High Density Of Individuals Research Articles

Biologia reprodutiva de L. leucocephala (Lam.) R. de Wit (Fabaceae: Mimosoideae): sucesso de uma espécie invasora

The species Leucaena leucocephala (Lam.) R. de Wit., known as leucaena, is originally from Central America. It has been considered a pioneer with high densities of individuals in its populations that could prevent the development of native species. The present study aims to understand the reproductive biology of L. leucocephala , synthetizing information about its reproductive success. The study was conducted in Trindade, central Brazil, from July to November 2012. All areas contained specimens in bloom. We selected four study areas containing populations of leucaena with at least six individuals with flowering. Observations were made of floral visitors and we did tests of first, second and third visit, and cross-pollination between plants, self-pollination and control group (without human intervention). There was a predominance of Apis mellifera and Trigona spinips as flower visitors in these areas. The flowers undergo senescence at the end of the day, however, there is a decrease in flower visiting by insects after 10 am. We found 342 visitors belonging to 12 insect species. After assessing the number of visits of pollinators and their influence on fruit production, we found that the number of visits of the main pollinator ( A. mellifera ) does not influence the production of fruits, showing the efficiency of this bee in its first visit to flowers. Leucaena leucocephala combines several attributes to be considered an invasive species, such as the efficient action of generalist pollinators as Apis mellifera , being able to produce considerable amounts of fruits and seeds that contribute to the potential dispersal and reproductive success of the plant. Keywords : pollination, Apis mellifera , reproductive success.

Population structure and genetic diversity of the only extant Baroninae swallowtail butterfly, Baronia brevicornis, revealed by ISSR markers

Due to its relict nature, the unique Baroninae swallowtail, Baronia brevicornis, is considered a “living fossil”. It is also one of the most enigmatic butterfly species with contentious origins and peculiar ecological characteristics. The aim of this study is to evaluate the genetic diversity and population structure of this endemic species of butterfly in Mexico. We sampled populations in two areas within its restricted geographical range in central Mexico and the isolated subspecies population in the state of Chiapas. Three ISSR primers produced 66 loci, indicating a high genetic diversity (P = 100 %, H e = 0.22) and variation range in these populations (62 % < P < 85 %, 0.18 < H e < 0.25). The Chiapas population presented the lowest values. The observed high values can be explained by the population dynamic of this species characterized by a very high density of individuals over very limited areas. Variation between populations appears to reflect both the age of colonization and locality perturbation level. Two methods of genetic structure analysis (Self-Organizing Map and Structure analysis) match to define three clusters. Natural and anthropogenic barriers may explain the separation between two clusters (cluster 1 and 2) of central Mexico but an unexpected result revealed that the Chiapas population is not genetically distinguishable from the central Mexico populations (cluster 3) leading us to hypothesize a possible “recent” separation or anthropogenic introduction. Habitat and host plant specificity probably limits the exchange of individuals between populations thus increasing fragmentation and leading to a complex genetic structure. We should put in place population monitoring schemes at different spatial scales, combining field occurrences and genetic tools, in order to reduce extinction susceptibility and keep track of recolonization events for this enigmatic species.

Effects of interspecific competition on the growth and competitiveness of five emergent macrophytes in a constructed lentic wetland

A competition experiment was conducted for two years, to assess the effects of interspecific competition between five macrophytes on growth and coverage, in a constructed wetland with a natural water regime. We compared growth results from the competition experiment with those from a field survey in pure stands, where interspecific competition does not occur. The shoot height values of most species in the constructed wetland did not reach the maximum values, compared to those from the field data, indicating that the effect of interspecific competition was notable on the shoot height in the constructed wetland. Zizania latifolia showed the highest growth performance in the constructed wetland. Although Typha latifolia showed a high above-ground dry weight value, similar to that of ZL, TL did not expand its coverage as wide as that of ZL in the constructed wetland. Relatively high density and individual dry weight among species determined the high AGDW of ZL and TL, respectively, in the pure stands. In contrast, high individual dry weight and density among planted species determined the high AGDW of ZL and TL, respectively, in the constructed wetland, indicating that interspecific competition seemed to cause different ecological responses of plant, compared to a non-competitive situation. The dominance of ZL in the competition experiment appeared to be facilitated by planting material of seedling form, relatively rapid growth in an early growth phase, natural water regime in a lentic sheltered site, non-eutrophic water condition, and the absence of companion species belonging to the same genus.

