bowen_1996_ecolapp

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Origin of Hawksbill Turtles in a Caribbean Feeding Area as Indicated byGenetic Markers

B. W. Bowen; A. L. Bass; A. Garcia-Rodriguez; C. E. Diez; R. van Dam; A. Bolten; K.A. Bjorndal; M. M. Miyamoto; R. J. Per1Ecological Applications, Volume 6, Issue 2 (May, 1996), 566-572.

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Ecological Applications, 6(2), 1996, p p . 566-5720 996 by the Ecological Society of Amer~ca

ORIGIN OF HAWKSBILL TURTLES IN A CARIBBEAN FEEDINGAREA AS INDICATED BY GENETIC MARKERS'

B. W. BOWENBEECS Genetic Analysis Co re, Biotechnology Development Inst i tute, Universi ty of Florida, Alachua, Florida 326 15 U SAA . L . BASS^Museum of Natural Science and Department of Zoology and Physiology, 119 Foster Hall ,Louisiana State Universi ty, Baton Rouge, Louisiana 7080 3 USA

A . G A RCI A - RO D RI G U E ZBEECS Genetic Analysis Core, Biotechnology Development Inst i tute, Universi ty of Florida, Alachua, Florida 32615 USAC . E. DIEZDepartment of Biological Sciences, Universi ty of Central Florida, Orlando, Florida 3281 6 U SA

R . VA N DA MCenter for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, La Jolla, California 92093-0204 USAA. BOLTENDepartment of Wildli fe Ecology and Conservation and Archie Carr Cen ter for Sea T urtle Research, 223 Bartram Hall ,Universi ty o f Florida, Gainesvil le, Florida 32611 USA

K . A . BJ O RN D A LDepartment of Zoo logy and Archie Carr Center for Sea T urtle Research, 223 Bartram Hall , Universi ty of Florida,Gainesvil le, Florida 32611 USAM . M . M I Y A M O T ODepartment of Zoology, 223 Bartram Hall , Universi ty of Florida, Gainesvil le, Florida 32611 USA

R . J. FERLBEECS Genetic Analysis Core, Biotechnology Development Inst itute, Universi ty of Florida, Alachua, Florida 326 15 U SAand Program in Plant Molecular and Cellular Biology, Horticultural Sciences Department, U niversi ty of Florida,Gainesvil le, Florida 32611 USAAbstract . Hawksbil l turt les mov e between nesting colonies and feeding grounds, butin most cases i t is not known which reproductive populations occupy a par t icular feedinghabita t . In this s tudy , genetic markers der ived from m itochondria1 DN A sequences are usedto est imate the contr ibution of Caribbean nesting colonies to a feeding ground a t MonaIsland, Puer to Rico ( n = 41). Maximum likelihood analysis indicates that this feedingpopulation is not compo sed pr imarily of tur t les f rom the neighboring n esting colony (a lsoon Mona Island) , but is drawn from nesting populations throughout the Caribbean region.A sampled nesting colony in the southern hemisphere (Bahia , Brazil) did not contr ibute ,a t detectable levels , to the Mon a Island feeding ground. From this evidence, we concludedthat hawksbil l tur t les recruit to feeding grounds over a scale of hundreds of kilometres,but not over the scale of 7000 km that separate Mo na Island from Bahia , Brazil . Thesedata indicate that a hawksbil l tur t le harvest on feeding grounds will reduce nesting pop-ula tions throughout the Caribbean region.Key words: Caribbean Sea; conservation genetics; DNA sequencing; demo graph y; Eretmochelysimbricata; feeding ground composition; genetic markers; marine turtles; mitochondria1 DNA; mixedstock analysis; population s tructure.

