Det bortkomne faget … Naturfaget tilbake i norsk grunnskole Synteserapport for prosjektet: Natur- og miljøfag etter Reform 97, en evaluering ut fra et elevperspektiv

Flere studier på 90-tallet viste at naturfagets stilling var svekket (Sjøberg 1994; Lie, Kjærnsli og Brekke 1997; Nergård 1994). I det intergrerte orienteringsfaget (o-fag) i barneskolen var naturfagets plass svak både i lærebøkene og i klasserommet. Den internasjonale TIMSS-undersøkelsen (Third International Mathematics and Science Study) viste at norske 13. åringer lå under eller rundt gjennomsnittet når det gjaldt kunnskaper i naturfag (Lie, Kjærnsli og Brekke 1997). Spesielt var resultatene dårlige i emner knyttet til fagområdene kjemi og fysikk. Videre viste TIMSS-undersøkelsen at Norge var etter Japan det landet som hadde størst forskjell mellom gutter og jenters holdninger til faget. Gjennom arbeidet med ny læreplan for grunnskolen ble naturfagets situasjon vektlagt og et viktig resultat er at en har fått et natur- og miljøfag på alle klassetrinn i grunnskolen, og spesielt i barneskolen. Dette er utvilsomt en av de større strukturelle endringene fra Mønsterplanen 87 (M87) til Reform 97 (R97). I dette prosjektet har vi valgt å evaluere natur- og miljøfaget på slutten av mellomtrinnet. Det er på barnetrinnet en har fått overgang fra det integrerte ”orienteringsfaget” til ”natur- og miljøfag”, den største endring for naturfaget med innføring av den ny læreplanen. Hovedmålet for prosjektet har vært: I hvilken grad har en nådd de faglige og holdningsmessige målsetninger Reform 97 setter for natur og miljøfaget? Dette er konkretisert i disse spørsmåla som er laget ut fra de felles måla i Læreplanen i natur- og miljøfag 97 (L97): · har jenter og gutter på lik linje utviklet kunnskaper, ferdigheter, engasjement, interesse og holdninger til alle deler av faget? · har elevene utviklet kunnskaper og ferdigheter i alle deler av faget som de kan anvende i dagliglivet og i forhold til samfunnet og miljøet rundt seg? · har elevene fått kunnskap og øvelse i naturvitenskaplig historie, tenke- og arbeidsmåte? · har elevene møtt et bredt spekter av arbeidsmåter og gjennom praktiske aktiviteter fått opplevelser, ferdigheter og erfaringer som kan anvendes i praktiske gjøremål

Regressive evolution of the pelvic complex in stickleback fishes: a study of convergent evolution

Background: Regressive evolution of the pelvic complex has been observed in populations of three of five stickleback genera, Gasterosteus, Pungitius, and Culaea, from young freshwater habitats (<18,000 years old). It has been hypothesized to be selected for by ion limitation, lack of predation by fishes, and increased predation by large aquatic insects. Stickleback pelvic reduction is often caused by deletion mutations of the Pitx1 gene, which prevent its expression during pelvic development. Lack of Pitx1 expression may be partly compensated for by Pitx2, which is preferentially expressed on the left side of the body, causing the left pelvic vestige to be larger than the right. Thus, left-biased directional asymmetry of pelvic vestiges implicates null Pitx1 alleles. Aim: Review the geographical patterns of pelvic variation in the three stickleback genera and consider their implications for hypotheses regarding the genetics and evolution of pelvic reduction in the Gasterosteidae. Data: We review published data on pelvic reduction and add previously unpublished information from populations in Scotland and Norway. Methods: We assign individual stickleback to one of three pelvic phenotypes – normal, vestigial, and lost pelvis – and explore the distribution of these three broad classes among populations. We study bilateral symmetry of the pelvis by scoring pelvic phenotypes on the left and right sides. Results: Pelvic reduction is rare in sticklebacks and occurs only in fresh water. Sticklebacks with pelvic reduction tend to occur in the western and northern parts of their ranges in Eurasia and North America, but this pattern is less evident for the ninespine stickleback. Pelvic phenotype frequency distributions within populations differ among stickleback genera. The vestigial pelvic phenotype dominates in many populations of Gasterosteus aculeatus, rarely in Pungitius, and never in Culaea inconstans. In Culaea, the lost and normal pelvic phenotypes are often dimorphic, but a vestigial pelvis is rare. This dimorphism does not occur in the other two genera. Monomorphism of the lost pelvic phenotype does not occur in Gasterosteus, and is rare in the other two genera. Asymmetry of pelvic vestiges is common in all three genera, but left-larger directional asymmetry predominates only in Gasterosteus. This bias could be due to the suggested regulatory mutation in the Pitx1 gene and/or mutations in downstream targets of Pitx1, and suggests involvement of other genes for pelvic reduction in the other genera.2014-08-3

