scholarly journals Life-history variability and conservation status of landlocked Atlantic salmon: an overview

2019 ◽  
Vol 76 (10) ◽  
pp. 1697-1708 ◽  
Author(s):  
Jeffrey A. Hutchings ◽  
William R. Ardren ◽  
Bjørn T. Barlaup ◽  
Eva Bergman ◽  
Keith D. Clarke ◽  
...  
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Conservation Status ◽  
Large Body ◽  
Eastern North America ◽  
Osmerus Mordax ◽  
Large Body Size ◽  
Coregonus Albula ◽  
Multiple Challenges ◽  
High Diversity

Nonanadromous Atlantic salmon (Salmo salar) exhibit a combination of variation in life history, habitat, and species co-existence matched by few vertebrates. Distributed in eastern North America and northern Europe, habitat ranges from hundreds of metres of river to Europe’s largest lakes. As juveniles, those with access to a lake usually migrate to feed and grow prior to reproduction. Prey such as smelt (Osmerus mordax, Osmerus eperlanus) and vendace (Coregonus albula) facilitate large body size (50–85 cm at maturity) and persistence in high-diversity (>20 fish species) environments; small-bodied salmon (10–30 cm at maturity), relying on insects as prey, coexist with few (fewer than five) other fishes. At maturity, weight varies more than 400-fold (17 to 7200 g) among populations, fecundity more than 150-fold (33 to 5600), and longevity almost fivefold (3 to 14 years). Landlocked salmon are managed to support sustainable fishing, achieve conservation and restoration targets, and mitigate threats; successes are evident but multiple challenges persist. Extraordinary variability in life history coupled with extensive breadth of habitat and species co-existence render landlocked Atlantic salmon singularly impressive from a biodiversity perspective.

scholarly journals The evolution of tail weaponization in amniotes

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172299 ◽  
Author(s):  
Victoria M. Arbour ◽  
Lindsay E. Zanno
Keyword(s):  
Life History ◽  
Evolutionary History ◽  
Phenotypic Diversity ◽  
Large Body ◽  
Phylogenetic Comparative Methods ◽  
Rare Form ◽  
Large Body Size ◽  
Selective Pressures ◽  
Body Armour ◽  
Predator Defence

Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not well understood. Here, we investigate the evolution of tail weaponry in amniotes, a rare form of weaponry that nonetheless evolved independently among a broad spectrum of life including mammals, turtles and dinosaurs. Using phylogenetic comparative methods, we test for links between morphology, ecology and behaviour in extant amniotes known to use the tail as a weapon, and in extinct taxa bearing osseous tail armaments. We find robust ecological and morphological correlates of both tail lashing behaviour and bony tail weaponry, including large body size, body armour and herbivory, suggesting these life-history parameters factor into the evolution of antipredator behaviours and tail armaments. We suggest that the evolution of tail weaponry is rare because large, armoured herbivores are uncommon in extant terrestrial faunas, as they have been throughout evolutionary history.

scholarly journals Unidirectional response to bidirectional selection on body size. I. Phenotypic, life history and endocrine response

2018 ◽  
Author(s):  
Clémentine Renneville ◽  
Alexis Millot ◽  
Simon Agostini ◽  
David Carmignac ◽  
Gersende Maugars ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Small Body ◽  
Large Body ◽  
Detailed Knowledge ◽  
Control Line ◽  
Large Body Size ◽  
Size Dependent ◽  
Body Sizes ◽  
Anthropogenic Perturbations

ABSTRACTAnthropogenic perturbations such as harvesting often select against a large body size and are predicted to induce rapid evolution towards smaller body sizes and earlier maturation. However, body-size evolvability and, hence, adaptability to anthropogenic perturbations remain seldom evaluated in wild populations. Here, we use a laboratory experiment over 6 generations to measure the ability of wild-caught medaka fish (Oryzias latipes) to evolve in response to bidirectional size-dependent selection mimicking opposite harvest regimes. Specifically, we imposed selection against a small body size (Large line), against a large body size (Small line) or random selection (Control line), and measured correlated responses across multiple phenotypic, life-history and endocrine traits. As expected, the Large line evolved faster somatic growth and delayed maturation, but also evolved smaller body sizes at hatch, with no change in average levels of pituitary gene expressions of luteinizing, folliclestimulating or growth (GH) hormones. In contrast, the Small medaka line was unable to evolve smaller body sizes or earlier maturation, but evolved smaller body sizes at hatch and showed marginally-significant signs of increased reproductive investment, including larger egg sizes and elevated pituitary GH production. Natural selection on medaka body size was too weak to significantly hinder the effect of artificial selection, indicating that the asymmetric body-size response to size-dependent selection reflected an asymmetry in body-size evolvability. Our results show that trait evolvability may be contingent upon the direction of selection, and that a detailed knowledge of trait evolutionary potential is needed to forecast population response to anthropogenic change.

scholarly journals Density-dependent natural selection mediates harvest-induced trait changes

2019 ◽  
Author(s):  
Alix Bouffet-Halle ◽  
Jacques Mériguet ◽  
David Carmignac ◽  
Simon Agostini ◽  
Alexis Millot ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Natural Selection ◽  
Large Body ◽  
Population Densities ◽  
Large Body Size ◽  
Density Dependent ◽  
Show Evidence ◽  
Selection For ◽  
Density Dependent Selection

ABSTRACTRapid life-history changes caused by size-selective harvesting are often interpreted as a response to direct harvest selection against a large body size. However, similar trait changes may result from a harvest-induced relaxation of natural selection for a large body size via density-dependent selection. Here, we show evidence of such density-dependent selection favouring large-bodied individuals at high population densities, in replicated pond populations of medaka fish. Harvesting, in contrast, selected medaka directly against large-bodied medaka and, in parallel, decreased medaka population densities. Five years of harvesting were enough for harvested and unharvested medaka populations to inherit the classically-predicted trait differences, whereby harvested medaka grew slower and matured earlier than unharvested medaka. We demonstrate that this life-history divergence was not driven by direct harvest selection for a smaller body size in harvested populations, but by density-dependent natural selection for a larger body size in unharvested populations.

