Browsing Biological Sciences by Subjects
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The effect of rainfall upon the behaviour and use of under-road culverts in four amphibian speciesHabitat fragmentation and road mortalities are major contributors towards declines in amphibian populations. This has seen the introduction of culverts, passages that run under roads and provide safe passage for amphibians. Research investigating the effects of rainfall upon amphibian culvert use is limited. This study, conducted at Frankfield Loch in Glasgow, assesses how time elapsed since rainfall influences migration behaviour and the use of culverts across four different species; common toads (Bufo bufo), common frogs (Rana temporaria and newts, a group composed of smooth newts (Lissotriton vulgaris) and palmate newts (Lissotriton helveticus). Analysis of images taken by a custom made, time lapse camera found that significantly fewer common toads (r = 0.148, n = 468, p = 0.001) and common frogs (r = −0.175, n = 106, p = 0.037) used the culvert as time since rainfall increased. This may have been caused by the culvert not maintaining wet enough conditions for amphi- bians. The study also found that more newts (r = 0.272, n = 92, p = 0.004) and common toads (r = 0.531, n = 19, p = 0.010) were using the culvert to move away from Frankfield Loch as time since rainfall increased. An increase in juvenile newts was also observed as time since rainfall increased (r = 0.214, n = 92, p = 0.020). This may have been caused by a decrease in baro- metric pressure, which follows a decrease in rainfall, acting as a cue for migration and juvenile dispersal. The study recom- mends careful consideration of the design of each culvert, incorporating species-specific preferences and the requirements of juveniles. The study also suggests that where possible the culvert should be designed to hold water for longer.
The importance of long-term genetic monitoring of reintroduced populations: inbreeding in the natterjack toad (Epidalea calamita)Genetic monitoring is an important, but frequently lacking, component of management actions to support long-term persistence in reintroduced populations. Populations that remain small, due to demographic processes and genetic diversity, are more likely to experience a second extinction event. The natterjack toad (Epidelea calamita) is legally protected in Britain and was the subject of a reintroduction programme in the 1990s. However, subsequent genetic assessment has been mostly lacking. The aim of this study was to assess the genetic diversity of two reintroduced populations of natterjack toads in order to inform conservation management. Adults were sampled and nine microsatellites amplified to assess neutral genetic variation within each site and for comparison with the source population. Inbreeding was observed at the reintroduction sites, as evidenced by high FIS values (0.43 and 0.72), low observed compared to expected heterozygosities, and significant deviation from Hardy-Weinberg equilibrium. Observed heterozygosity is currently lower in the reintroduction sites than it was in the source population at the time of the reintroductions (Red Rocks: 0.15±0.20; Talacre: 0.12±0.20; Ainsdale (source): 0.29). Evidence for a bottleneck was not found, although this is likely a result of sampling overlapping generations. No within-site population structuring was observed. Such low genetic diversity has not previously been recorded in any natterjack population. Genetic rescue, combined with pool creation, is the most viable option for safeguarding the species at these sites into the future. Our work highlights the importance of ongoing genetic monitoring, in collaboration with conservation organisations, to support conservation management.