Cozumel Research Articles

Diversity of sand inhabiting marine ascomycetes in some tourist beaches on Cozumel Island, Mexico

Globally marine fungal diversity is poorly known, especially in Mexico. We evaluated the diversity of marine ascomycetes on five tourist beaches on Cozumel Island in September 2004, and in February 2007. Fifty sample units were collected randomly from each beach during each sampling time. Seven species were recovered, of which Lindra thalassiae and Corollospora maritima were the most dominant species. Corollospora gracilis and Lulworthia grandispora are new records for Cozumel Island. The highest diversity value was found in San Francisco beach, probably because the surrounding coral reefs are an important source of a wide variety of substrata for these fungi.

High genetic structure of the Cozumel Harvest mice, a critically endangered island endemic: conservation implications

We assessed the genetic structure and diversity of Reithrodontomys spectabilis, a critically endangered, endemic rodent from Cozumel Island, Mexico. A total of 90 individuals were trapped from September 2001 to January 2005. Microsatellite data analysis revealed high genetic diversity values: a total of 113 alleles (average 12.5 per locus), H o = 0.78, H e = 0.80. These high values can be related to Cozumel’s size (478 km2) and extensive native vegetation cover, factors that could be promoting a suitable population size, high heterozygosity and the persistence of rare alleles in the species, as well as some long-term movement of individuals between sampling localities. A strong genetic structure was also observed, with at least four genetic groups, associated with a pattern of isolation by distance. We found a strong allelic and genetic differentiation shown between localities, with negligible recent gene flow and low inbreeding coefficients. The species life history and ecological characteristics—being nocturnal, semi-terrestrial, a good tree climber, having lunar phobia and significant edge effect—are likely affecting its genetic structure and differentiation. The high genetic diversity and population structure award R. spectabilis a significant conservation value. Our results can serve as a basis for future research and conservation of the species, particularly considering the problems the island is facing from habitat perturbation, urbanization and introduction of exotic species. In view of the structure and genetic variability observed, it is essential to establish and reinforce protected areas and management programs for the conservation of the endemic and endangered Cozumel Harvest mice.

Mesofaunal arthropod diversity in shrub mangrove litter of Cozumel Island, Quintana Roo, México

We studied the mesofaunal arthropod diversity in a shrub mangrove in the Punta Sur area within the National Park Reefs of Cozumel Island in the South of Mexico. Two mangrove areas were selected for sampling, dominated by Rhizophora mangle and Avicennia nitida, respectively. Four sampling periods, two during the dry season and two during the rainy season, and 25 random litter samples of litter (225cm2) per site and date led to a total of 200 samples. Spatial and temporal variation of arthropod diversity was analyzed at the order/suborder level. A total of 90,680 arthropods belonging to 30 taxa were recorded during the study, Oribatida being most abundant with 61.8%, followed by springtails (14%). Densities of arthropods were higher in the rainy season than in the dry season, showing a strong positive correlation with humidity. Highest abundance was found in the R. mangle mangrove in the rainy season, and highest diversity was found in the A. nitida mangrove in the dry season. Seasonal distribution of litter fauna in two mangroves are related with the particular characteristics shown in each one.

Vocal behaviour of the island-endemic Cozumel Wren (Troglodytes aedon beani): song structure, repertoires, and song sharing

Documenting the diversity of vocal behaviour across different avian taxa is key to understanding the ecology and evolution of complex behaviours. Unique to Cozumel Island in the Mexican Caribbean Sea, the Cozumel Wren (Troglodytes aedon beani) provides an opportunity to investigate how isolation influences complex cultural traits. Most aspects of the biology, natural history, and taxonomy of Cozumel Wrens are unknown. In an attempt to better understand the Cozumel Wren’s biology, we provide the first description of the songs and the vocal behaviour of this island-endemic bird. Based on more than 700 h of recordings, including more than 36,000 songs, we describe the fine structural characteristics of male Cozumel Wrens songs, and explore patterns of repertoire organization and song sharing. Cozumel Wrens sing songs composed of highly variable syllables, with prominent trills at the end of each song. Each bird has a limited repertoire of songs, which they create by recombining a restricted number of syllable and trill types. They repeat a song type several times before switching to a different one, with some variation in the number of times they repeat specific elements. Cozumel Wrens share more song types with neighbours than distant individuals. Syllable sharing, however, is equivalent between neighbours and distant individuals. Our results provide important data for future research on the ecology, evolution, and behaviour of this island-endemic songbird, and for helping to clarify the taxonomic status of Cozumel Wrens.

