Sökning: "evolutionen"

Visar resultat 1 - 5 av 55 avhandlingar innehållade ordet evolutionen.

1. 1. Den svårformulerade evolutionen : gränssnittets och innehållets betydelse för de meningar om evolutionen som erbjuds användaren av tre digitala läromedel i biologi

   Författare :Per Anderhag; Stockholms universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES;

   Sammanfattning : .... LÄS MER

3. 2. The evolution of ribonucleotide reductases

   Författare :Daniel Lundin; Anthony Poole; Britt-Marie Sjöberg; Christos Ouzounis; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Evolution; ribonucleotide reductase; horizontal gene transfer; phylogeny; protein classification; Molecular biology; Molekylärbiologi; Molecular Biology; molekylärbiologi;

   Sammanfattning : Ribonucleotide reductase (RNR) catalyses the transformation of RNA building blocks, ribonucleotides, to DNA building blocks, deoxyribonucleotides. This is the only extant reaction pathway for de novo synthesis of DNA building blocks and the enzyme is thus necessary for life. RNR is found in all but a few organisms. LÄS MER

4. 3. The tempo and mode of evolution : a neontological reappraisal

   Författare :Melanie Monroe; Folmer Bokma; Pär Ingvarsson; Mikael Fortelius; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; birds; extinction; macroevolution; mammals; microevolution; punctuated equilibrium; speciation;

   Sammanfattning : The theory of “punctuated equilibrium” suggests that species evolve rapidly during or immediately upon speciation, “punctuating” long periods of little or no morphological evolution. Here I confirm that body size differences within clades of birds and mammals are best explained using a model of punctuated evolution. LÄS MER

5. 4. Adaptation and Constraint in the Plant Reproductive Phase

   Författare :Kjell Bolmgren; Ove Eriksson; Bengt Oxelman; Jeff Ollerton; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; phenology; fleshy fruits; phylogenetic comparative methods; phylogenetic constraints; Rhamnus; Frangula; Frangula alnus; key innovations; allometry; diversity; phylogeny; seed size; frugivory; germination; recruitment; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Sammanfattning : Conservatism is a central theme of organismic evolution. Related species share characteristics due to their common ancestry. Some concern have been raised among evolutionary biologists, whether such conservatism is an expression of natural selection or of a constrained ability to adapt. LÄS MER

7. 5. The descent of damselflies and variation in relation to sex

   Författare :Beatriz Willink Castro; Evolutionär ekologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; sexual conflict; development; diversification; pleiotropy; correlational selection; damselfly;

   Sammanfattning : Sexual conflict over mating shapes the interactions between males and females in many animals and is also responsible for dramatic adaptations in both sexes. In some species of pond damselflies (Odonata:Coeangrionidae), sexual conflict maintains discrete female-limited colour morphs over multiple generations and within populations. LÄS MER