A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

2020 ◽  
Vol 29 (2) ◽  
pp. 278-283
Author(s):  
S.G. Ermilov
Keyword(s):  
New Species ◽  
Body Size ◽  
Leaf Litter ◽  
Related Species ◽  
Large Body ◽  
Oribatid Mite ◽  
Neotropical Region ◽  
Large Body Size ◽  
First Time ◽  
A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

scholarly journals Atmospheric Hypoxia Limits Selection for Large Body Size in Insects

PLoS ONE ◽  
2009 ◽  
Vol 4 (1) ◽  
pp. e3876 ◽  
Author(s):  
C. Jaco Klok ◽  
Jon F. Harrison
Keyword(s):  
Body Size ◽  
Large Body ◽  
Large Body Size ◽  
Selection For

Effect of time of day, time of year, and life history strategy on time budgeting in juvenile Atlantic salmon, Salmo salar

1999 ◽  
Vol 56 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
Sveinn K Valdimarsson ◽  
Neil B Metcalfe
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Life History Strategy ◽  
Time Of Day ◽  
Life History Strategies ◽  
Foraging Efficiency ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Time Of Year

Traditionally, behavioural studies on juvenile Atlantic salmon, Salmo salar, have been conducted during the day in summer. It is known that Atlantic salmon become nocturnal in winter, but very little is known about their behaviour at that time. Therefore, observations in a seminatural stream were carried out during the day and night, from February to June, comparing diel and seasonal differences in behaviour between fish adopting alternative life history strategies. The results showed a general trend for more activity in spring than in winter, and the fish were found to be foraging at surprisingly low light levels. There were differences in relative feeding rate between the life history strategies; the early migrant fish foraged mostly during the day whereas the delayed migrant fish did more foraging at night. There is some evidence that the early migrant fish made fewer feeding attempts over the winter, which is surprising, since they grow faster over that period. This suggests differences in foraging efficiency, which could contribute to the separation into these two life history strategies.

SYSTEMATICS OF THE TRICHADENOTECNUM ALEXANDERAE SPECIES COMPLEX (PSOCOPTERA: PSOCIDAE) BASED ON AN INVESTIGATION OF MODES OF REPRODUCTION AND MORPHOLOGY

1983 ◽  
Vol 115 (10) ◽  
pp. 1329-1354 ◽  
Author(s):  
B. W. Betz
Keyword(s):  
Life History ◽  
North America ◽  
Sibling Species ◽  
Species Complex ◽  
Morphological Analysis ◽  
Geographic Range ◽  
Eastern North America ◽  
Facultative Parthenogenesis

AbstractTrichadenotecnum alexanderae Sommerman is shown to represent one biparental (= euphrasic) species capable of facultative parthenogenesis (thelytoky) and three uniparental (= obligatorily parthenogenetic) sibling species, as determined by tests for mating, life history observations, and morphological analysis of specimens over the geographic range of the species complex. The name T. alexanderae is restricted to the biparental species because the holotype is a male. The three uniparental species are here named and described as T. castum n. sp., T. merum n. sp., and T. innuptum n. sp. The female of T. alexanderae is redescribed to allow its separation from the three uniparental species. A key to females of the species complex is supplied. All three uniparental species were derived from the biparental ancestor of T. alexanderae. Most collections of populations represented only by females consist of one or more uniparental species. Facultative parthenogenesis is shown to maintain a population of T. alexanderae through one generation only. The biparental species is found not to be restricted geographically to a relictual or peripheral range within the species complex, but to occupy a rather wide, north-temperate distribution across eastern North America.

scholarly journals New records of ring nematodes, Bakernema enormese n. sp. and Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, 1997 (Nematoda: Criconematidae) from natural forests of Vietnam

2019 ◽  
Vol 41 (3) ◽  
Author(s):  
Nguyen Ngoc Chau
Keyword(s):  
New Species ◽  
Body Size ◽  
New Records ◽  
Large Body ◽  
Lateral View ◽  
The Body ◽  
Natural Forests ◽  
Large Body Size ◽  
Stylet Length ◽  
North Vietnam

Bakernema enormese sp. n., collected from rhizosphere of forest wood trees in Muong Phang, Dien Bien Province (north Vietnam) is described and illustrated. The new species is characterized by large body size and stylet. In general, this new species is close to two existing species of the same genus, B. inaequale and B. dauniense by cuticle structure in transparent membranous projections which appear in lateral view as spine-like structures on each annulus. These structure arranged into several rows along the body. In morphology, the new species differs from B. inaequale and B. dauniense  by body and stylet length, i.e. 609–842 µm and 143.5–150 µm vs. 391–578 µm and 59–74 µm for B. inaequale and vs. 391–461 µm and 65–74 µm for B. dauniense. In addition, new species can be distinguished from B. inaequale by the longer membranous projection, 8–12 vs. 6–10 µm and vagina shape, curved vs. sigmoid. From B. dauniense, the new species differs by the much longer membranous projection, 8–12 vs. 1.4–2.2 µm and less number annules between vulva and tail end (RV), 3–4 vs. 7.8 annules. The presence of Criconema (Nothocriconemella) graminicola Loof, Wouts & Yeates, in Vietnam with morphometrics, illustrators and remarks given.

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