Community Structure of Scleractinian Corals outside Protected Areas in Cozumel Island, Mexico

Cozumel Island is of paramount importance for Mexico, because of the good state of its marine ecosystems, and as a touristic spot that attracts thousands of divers every day. Most studies about the local reefs have been devoted to those formations located inside the Cozumel Reefs National Park, in the southwest side of the island; however there are other important reefs that have received little attention. The objective of this paper was to conduct an analysis of zooxanthellate coral community structure in six sites of the eastern and northwestern coasts of Cozumel, and to compare them with the status of the reefs already under federal management. The results showed that there were no significant differences in coral cover, diversity, evenness and taxonomic distinctness of reefs inside and outside the protected area, a pattern that differed from that reported in previous studies. The homogeneity in the ecological structure may have resulted from the combined effects of differential human pressure (high in PNAC reefs, low outside of the park), and the high coral mortality caused in all areas by category 5 hurricanes “Emily” and “Wilma” in 2005. Considering these findings, we suggest that local authorities must allocate more effort dedicated to the conservation of reefs in the eastern coast of the island, as some of them (especially Hanan) are very well developed and house species of particular interest such as Acropora spp.

High Dispersal and Generalist Habits of the BatArtibeus jamaicensison Cozumel Island, Mexico: An Assessment Using Molecular Genetics

Islands and insular biotas have been recognized as ideal models for studying adaptive radiations and evolutionary processes. In the present study we investigated the Jamaican fruit-eating bat, Artibeus jamaicensis from Cozumel Island, to evaluate the effect of ecological features on genetic diversity and structure across three different environments, semi-evergreen tropical forest, mangrove, and cenotes, using six microsatellite loci in 105 individuals. Genetic diversity was relatively high (forest HO = 0.693, HNei = 0.825; mangrove HO = 0.702, HNei = 0.710; cenotes HO = 0.695, HNei = 0.847). Pairwise genetic differentiation measures between localities were not significant and the overall level of differentiation was markedly low (FST = 0.009, G'ST = 0.088). Likewise, results showed that A. jamaicensis consists of one genetic group and relatedness among individuals was low. Results are concordant with our predictions that the island population will show high genetic diversity and null structure at the fin...

Morphological and Color Differences between Island and Mainland Populations in the Mexican Red Rump Tarantula,Brachypelma vagans

The introduction of species into new ecosystems, especially in small and isolated regions such as islands, offers an excellent opportunity to answer questions of the evolutionary processes occurring in natural conditions on a scale that could never be achieved in laboratory conditions. In this study, we examined the Mexican red rump tarantula Brachypelma vagans Ausserer (Mygalomorphae: Theraphosidae), a species that was introduced to Cozumel Island, Mexico, 40 years ago. This introduction provides an exceptional model to study effects such as morphological variation between island populations and those on the mainland in open habitats facing the island. Intraspecific variation related to the color polymorphism was compared. The aim of this study was to determine the phenotypic differences between continental populations of B. vagans and the introduced population on Cozumel Island. Phenotypic difference was evaluated using two approaches: 1) comparison of the morphometric measurements of adult and juvenile individuals at the local scale and between continental and island populations, and 2) comparison of individual color polymorphism between mainland and island populations. Two locations were sampled within the continental part of the Yucatan peninsula and two on the island of Cozumel. The number of samples analyzed at each site was 30 individuals. The morphometric results showed significant differences between continental and island populations, with bigger individuals on the island. In addition, three new variations of the typical color pattern of B. vagans recorded so far were observed. This study opens the door to further investigations to elucidate the origin of the phenotypic variation of the isolated individuals on Cozumel Island. Also, the widest range of color morphs found for a tarantula species is reported.

Phylogeographic pattern and extensive mitochondrial DNA divergence disclose a species complex within the Chagas disease vector Triatoma dimidiata.

