▪ Abstract Resource polymorphism in vertebrates is generally underappreciated as a diversifying force and probably more common than currently recognized. Research across diverse taxa suggest they may play important roles population divergence speciation. They involve various kinds of traits, including morphological behavioral traits those related to life history. Many the evolutionary, ecological, genetic mechanisms producing maintaining resource polymorphisms are similar among...

Lake Thingvallavatn supports four trophic morphs of Arctic charr, Salvelinus alpinus (L.); two the are benthic (small and large benthivorous charr) one exploits pelagic waters (planktivorous fourth is found in both habitats (piscivorous charr). The morphological variation among these was analysed by use principal component analysis canonical discriminant analysis. benihic have a short lower jaw long pectoral fins. fish also fewer gillrakers than other morphs. Small charrs attain sexual...

Journal Article Ontogeny of trophic morphology in four sympatric morphs arctic charr Salvelinus alpinus Thingvallavatn, Iceland Get access SKÚLI SKÚLASON, SKÚLASON †Institute Biology, University Iceland, Grensásvegur 12, 108 Reykjavík, Iceland‡Department Zoology, Guelph, Ontario, Canadu, N1G 2W1 Search for other works by this author on: Oxford Academic Google Scholar DAVID L. G. NOAKES, NOAKES ‡Department SIGURDUR S. SNORRASON Biological the Linnean Society, Volume 38, Issue 3, November...

The coexistence of four morphs arctic charr in Thingvallavatn, Iceland, was demonstrated by investigations morphology, habitat use, diet, endoparasitic fauna, life history, time and place spawning, early ontogeny, population genetics. Head morphology embryos, juveniles adults revealed the presence two morphotypes, each including morphs: (1) a benthic morphotype large benthivorous (LB-) small (SB-) charr, featuring overshot mouth relatively pectoral fins, (2) pelagic planktivorous (PL-)...

Resource polymorphism has been proposed as an important phase of diversification and speciation in vertebrates. Studies fish young lakes the Northern Hemisphere indicate variably advanced cases adaptive trophic diversification. We have previously a scheme describing this variation terms gradient resource-based polymorphic traits, emphasizing flexible behaviour early phases morphological divergence more phases. Here, we present data on Arctic char (Salvelinus alpinus) Icelandic exhibiting...

The Arctic charr (Salvelinus alpinus) in Thingvallavatn, Iceland, exhibits four morphs. Small benthivorous grow slowly, have an asymptotic length of 13 cm, and mature at age 2–4 yr. Large faster almost rectilinearly with age. They 3–11 Planktivorous piscivorous even higher initial growth rate, but planktivorous cease growing 20 cm a fork 30 cm. 3–5 yr 5–10 age, respectively. gonadosomatic index the annual allocation energy into gonads relative to soma were for than charr. results indicate...

Abstract To examine the population genetic structure of lake‐resident Arctic charr, Salvelinus alpinus from northwest Europe on multiple spatial scales, 2367 individuals 43 lakes located in three geographical regions (Iceland, British Isles and Scandinavia) were genotyped at six microsatellite loci. On a large scale, data provided little evidence to support clustering populations according region. Hierarchical analysis molecular variance indicated that, although statistically significant,...

Phenotypic plasticity is a developmental process that plays role as source of variation for evolution. Models adaptive divergence make the prediction increasing ecological specialization should be associated with lower levels plasticity. We tested differences in magnitude, rate and trajectory morphological two lake populations Arctic charr (Salvelinus alpinus) exhibited degree resource polymorphism. reared offspring on diet treatments mimicked benthic pelagic prey. Offspring from more...

Four morphs of arctic char, Salvelinus alpinus, which differ substantially in morphology, behaviour, and life-history characteristics, occupy different habitats the landlocked lake Thingvallavatn, Iceland. Progeny wild reared a common environment showed early size differences among that were maintained throughout 3-year experiment. Large benthivorous piscivorous char progeny became larger on average than planktivorous small progeny. large had highest specific growth rates whereas benthivores...

Icelandic threespine sticklebacks show parallel sympatric morphological differences related to different substrate habitats in four lakes. The level of diversification varies among the lakes, ranging from a population with wide distribution clear resource morphs, where was reflected diet differences. These divergence are closely ecological surroundings each population. This appears be polymorphism, which may lead differentiation and speciation. Trophically sexual dimorphism also common these...

Parasite communities of fishes are known to respond directly the abiotic environment host, for example, water quality and temperature. Biotic factors also important as they affect exposure profile through heterogeneities in parasite distribution environment. Parasites a particular may pose strong selection on fish. For ecological differences by parasites have been hypothesized facilitate evolutionary differentiation freshwater fish morphs specializing different food types. However, risk does...

In light of global climate change, there is a pressing need to understand and predict the capacity populations respond rising temperatures. Metabolic rate key trait that likely influence ability cope with change. Yet, empirical theoretical work on metabolic responses temperature changes has so far produced mixed results conflicting predictions.Our study addresses this issue using novel approach comparing fish in geothermally warmed lakes adjacent ambient-temperature Iceland. This unique...

ABSTRACT In this paper, we argue that the concept of ‘species’ should not be main focus research and policies in biodiversity conservation. Diversity is important at all levels life: within species as well among them ecosystems. First, give a brief overview debate about necessity to find unified ‘species’. this, side with Charles Darwin, who insisted no strict definition could given term, which ultimately matter arbitrary pragmatic human language. This did worry neither it concern biologists...

Climate change is causing rapid increases in temperature which drives genomic changes tied to adaptation. However, predicting the outcomes of climate presents challenges as anticipated conditions have yet be experienced by natural populations. Modelling and lab experiments suggest that populations will experience shifts life history, physiology, phenology, ecology, but underlying mechanisms involved are unknown. some contemporary habitat warming through geothermal activity can provide...

The relationships among time of spawning, incubation temperature, timing first feeding and early growth were examined in four sympatric morphs Arctic charr Thingvallavatn, Iceland. Large benthivorous spawn July‐August at sites with cold ground‐water flow. Planktivorous piscivorous September‐November are not confined to sites. spawning small overlaps that other morphs. Progeny large start 2‐3 months earlier than the progeny autumn spawners. This results differential size distribution rates...

Thingvallavatn, the largest and one of oldest lakes in Iceland, contains four morphs Arctic charr Salvelinus alpinus. Dwarf benthic (DB), large (LB), planktivorous (PL) piscivorous (PI) can be distinguished differ markedly head morphology, colouration maximum fork length (FL(max)), reflecting their different resource specialisations within lake. The Thingvallavatn are thought to have been isolated for approximately 10 000 years, since shortly after end last Ice Age. We tested null hypothesis...

Restriction fragment length polymorphisms in mitochondrial DNA (mtDNA) were examined progeny of four sympatric morphs Arctic charr ( Salvelinus alpinus L.) from Thingvallavatn, Iceland. The mtDNA analysis with 46 hexanucleotide restriction enzymes indicates that the Thingvallavatn are very closely related. Sequence divergence was less than 0.2% between any five clones detected. Although not significant, topology UPGMA dendogram similar to a previous allozyme survey. Icelandic show greater...