<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0034-7744</journal-id>
<journal-title><![CDATA[Revista de Biología Tropical]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. biol. trop]]></abbrev-journal-title>
<issn>0034-7744</issn>
<publisher>
<publisher-name><![CDATA[Universidad de Costa Rica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0034-77442016000200837</article-id>
<article-id pub-id-type="doi">10.15517/rbt.v64i2.19366</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Understanding trophic relationships among Caribbean sea urchins]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rodríguez-Barreras]]></surname>
<given-names><![CDATA[Ruber]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cuevas]]></surname>
<given-names><![CDATA[Elvira]]></given-names>
</name>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cabanillas-Terán]]></surname>
<given-names><![CDATA[Nancy]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Branoff]]></surname>
<given-names><![CDATA[Benjamin]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,University of Puerto Rico  ]]></institution>
<addr-line><![CDATA[ Bayamón]]></addr-line>
<country>PR</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,University of Puerto Rico  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>PR</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,University of Puerto Rico  ]]></institution>
<addr-line><![CDATA[ San Juan]]></addr-line>
<country>PR</country>
</aff>
<aff id="Af4">
<institution><![CDATA[,El Colegio de la Frontera Sur  ]]></institution>
<addr-line><![CDATA[ Quintana Roo]]></addr-line>
<country>MX</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>06</month>
<year>2016</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>06</month>
<year>2016</year>
</pub-date>
<volume>64</volume>
<numero>2</numero>
<fpage>837</fpage>
<lpage>848</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S0034-77442016000200837&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S0034-77442016000200837&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S0034-77442016000200837&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[ResumenLas especies Echinometra lucunter, Echinometra viridis, Lytechinus variegatus, Tripneustes ventricosus, and Diadema antillarum son los erizos de mar más comunes en los hábitat litorales del Caribe. Los erizos de mar T. ventricosus y L. variegatus habitan generalmente los pastos marinos mientras que las otras tres especies se encuentran asociadas a sustratos rocosos. Los hábitos alimentarios de estas especies han sido bien documentados y son reconocidas como herbívoros - omnívoros; sin embargo, pocas de estas especies han sido caracterizadas isotópicamente. Utilizamos los isótopos estables para caracterizar estas cinco especies de erizos y establecer las posiciones tróficas para las especies que cohabitan los mismos ecosistemas. También cuantificamos la contribución de los recursos alimentarios para E. lucunter. Los erizos T. ventricosus y D. antillarum mostraron los mayores valores de &#948;15N y valores similares de &#948;13C que variaron desde -11.6 ± 0.63 a -10.4 ± 0.99 %; donde el erizo E. lucunter mostró los valores más negativos con -15.40 ± 0.76 %. Las comunidades de algas no mostraron diferencias en valores promedio de &#948;15N (F= 1.300, df= 3, p= 0.301), pero sí mostraron variaciones en los valores de &#948;13C (F= 7.410, df= 3, p= 0.001). Los estudios de amplitud de elipses de nicho determinaron que las especies de los biotopos rocosos (D. antillarum, E. lucunter y E. viridis) no mostraron solapamiento de nicho. Similar resultado también se encontró en las especies de erizos que habitan en los pastos marinos. Sin embargo, la distancia entre estas dos especies fue menor respecto a la distancia entre las especies de erizos que habitan en los sustratos rocosos. Nuestros resultados muestran que las especies que habitan en los pastos marinos mostraron valores más elevados de &#948;13C en comparación con las especies de los sustratos rocosos. No se encontraron diferencias espaciales para E. lucunter en &#948;15N, pero sí en &#948;13C. Los modelos de mezcla bayesianos demuestran la plasticidad alimentaria de E. lucunter, especie capaz de utilizar múltiples recursos algales dependiendo de la disponibilidad por sitio. Semejanzas en &#948;15N entre D. antillarum y T. ventricosus parecen indicar similitudes tróficas entre ambas especies. Si bien T. ventricosus es reconocido como omnívoro, D. antillarum siempre ha sido considerado un herbívoro generalista. Finalmente, la falta de solapamiento entre las especies en los dos biotopos parece indicar una estrategia de partición de recursos para evitar la competencia de nicho entre especies concurrentes.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[AbstractThe species Echinometra lucunter, Echinometra viridis, Lytechinus variegatus, Tripneustes ventricosus, and Diadema antillarum are the most common sea urchins of littoral habitats in the Caribbean. T. ventricosus and L. variegatus are associated with seagrass beds, while the other three species usually inhabit hardground substrates. Food preferences of these species are well documented and they are commonly accepted as being primarily herbivorous-omnivorous; nevertheless, few of them have previously been characterized isotopically. We used this approach for assessing the isotopic characterization of five echinoids. We established the trophic position of two groups of co-occurring species and quantified the contribution of food resources in the diet of Echinometra lucunter, considered the most common sea urchin in the Caribbean region. The species T. ventricosus and D. antillarum showed the highest values of &#948;15N. Sea urchins exhibited similar values of &#948;13C varying from -11.6 ± 0.63 to -10.4 ± 0.99%. The echinoid E. lucunter displayed the lowest values of carbon, from -15.40 ± 0.76%. Significant differences among species were found for &#948;15N and &#948;13C. Seaweed communities exhibited no differences among sites for overall &#948;15N (F= 1.300, df= 3, p= 0.301), but we found spatial differences for &#948;13C (F= 7.410, df= 3, p= 0.001). The ellipse-based metrics of niche width analysis found that the hardground biotope species (D. antillarum, E. lucunter, and E. viridis) did not overlap each other. Similar results were obtained for the co-occurring species of the seagrass biotope; however, the distance between these species was closer than that of the hardground biotope species. The Bayesian mixing models run for E. lucunter at all four localities found differences in food resources contribution. The algae D. menstrualis, C. crassa and B. triquetrum dominated in CGD; whereas C. nitens, Gracilaria spp., and D. caribaea represented the main contributor algae to the diet of E. lucunter at LQY. In Culebra Island, no dominance of any particular algae was detected in TMD, where six of the eight species exhibited a similar contribution. Similarities in &#948;15N between D. antillarum and T. ventricosus may hint towards a similar trophic level for these species, although T. ventricosus is widely accepted as an omnivore, while D. antillarum is considered a generalist herbivore. The lack of overlap among species in the two biotopes seems to indicate a resource partitioning strategy to avoid niche competition among co-occurring species. Rev. Biol. Trop. 64 (2): 837-848. Epub 2016 June 01.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[isótopos estables]]></kwd>
<kwd lng="es"><![CDATA[ecología trófica]]></kwd>
<kwd lng="es"><![CDATA[modelos de mezcla]]></kwd>
<kwd lng="es"><![CDATA[erizos de mar]]></kwd>
<kwd lng="es"><![CDATA[Puerto Rico]]></kwd>
<kwd lng="en"><![CDATA[stable isotopes]]></kwd>
<kwd lng="en"><![CDATA[trophic ecology]]></kwd>
<kwd lng="en"><![CDATA[Bayesian mixing models]]></kwd>
<kwd lng="en"><![CDATA[sea urchins]]></kwd>
<kwd lng="en"><![CDATA[Puerto Rico]]></kwd>
</kwd-group>
</article-meta>
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