Household repayment behaviour and neighbourhood effects

The recent financial crisis has revealed the financial vulnerability faced by a significant number of households in the UK. Households experiencing financial problems may potentially fall into arrears in meeting financial obligations such as rent, mortgage payments or household bills. Indeed, such arrears have been regarded as one of the most direct measures of financial stress at the household level. In this paper, we explore the relationship between household repayment behaviour and neighbourhood ties in order to identify possible channels of support for households experiencing financial stress. We analyse data on 17,723 households drawn from wave 1 of the UK longitudinal study, Understanding Society, merged with information on neighbourhood ties defined at the postcode area level elicited from a sample of 48,906 individuals. Our findings, which relate to the post financial crisis era, suggest that households in regions characterised by strong neighbourhood ties are less likely to report being in arrears and that this relationship is particularly apparent in the case of housing costs. This inverse relationship is strongest in regions characterised by a high density of individuals who feel able to turn to someone in the neighbourhood for support or advice. Thus, neighbourhood and community groups, which enhance social interaction and neighbourhood ties, may be effective channels of support for financially vulnerable households.

Genetic consequences of fragmentation on populations of the terrestrial orchid Cymbidium goeringii

Population genetics theory predicts that fragmented plant populations do exhibit less genetic diversity, greater genetic divergence, and higher rates of inbreeding than well-preserved, continuous populations. We investigated the effects of habitat fragmentation on levels and distribution of genetic diversity and inbreeding in the terrestrial orchid Cymbidium goeringii on three islands off the south coast of South Korea. We selected two case studies, each containing 10 fragmented and 10 continuous (i.e. undisturbed) populations (40 populations and 1493 individuals in total); for both case studies, fragmentation has been recorded for almost 200years. Using nine polymorphic allozyme loci, we compared genetic diversity and structure between fragmented and continuous populations for each of two case studies. We found that continuous populations harboured significantly greater allelic richness (AR) than fragmented ones. We also found that fragmented populations exhibited two- to threefold higher degree of genetic differentiation (FST) than continuous ones. We did not found, however, significant differences for expected heterozygosity (He) and fixation index (FIS). Fragmentation effects are noticeable in C. goeringii as AR was significantly reduced in fragmented populations. The lack of significant differences for He would be attributable either to insufficient number of generations elapsed from the beginning of fragmentation, to the high density of individuals in undisturbed populations, or to both. The loss of allelic diversity detected in disturbed populations of C. goeringii is still small, and could be recovered if the current moderate levels of gene flow are maintained and no further fragmentation is occurring.

Macrobenthic Invertebrates in the Intertidal Zone at both Sides of the Suez Gulf

Macrobenthic invertebrates were sampled in Suez Gulf ′s branches (Eastern and Western sides) from Winter, 2009 to Autumn, 2010. A total of 76 species of benthic invertebrates were recorded. The spatial distribution showed that the highest density of individuals were estimated in the stations of the western side. There were 57023 and 38784 animals / m 2 recorded for the western and the eastern sides, respectively. The stations in the eastern side were distinguished by the high number of species (75 species). The temporal distribution showed that Winter and Spring gave the highest number of both individuals and species number. Otherwise the lowest number of species and density were found in Autumn and Summer. Rocky substrates contained higher fauna than the sandy beds.

Are coffee agroforestry systems suitable for circa situm conservation of indigenous trees? A case study from Central Kenya

Coffee agroforestry systems (CAFS) are often considered to be species-rich, potentially contributing to the conservation of indigenous trees. To investigate the conservation capacity of a Kenyan CAFS, all tree species on 62 smallholder coffee farms (covering 39 ha in total) in the Aberdare Mountains of Central Kenya were recorded. In total, 6,642 trees of 59 species were enumerated, with a mean density of 256 trees per ha and a mean species richness of 11.2 species per farm. Indigenous species represented 63 % of the richness but only 31 % of the abundance. For individual farms, as expected, farm size had a positive correlation with tree species richness, but more interestingly there was a negative correlation with tree density. Cluster analysis based on densities of the 18 most important species (defined by an importance value index) revealed two groups of farms: one cluster represented small farms (mean size = 0.4 ha) with high tree species diversity and individual density, particularly of indigenous trees; the other cluster represented large (mean size = 1 ha) and less diverse farms with low tree densities, particularly regarding indigenous species. Tree individuals were unevenly distributed within farms, being more frequent in living fences (38 % of all individuals), the garden zone (20 %) and in coffee plots (18 %). The relative occurrence of indigenous species was also uneven, being greater in living fences and the garden zone. Most adult trees (83 %) were planted, but only 46 % of seedlings were, revealing the active removal of volunteer seedlings by farmers as trees mature. Surveyed coffee farms harboured 20 % of the 135 tree species of the potential natural vegetation for the region, but only 3.6 % of the on-farm tree individuals belonged to the most valuable types of dominant and forest vegetation. Thus, although a source of significant tree cover and heterogeneity at landscape level, the value of these CAFS as circa situm reservoirs of forest tree species is questionable.

