Morphological Variation Among Populations of the Federally Endangered Duskytail Darter,

Etheostoma (Catonotus) percnurum

Rebecca E. Blanton1, Robert E. Jenkins2, and Henry L. Bart, Jr.1

1Dept. Ecology and Evolutionary Biology,

Tulane University, New Orleans, LA2Dept. Biology, Roanoke College, Salem, VA

Taxonomic History

• Formerly Etheostoma flabellare, Fantail Darter– First recognized as distinct species

• R. E. Jenkins 1976

– Diagnosed and described by Jenkins in 1994 • Freshwater Fishes of Virginia (Jenkins and Burkhead 1994)

– E. percnurum – Duskytail Darter

• Reduced caudal barring relative to other closely related taxa

E. percnurum E. flabellare

Classification: Catonotus

E. squamiceps group “spottails” 10

spp.

E. virgatum group “barcheeks”

7 spp.

E. flabellare group “fantails” 3

spp.

Egg clustering Female with broad, flat, non-bifurcate genital papilla

3 black spots on caudal peduncle

“Egg Mimics” pronounced on second dorsal

Female inverted for entire spawning event

Nape, prepectoral area unscaled

Enlarged golden knobs

(egg mimics) on first dorsal

Bar pattern (egg mimics) on cheek

Blue, red in male fins

Distribution

Modified from Jenkins and Burkhead 1994 = historically extirpated population

Morphological Variation

• Noted by Jenkins (Jenkins and Burkhead 1994)

– Differences in squamation and color • Substantial between Copper Cr. and others

• Examined further by Eisenhour and Burr (2000)– Found differences in:

• squamation and shape• egg and ova counts• nest size preference

– Hypothesized Big South Fork population was independent evolutionary unit

Question

• Noted morphological variation along with high degree of isolation of populations– Suggests each is likely on its own evolutionary

trajectory

• Are disjunct populations morphologically diagnosable, warranting species-level recognition??

Objectives

• Examine morphological variation:– Determine taxonomic status of each population

– Describe species that warrant recognition

– Address conservation issues that may result from recognition of additional taxa

Methods

Methods

• Specimens – Borrowed from museums and universities

• Variation examined using:– Meristics– Morphometrics – Pigmentation

• Intra and Inter-population variation

Methods

• MERISTICS:– 26 counts

• Largely followed Hubbs and Lagler (1958), Page (1983), and Jenkins and Burkhead (1994)

– 194 specimens examined from 6 populations and 2 drainages

• Males and females > 30 mm SL

– Tested for sexual dimorphism• Males and females combined

Methods

• MERISTIC DATA ANALYSIS:– Univariate: Frequency distributions

– Multivariate: PCA (SYSTAT 5.2.1)• 16 of 26 variables used for all individuals• Factor scores plotted in Cricket Graph III• Variables with component loadings >.50 were considered

most important

Methods

• MORPHOMETRICS– Comparisons of body shape based on:

• Truss protocol (Bookstein et al., 1985) using 19 interlandmark distances

• 12 additional length/depth measurements (Hubbs and Lagler 1958)

E. percnurum_Copper Cr.

Methods

• MORPHOMETRIC ANALYSIS– Multivariate sheared PCA (Swofford; SAS 8.2)

• 12 variables and 123 individuals

– Univariate comparisons• Measurements standardized with Standard Length

– Males and females analyzed separately • Nuptial and non-nuptial males examined separately

– Included individuals > 35mm SL

Methods • PIGMENTATION:

– Limited data due to lack of nuptial and live individuals– Data examined for 4 pigmentation variables

• Jenkins previously examined other color and pigmentation

characters of nuptial males (Jenkins and Burkhead 1994)

• ANALYSIS – Univariate (frequency distributions, means)

– Descriptive comparisons

Results

MERISTICS

-6

-4

-2

0

2

4-3 -2 -1 0 1 2 3

PC 1

Copper Creek

Little River

Abrams Creek

South Fork Holston River

Citico Creek

Big South Fork

Copper Cr.

Citico Cr.

Little R.

Big SouthFork

AbramsCr.

South ForkHolston R.

PC

2PCA: Meristics

Fewer:Pored Lateral LineBelly ScalesHigher:Caudal Fin Rays

Higher:Transverse ScalesCaudal Peduncle ScalesScales Along D1 Base

Squamation Along D1

0%100% 50%

Little R.

Big South Fk.

Citico Cr.

Abrams Cr.Copper Cr.

Results

MORPHOMETRICS

ResultsMorphometrics

• No variation between females from different populations

• Substantial overlap between non-nuptial males from different populations

• Nuptial males with high degree of body shape variation between populations

PC

3

-2

-1

0

1

2

3-4 -3 -2 -1 0 1 2 3

PC 2

Little River

Copper Creek

Clinch River

Citico Creek

Big South Fork

Big SouthFork

Copper Cr.Little R.