I N T RO D U CT I O N and to recruit eventually to juvenile feeding groundsalong coasta l margins (Carr 1987) . However , i t is notMarine tur t les are dif f icult to observe in foraging generally known which nesting areas contr ibute to ahabita t and, for this reason, several com ponen ts of their par t icular feeding area , and this gap hampers a com-life history rem ain obscure . Most marin e tur t le species ple te understanding of marin e tur t le l ife history (Lim-are believed to occupy a pelagic habita t af ter hatching, pus 1992, Limpus e t a l . 1992) . S ince mar ine tu r t lescontinue to be harvested on foraging areas, this facet' received 21 1995; of their natura l history a lso hag prominent c onserva tion1995; final version received 9 June 1995.2 Present address: BEECS Genetic Analysis Core, Biotech. implications. When a hawksbil l tur t le (Eretmochelys

noloev Development Institute. University of Florida. 12085 imbric ata) is captured on a feeding area , does this ac-~ e s e a r c hrive, Alachua, Florida 3 2 6 1 5 ' ~ ~ ~ . t ivi ty impact a neighboring rookery or more distant


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May 1996 HAWKSBILL TURTLE FEEDING GROUND 567nesting populations? Establishing which nesting pop-ulations co ntribute to a part icular feeding area (i .e. , ademographic l ink between nesting aggregates and feed-ing aggregates) can indicate which breeding popula-t ions are affected by commercial fisheries and otherhuman incursions.

One relatively new approach to est imating the originof migratory cohorts or mixed stocks involves the useof natural genetic markers (A vise 1994) . To resolve thecomplex stock structure of anadromous salmon in ma-rine fisheries, researchers developed a maximum like-l ihood (ML ) model to est imate the contribution of mul-t iple freshwater spawning grounds to coastal and oce-anic fisheries (Grant e t al . 1980, Millar 1 987, Pella andMilner 1987) . M L estimates are typically based on dif-ferences in al lele frequencies among riverine stocks,as detected by protein electrophoresis.In principle, this approach is applicable to the anal-ysis of marine turt le feeding areas and migratory cor-ridors. Nesting-beach surveys demonstrate the pres-ence of rookery-specific mitochondria1 (mt) DN A hap-lotypes in green turt les (Chelonia mydas; Bowe n et al .1992, Norman et al . 1994, Encalada 19959, loggerheadturtles (C are tta caretta; B owen et al . 1993, 1994), andhawksbil l turt les (B roderick et al . 1 994, Bass et al .1996). Thes e "endemic" haplotypes and related hap-lotype frequency shifts among nesting colonies mayprovide suitable markers to est imate the relat ive con-tribution of breeding popu lations to a particula r feedingground (Avise and Bowen 1994, Norman et a l . 1994).Bass et al . (1996) used mtD NA sequence analysis toassess the genetic relationships amo ng seven hawksbil lnesting colonies in the tropical West Atlantic Ocean.This survey demonstrates significant mtDNA haplo-type frequency shifts among most Caribbean nestingpopulations, and reveals a number of "endemic" hap-lotypes in sampled nesting aggregates. These strongpopulation genetic part i t ions provide an appropriate ba-sis for assessment of hawksbil l feeding aggregates.Here, we use mtDNA haplotype frequencies to re-solve the demographic origins of a (primarily juvenile)feeding cohort at Mona Island, Puerto Rico. The sci-entific l i terature contains suggestions that hawksbil lturt les may be nonmigratory or less migratory thanother marine turt les (Carr 1952, Carr et al . 1966), butmore recent studies have demonstrated at least occa-sional long-distance movements (Carr and Stancyk1975, Meylan 1982, Parmenter 1 983, Bjorndal et al .1985), including a trans-Atlantic tag recovery (Mar-covaldi and Fil ippini 1991). If the hawksbil l turt le isrelatively sedentary during post-pelagic l ife history,one expected consequence would be extensive sharingof mtDNA haplotypes between nesting areas and ad-jacent foraging areas. Alternatively, if the hawksbil lturt le typically migrates between spatial ly dist inctfeeding and nesting habitat , this migratory behaviorshould be reflected in extensive mixing of m tDNA ha p-lotypes (representing regional nesting populations) on

foraging habitats. Hence, the most basic question ad-dressed here is whether or not a feeding ground is com-posed primarily of turt les from adjacent nesting habitat .A m ore complex version of this question is whether ornot the relat ive contributions of regional rookeries toa foraging habitat can be resolved with ML analysis.

