1) or elongated cylindrical (ratio, 3: 1). The copulative organ is compact and resides behind the pharynx, with its apical part directed downwards. The seminal receptacle, its canal, and the male and common atriums are asymmetrically located relative to the medial longitudinal body axis and centrally located gonopore.

Gene expression profiling of trout regenerating muscle reveals common transcriptional signatures with hyperplastic growth zones of the post-embryonic myotome

BackgroundMuscle fibre hyperplasia stops in most fish when they reach approximately 50 % of their maximum body length. However, new small-diameter muscle fibres can be produced de novo in aged fish after muscle injury. Given that virtually nothing is known regarding the transcriptional mechanisms that regulate regenerative myogenesis in adult fish, we explored the temporal changes in gene expression during trout muscle regeneration following mechanical crushing. Then, we compared the gene transcription profiles of regenerating muscle with the previously reported gene expression signature associated with muscle fibre hyperplasia.ResultsUsing an Agilent-based microarray platform we conducted a time-course analysis of transcript expression in 29 month-old trout muscle before injury (time 0) and at the site of injury 1, 8, 16 and 30 days after lesions were made. We identified more than 7000 unique differentially expressed transcripts that segregated into four major clusters with distinct temporal profiles and functional categories. Functional categories related to response to wounding, response to oxidative stress, inflammatory processes and angiogenesis were inferred from the early up-regulated genes, while functions related to cell proliferation, extracellular matrix remodelling, muscle development and myofibrillogenesis were inferred from genes up-regulated 30 days post-lesion, when new small myofibres were visible at the site of injury. Remarkably, a large set of genes previously reported to be up-regulated in hyperplastic muscle growth areas was also found to be overexpressed at 30 days post-lesion, indicating that many features of the transcriptional program underlying muscle hyperplasia are reactivated when new myofibres are transiently produced during fish muscle regeneration.ConclusionThe results of the present study demonstrate a coordinated expression of functionally related genes during muscle regeneration in fish. Furthermore, this study generated a useful list of novel genes associated with muscle regeneration that will allow further investigations on the genes, pathways or biological processes involved in muscle growth and regeneration in vertebrates.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3160-x) contains supplementary material, which is available to authorized users.

Morphometric and molecular analyses of Skrjabinolecithum pyriforme n. sp. (Digenea: Haploporidae) in mullet fish from the Primorsky Region, Russia.

A new species of Skrjabinolecithum (Digenea: Waretrematinae), Skrjabinolecithum pyriforme n. sp., has been found in the intestines of Liza haematocheila and Mugil cephalus from the Primorsky Region, Russia. These worms differ from S. vitellosum and S. lobolecithum by the presence of two caeca, as do S. spasskii, S. indicum and S. bengalensis. These species differ morphologically from S. pyriforme n. sp. by a number of features, including body width, oral sucker, pharynx, eggs and ratio of length and width of the body. The most similar species to S. pyriforme n. sp. is Platydidymus flecterotestis (Zhukov, 1971) with some differences in maximal body length, testis and egg sizes. The results of molecular analysis confirmed that this new species belongs to Skrjabinolecithum on the basis of close relationships with S. spasskii-type species.

Life history of Dulichiella appendiculata (Amphipoda, Senticaudata, Melitidae) in Maryland Coastal Bays, USA

Epibenthic samples collected from March to December 2012 (except September) in Maryland Coastal Bays (MCBs) were used to study the reproductive biology of Dulichiella appen- diculata, an amphipod species common in estuaries of the Atlantic and Gulf coasts of the USA, whose life history is not well known. Mean densities (± SE) of D. appendiculata increased from May to July, and declined thereafter. The species reproduced continuously from April (spring) to October (fall). The proportions of ovigerous to non-ovigerous females increased with temperature, from ~70% (April), when mean water temperature was 14.7 ± 0.77°C, to ~94% (July), when water temperature was at its peak (26.4 ± 0.23°C), before decreasing to 0% (November) when the temperature was 9.6 ± 0.2°C. The maximum body lengths of non-ovigerous (9.75 mm) and ovigerous (9.85 mm) females, and males (11.1 mm) were larger than values previously reported in a D. appendiculata population in Beaufort, North Carolina, USA. Large ovigerous females from an overwintering cohort produced juveniles in April, and then disappeared from the population by June, leaving behind small, less fecund ovigerous females belonging to a new generation to pro- duce juveniles. Thus, ovigerous females were smaller in size in June (mean ± SE: 4.8 ± 0.2 mm) than in April (7.3 ± 0.1 mm) and May (8.8 ± 0.5 mm). Males outnumbered females from May to October, but the reverse was the case in April (p < 0.05). The D. appendiculata population in MCBs has a semi-annual, iteroparous life history, with a longevity of about 6 mo (spring breeder) and 9 mo (fall breeder).

Hierarchical analysis of taxonomic variation in intraspecific competition across fish species.

The nature and intensity of intraspecific competition can vary greatly among taxa, yet similarities in these interactions can lead to similar population dynamics among related organisms. Variation along the spectrum of intraspecific competition, with contest and scramble competition as endpoints, leads to vastly different responses to population density. Here we investigated the diversity of intraspecific competition among fish species, predicting that functional forms of density-dependent reproduction would be conserved in related taxa. Using a hierarchical model that links stock-recruitment parameters among populations, species, and orders, we found that the strength of overcompensation, and therefore the type of intraspecific competition, is tightly clustered within taxonomic groupings, as species within an order share similar degrees of compensation. Specifically, species within the orders Salmoniformes and Pleuronectiformes exhibited density dependence indicative of scramble competition (overcompensation) while the orders Clupeiformes, Gadiformes, Perciformes, and Scorpaeniformes exhibited dynamics consistent with contest competition (compensation). Maximum potential recruitment also varied among orders, but with less clustering across species. We also tested whether stock-recruitment parameters correlated with maximum body length among species, but found no strong relationship. Our results suggest that much of the variation in the form of density-dependent reproduction among fish species may be predicted taxonomically due to evolved life history traits and reproductive behaviors.