Background Triatoma dimidiata is among the main vectors of Chagas disease in Latin America. However, and despite important advances, there is no consensus about the taxonomic status of phenotypically divergent T. dimidiata populations, which in most recent papers are regarded as subspecies.Methodology and FindingsA total of 126 cyt b sequences (621 bp long) were produced for specimens from across the species range. Forty-seven selected specimens representing the main cyt b clades observed (after a preliminary phylogenetic analysis) were also sequenced for an ND4 fragment (554 bp long) and concatenated with their respective cyt b sequences to produce a combined data set totalling 1175 bp/individual. Bayesian and Maximum-Likelihood phylogenetic analyses of both data sets (cyt b, and cyt b+ND4) disclosed four strongly divergent (all pairwise Kimura 2-parameter distances >0.08), monophyletic groups: Group I occurs from Southern Mexico through Central America into Colombia, with Ecuadorian specimens resembling Nicaraguan material; Group II includes samples from Western-Southwestern Mexico; Group III comprises specimens from the Yucatán peninsula; and Group IV consists of sylvatic samples from Belize. The closely-related, yet formally recognized species T. hegneri from the island of Cozumel falls within the divergence range of the T. dimidiata populations studied.ConclusionsWe propose that Groups I–IV, as well as T. hegneri, should be regarded as separate species. In the Petén of Guatemala, representatives of Groups I, II, and III occur in sympatry; the absence of haplotypes with intermediate genetic distances, as shown by multimodal mismatch distribution plots, clearly indicates that reproductive barriers actively promote within-group cohesion. Some sylvatic specimens from Belize belong to a different species – likely the basal lineage of the T. dimidiata complex, originated ∼8.25 Mya. The evidence presented here strongly supports the proposition that T. dimidiata is a complex of five cryptic species (Groups I–IV plus T. hegneri) that play different roles as vectors of Chagas disease in the region.

First record of Ophioderma ensiferum (Echinodermata: Ophiuroidea) from the southeastern continental shelf of the Gulf of Mexico and from an anchialine cave

Two specimens of Ophioderma ensiferum Hendler and Miller, 1984 were collected at 2 different localities in the Yucatán Peninsula, Mexico. The first one collected at Alacranes Reef, Yucatán, a transition zone between the Gulf of Mexico and the Caribbean, and the second one in an anchialine cave located in Cozumel Island, Quintana Roo. These records expand the known distribution of the species to the southern part of the continental shelf of the Gulf of Mexico. This finding represents the first record of this ophiuroid on the continental shelf of Mexico, and also the first record of this species in an anchialine cave.

Identification of echinoderms (Echinodermata) from an anchialine cave in Cozumel Island, Mexico, using DNA barcodes

The echinoderm species richness of the Aerolito de Paraiso anchialine cave, on Cozumel Island, in the Mexican Caribbean, is assessed on the basis of morphological and DNA barcoding data. We included specimens from this cave system and from different open sea areas, and employed two different approaches for species delineation based on DNA barcoding data: a 2% cox1 divergence and the general mixed Yule-coalescent (GMYC) approaches. We subsequently compared the results derived from these approaches with our morphospecies discrimination. A total of 188 cox1 sequences belonging to specimens of four echinoderm classes were examined. The 2% cox1 divergence and GMYC approaches recovered 78 and 70 putative species, respectively, 24 and 22 of which corresponded to specimens from the anchialine system. Of 26 echinoderm species identified in the cave system, seven appear to be endemic to it. Among these are Copidaster carvenicola Solís-Marín & Laguarda-Figueras, 2010, two morphologically distinctive, undescribed species belonging to Asterinides and Ophionereis and four probably cryptic undescribed species originally assigned to Amphipholis squamata (Delle Chiaje, 1839), Astropecten duplicatus Gray, 1840, Copidaster lymani (AH Clark, 1948) and Ophiothrix angulata (Say, 1825). Further research and protection of this particularly fragile ecosystem becomes urgent because construction of tourism developments is planned nearby.

New bird records for cozumel island found in scientific collections

We report here 4 new bird records found among a large-scale compilation of specimen records in museums worldwide, Atlas de las Aves de Mexico. The new records are for 4 migratory species, Empidonax alnorum (Alder Flycatcher), Vireo solitarius (Solitary Vireo), Catharus fuscescens (Veery), and Zonotrichia leucophrys (White-crowned Sparrow). These species are not to-date known from Cozumel, although they are considered transients in the Yucatán Peninsula.