The motivation for resolving stock composit ion in-tensifies as the conse rvation status of this species con-tinues to deteriorate (National Research Council 1990).The abundance of Eretmochelys imbricata is greatlyreduced relative to historical levels, and this speciescontinues to be commercially harvested in the WestAtlantic Ocean and Caribbean Sea (Carr and Meylan1980, Canin 1989, Ottenwalder and Ross 1992). "Tor-toiseshell" is the prima ry product of the hawksbill fish-ery, but eggs, meat, leather, and stuffed, mounted ju-veniles are also marketed in some areas (King 1982,Witzell 19 83, Mill iken and Tokunaga 1987) . While 1 yr) at room temperature withoutsignificant DN A degradation.DNA isolations were conducted with standard phe-nol/chloroform methodology (Hill is and Moritz 1990).mtDNA control region sequences were amplified viapolymerase chain reaction methodology (PCR; Mullisand Faloona 1987) using biotinylated versions of prim-ers TCR-5 and TCR-6 (Norman et a l . 1994). An 18-base "universal" M1 3 sequence was added to the 5 'end of primers to facil i tate automated sequencing. T hecycling thermal parameters used are as follow: 1 cycleat 94OC (3 min) follow ed by 35 cycles at 94' (1 min),50' (1 min), and 72' (1 min). Standard precautions,including negative controls (template-free PCR reac-


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B . W. B O W E N ET AL. Ecological ApplicationsVol. 6, N o. 2

FIG. 1 . Distr ibu t ion o f sampled nest ing co l-on ies fo r the Car ibbean hawksb i l l tu r t le , fo l -lowing Bass e t a l . (1996). T h e M o n a I s l an dfeed ing g round and nest ing co lony are ad jacen tto the eas tern coast o f Puer to Rico .

t ions) , were used to test for contamination and to assurethe f ideli ty of PCR reactions.

Streptavidin-coated magnetic beads (DynabeadsM2 80 s t r ep tav id in , Dynal , Swed en) were used to pur i fyPCR products (Mitchell and Merr i l l 1989) . Single-stranded template was generated by denatur ing themagnetical ly captured double-stranded D NA with f resh0 .15 mol /L NaOH, and us ing the r e leased (nonb io t i -nylated) s trand as a template for sequencing reactions.Single-stranded sequencing reactions were conductedwith f luorescently labelled M13 pr imers in a roboticwork s ta t ion (Appl ied Biosys tems m odel 800) , and thelabelled extension products were analyzed with an au-tomated DNA sequencer (Appl ied Biosys tems model373A) in the DNA Sequencing Core a t Univer s i ty o fFlo r ida .Cont ro l r eg ions sequences f rom the Mona I s landfeeding ground were compared to a bank of sequencesfrom rookery samples descr ibed in Bass et al . (1996) .Rookery samples ( eggs o r b lood a l iquots f rom d i f feren tf emales ; n = 14-15 per location) include locations inBelize, Quintana Roo (Yucatan, Mexico) , U.S. VirginIslands, Antigua, Barbados (Bri t ish West Indies) , Bahia(Brazil) , and M ona Island (Puer to Rico, USA) (Fig. 1) .These locations represent most of the major nest ingaggregates for Eretmochelys imb ricata in the Car ib-bean .Sequences tha t matched known hap lo types we re co l -la ted fo r analys i s , whereas new or ambiguous geno-types were seq uenced in the opp os i te d ir ec t ion to assureaccuracy . A t leas t one r epresen ta t ive fo r every hap-lotype was sequenced in both direct ions. Feeding areaspecimens tha t matched known hap lo types were as -signed a let ter code, fol lowi ng Bass et al . (1996) . Newhaplotypes observed only in the feeding populat ionwere assigned Greek let ters (alpha, beta, gamma) todist inguish them from known nest ing-beach haplo-types.

