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ABSTRACT: Summary1. After a major decline, the UK otter Lutra lutra population is now recovering in its known strongholds (northern England, Wales and Borders and southwest England) and also in central England where the population had become small, fragmented and was reinforced with captive bred individuals. Bayesian clustering and GIS are used here to identify the genetic structure of the UK otter population and to assess expansion from strongholds and the contribution of introduced otters. Large carnivores have recently started to recolonize landscapes where they were formerly absent, especially in developed countries and understanding the expansion of these populations is essential for informing conservation management, linking fragmented populations and re-establishing gene flow.2. Three Bayesian clustering techniques were used (structure, geneland spatial and baps4 spatial) to estimate the number of otter populations (K). A novel progressive partitioning approach was tested to identify genetic substructuring at various hierarchical levels using successive partitions at K = 2.3. Four regional populations were identified that reflect known population history. Isolated populations in southwest England and in Wales and its borders showed the lowest levels of genetic diversity. Higher diversity and private alleles in northern and central England reflect the proximity to genetically diverse Scottish populations and the positive effect of reintroductions.4. Progressive partitioning was used to produce a more detailed analysis, by allowing comparison and combination of clusters identified by different techniques and by avoiding the subjective estimation and choice of K.5. Synthesis and applications.. Although the otter population is increasing, our data show little sign of population expansion from the stronghold regions into central England, instead reflecting the success of population reinforcement in this area. Our progressive partitioning approach allows the identification of fine-scale substructure (11 groups) that enables the prioritization of management effort including identifying barriers to dispersal within and between populations and monitoring of introduced individuals.
Journal of Applied Ecology 06/2011; 48(5):1206 - 1217. · 5.05 Impact Factor
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ABSTRACT: Scent is used across taxa to communicate information about signaler identity. Eurasian otters Lutra lutra are mainly solitary and thought to use scent as their primary means of communication. Little is known, however, about what information otters communicate through scent or what social function this performs. Headspace solid-phase microextraction and gas chromatography-mass spectrometry were used to sample and analyze volatile organic compounds from anal scent gland secretion from 158 otters of differing sex, age, and female reproductive status. Univariate and multivariate differences were clear between adult and juvenile otters. Complex sex differences were apparent in adult otters but not in younger individuals, suggesting the use of this scent secretion in mate attraction. The scent of pregnant and lactating females was highly differentiated from male and juvenile scent, but anecdotal reports suggest females avoid communication during these times.
Chemical Senses 03/2011; 36(6):555-64. · 2.60 Impact Factor
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ABSTRACT: The uptake of contaminants by biota varies spatially and temporally due to a complex range of interacting environmental variables, but such complexities are typically disregarded in studies of temporal change. Here, we use linear modeling to explore spatial and temporal variation in bone Pb levels measured in samples taken from 329 Eurasian otters (Lutra lutra) found dead in southwest England. Between 1992 and 2004 Pb levels in otters fell by 73%, following UK legislative control of Pb emissions implemented since the mid 1980s. Spatial variation in bone Pb was positively correlated with modeled Pb emissions and stream sediment Pb, which interacted negatively with wind-speed and sediment Ca, respectively. Opportunistic collection of samples from wildlife mortalities provided a valuable opportunity for monitoring environmental contamination, interpretation of which was aided by spatially explicit analysis of environmental variables.
Environmental Science & Technology 02/2011; 45(5):1911-6. · 4.80 Impact Factor
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ABSTRACT: Climate and weather affect phenological events in a wide range of taxa, and future changes might disrupt ecological interactions. Amphibians are particularly sensitive to climate, but few studies have addressed climatically mediated change in the phenology of closely related species or sexes. Here, we test the hypothesis that changes in spring temperatures result in phenological change among Triturus, and we examine inter- and intraspecific differences in response. Coexisting populations of Triturus helveticus and Triturus vulgaris at Llysdinam pond in mid-Wales (53°12′59″N 3°27′3″W) were monitored using pitfall traps along a drift fence during 1981–1987, and again in 1997–2005. Spring temperature over the same period explained up to 74% of between-year variability in median arrival date, with a significant advance of 2–5 days with every degree centigrade increase. Changes were greater for males than females of both species, and greater for T. helveticus than T. vulgaris within sexes, resulting in an increasing temporal separation between arrivals of male T. helveticus and all other groups. These data illustrate for the first time how climatic change might have differential effects on sympatric species and on the two sexes.
Global Change Biology 04/2006; 12(6):1069 - 1078. · 6.86 Impact Factor
