Seed Mast Induced Population Seed Mast Induced Population
Synchrony in the White-footed Mouse Synchrony in the White-footed Mouse
Peromyscus leucopusPeromyscus leucopus
Pei-Jen ShanerPei-Jen ShanerMarch 2005March 2005
Population SynchronyPopulation Synchrony
Definition: Spatial covariation in population density fluctuations
Measure: Cross-correlation coefficient
(Bjørnstad et al. 1999)
Eample: Soay sheep synchrony by Moran effect (Grenfell et al. 1998)
Seed Mast and the Deer Mouse Seed Mast and the Deer Mouse ((Peromyscus sppPeromyscus spp.).)
-Does seed mast induce population synchrony in the deer mouse?
-What demographic processes drive the synchrony?
Ac
orn
s p
er
he
cta
re
(in
th
ou
sa
nd
s)
Nu
mb
er
of
mic
ep
er
10
0 t
rap
pin
gs
(Elias et al. 2004)
Model I: direct demographic effectsModel I: direct demographic effects
seed masting
reproduction
adult survivalin situ
recruitmentjuvenilesurvival
recruitment
adultmovement
adult survival
reproduction
juvenilesurvival
in situ recruitment
recruitment
population growth
Model II: indirect dispersal effectsModel II: indirect dispersal effects
juveniledispersal
seed masting
reproduction
adult survivalin situ
recruitmentjuvenilesurvival
recruitment
adult survival
reproduction
juvenilesurvival
in situ recruitment
recruitment
population growth
Methods I: Mark-recapture and Methods I: Mark-recapture and DemographyDemography
Three annual cycles
Population density (MNA)
Survivorship (MARK)
Reproduction:
percent breeding females
Recruitment:
number juveniles per adult
female
Demographic variables estimatedDemographic variables estimated
seed masting juvenile
dispersal
reproduction
adult survival
recruitment
adult survival
reproduction
in situ recruitmentjuvenile
survival
juvenilesurvival
in situ recruitment
recruitment
population growthadult
movement
in situ recruitmentjuvenile
survival
juvenilesurvival
in situ recruitment
Methods II: Isotopic Tracing of Adults Methods II: Isotopic Tracing of Adults and Juvenilesand Juveniles
September-October 2003 with a total of 200 pounds of seeds / grid
-3
0
3
6
9
12
-35-30-25-20-15-10
13C
15N
Mixing equation:
Δ xE (‰) = fb x (xEb) + (fm) x (xEm), where (fb + fm) = 1
Habitat-specific Patterns in Population Habitat-specific Patterns in Population Synchrony Synchrony
2001-02 2002-03 2003-04
2001-02 2002-03 2003-04
Forest
Field
Cro
ss-c
orr
elat
ion
co
effi
cien
t
Annual SurvivalAnnual Survival
*
Adult Female ReproductionAdult Female Reproduction
*
*
Juvenile RecruitmentJuvenile Recruitment
*
Adult Movement vs. Juvenile DispersalAdult Movement vs. Juvenile Dispersal
*
Summary: direct versus indirect Summary: direct versus indirect demographic effectsdemographic effects
reproduction
adult survival
recruitment
adult survival
reproduction
in situ recruitmentjuvenile
survival
juvenilesurvival
in situ recruitment
recruitment
population growthseed
mastingadult
movementjuveniledispersal
Conclusions Conclusions
Habitat-specific synchrony
- effects of landscape fragmentation on population synchrony
Seed mast induces synchrony mainly through juvenile
dispersal
- meta-population dynamics
- genetic flow between populations
Seed mast and spatial dynamics of consumer populations
- landscape compositions and demographic processes are important
AcknowledgementAcknowledgement
Bowers, Michael
Carr, Dave
Morris, Clay
Sparding, Kimberly
Funding:
National Science Foundation
Blandy Experimental Farm,
VA
Kraus, Johanna
Low, Candace
Pedersen, Amy