Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates without an egg diapause significantly advanced the leading edge (first quartile date) of the flight period by a mean of 2.73 days per decade ± 0.055 (s.e.m., n=19) or 5.82 ± 1.15 (s.e.m., n=19) per degree rise in temperature. Species exhibiting a diapause in the egg stage did not respond significantly to increases in UK temperatures. This study represents the first review of changes in odonate phenology in relation to climate change and shows that responses to global warming are mediated by life-history traits. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared to terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa.

No abstract

Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates without an egg diapause significantly advanced the leading edge (first quartile date) of the flight period by a mean of 2.73 days per decade ± 0.055 (s.e.m., n=19) or 5.82 ± 1.15 (s.e.m., n=19) per degree rise in temperature. Species exhibiting a diapause in the egg stage did not respond significantly to increases in UK temperatures. This study represents the first review of changes in odonate phenology in relation to climate change and shows that responses to global warming are mediated by life-history traits. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared to terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa.

In Britain the genus Euphrasia comprises ca 20 diploid and tetraploid plant species, including several endemics. However, their conservation is impeded by taxonomic uncertainty. Analysis of cpDNA and AFLP variation was used to assess their taxonomic status and establish the extent of barriers to gene exchange among them. Differences in ploidy level constitute a very strong barrier to genetic exchange, although this is not absolute. The diploid endemics E. vigursii and E. rivularis form morphologically and genetically definable units which show some level of reproductive isolation. Within tetraploid Euphrasia, the species showed varying degrees of distinctness. Analysis of geographically paired samples from two widespread outcrossing taxa E. arctica and E. nemorosa provides evidence for extensive genetic exchange between them. However AFLP data indicate that this outbreeding species complex possesses a gene pool distinct from that of the widespread inbreeding tetraploids. The widespread and endemic inbreeding tetraploids contain examples of morphologically and genetically definable taxa, but also species whose distinctness is more equivocal. The conservation implications of this study are that species-based action plans are potentially suitable for conservation of the diploid endemics E. vigursii and E. rivularis. In contrast we contend that a species-based conservation framework, developed with reproductively isolated and genetically distinct groups in mind, requires modification for conservation of the complex and dynamic diversity found within the tetraploids. The adoption of 'taxonomic' action plans, designed to protect the evolutionary processes generating Euphrasia diversity, may provide a supplementary solution for conserving this type of variation.