wrt caba/crf conference 02/12/14 - andy king & jamie stevens
TRANSCRIPT
Exploring the genetic basis of metal tolerance in populations of the brown trout (Salmo trutta L.)
Josephine Paris, Andrew King &
Jamie Stevens
Camel Fal Hayle Red RiverZinc (ug/l) 17 37 350 238
Copper (ug/l) 5 5 28 27Arsenic (ug/l) 4 4 9 86
Clean Metal
For example, the River Hayle
• Essentially copper producing mines
• Record production approaching 160,000 tons of concentrates.
• Small amounts of zinc and lead, plus some silver.
• Tin is recorded from only three of the mines and outputs are insignificant.
What we’ve found
Each trout metal population has a different genetic profile compared to trout from clean rivers, and other metal populations
We have timed the generation of each distinct heavy metal
population to historical events relating to mining activity
Metal-impacted populations have lower genetic diversity compared to reference ‘clean’ rivers… evidence of population bottlenecks & local adaptation
15 populations 641 individuals
25 microsatellite loci 9 potentially under selection
Lower genetic diversity in heavy metal rivers
25 microsatellite loci 15 populations 641 individuals
5.50
6.50
7.50
8.50
9.50
10.50
AR
0.55
0.60
0.65
0.70
0.75
0.80
He
0.55
0.60
0.65
0.70
0.75
0.80
Ho
Distinct population structure
Hayle 1
Gannel 2 Fal
Camel 1 Camel 2
Gannel 1
Tresillian
Hayle 2
Crowlas
Trevaylor 1
Trevaylor 2
Hayle 3 Hayle 4
Red River 1
Red River 2
Coor
d. 2
: 19.
8%
Coord. 1: 45.2%
Next step: RAD-seq-based SNP discovery
• Allows for rapid genome-wide screening for fine-scale (inter-population) variation
• Allows for detection of genetic markers (SNPs) associated with adaptive traits (= identification of non-neutral genetic loci)
• Preliminary analysis identifies SNPs (polymorphisms) associated with survival in metal impacted waters; some of these SNPs are in areas of the genome associated with metal processing, e.g. metallothionein.
Genetic Investigations on Brown Trout from the
Devon Avon R. Andrew King, Bruce Stockley & Jamie R. Stevens Exeter University & Westcountry Rivers Trust
Devon Avon • Also known as the River Aune • Catchment is in the South Hams district of Devon • River is approx. 35km in length and 105km2, rising
on Dartmoor and entering the sea at Bigbury-on-Sea • Catchment is included, along with the Erme and
Yealm, in the CRF South Hams River Improvement Project (SHRImP)
WFD Failures • EA report published January 2011 • Upper Avon is failing Water
Framework Directive (WFD) for fish and acidity
• Section downstream of the Avon Dam is notable for the absence of salmon and eels, but trout are present
• This was suspected as being due to the combined influence of the Avon Dam (1957) and low acidity (post-Industrial Revolution)
WRT Management Questions • Q1 - Is the Avon Dam having a genetic affect on
the trout populations downstream of the dam? • Q2 - Are there genetic differences between the
trout populations above and below the Avon Dam?
Genetic Analyses • Samples collected from multiple sites along the river by
Environment Agency and Westcountry Rivers Trust staff during routine electrofishing surveys
• Total sample of 236 fish • Grouped into five ‘populations’
• Us Avon Dam • Avon Dam to Shipley • Shipley to South Brent • Avonwick • Bickham Bridge
• Screened for variation at 19 putatively neutral microsatellite loci used during the AARC Project • Basic measures of genetic diversity calculated and genetic structuring investigated
Bickham Br 2012 - N=29
Avonwick 2011 - N=44
N=number collected
us Avon Dam 2013 - N=76
Dam to Shipley 2013 - N=14 2014 - N=36
Shipley to South Brent 2013 - N=10 2014 - N=29
Conclusions • We can give answers to WRT’s management questions • The Avon Dam has had an affect on the levels of genetic
diversity in brown trout in the reaches downstream of the dam
• There are two distinct genetic groups of brown trout in the Devon Avon, but the boundary between the two is not coincident with the dam
• Divergence time of the two groups suggests that the split is not recent and that the trout population in the upper Avon has been isolated above Shipley Falls for at least 3500 years
• This would suggest that the WFD failures for salmon and eel are due to Shipley Falls acting as a natural migration barrier (also for sea trout)