The most basic test of demographic af f ini t ies in-volves a compar ison of haplotype f requencies betweenthe feeding populat ions and regional rooker ies . In thiss tudy , the Mona I s land f eed ing popula t ion was com-pared to regional rooker ies using a G test of indepen-dence with Yates correction (Sokal and Rohlf 1981) .Haplotype diversi ty was calculated following the ap-proach of Nei (1987: Eq. 8 .4) .To assess the relat ive contr ibution of regional nest ingcolonies to the Mona Island foraging area, we used anuncondi tional M L analys i s (Pel la and Mi lner 1987) inthe DOS-compat ib le p rogram UCON (Masuda e t a l .1991) . The uncondi t ional M L approach i s r ecomm end-ed when the presence of rare haplotypes may bias theo u t co m e (J. Pe l la an d M . M as u d a , p e r s o n a l co m m u -nication) , but , in most case s, i t y ields quali tatively s im-ilar results to the condit ional ML algor i thm (Xu et al .1994) . Standard deviat ions on ML est imates were cal-culated with the "jackknife" option in UC ON .

Broder ick (1992) used the condit ional maximumlikel ihood (ML) p rogram GIRLSYM (Masuda e t a l .1991) to evaluate the impact o f sample s ize on theaccuracy of mixed stock assessments , under condit ionstypical for regional (mtD NA ) populat ion structure inmarine tur t les . These s imulations indicate that 30-40specimens f rom a p resumed mixed s tock wi l l y ie ld r ea-sonably accurate ( 0% ) est imates of feeding-groundcomposit ion under typical condit ions. An importantcondit ion of this general izat ion is that most candidatenest ing areas are character ized by at least a 30% fre-quency sh i f t in mtDNA hap lo type f r equencies . In gen-eral , a higher f requency shif t between c andida te rook-er ies p rov ides a more power fu l tes t o f mixed s tockcompos i tion (Pel la and Mi lner 1987 , Xu e t a l . 1994 ) .

RESULTSAND DISCUSSIONIn th i s su rvey , we examined a 351 bp (base pai r s ,

the fundamenta l un i t s o f doub le-s t r anded DNA ) f r ag-


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May 1996 HAWKSBILL TURTLE FEEDING GROUND 56 9TABLE . Po lymorph ic s i t e s obse rved in a 351 bp (base pai r s ) fr agmen t o f the mtDNA con t ro l r eg ion f rom 41 hawksb i l ltu r t l es s ampled in fo rag ing hab i t a t a round Mona I s l and , Pue r to Rico . Sequence num ber ing beg ins a t the 3 ' end o f p r imerTC R-5 (Norm an e l a l. 1994) and l e t te r des igna tions fo r hap lo types fo l low Bass e t a l . (1996) , wi th new hap lo types ind ica tedby g reek l e t t e r s ( a , P , 7). For a com ple te r e fe rence sequ ence , s ee Bass e t a l . (1996) . As te r i sks (* ) indicate two s i tes thatwere po lym orph ic in f eed ing g round samples bu t no t in the compan ion nes t ing popu la tion su rvey .

Geno typ e Po lymorph ic s i t e sle t terc o d e 1 3 6 2 9 6 1 5 8 2 10 252* 255* 309 3 10 341A A T A C T A T T G G13 G T G T C A T C G AF G C G T C A T C G AL, G C A T C A T C A AN G C G T C A T C A AQ G C A T C A T C G Aa A T A C T A C T G GI3 A C A T C A T G G A'v G C A T C G T C G A