Spatio-temporal patterns in pelvic reduction in threespine stickleback (Gasterosteus aculeatus L.) in Lake Storvatnet

Questions: The pelvic girdle with associated spines is an integrated anti-predator defence apparatus, and is assumed to protect against piscivores in the threespine stickleback. On the other hand, it might be costly to produce the pelvic apparatus in ion-poor and mineralchallenging freshwater. Hypothesis: Stickleback with a reduced pelvic apparatus should use more shelter and be more nocturnal, avoiding predation risk. In contrast, stickleback with a well-developed pelvic apparatus should have reduced mortality during ontogeny in encounters with piscivores and thus have a longer expected lifespan. Given these two life-history strategies, we expect assortative mating as a result of divergent selection. Organism: Marine and freshwater threespine stickleback (Gasterosteus aculeatus L.). Places and times: Two representative ancestral marine populations and 36 freshwater populations in northwestern Norway (Lake Storvatnet, the main focus of the study, and three lakes downstream of it). Material was collected from 2006 to 2009. Analytical methods: We categorized nominal pelvic apparatus development (CPS morphs) in all fish, and measured metrics associated with these categories in a subsample. We also studied temporal, spatial, and habitat variation in the distribution of pelvic morphs in Lake Storvatnet. In this population, and downstream populations, we contrasted the detailed pelvic morphology with the measured genetic diversity (microsatellites), also estimating gene flow. In Lake Storvatnet, we tested for genetic divergence and signs of potential build-up of reproductive isolation via assortative mating among the observed nominal categories of pelvic reduction (CPS). Results: Pelvic reduction was seen only in Lake Storvatnet, where more than 50% of fish had a reduced pelvis. The distribution of pelvic morphs was stable over time and did not differ between habitats. The proportion of fish with pelvic reduction decreased with age. Freshwater stickleback tended to have a smaller pelvis than marine fish. The Lake Storvatnet stickleback were genetically differentiated from the downstream Lake Gjerhaugsvatn population, and both of these were different from the marine populations, with little gene flow among populations. No apparent genetic structure was found between CPS morphs within Lake Storvatnet. However, genetic factorial correspondence axes were significantly correlated with pelvic principal component axes in Lake Storvatnet, suggesting some phenotype × genetic association. Conclusion: The weak association between phenotypes and genetic structure observed in this study may reflect the build-up of early steps of reproductive isolation. Given time, such mechanisms may lead to the evolution of assortative mating, which may drive adaptive pelvic morphs (niche peaks), further resulting in genetically divergent populations and pelvic morphs

Regressive evolution of the pelvic complex in stickleback fishes: a study of convergent evolution

Background: Regressive evolution of the pelvic complex has been observed in populations of three of five stickleback genera, Gasterosteus, Pungitius, and Culaea, from young freshwater habitats (<18,000 years old). It has been hypothesized to be selected for by ion limitation, lack of predation by fishes, and increased predation by large aquatic insects. Stickleback pelvic reduction is often caused by deletion mutations of the Pitx1 gene, which prevent its expression during pelvic development. Lack of Pitx1 expression may be partly compensated for by Pitx2, which is preferentially expressed on the left side of the body, causing the left pelvic vestige to be larger than the right. Thus, left-biased directional asymmetry of pelvic vestiges implicates null Pitx1 alleles. Aim: Review the geographical patterns of pelvic variation in the three stickleback genera and consider their implications for hypotheses regarding the genetics and evolution of pelvic reduction in the Gasterosteidae. Data: We review published data on pelvic reduction and add previously unpublished information from populations in Scotland and Norway. Methods: We assign individual stickleback to one of three pelvic phenotypes – normal, vestigial, and lost pelvis – and explore the distribution of these three broad classes among populations. We study bilateral symmetry of the pelvis by scoring pelvic phenotypes on the left and right sides. Results: Pelvic reduction is rare in sticklebacks and occurs only in fresh water. Sticklebacks with pelvic reduction tend to occur in the western and northern parts of their ranges in Eurasia and North America, but this pattern is less evident for the ninespine stickleback. Pelvic phenotype frequency distributions within populations differ among stickleback genera. The vestigial pelvic phenotype dominates in many populations of Gasterosteus aculeatus, rarely in Pungitius, and never in Culaea inconstans. In Culaea, the lost and normal pelvic phenotypes are often dimorphic, but a vestigial pelvis is rare. This dimorphism does not occur in the other two genera. Monomorphism of the lost pelvic phenotype does not occur in Gasterosteus, and is rare in the other two genera. Asymmetry of pelvic vestiges is common in all three genera, but left-larger directional asymmetry predominates only in Gasterosteus. This bias could be due to the suggested regulatory mutation in the Pitx1 gene and/or mutations in downstream targets of Pitx1, and suggests involvement of other genes for pelvic reduction in the other genera

