Sökning: "amphibians"

Visar resultat 1 - 5 av 33 avhandlingar innehållade ordet amphibians.

1. 1. Evolutionary ecology of ultraviolet-B radiation stress tolerance in amphibians

   Författare :Maarit Pahkala; Trevor Beebee; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; amphibians; anomalies; embryonic development; geographic variation; growth; Rana arvalis; Rana temporaria; survival; UV-B radiation; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; populationsbiologi; Population Biology;

   Sammanfattning : During the last decades many amphibian species and populations have experienced declines and extinctions in different parts of the world. Anthropogenic activities are believed to account for these declines, and one of the hypothesized causes has been the increased level of ultraviolet-B (UV-B) radiation due to depletion of the stratospheric ozone layer. LÄS MER

3. 2. The response in native wildlife to an invading pathogen: Swedish amphibians and Batrachochytrium dendrobatidis

   Författare :Sara Meurling; Anssi Laurila; Jacob Höglund; Christer Brönmark; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Emerging diseases; chytrid; amphibians; wildlife; Biology with specialization in Animal Conservation; Biologi med inriktning mot zoologisk bevarandebiologi;

   Sammanfattning : Emerging infectious diseases are causing mortality and declines in wildlife populations globally. My thesis aims to get as clear a picture as possible of the effect the invasive chytrid fungus Batrachochytrium dendrobatidis has on the Swedish amphibian community. LÄS MER

4. 3. Endocrine Disruption in Amphibians : Developmental Effects of Ethynylestradiol and Clotrimazole on the Reproductive System

   Författare :Irina Gyllenhammar; Cecilia Berg; Ingvar Brandt; Lena Holm; Joakim Larsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Test system; Xenopus tropicalis; Rana temporaria; sex ratio; sex differentiation; fertility; aromatase; ovary; testis; oviduct; Biology; Biologi;

   Sammanfattning : Amphibian populations are declining world-wide and one of the suggested reasons is environmental pollutants. Studies of long-term effects on the reproductive system in frogs following larval exposure to environmental pollutants are scarce. It is therefore important to develop methods to study developmental reproductive toxicity in amphibians. LÄS MER

5. 4. Evolutionary implications of acidification: a frog’s eye view

   Författare :Katja Räsänen; Andrew Hendry; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; acid stress; amphibians; local adaptation; maternal effects; maternal investment; Biologi; Biology; Biologi; populationsbiologi; Population Biology;

   Sammanfattning : Understanding the diversity of life is one of the main aims of evolutionary biology, and requires knowledge of the occurrence and causes of adaptive genetic differentiation among geographically distinct populations. Environmental stress caused by acidity may cause strong directional selection in natural populations, but is little explored from an evolutionary perspective. LÄS MER

7. 5. Effects of Agriculture on Abundance, Genetic Diversity and Fitness in the Common Frog, Rana temporaria

   Författare :Markus Johansson; Anssi Laurila; Juha Merilä; Craig R. Primmer; Michael W. Bruford; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; agriculture; agrochemicals; amphibians; effective population size; genetic diversity; genetic structure; hierarchical sampling; microsatellites; Rana temporaria; Biologi; Biology; Biologi;

   Sammanfattning : The aims of this thesis were to evaluate the effects of agriculture on amphibians in terms of (i) population genetic consequences of agriculture-induced spatial changes of the landscape and (ii) local adaptation and tolerance to frequently used agrochemicals. The study was performed using the common frog Rana temporaria as a model. LÄS MER