ment of the mtDN A control region [matching si tes 10-360 i n Bass e t a l . ( 1 9 9 6 ) J tha t conta ins a l l of the poly-morphic s i tes reported in the nest ing-popula t ion s urveyof 3 8 4 bp. Ten polymorphic s i tes were observed inforaging-area samples (Table I) , inc luding e ight of the1 7 variable posi t ions reported for survey ed nest ing col -onies and two addi t ional polymorphic s i tes . Thesepolymorphic s i tes define nine haplotypes (Table 2): s ixhaplotypes tha t match sequen ces descr ibed in the nest -ing-colony survey and three new haplotypes. Notably,the six haplotypes tha t match nest ing colony haplotypesaccount for 37 of 4 1 sample s , and i nc lude t he four mos tabundant haplotypes repo rted in the nest ing-popula t ionsurvey . Hap lo typi c d ive r s it y fo r Mo na I s l and fo rag ingsamp les i s re la t ive ly high (h = 0 . 7 3 9 ) compared to therange of va lues reported in the nest ing-beach survey(h = 0 . 1 2 5 - 0 . 7 8 2 ; Bass e t a l . 1 9 9 6 ) .The simplest assessment of the re la t ionship of feed-ing popula t ions to nest ing popula t ions invo lves a com-par ison of the Mona Island rookery to the Mon a Islandforaging area . A G test of indep enden ce demonst ra testha t the feeding popula t ion i s s igni f icant ly di f ferentfrom the adjacent nest ing popula t ion (P < 0 . 0 0 5 ) an dfrom a l l o ther assayed nest ing si tes (P < 0 . 0 1 ) . Fromthis informat ion, we conclude tha t the Mona Islandfeeding popula t ion i s not drawn pr imari ly f rom theproximal nest ing colony o r f rom any single assayed

nest ing colony. W hereas mo re convoluted explanat ionsmay be invoked to expla in these resul ts (such as un-surve yed rooker ies in the vic ini ty of M ona Island) , thesimplest explanat ion enta i l s immigra t ion f ro m mul t iplenest ing popula t ions.

This conclusion i s supported, in a qual i ta t ive fashion,by the presence of haplotypes in feeding ground sam-ples tha t a re observed only in s ingle assayed nest ingco lon i e s . Spec imens f rom the Mona I s l and fo rag ingarea conta in haplotypes B (n = I ) , L (n = I ) , N (n =3 ) , an d Q (n = 7), obse rved on ly i n Ant igua (B) , MonaIsland (L and N), and Yucatan (Q) nest ing areas, re -spect ive ly (Table 2). Whereas som e o f t he se hap lo typeseventual ly may be de tec ted in other nest ing colonies,the overa l l pa t te rn i s consistent wi th the hypothesis tha tforaging aggregates a re composed of tur t les f rom nest -ing habi ta ts throughout the region.Th e ML analysis indica tes tha t f ive of the seven sam -pled rooker ies cont r ibute to this feeding popula t ion a tlevels grea ter than zero, wi th the la rgest cont r ibut ionsfrom the U.S. Virgin Islands and the Yucatan Peninsula(Table 3 ) . How ever , addi tional nest ing popula t ions mayalso contr ibu te to these feeding grounds. Rookeries a reknown f rom the Dom in ican Repub li c , Cuba , and e l se -where , but samples were unavai lable f rom these lo-ca t ions due to logisi t ic l imi ta tions, permi t problems, orpol i t ica l considera t ions. Many diminut ive nest ing col -

TABLE . Di s t r ibu tion o f hap lo types on seven nes t ing a reas and the Mon a I s l and f eed ing g round . Mos t (37 o f 41 ) f eed ingground sam ples a re juven i l es . A mong the fou r adu l t s amples , one ma le con ta ined hap lo type Q, two ma les con ta inedhap lo type N, and o ne f ema le con ta ined hap lo type F. See B ass e l a l . (1996) fo r de ta i ls abou t s am ple loca t ions.H a p l o t y p e

L oca tion A B C D E F G H I J K L M N 0 P Q R S T U a P - yB e lize 1 1 1 1 1Yuca tan 2 1 3M o n a I s. 1 1 2 1 1 2 6 1Virgin Is . 1 14A ntigua 9 4 2B a rb ad o s 11 1 3Bah ia , Braz i l 4 6 2 1 1Mona I s l andforaging habi ta t 7 1 18 1 3 7 2 1 1