Citico Cr.

Sheared PCA: Nuptial Males

Longer: Pectoral Fin Length Anal Fin Height

Shorter:First Dorsal HeightSecond Dorsal Height Caudal Fin LengthLonger:Pelvic insertion to Anal Fin insertion

Results

PIGMENTATION

Means for Pigmentation Variables

Drainage/System N x Range SD x Range SD x Range SD

Cumberland R. DrainageBig South Fork 27 11.74 10-14 0.90 7.11 7-8 0.32 5.41 0-8 1.67

Tennessee R. DrainageCopper Creek -Clinch R. 92 12.34 10-15 1.12 7.00 5-8 0.35 5.80 3-10 1.96

Little R. 30 11.51 0-15 3.74 7.00 7-8 0.28 5.77 4-8 1.31

Citico Creek-Little Tenn. R. 13 9.15 0-13 5.25 5.54 0-8 3.18 4.92 0-7 2.29

Lateral Bars Saddles Caudal Bands

*No. caudal spots also examined but showed no variation

Other Pigmentation DifferencesLittle R. vs. Copper Cr. Nuptial Males

• Pelvic fins best pigmented in Copper Cr.

• Rays of D2 more prominently marbled in Little R.– Rays uniformly dusky in Copper Cr.

• Tessellations on Caudal Fin more intense in Little R.– Tessellations lost in Copper Cr.

Conclusions

• Substantial morphological variation among four extant populations

• Status of extirpated populations unclear due to low number of existing specimens– Abram Creek and South Fork Holston River

• Grouped with closest geographic counterparts

Conclusions

• Do any populations warrant species recognition?– Little River E. percnurum diagnosed with % scale cover

along D1 base • also show distinct variation in morphometrics, and

pigmentation

– Others diagnosed with combination of characters:• Citico Creek – meristics and pigmentation

• Big South Fork – measurements

– Data needed for additional nuptial males

• Copper Creek –combination of characters

Conclusions

• Each population should be recognized:– Independent evolutionary units/species

• Conservation efforts should be structured to conserve all populations– not just to maintain diversity, but because all are

important independent units in the E. percnurum lineage

Future Questions and Work

• Examine additional nuptial males from Citico Creek and Big South Fork– Live and nuptial males for better pigmentation comparisons

• Diagnose and Describe

• Relationships within the E.flabellare group of Catonotus– Are E. percnurum spp. monophyletic?– Is there high levels of genetic structure within populations

similar to that observed for its supposed sister taxon, E.flabellare?

• If so, important information for proper management and conservation

Hap 2

Hap 1

Hap 1

Hap 4

Hap 27

Hap 28

Hap 5

Hap 6

Hap 6

Hap 6

Hap 7

NC

Yadkin R.

NC

SC

Ararat R.5 (20%)6 (60%)7 (20%)

Stoney Cr.2 (100%)

Johnson Cr.1 (40%)4 (20%)

27 (20%)28 (20%)

19 rmi.

7 rmi.

22 rmi.

ND2 Haplotype Locality Relationships

Etheostoma flabellare

Acknowledgements

• Institutions for loan of specimens:– INHS– UMMZ– University of Tennessee– Tulane Museum Natural History– Southern Illinois University Carbondale– American Museum Natural History– National Museum Natural History

• Tulane University for facilities and equipment

Questions

Classification

• Order: Perciformes– Family: Percidae

• Genus: Etheostoma– Subgenus: Catonotus

Etheostoma percnurumDuskytail Darter

Habitat

Big South Fork, TN

Citico Creek, TN

Conservation Status

• Upon Description:– Jenkins called for federal protection

• Relict distribution• Extirpation of two populations• Threats to habitat and water quality

• Listed 1993 as Federally Endangered (Biggins 1993)

– Recovery Plan developed 1994 (Biggins and Shute)

Drainage/System N x SD x SD x SD x SD

Cumberland R. DrainageBig South Fork 13 0.332 0.02 0.099 0.01 0.134 0.02 0.194 0.02

Tennessee R. DrainageCopper Creek -Clinch R. 21 0.317 0.02 0.100 0.01 0.148 0.01 0.208 0.01

Little R. 23 0.314 0.02 0.117 0.01 0.150 0.01 0.212 0.02

Citico Creek-Little Tenn. R. 4 0.315 0.02 0.105 0.01 0.135 0.01 0.208 0.02

P2 to Anal D1H D2H CFL

Means of variables that loaded heavily on sheared PC 3

*Measurements standardized using SL

ResultsMeristics

• Copper Creek and Citico Creek E. percnurum can be distinguished from one another based on meristics - no overlap in variation– Both also show high degree of meristic differences

from Little R. and Big South Fork individuals

• Little River and Big South Fork individuals with high degree of meristic similarity– Little River diagnosible based on scalation along

D1 base