Effects of Habitat Fragmentation on Bobcat
(Lynx rufus) Populations in the Pocono Mountains
Suzanne H. Chouljian
Department of Biological Sciences, York College of Pennsylvania
http://en.wikipedia.org/wiki/Bobcat
http://carnivoraforum.com/topic/9329146/1/
Introduction
• In response to persistent deforestation, scientists have
investigated effects of habitat fragmentation on carnivores,
including the bobcat (Lynx rufus). Aside from natural landscape
changes, research has identified other causes, including highways
and roads, urban constructs, and farmland.
Review of Literature (continued)
How will habitat fragmentation affect bobcats in the
Pocono Mountains?
• These barriers are known to
influence dispersal in areas of
increasing urban development.
• Barriers produce direct and
indirect effects on isolated
ecosystems.
• Direct effects: changes in habitat size and quality within patches,
fragmented populations, and inhibited dispersal between
fragments.
• Indirect effects: increased genetic differentiation across patches
and the loss of heterozygosity within patches, resulting in
deleterious alleles, greater likelihood for inbreeding depression,
and the threat of local extinction.
• The inherent loss of heterozygosity within patches, due to
inadequate mating options, may increase the likelihood of
inbreeding within a polygynous species such as Lynx rufus.
Review of Literature
How might habitat fragmentation influence bobcats?
• Bobcats opt to disperse
through routes completely
untouched by human
development4.
• It is currently unknown
how this percentage is
distributed across the
state.
Lovallo (2003)
Riley et al. (2006)
Lovallo (2003)
Figure 2. An individual bobcat is identified by
pelage patterns on its tail and front left leg.
DNA Analysis
Extract Lynx rufus DNA from fecal samples
on opposite sides of roads, urban
constructs, and natural barriers
2. Analyze microsatellite loci to determine whether significant
genetic differentiation exists between bobcats with home
ranges on opposite sides of urban constructs.
• Establish a sampling grid
(1km2 units) over the study
site.
Genotype Lynx rufus DNA samples
• Grid squares will be manually
surveyed (≤ 2 effort hours
per 1km2) for bobcat latrines
and/or scent markings.
• Grid squares that do not yield
signs of bobcat presence will not
be utilized during the study.
• To counteract imperfect detection
(mistaking non-detection for true
absence), 5 preliminary surveys
(0.5-1.0 effort hours/1km2) will
be conducted.
The area west of I-380 is bisected by I-80,
and both I-84 and US Route 209 bisect the
area east of I-380. Lynx rufus travel histories
will reveal significantly overlapping home
ranges between females and between males.
Complete PCR cycles and gel
electrophoresis to amplify dinucleotide
microsatellite loci (FCA026, FCA043,
FCA045, FCA077, FCA090, FCA096, and
FCA132)
Proposed Pilot Study
Table 1. Coordinates of Lynx rufus
latrine and scent markings.
East
Mendoza et al. (2011)
1. Compile Lynx rufus travel histories to track passage across
urban constructs and to observe any significant overlap
between individual home ranges.
• Grids composed entirely of
urban constructs or natural
barriers will not be surveyed.
4.1
0.046 (0.015)
Figure 3. The pairwise FST value (above line)
between Lynx rufus populations on the west and
east sides of I-380 is significantly different from
zero (P <0.003). The number of migrants (below
line) is also significantly smaller than those
between bobcats on the same side.
Objectives
Figure 1. One sampling location
(Tobyhanna and Gouldsboro State
Parks; 156.86 Km2) bisected by I-380,
in Monroe County, PA.
DNA
analysis
will
indicate
genetic
differentiation between populations on either
side of I-380, via significantly high pairwise
FST values and low migrant numbers.
West
• As of yet, there are no known studies that explore the direct
and indirect effects of habitat fragmentation upon the Pocono
Mountains’ Lynx rufus population.
• Female bobcats tolerate home-range overlap with other females
only when dispersal is limited9.
Interstate 380 carries heavy traffic daily from
New York City and New Jersey, and will act
as a barrier to gene flow for bobcats.
Calculate percentage of home-range
overlap between same-sex individuals
• Urban development may be impeding
bobcat dispersal and preventing
bobcats from establishing exclusive
home ranges that are separate from
humans.
Reding et al. (2013)
Pairwise FST values (below line) for microsatellite
loci are significantly different from zero (P <0.003).
The numbers of genetic migrants (above line) are
2-9 times smaller than those on the same sides.6
Local roads and the minor developments
near them will not impede Lynx rufus
dispersal across the study site.
Compile bobcat travel histories across
sampling grid based on time of capture
• Reports indicate more frequent
sightings and bobcat deaths due to
vehicular accidents throughout the
Poconos.
• Habitat fragmentation via
urbanization introduces
barriers that cleave travel
paths and may inhibit
dispersal between patches4.
• Studies investigating the impact on genetic structure yield mixed
findings. In an Illinois region bisected by busy highways, Croteau
et al. (2010) found no significant changes in heterozygosity among
bobcats.
• Riley et al. (2006) determined
that a California freeway acts as a
barrier to gene flow. They found
that female bobcats living near
these barriers experience more
home-range overlap with other
females.
Camera Trapping
Complete one sampling occasion every
seven days and identify individual
bobcats after each occasion
• In 2003, 15.8% of PA
was considered suitable
habitat for male and
female bobcats2.
• Highways and roads,
farmland, and expanses of
urban development bisect the
Poconos.
Expected Results
Establish camera traps at latrine and
scent marking sites
• Barriers that bisect the Poconos may isolate habitat fragments,
inhibit dispersal, and possibly disrupt gene flow within Lynx
rufus populations1,4.
• Bobcats disperse to maintain a) home ranges completely
separated from humans, b) home ranges with little to no overlap
between individuals, and c) a polygynous mating system in which
males disperse and females are philopatric.
Proposed Methods
Calculate observed
and expected
heterozygosities,
allelic diversity,
and deviations
from H-W
equilibrium with
program GENEPOP
1.
2.
3.
4.
5.
6.
7.
8.
9.
Use Bayesian
clustering program
STRUCTURE to
assign populations
of origin
Use program FSTAT
to generate FST
values and number
of migrants between
populations across
barriers
Figure 4. Lynx rufus home ranges, derived from a
compilation of travel histories. Neither male (blue)
nor female (yellow) home ranges pass through
opposite sides of I-380. Both male and female
bobcats uncharacteristically overlap home ranges
with members of the same sex.
Importance
Use program
KINSHIP to
determine pairwise
relatedness
coefficient (R)
Lynx rufus is Pennsylvania’s only feline predator and, as
urbanization persists, members of its species will continue to be at
risk for the negative consequences of habitat fragmentation. The
results of this proposed study, along with future research
endeavors, will guide further development within the region and
shape bobcats’ distribution.
Acknowledgements
Literature Cited
I sincerely thank Dr. Bridgette Hagerty for helping me bring this
project to life with her invaluable guidance and expertise. I would
like to extend my thanks to Harout K. Chouljian, Virginia L.
Chouljian, and Kyle M. Ilgenfritz for their patience and constant
support.
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