Transcript yates_presentation - University of Alberta

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The influence of dispersal &
seasonality on lynx dynamics
in W. Canada
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Gabriela Yates & Mark Boyce
University of Alberta
Hudson’s Bay Co. Fur Trading Records
& MacLulich 1937
Cycle breakdown- localized areas
Ln Tranformed Lynx Harvest
10
Wood Buffalo Nat. Park
Central Eastern Slopes Area
8
6
4
2
0
1965
1970
1975
1980
1985
1990
1995
2000
2005
Year

Lynx harvest in northern Alberta (Wood Buffalo Nat. Park)
compared to Nordegg, Alberta site (Central Eastern Slopes).
Boyce et al. 2005. Biological Conservation 126: 395.
Mullen. 2006. M.S. Thesis, University of Alberta.
Cycle breakdown- provincial scale
Results of spectral analysis of lynx population timeseries from harvest data
AB & BC have
significant
cycles at a
provincial scale
Murray et al. In press. Journal of Wildlife Management.
Cycle breakdown- provincial scale
Results of spectral analysis of lynx population timeseries from harvest data
Border States
do NOT have
significant
cycles
Murray et al. In press. Journal of Wildlife Management.
Biological mechanisms
affecting southern cycles

Predator dispersal
Pulse from epicenter (Ranta et al. 1997)
 Southern prey densities too low to
support cyclic dynamics

(Steury & Murray 2004)
Population sink
 Immigration pulse from the core (McKelvey et al. 2000)


Hypotheses 1: Southern dynamics & persistence
dependent on dispersal
Biological mechanisms
affecting southern cycles

Climate - seasonality

Synchrony vs. asynchrony
(Stenseth et al. 1999,2004)
 NAO
 East-west (provincial statistics)

Sunspot driven weather (Sinclair et al. 1993, Sinclair & Gosline 1997)



Doesn’t explain eastern asynchrony (affected by NAO)
Seasonality produces phase locking (King & Schaffer 2001)
Hypothesis 2: Weakened seasonality reduces
seasonal forcing sustaining multi-year oscillator
Research question

Are changes in lynx dynamics related to
. human induced change?

Barriers to predator dispersal


Fragmentation due to industrial/urban
development
Weakened seasonality
Temperatures of the boreal increasing since 70s
 Climate change may have widespread
consequences

Research objectives

Evaluate dispersal vs. seasonal-forcing hypotheses
1. Regionally document cycle break down
-North-south gradient
2. Evaluate barriers to dispersal (via gene flow)
across a latitudinal gradient
3. Radiocollar lynx to estimate model of habitats
-Facilitate dispersal into South
4. Examine timeseries relative to climate data to evaluate
seasonal-forcing
Obj 1. Cycles at appropriate scale

Untangling the South




Reduced amplitude
More variable periodicities
Less synchrony
Compile harvest data

Alberta & BC



Lynx harvest
by trapline
1994-1999
Poole & Mowat 2001

Hudson’s Bay Company Archives prior
to1950
Provincial traplines 1950 - 2006.
Aggregate appropriately
Analyze across a latitudinal gradient
using time-series methods
Obj 2. Genetic view of dispersal

Dispersal – gene flow



Barriers in the increasingly fragmented south
Large sample sizes
Previous work

Central & northern Alberta study ignored south
(Campbell & Strobeck)

Genetic drift in BC even w/ coarse-scale testing
(Schwartz et al. 2002, Rueness et al. 2003)

Differentiation in the US
(Schwartz personal communication)
Campbell &
Strobeck 2006
Obj 2. Genetic view of dispersal
cont.

Planned methods

2007-08 Alberta & BC trapping seasons




Skin from pelts
Estimated n = 250
20 microsatellite loci effective in lynx
Analysis


Genetic subpopulations using STRUCTURE software
Isolation at individual level



Isolation by distance
Isolation by landscape resistance (see Cushman et al. 2006)
Compare with habitat use data to unravel dispersal dynamics
Obj 3. Habitat selection for dispersal

Radiocollar sample


Central Eastern Slopes Area



Southwestern Alberta along Rockies
Exposed to forestry & land use change
Collaborate for robust model



Estimated n = 20
Washington sample near BC border
NWT sample near Alberta border
Analysis



Step selection function (SSF)
Identify movement barriers throughout the region
Compare with evidence of gene-flow barriers
Obj 4. Climate analysis

Examine seasonality metrics


Pacific Decadal Oscillation (PDO)


Warmer winters,  precipitation,
 winter rain ratio, earlier snowpack melt
Research key component(s) of seasonality






50+ years of data from weather stations
Winter (November–March) PDO index
Temperature
snow pack depth
snow water equivalent
season length
Compare reduced seasonality & deterioration of cycles
Significance

Explaining breakdown in cycle
Dispersal in s. populations
 Seasonality hypothesized to maintain cycle


Consequences - fragmentation & climate change

Seasonality as primary driver


Show how climate change is altering population cycles
Dispersal as primary driver
Habitat/dispersal maps identifying barriers in key habitats
 Model modified human use for persistent populations &
habitat connections

Questions?
Advice?
Gabriela Yates
Mark Boyce
University of Alberta
Project Website:
www.ualberta.ca/~gyates/projectlynx