Download - Managing habitat for the eastern tiger salamander and other Ambystomid salamander species
Managing habitat for the eastern tiger salamander and other Ambystomid salamander species
Valorie R. Titus, PhDAmerican Public University System
Amphibian Decline
Climate Change
Invasive Species
Pollution
Pet Trade
Disease
Habitat LossAdult A. tigrinum
Management Issues
Habitat Use/Quality
Movement/Buffer Zones
Population genetics
Relocation, Repatriation, Translocation
Typical A. tigrinum breeding pond
Eastern Tiger Salamander
Ambystoma tigrinum
NYS Endangered
Decreasing throughout their range
Many areas on Long Island are in danger of development
Pre-metamorphic A. tigrinum
Current Range
http://www.dec.state.ny.us/website/dfwmr/wildlife/endspec/tisafs.html
Historic Range in N.Y.
Current Range in N.Y.
http://www.dec.state.ny.us/website/dfwmr/wildlife/herp/eatisala.gif
Current Legal ProtectionNew York State Freshwater Wetland Act: 30 m buffer surrounding wetlands
NYS DEC Recommendations: 164 m, no more than 50% upland habitat within 305 m of breeding pond be converted to unusable habitat (based on Semlitsch 1998)
Recent metamorph
Brookhaven National Laboratory, Long Island, N.Y.
Over 5000 acres
22+ confirmed salamander ponds on site
3 Focal Ponds: L1, L3, L7
Tiger Salamander management and monitoring protocols already in place
Movements
Methods
Collected males and females upon emigration from breeding ponds
Collected juveniles upon emigration or just before final metamorphosis
Pre-metamorphic A. tigrinum
ResultsMovements at night during rain event
Some short movements after implant replacement
Avoided open fields, development, planted white pine stands
Adult A. tigrinum outside burrow
Results
Tracked 33 males, 26 females, 47 metamorphs
Predation: Bullfrog, Eastern Hognose Snake, Raccoon, Northern Short-Tailed Shrew, Eastern Ribbon Snake Radiotransmitter with
B. brevicauda tooth marks
ResultsRecovered a greater proportion of implants from males (72.2%, 24 of 33) than females (30%, 8 of 26) (Fisher Exact Probability, P=0.001)
No difference between number of implants recovered (N=25) and lost (N=22) for juveniles
More likely to recover implant from juveniles remaining closer to the breeding pond (Z=2.750, P=0.006) Juvenile A. tigrinum size
differences
ConclusionsPredation may be higher closer to breeding pond
Males may stay closer as a reproductive strategy
Females may move farther to reduce resource competition
Optimal pond conditions during development may influence juvenile dispersal
Traditionally calculated buffer zones may be inadequate for this species
Fails to protect 20% of individuals in this study, however, incorporating a 50 m edge effect, only protects 62%
May encompass unsuitable habitat and reduce availability of good habitat
Pre-metamorphic A. tigrinum
Connectivity
Fragmented landscapes resulting from anthropogenic habitat modification can have a significant impact on dispersal, gene flow, and persistence of wildlife populations
Reduced genetic variation can severely compromise the ability of a population to respond to subsequent environmental change Adult A.
tigrinum
GoalsAssess population genetic diversity of remaining tiger salamander populations
Quantify genetic and landscape connectivity among ponds and populations to identify potential corridors and barriers to migration Adult A.
tigrinum
MethodsCollected samples from 17 breeding sites across Long Island and 9 sites in New Jersey
Collected as many samples as possible (N=2-93) from each site
Genotyped 439 individuals across 12 microsatellite loci
Samples included toe and tail clips and individual eggs from egg masses A. tigrinum egg
mass
Low allelic diversity
Markers not highly polymorphic (1-13 alleles)
Mean numbers of alleles ranged from 1.1 to 3.3 in New York and 1.7 to 2.4 in New Jersey
GENEALEX version 6 (Peakall and Smouse 2006)
Results- Regional Population Structure and Migration
GENEALEX version 6 (Peakall and Smouse 2006)
Results- Regional Population Structure and Migration
Results- Regional Population Structure and Migration
High levels of population differentiation between NY and NJ (average Fst=0.217) (FSTAT Goudet 1995; Weir and Cockerham 1984).