Nest survival in the Neotropical Black Catbird (Melanoptila glabrirostris)

We estimated nest survival and evaluated factors affecting this demographic parameter for the Black Catbird (Melanoptila glabrirostris), a poorly known mimid endemic to the Yucatan Peninsula. During the 2008 and 2009 breeding seasons, we monitored 136 nests spread across four sites in Mexico, including three mainland coastal sites in the Sian Ka’an Biosphere Reserve and one site on Cozumel Island. We documented higher nest loss in the mainland sites (74 % failed) in contrast to the island site (21 % failed). Based on our observations, we suspect that predation was the main cause of nest failure. Using logistic exposure models and Akaike’s Information Criterion, we found date, nest age, and nest type to be the main factors influencing nest survival. Nest survival was lower for open cup-nests in comparison with semi-cavity nests. Interval nest survival (proportion of nests expected to survive the entire nesting season) was 0.102 (CI = 0–0.660) for open-cup nests and 0.618 (CI = 0–0.981) for semi-cavity nests. Additional research on adult and juvenile survival and dispersal patterns, especially for the mainland population, is needed to determine if these rates of nest survival are sufficient to maintain stable populations.

Dwarfism in insular carnivores: a case study of the pygmy raccoon

AbstractInsular dwarfism is common in mammals. Many theories have been put forward to explain it, including competitive release, predation release, resource limitation and limited dispersal abilities. However, recent analyses have challenged many of these assertions and indicate that size evolution is more complex with populations and species developing unique patterns of morphological variation. We explore the evolution of body size in a poorly studied island carnivore, the pygmy raccoon Procyon pygmaeus, and compare it with other mainland and island populations within its genus. We studied 36 males and 42 females of the endemic and endangered pygmy raccoon on Cozumel Island, Mexico, from 2001 to 2003. Insular P. pygmaeus are, on average, 17.5% smaller in linear dimensions than their closest mainland relative. Minimum linear rate of size change was 6.21% per 1000 years or 5.43 darwins. Size reduction is likely to have been an adaptation to fewer resources and predators. Our population genetic examination identified different patterns of divergence than the morphological examination, indicating that the rate of morphological evolution likely exceeds that represented in this genus’ neutral genetic history. This case study highlights the importance of an autecological approach toward examining insular dwarfism given that clear patterns are not visible across the Carnivora.

Marriage and the Family Among the Maya of Cozumel Island, 1570

In his obituary of the late Maya scholar, Ralph L. Roys, Thompson (1967, p. 97) calls attention to important document, on which Roys worked, which has been neglected by those currently engaged in Maya settlement pattern research. The document in question is the Cozumel Census of 1570, which has been called only detailed account of the way the Maya lived at the time of the Spanish conquest (Roys, Scholes and Adams, 1949, p. 14). If this is the case, obviously the neglect of this source of information is a serious matter. It is the porpoise of this paper to take a new look at the Cozumel Census, to see what conclusions may be drawn from it.

Characterization of ten new microsatellite loci from the endangered endemic rodent, Reithrodontomys spectabilis

Reithrodontomys spectabilis is an endemic rodent inhabiting Cozumel island in the Mexican Caribbean. This species is categorized as Threatened by Mexican law and as Critically Endangered by the IUCN. We report 10 polymorphic microsatellite loci, which were tested in 30 individuals trapped on the island. Results show a number of alleles ranging from 3 to 14, an observed heterozygosity of 0.200–0.967 and expected heterozygosities from 0.396 to 0.899. Two loci showed deviation from Hardy–Weinberg equilibrium. None of the loci showed linkage disequilibrium. These new microsatellite loci for R. spectabilis are vital to investigate different aspects of genetic diversity and help conservation of this endemic, threatened species.

Activities of Cruise-Ship Employees in Cozumel, Mexico

Despite the increasing importance of cruise tourism worldwide, very little is known about the lives of cruise-ship employees, and how they use their free time at the ports of call. This paper presents the results of a small-scale exploratory research on the activities of cruise crew and staff members on the island of Cozumel, Mexico, an important port of call for Caribbean routes. Conducted in 2009, qualitative research for this paper included participant observation and several informal conversations and semi-structured interviews with twenty cruise-ship employees and six owners and employees of local businesses. Our conclusions confirm other authors' findings and provide fresh information on the factors that determine these individuals' choices of activities, places and company. Availability of time and money depends on each worker's place in the labor hierarchy, but choices are also influenced by cultural background. More in-depth research will be needed at the demand as well as the offer sides to complement these preliminary findings.