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B . W . BOWEN ET AL. Ecological ApplicationsVol. 6, N o. 2T A B L E3. Con tr ibu t ion o f assayed nest ing co lon ies to thecoastal feed ing area a t Mona Is land , Puer to Rico , as in -d icated by uncond i t ional max imum l ikel ihood analysis .The four su rveyed ind iv iduals that con tained hap lo typesno t observed in nest ing popu lat ions were remo ved f rom theanalysis . S tandard dev iat ions were calcu lated wi th the in -

f in ites imal jackkn ife op t ion in the p rogram U CO N (Ma sudaet a l . 1991) .Locat ion Con tr ibu t ion SD

G ale ' s P o in t , B e l i ze 0 . 0 2 1 0 . 0 0 4Q u in tan a R o o , M ex ico 0 . 1 8 9 0 . 0 6 4M o n a I s ., P u e r to R ico 0 . 1 2 7 0 . 0 5 8Buck Is land , U .S .V.1 , 0 .510 0 .09 0Ju m b y B ay , A n t ig u a 0 . 1 2 1 0 . 0 7 1B arb ad o s 0 . 0 3 0 0 . 0 4 1B ah ia , B raz i l 0 . 0 0 0 0 .0 0 0

onies exist throughout the West Atlantic, and if oneconsiders the beaches where only a handful of hawks-bil l tur t les nest , there may be dozens of unsampledlocations. Hawksbil l tur t les are less colonial in theirnest ing habits than other sea tur t les , and this dif fusenesting is ref ractory to conventional sampling strate-gies . However , in consider ing the geographic breadthof (genetical ly def ined) nest ing populat ions, the pres-ence of unsampled nest ing beaches may not be an over-whelming l imitat ion. Broder ick et al . (1994) repor tedthat Indo-Pacif ic nest ing beaches separated by severalhundred kilometres were not s ignif icantly dif ferent interms of mtDN A -frequen cy distr ibution, consistentwith tagging studies demonstrat ing that hawksbil l tur -t les may move between adjacent nest ing habitats (Di-amond 1976 , L impus e t a l . 1983) . Hence , when onenesting beach is sampled for mtDNA analysis , i t prob-ably represents an extended nest ing populat ion includ-ing several adjacent nest ing si tes .

We regard the results of the ML analysis as generalquali tat ive indicators of the contr ibution to Mona Is-land feeding habitat f rom regional nest ing populat ions.Although the specif ic contr ibutions of surveyed rook-er ies may no t be p rec ise ly r eso lved , the ML analys i snonetheless provides clues as to the geographic scaleof recruitment to the Mona Island foraging area. Thisfeeding populat ion evidently is not drawn exclusivelyfrom the neighbor ing (M ona Island) rookery, a nd is notd rawn a t de tec tab le levels f rom the su rveyed Sou thAtlantic (Bahia, Brazil) nest ing populat ion. Henc e, theM L an alysis indicates that tur t les recruit to this feedingpopula tion on a sca le > l o 0 km bu t less than the 7000km that separa te Mona I s land f rom Bahia , B razi l. Wesugge st , as a f irs t approximation, that this feeding pop-ulat ion contains cohor ts f rom throughout the Car ibbea nreg ion .The conclusion of mixed-stock composit ion in Ca-r ibbean feeding grounds is consistent with results ofthe survey of mtDNA haplotypes in Indo-Pacif ichawksbil l populat ions; Broder ick et al . (1994) con-cluded that a foraging aggregate in the Torres Strai tregion of nor thern Austral ia is occupied by juveniles