Few individuals were assigned to the pond at which they were sampled with either 80% or 95% confidence, and many of these individuals were assigned to other ponds with high confidence (GENECLASS2; Piry et al. 2004)
Results- Landscape Barriers to Migration
Defined land cover resistance values from Compton et al. (2007) and Greenwald et al. (2009)
Calculated euclidean distance, euclidean resistance, and surface resistance (using CIRCUITSCAPE version 3.3; McRae and Shah 2009);
Correlated these values with Fst using a Mantel test (Rosenburg and Anderson 2011)
Adult A. tigrinum in burrow
Results- Landscape Barriers to MigrationNo relationship between connectivity indices and Fst in either New York (euclidean distance: r = -0.044, p = 0.827; euclidean resistance: r = -0.047, p = 0.812; surface resistance: r = -0.056, p = 0.786) or New Jersey (euclidean distance: r = 0.120, p = 0.388; euclidean resistance: r = 0.183, p = 0.312; surface resistance: r = 0.226, p = 0.246)
No relationship between Euclidean distance and assignment probabilities in NY (R2 = 0.0005, P = 0.791), but significant for NJ (R2 = 0.361, P = 0.00001)
ConclusionsLow allelic diversity; likely from few migrants during Pleistocene (Church et al. 2002)
May make whole population susceptible to collapse in case of catastrophic event
High risk of inbreeding depression if ponds become more isolated from each other
Conclusions3 distinct genetic demes; while evidence of admixture, this is likely due to ancestral polymorphism rather than gene flow between NY and NJ
The second NY deme is centrally located and within 10 m of each other; likely caused by wetland remediation from 2005-2007
Conclusions
Assignment probabilities provide evidence of recent migration between several ponds
Difference between NY and NJ is likely due to distance between ponds
Corridors appear to be present in both NY and NJ, but no relationship between distance/land cover and Fst
ManagementCalculate protection (buffer zones) on a case-by-case basis
Estimate probable dispersal habitat and determine available corridors
Individual breeding ponds can be susceptible to perturbations that may limit migration and dispersal
So What?Global amphibian declines
Desire to know how to properly conserve and manage this and other amphibian species
Disease outbreaks; already confirmed Bd and Ranavirus on site
Can we actively manage this species (e.g. relocation, assisted migration)?
Literature CitedChurch, SA, Kraus JM, Mitchell JC, Church DR, Taylor DR (2002) Evidence for multiple Pleistocene refugia in the postglacial expansion of the eastern tiger salamander, Ambystoma tigrinum tigrinum. Evolution 52:372-383
Evanno G, Regnaut S, Goudet J (2005) Detecting the number of clusters of individuals using the software structure: a simulation study. Mol Ecol 14:2611-2620
Excoffier L, Smouse PE, Quattro, JM (1992) Analysis of molecular variance inferred from metric distances among DNA haplotypes: application to human mitochondrial DNA restriction data Genetics 131:479-491.
Goudet J (1995) fstat (version 1.2): a computer program to calculate F-statistics. J of Hered 86:485-486
McRae BH, Shah VB (2009) Circuitscape user’s guide. The University of California, Santa Barbara. Available at: http://www.circuitscape.org.
Peakall R, Smouse PE (2006) Genalex 6: genetic analysis in Excel. Population genetic software for teaching and research. Molecular Ecology Notes. 6:288-295.
Piry S, Alapetite A, Cornuet JM, Paetkau D, Baudouin L, Estoup A (2004) GENECLASS2: a software for genetic assignment and first-generation migrant detection. J. of Hered. 95:536-539
Pritchard JK, Stephens M and Donnelly P, (2000) Inference of population structure using multilocus genotype data. Genetics 155: 945-959.
Raymond M, Rousset F (1995) GENEPOP (version 1.2): population genetics software for exact tests and ecumenicism. J Hered 86:248-249.
Rosenburg, NA (2004) distruct: a program for the graphical display of population structure. Molecular Ecology Notes. 4:137-138.
Rosenberg MS, Anderson CD (2011) Passage: Pattern Analysis, Spatial Statistics, and Geographic Exegesis. V.2. Methods in Ecology and Evolution 2:229-232
Schneider S, Roessli D, Excoffier L (2000) Arlequin: A software program for population genetics data analysis (version 2.0). Genetics and Biometry Lab, Department of Anthropology, University of Genevam Switzerland.
Semlitsch, R.D. 1998. Biological delineation of terrestrial buffer zones for pond-breeding salamanders. Conservation Biology 12:1113-1119.
Van Oosterhout C, Hutchinson WF, Wills DPM, Shipley P (2004) MICRO-CHECKER: software for identifying and correcting genotyping errors in microsatellite data. Molec Ecol Notes 4:535-538
Weir BS, Cockerham CC (1984) Estimating F-statistics for the analysis of population structure. Evolution 38:1358-1370.
Acknowledgements
NYS DEC Project MOU # AM 05513
Brookhaven National Laboratory
NYS DEC
Foundation for Ecological Research in the Northeast (FERN)
Dave Golden and the Endangered and Nongame Species Program of the New Jersey Division of Fish and Wildlife
Upstate Herpetolgical Society
Acknowledgements
Dr. Dale Madison
Dr. Tim Green
Dr. Kelly Zamudio
Al Breisch
Dr. Dan Rosenblatt
Dr. Julian Shepherd
Dr. Richard Andrus
Dr. Matthew Parker
AcknowledgementsThank you to interns and fellow students: Sarah, Chauncey, Wendy, Frank, Jeremy, Jennifer, Esperanza, Stephen, Sarah, Emily, Carmen, Renee, Stephanie, Doris, Rachel, Dane, Katie, Kristine, Susan, Diana, Tyra, Shirin, Lauren, Matt, Miranda, Becky, Mike, Omar, Andy, Nate, Ellie, Jennifer, Miranda, Heather, Bri, Jin Joo, Sarah, Clara, Dave, Rayna, Angie, and Gui