Kelly E. Hattori
description
Transcript of Kelly E. Hattori
Kelly E. Hattori
VALIDITY OF TAXON-SPECIFIC SAMPLING FOR STUDIES OF
DRILLING PREDATION: CONFIRMATION FROM FOUR BIVALVE
SPECIES IN THE PLEISTOCENE OF NORTH CAROLINA
with Patricia H. Kelley, Kristina Ottens, Nicholas O. Moore, Sarah L. Simpson, Anna M. Zappulla,
Gregory P. Dietl, and Christy C. Visaggi
BACKGROUNDPredatory gastropods
frequently feed upon bivalvesPredation trace fossils
occur in fossil recordDrilling predation studies useful for
examining community composition and interactions
Many sampling method options, including:BulkTaxon-specific (targeted)Surveys (museum, monograph,
outcrop)
RESEARCH GOALSInvestigate:1.Validity of taxon-specific (targeted) sampling as an
alternative to bulk sampling when select taxa are needed for drilling predation studiesBased on preliminary study conducted by Ottens et al.
(2012)
2.Effects of collector expertise on bias in targeted samples
3.Effects of size variability of specimens on bias in targeted samples
GENERA STUDIED / LOCALITY
Lirophora latilirata (A)
Cyclocardia granulata (B)
Astarte concentrica (C)
Glycymeris americana (D)
B CA D
Location of Register Quarry in NC
COLLECTION METHODSSix bulk sample replicates taken during a
Research Experiences for Undergraduates project in June 2008 Sieved using 5mm mesh~ 2 liters of material per sample
Each collector took five replicate targeted samples1m2 quadrat size25 specimen minimum per sample
Layout of Register Quarry with location of targeted replicates
MEASUREMENTS & CALCULATIONSMeasured:
Length and thicknessValve frequency (left
versus right)Drillhole presence,
location, and outer borehole diameter
Calculated:Drilling frequency (DF)Prey effectiveness (PE)Size and site selectivity
Diagram of drillhole location sectors from Kelley (1988)
Size-standardize data using parameters used by Ottens et al. (2012)
STATISTICAL TESTS & ANALYSISMethods and collector experience for both
standardized and unstandardized dataReplicates analyzed in four groups:
1.All replicates separate2.All replicates with a minimum of 10 specimens3.All replicates with a minimum of 20 specimens4.All replicates combined
Mann-Whitney U tests, chi-squared tests, Kolmogorov-Smirnov one-sample tests, covariance tests
2.6%(n=5)
97.4%(n=188)
Method Standardized
10.4%(n=41)
89.6%(n=352)
Method Unstandardized
SignificantNon-significant
4.7%(n=16)
95.3%(n=322)
Collector Unstandardized
0.6%(n=1)
99.4%(n=165)
Collector Standardized
RESULTS –Drilling Predation Metric Total specimens
collected: 6826
Number of tests conducted: 1090
Size-standardized data show fewer significant differences than unstandardized data
Taxon-specific sampling minimally significantly different from bulk sampling results
16.7
15.1
7.1 6.8
8.3
2.2
0 0
4.65.2
4.5 4.8
0 0 0 00
2
4
6
8
10
12
14
16
18
Astarte Cyclocardia Lirophora Glycymeris
Perc
enta
ge o
f Sig
nific
ant T
ests
Taxon
Percentage of significant tests for each taxon
Method Unstandardized Method Standardized Collector Unstandardized Collector Standardized
RESULTS - Taxon
Astarte Cyclocardia Lirophora Glycymeris Novice 358 203 348 310 Veteran 502 205 354 758 Bulk 59 31 470 582
Size variability of Glycymeris americana did not cause additional bias in collected targeted samples
Bulk samples frequently had inadequate sample sizes, especially in less common taxa
9.1
11.9
6.8
4.32.9
4.8
0
2
4
6
8
10
12
14
PK GD CCV
Perc
enta
ge o
f Sig
nific
ant T
ests
Veteran Collector
Percentage of significant tests for each veteran collector
Method Unstandardized Method Standardized
15.9
13.6 14.0
4.7
11.3
0
4.8
10.0
5.0
0
1.6
4.9
1.7
9.7
5.8
0 0 0 0 00
2
4
6
8
10
12
14
16
18
KEH NOM SLS AMZ KO
Perc
enta
ge o
f Sig
nific
ant T
ests
Novice Collector
Percentage of significant tests for each novice collector
Method Unstandardized Method Standardized Collector Unstandardized Collector Standardized
RESULTS – CollectorsNovice
collectors did not differ significantly from veteran collectors
CONCLUSIONS1.Taxon-specific sampling is
a viable collection method for drilling predation studies in targeted species
Limitations must be fully understoodCare must be taken to
avoid bias
Sample size can be controlled
More efficient
CONCLUSIONS2. Novices are able to collect
samples of the same caliber as those collected by veteran collectors.
Must be properly trained in identification, collection, and measurement techniques
More efficient Larger pool of people to
assist with studies
Thank You!