f rom seve ral nest ing populat ions. Indeed, results of thisstudy, along with feeding-ground survey s of green tur-t les (Car r 1975 , L impus e t a l . 1992) and loggerheadtur t les (Laurent et al . 1993, Sears et al . 1995) , indicatethat over lap of nest ing populat ions in regional feedingareas may be a general feature of mar ine tur t le popu-lat ion biology.The presence of hawksbil l tur t les on distant feedingareas demonstrates the complex nature of mar ine tur t leconservation. A nest ing populat ion within the bound-ar ies of one nation can be diminished by a harvest ina neighbor ing (or even a dis tant) nation. The Car ibbea nhawksbil l t rade has been active in recent years , withCuba, Hai t i , and Panama being the larges t expor ter s(Can in 1989 , O t tenwalder and Ross 1992) and Japanbeing the largest importer (Mill iken and Tokunaga1987) . This international commerce was discontinuedin Decem ber 1992, but a local t rade f lour ishes in manylocations and there is continuing interest in reopeningthe international t rade (M. Donnolly, personal com-munication) . In l ight of the results obtained here, theorganized harv est of adults and juveniles on coastalf eed ing g rounds ( see Ot tenwalder and Ross 1992) maybe especial ly damaging, as this type of f ishery wil ldiminish reproductive populat ions throughout the re-g ion .Clear ly, mtDNA markers can be a powerful tool forassessing anthropogenic impact on migratory cohor ts(Bow en et al . 1995, Sears et al . 1995) , and i t is apparentthat nuclear DNA assays wil l provide addit ional mark-er s fo r demograph ic assessment (Kar l e t a l . 1992 ,Fi tzSimmo ns e t a l . 1995) . In the par lance o f in terna-t ional conservation, genetic markers al low wildlifeagencies to identify "range states ," nations impactedby the harve st of natural resources at a dis tant location.The concept of range states implies some level of ju-r isdict ion: the 1982 U.N . Convention on the Law ofthe High Seas recognizes that nations hosting the de-velopmental habitat for migratory marine species holdexclusive f ishing r ights for these animals on the highseas (Van Dyke 1993) . The 1983 U .N Conven t ion onthe Conservat ion o f M igra to ry Species ( a .k .a . the BonnConvention) prohibits taking endangered species dur-ing migrations on the high seas (H ykle 1992) . The pr in-ciples outl ined in these conventions, as applied to seatur t les , provide nations that host nest ing and devel-opmental habitats with some level of jur isdict ion overthese animals on geographically remote feedinggrounds. Genetic tags can play a cr i t ical role in iden-t ifying the or igins of beleaguered m arine tur t le feedingpopulat ions (Bowen 1995 , Bowen and Avise 1995) ,and eventually may provide a foundation for interna-t ional agreements concern ing the s tewardsh ip o f mi-gra to ry m ar ine species.

This p ro ject was made possib le by the ou ts tand ing con tr i -b u t io ns o f M . B u s t am an te , H . K o y am a-D iez , D . G o o d , Z . -M .Hil l is , J . Horrocks , M. Mar covald i , J . R ichardso n , G . Smith ,


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May 1996 H A W K S B I L L T U R T L E F E E D IN G G R O U N D 5 7 1J . Thom e, W. Weber, J. Woody, J. Zurita, and the Puerto R icoDepartment of Natural Resources. For technical and logisticalassistance, we gratefully recogn ize E. Almira, D. B roderick,R. Byles , A,-M. Clark, S . Encalada, C. Kobak, M. Masu da,C. Mori tz , J . Norman, J . Pella, P. Sm ouse , L. Walz, CIQR O(Mex ico), Fundacao Pro-Tamar (Brazil) , the InterdisciplinaryCenter for Biotechnology Research and the DNA SequencingCore (University of Florida). Special thanks to J. Frazier, R.Klinger, C. Lim pus, J. P. Ross, K. Sie ving, and G . Smith foradvice and co nsultation. This research was suppo rted by theU.S. Fish and Wildlife Service (RWO 67:14-16-0009-1544-67) and the National Science Foundation Conservation andRestoration Program (DEB-9225082).