The temporal window of ecological adaptation in postglacial lakes: a comparison of head morphology, trophic position and habitat use in Norwegian threespine stickleback populations

Background: Studying how trophic traits and niche use are related in natural populations is important in order to understand adaptation and specialization. Here, we des cribe trophic trait diversity in twenty-five Norwegian freshwater threespine stickleback populations and their putative marine ancestor, and relate trait differences to postglacial lake age. By studying lakes of different ages, depths and distance to the sea we examine key environmental variables that may predict adaptation in trophic position and habitat use. We measured trophic traits including geometric landmarks that integrate d variation in head shape as well as gillraker length and number. Trophic position (Tpos) and niche use ( α ) were estimated from stable isotopes ( δ 13 C, δ 15 N). A comparison of head shape was also made with two North American benthic-limnetic species pairs. Results: We found that head shape differed between marine and freshwater sticklebacks, with marine sticklebacks having more upturned mouths, smaller eyes, larger opercula and deeper heads. Size-adjusted gillraker lengths were larger in marine than in freshwater stickleback. Norwegian sticklebacks were compared on the same head shape axis as the one differentiating the benthic-limnetic North American threespine stickleback species pairs. Here, Norwegian freshwater sticklebacks with a more “ limnetic head shape ” had more and longer gillrakers than sticklebacks with “ benthic head shape ” .The “ limnetic morph ” was positively associated with deeper lakes. Populations differed in α (mean ± sd: 0.76 ± 0.29) and Tpos (3.47 ± 0.27), where α increased with gillraker length. Larger fish had a higher Tpos than smaller fish. Compared to the ecologically divergent stickleback species pairs and solitary lake populations in North America, Norwegian freshwa ter sticklebacks had similar range in Tpos and α values, but much less trait divergences. Conclusions: Our results showed trait divergences between th reespine stickleback in marine and freshwater environments. Freshwater populations diverged in trophic ecology and trophic traits, but trophic ecology was not related to the elapsed time in freshwater. Norwegian sticklebacks used the same niches as the ecologically divergent North American stickleback species pairs. Ho wever, as trophic trait divergences were smaller, and not strongly associated with the ecological niche, ecologica l adaptations along the benthic-limnetic axis were less developed in Norwegian sticklebacks

Data from: The temporal window of ecological adaptation in postglacial lakes: a comparison of head morphology, trophic position and habitat use in Norwegian threespine stickleback populations

Background: Studying how trophic traits and niche use are related in natural populations is important in order to understand adaptation and specialization. Here, we describe trophic trait diversity in twenty-five Norwegian freshwater threespine stickleback populations and their putative marine ancestor, and relate trait differences to postglacial lake age. By studying lakes of different ages, depths and distance to the sea we examine key environmental variables that may predict adaptation in trophic position and habitat use. We measured trophic traits including geometric landmarks that integrated variation in head shape as well as gillraker length and number. Trophic position (Tpos) and niche use (α) were estimated from stable isotopes (δ13C, δ15N). A comparison of head shape was also made with two North American benthic-limnetic species pairs. Results: We found that head shape differed between marine and freshwater sticklebacks, with marine sticklebacks having more upturned mouths, smaller eyes, larger opercula and deeper heads. Size-adjusted gillraker lengths were larger in marine than in freshwater stickleback. Norwegian sticklebacks were compared on the same head shape axis as the one differentiating the benthic-limnetic North American threespine stickleback species pairs. Here, Norwegian freshwater sticklebacks with a more "limnetic head shape" had more and longer gillrakers than sticklebacks with "benthic head shape". The "limnetic morph" was positively associated with deeper lakes. Populations differed in α (mean ± sd: 0.76 ± 0.29) and Tpos (3.47 ± 0.27), where α increased with gillraker length. Larger fish had a higher Tpos than smaller fish. Compared to the ecologically divergent stickleback species pairs and solitary lake populations in North America, Norwegian freshwater sticklebacks had similar range in Tpos and α values, but much less trait divergences. Conclusions: Our results showed trait divergences between threespine stickleback in marine and freshwater environments. Freshwater populations diverged in trophic ecology and trophic traits, but trophic ecology was not related to the elapsed time in freshwater. Norwegian sticklebacks used the same niches as the ecologically divergent North American stickleback species pairs. However, as trophic trait divergences were smaller, and not strongly associated with the ecological niche, ecological adaptations along the benthic-limnetic axis were less developed in Norwegian sticklebacks