Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie...
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![Page 1: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/1.jpg)
Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads
Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay PyareUniversity of Alaska Southeast
![Page 2: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/2.jpg)
Landscapes have profound effects on species ecology
Colonization
Movement
DispersalPopulation dynamics
Geographic distributions
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Landscape genetics
Landscape ecology + population genetics
• Aims to quantify the effects of the landscape on microevolutionary processes– Cryptic boundaries– Secondary contact among previously isolated pops
• Hypothesis driven• Novel individual-based methods
![Page 4: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/4.jpg)
Landscape genetics
Two key steps:1. Detect genetic discontinuities2. Correlate these with landscape and
environmental features
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Amphibians
• Good models for studies of connectivity– Function as metapopulations– Patchy distributions = limited connectivity
• Population dynamics difficult to understand with traditional ecological methods– High population stochasticity
![Page 6: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/6.jpg)
Boreal toads
• Widespread• IUCN listed as near
threatened• Status in Alaska?– northern range
margin
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Boreal toads
• Pond breeding, but variable habitat and climate tolerance
• Capable of long distance movements• High breeding site fidelity
Highly differentiated?Strongly affected by the landscape?
![Page 8: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/8.jpg)
Study sitesAdmiralty Island Haines
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Hypotheses• H1: Isolation by distance– Euclidean distance
• H2-n: Isolation by landscape resistance– Habitat structure (x 5)– Insolation– Rugosity– Saltwater– Permanent snow and ice– Roads (Haines only)G
eneti
c di
stan
ceGeographic distance
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Methods
1. Sample breeding populations2. Amplify microsatellites3. Calculate genetic distance (Fst)4. Generate GIS models, calculate
geographic distances5. Correlate pairwise genetic with
pairwise geographic distance (Mantel tests)
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Geographic distance
Least cost paths Circuit theory• Distance that incorporates
multiple potential paths of least resistance
• Single path of least resistance
Mcrae et al. 2008
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Wolverine gene flowMcRae and Beir 2007, PNAS
Circuit theory outperforms traditional methods
Circuitscape software
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Sample locations + resistance surface
Circuitscape current map=
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Results
Toad populations moderately differentiated on a small scale
• Mean pairwise FstANM = 0.061, 0.008 - 0.122HNS = 0.053, 0.006 – 0.143
• Mean pairwise Euclidean distanceANM = 14.5 km, 0.33-45 kmHNS = 11.4 km, 0.11-50 km
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Small effective population sizes (Ne)
0 2 4 6 8 10 120
50
100
150
200
250HNSANM
Population
Effec
tive
Popu
latio
n Si
ze
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Permanent snow/ice strongest single factor model
euclid ice ru
gg salt
solar
struct1
struct2
struct3
struct4
struct5
road
s-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60ANM
HNS
Model
r
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Permanent snow and ice affects genetic connectivity
0 0.05 0.1 0.15 0.2 0.250
1
2
3
4
5
6
Pairwise Fst
Pair
wis
e Re
sist
ance
- Ic
e
R = 0.59
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Summary and conclusions
• Limited gene flow, small scale differentiation• Small Ne for many populations• Gene flow strongly affected by permanent
snow/ice– Differs from other parts of range– Barrier due to physiological/thermal limits
![Page 19: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/19.jpg)
Summary and conclusions
• Impacts of climate change?
Glaciers, permanent snow and ice
= Toad connectivity?
![Page 20: Effects of the Landscape on Gene Flow and Connectivity of Boreal Toads Jennifer Moore, Julie Nielsen, David Tallmon, Sanjay Pyare University of Alaska.](https://reader030.fdocuments.us/reader030/viewer/2022032800/56649d2c5503460f94a023dd/html5/thumbnails/20.jpg)
Future directions
• Improve model fit– Combine surfaces, multiple parameters
• Compare methods: least cost path vs. circuit theory
• Broad-scale phylogeographic analysis– Do patterns hold true at different scales?
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Thanks
• NSF Alaska EPSCoR• ADF&G Non Game program• USFS• USGS• Emma Caragano, Ray Slayton, Tim Shields, Kim
Obermeyer, Karin McCoy, Colin Shanley, Iris Shields, Robbie Piehl, Lance Lerum, Brett Addis, Cat Frock, Dave Moore