Avise, J. C. 1994. M olecular markers, natural history, andevolution. Chapman and Hall , New York, New York, USA.Avise, J. C., and B. W. Bowen 1994. Investigating sea turt lemigration using DNA ma rkers. Current Opinion in Geneticsand Development 4:882-886.Bass, A. L., D. A. Good, K. A. Bjorndal, J. I . Richardson,Z.-M. Hill is, J. Horrocks, and B. W. Bowen. 1996. Testingmodels of female migratory behavior and population struc-ture in the Caribbean hawksbill turt le, Eretmochelys im-bricata, with mtDNA control region sequences. MolecularEcology, in press.Bjorndal, K. A., A. Carr, A. B. M eylan, and J. A . Mortimer.1985. Reproductive biology of the hawksbill Eretmochelysimbricata at Tortuguero, Costa Rica, with notes on the ecol-ogy of the species in the Caribbean. Biological Conser-vation 34:353-368.Bowen, B . W. 1995. Voyages of the ancient mariners: track-ing marine turt les with genetic markers. BioScience 45:528-534.Bow en, B. W., F. A. Abreu-G robo is, G. H. Balaz s, N. Ka-mezaki, C. J. Limpus, and R. J. Ferl . 1995. Trans-Pacificmigrations of the loggerhead sea turt le (Caretta caretta)demonstrated with g enetic markers. Proceedings of the Na-tional Academy of Sciences (USA) 92:3731-3734.Bowen, B. W., and J. C. Avise. 1995. Conservation geneticsof marine turtles. In J. C. Avise and J. L H amrick, editors.Conservation genetics: case histories from nature. Chap-man and Hall , New York, New York, USA. In press.Bowen, B. W., J. C. Avise, J. I . Richardson, A. B. Meylan,D. Margaritoulis, and S. Hopkins-M urphy. 1993. Popu-lation structure of the loggerhead turt le (Caretta caretta)in the northwest Atlantic Ocean and Mediterranean Sea.Conservation Biology 7:834-844.Bowen, B. W., N. Kamezaki , C. J . L impus, G. R. Hughes ,A. B. Meylan, and J. C. Avise. 1994. Global phylogeog-raphy of the loggerhead turt le (Caretta ca retta) as indicatedby mitochondrial DNA haplotypes. Evolution 48:1820-1828.Bowen, B . W., A. B . Meylan, J. P. Ross, C. J. Limpus, G . H.Balazs, and J. C. Avise. 1992. Global population structureand natural history of the green turtle (Chelonia mydas) interms of m atriarchal phylogeny. Evo lution 46:865-881.Broderick, D. 1992. Population genetics of hawksbill turtles,Honors Thesis. University of Queensland, St. Lucia,Queensland, Australia.Broderick, D., C . Moritz, J. D. Miller, M. Guinea, R , J. Prince,and C. J. Limpus. 1994. G enetic studies of the hawksbillturt le (Eretmochelys imbricata): evidence for multiplestocks in Au stralian waters. Pacific Conservation Biology1:123-131.Canin, J. 1989. International trade in sea turt le products,Pages 27-29 in S. A. Eckert , K. L. Eckert , and T. H. Rich-ardson, compilers. Proceedings of the Ninth Annual W ork-shop on Sea Turtle Biology and C onservation. NO AA Tech-nical Memorandum NMFS-SEFC-232. National TechnicalInformation Service, Springfield, Virginia, USA.

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N o t e Added in P r o o fRecent research has demonstrated that four m tD N A haplotypes observed in the Brazilian nesting population(R , S , T , and U in Table 2) may be der ived from Atlan t ic loggerhead turt les (Care t ta care t ta). Avai lableevid enc e, including morphological exam ination (P. C . H. Pritchard, personal com mun ication ) and nuclearD N A assays ( S . A . Kar l, personal commu nicat ion) , ind icate that these samples are no t m is ident i f ied log-gerheads or f ir~t~generat ionybrids, but the product o f an older introgression event (B ass et al. 19 96). W h i l eit is uncertain how the introgression of loggerhead genotypes could a ff ec t hawksbill migratory behavior,these findings do not alter the conclusion that the Brazilian nesting co lony did not contribute to the assayedfeeding aggregate at detectable levels .

bowen_1996_ecolapp

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