Genetic evidence of a recent successful colonization of introduced species on islands: Boa constrictor imperator on Cozumel Island

Only one study has described the population genetic structure of Boa constrictor imperator and only in a single naturally colonized island. B.c. imperator, a snake with a naturally wide distribution across the Neotropics, was introduced to Cozumel Island, Mexico, in 1971. At present, it is one of the most abundant, widely distributed, terrestrial vertebrate on the island. We analysed the genetic diversity and structure, based on seven microsatellite loci, of 76 individuals of B.c. imperator from Cozumel. We also included 96 samples from different localities across mainland Mexico, to review the potential origin of the founder individuals. We identified two genetically differentiated populations on Cozumel that showed moderate levels of genetic diversity (Ho = 0.590–0.620), with a low but significant level of genetic structure (FST = 0.032). Individuals were highly unrelated (71 %) and the majority of genetic variation was distributed within individuals (84 %). We detected a signal of reduction in population size and evidence of genetic bottleneck. The genetically closest mainland populations, indicating potential source of island founders, are localities from the Gulf of Mexico and Yucatan peninsula. Results are in agreement with a recently introduced population, founded by a few individuals originating from several sources, which has been successful. B.c. imperator is jeopardizing a highly vulnerable insular ecosystem, hence its eradication from Cozumel is urgently needed. Our information is also valuable for other introduced-boa cases or as a basis for its conservation elsewhere given its classification as a threatened species.

Nest attendance and hatchling care in wild American crocodiles (Crocodylus acutus) in Quintana Roo, Mexico

AbstractCrocodilians show universal parental care, but few studies concentrate on this behavior in wild crocodiles. We studied nest and hatchling care in genetically pure wild American crocodiles (Crocodylus acutus) on two Caribbean islands of Mexico. From 2006 to 2009 we made direct observations of crocodile behavior upon discovery of nests and groups of hatchlings in Banco Chinchorro. In 2009, we installed camera traps at 4 nests from the time of their discovery to the hatching of each nest, in Banco Chinchorro and Cozumel Island. Twenty-one other species were observed to visit crocodile nests. No nest predation was observed but nine species represented some danger to nests and/or hatchlings. Females seemed to remain in the nest vicinity during incubation. There was variability in nest visit frequencies and no nest defense toward human intrusion was observed. Visit frequency by other species at nests decreased with increased crocodile visitation. Crocodiles mainly visited nests on darker nights, corresponding to the visits of species representing greater danger for nests. Repair of the nest by females after disturbance was observed for the first time in wild American crocodiles. Crocodile visits were more frequent at the beginning and the end of incubation, which could represent different antipredation strategies. Although adult crocodiles helped during hatching for the emergence of neonates, hatchling care seemed reduced compared to other crocodile species. We provide the first data on nesting behavior of genetically pure American crocodiles in the Yucatan peninsula, which provides a base for future comparisons with Morelet's crocodiles and their hybrids.

Nuevo registro del loro frente blanca (Amazona albifrons) para la Isla de Cozumel, Quintana Roo, México

Reportamos, por primera vez en la literatura científica, al loro frente blanca (Amazona albifrons) como especie introducida en áreas urbanas de la Isla de Cozumel, Quintana Roo, durante el trabajo de campo realizado en el mes de abril de 2011. Su presencia sólo en áreas urbanas de la isla, la capacidad de la especie para poder vivir con éxito en áreas urbanas, la abundancia de árboles frutales y su uso como mascota por los isleños nos permite sugerir que los individuos registrados son resultado de escapes o fueron liberados por sus dueños. Es probable que las condiciones sean favorables para el establecimiento de una población dentro del poblado de San Miguel de Cozumel, lo que debe monitorearse en el futuro.

First Records of Polychaetous Annelids from Cenote Aerolito (Sinkhole and Anchialine Cave) in Cozumel Island

In this study, polychaetous annelids are recorded for the first time in Mexican cenotes and anchialine caves. These organisms were collected in the Cenote Aerolito (Cozumel Island, on the Caribbean coast of Quintana Roo) during three sampling events from February 2006 to April 2008, among algae, roots of mangroves, and in karst sediments. A total of 1518 specimens belonging to five families (Paraonidae, Capitellidae, Nereididae, Dorvilleidae, and Syllidae), ten genera, and eleven species were collected. In the cave system, two specimens of the amphinomid Hermodice carunculata were found. This cenote and its biota are now in danger of disappearing because of a marina construction project in its western shore.