Climate pressures

Climate change is rising up many agendas, from over-arching politics to detailed and focused research. The anthropogenic input of carbon dioxide and other greenhouse gases into the atmosphere is well documented and evidence is already building that the earth's climate is warming but the impact of this and future changes remain uncertain, particularly in higher latitudes where changes may be more dramatic. Studies on the events surrounding past climate changes are therefore of increasing interest. While significant climate change may be expected to be devastating for many species, as has also been shown in the past, it also presents an opportunity for a few organisms. And a new genetic study on some ancient insects suggests such events may prompt diversification into new species that, interestingly, also show a pattern across different groups. report in American Naturalist (published online) a new genetic study of a group of damselflies, ancient insects thought to have evolved up to 300 million years ago. They looked at amplified fragment length polymorphisms and mitochondrial DNA to study the relationships amongst members of the Enallagma genus of damselflies which appear to have recently radiated to produce species occupying many sites in the northern hemisphere. Analyses suggest that 17 species are derived from two progenitor lines that radiated in recent geological time and are found mainly in northern America, whereas a third major lineage has led to the highest species richness in the southeastern US. The team describes these species as the 'northern' and 'southern' groups. From the DNA analyses, the team suggest that climate change during the Quaternary, the most recent period of geological history, is linked with increased rates of speciation in these three different clades of damselfly, and that, interestingly, similar combinations of speciation processes affected each lineage. Diversification rates across the entire genus of damselfly shows that both northern and southern primary clades were influenced by climatic upheaval during the Quaternary. " For most of their histories, the northern and southern clades had very similar diversification rates, but speciation rates in both clades greatly increased sometime in the last million years " , the authors say. This increase was much more pronounced in the northern clade, where the estimated speciation rate increased by around 24 times, as compared with an increase of around Climates past: A new study suggests that different lineages of related damselflies showed similar evolutionary responses to climate change during the …