The Race for Space: Using Acoustic Telemetry to Understand Density-Dependent Emigration and Habitat Selection in a Released Predatory Fish

The dynamics of fish behavior, migration, and habitat use following stock enhancement will influence the outcome of recovery programs and indicate the ecological limits of the system. This study tested the effect of release density on emigration, activity patterns, and space utilization by releasing juvenile mulloway (Sciaenidae: Argyrosomus japonicus) at low and high densities and monitoring movement intensively for 336 h post release. Mulloway released at high densities had faster emigration and greater overall emigration rates than low density releases. Also, mulloway released at high densities used sub-optimal habitats at a greater frequency. Released fish dispersed into habitat patches at densities proportional to the quality of the habitat patch, consistent with density-dependent habitat selection. Targeting releases of small numbers of fish to the carrying capacity of individual patches of habitat will contribute to the success and economic viability of release programs in open systems. Releases of high densities of individuals or repeated releases at the same site may lead to increased emigration and losses from the stocked system. The capacity of a target habitat to support released fish can be rapidly assessed using pilot releases and intensive monitoring of acoustically tagged fish, prior to the implementation of large-scale release programs.

Fitossociologia de uma Floresta Ombrófila Densa na Amazônia Setentrional, Roraima, Brasil

O presente estudo teve como objetivo caracterizar a composição florística e fitossociológica de uma floresta nativa no município de Caracaraí, Roraima, Brasil. Foram inventariadas todas as árvores com DAP &gt; 10 cm em 9 parcelas permanentes de 100 x 100 m (1 ha cada). Foram observados 4.724 indivíduos (525ind.ha-1), distribuídos em 42 famílias botânicas, 111 gêneros e 165 espécies. As famílias com maior número de indivíduos foram Fabaceae (1.883), Lecythidaceae (609) e Sapotaceae (434), perfazendo 52% do total de indivíduos amostrados. O grupo composto por espécies pioneiras apresentou maior número de indivíduos (219ind.ha-1), seguido das secundárias (193ind.ha-1) e climácicas (113ind.ha-1). No entanto, as secundárias obtiveram maior número de espécies (95), em detrimento de climácicas (44) e pioneiras (26). O índice de diversidade de Shannon (H' = 3,27) e o valor de equabilidade de Pielou (J = 0,64) foram inferiores aos obtidos em outros inventários florísticos na Amazônia Legal, contribuindo para isso o tamanho populacional de Pentaclethra macroloba. As espécies Pentaclethra macroloba (52,1), Eschweilera bracteosa (23,7) e Pouteria caimito (8,1) apresentaram os maiores valores de importância, perfazendo 28% do VI total. A maior parte dos indivíduos amostrados (71,3% = 374ind.ha-1) foram registrados no estrato médio (12,4 m &lt; altura &lt; 26,5 m) da floresta. A comunidade florestal pode ser considerada bem estruturada, madura e diversa, portanto em bom estado de conservação.

Soft-bottom diversity patterns in marine caves; Lessons from crustacean community

Previous marine cave studies have been generally qualitative, focusing on hard benthic communities of single caves. The ecological patterns of marine cave assemblages, particularly those with soft-sediment bottoms, are poorly known. The aim of this study was to investigate ecological patterns of macroinfauna inhabiting marine caves. Using a multifactorial design, the soft-bottom crustacean fauna of six previously unsampled Mediterranean marine caves was studied. To investigate the influence of the marine cave habitat on local crustacean assemblage two stations were compared in each cave; one internal site from within the marine cave cavity and one external site, in sediments near the opening of the cave. The caves selected had a wide range of profundity in order to explore the influence of depth on the community. External sediments had higher species richness, and a significant decline in diversity values inside the caves was found at all marine cave locations studied. The abundance of organisms was strongly influenced by depth, with deeper internal cave sites having lower abundance than the external stations, while more shallow internal cave sites provide a more stable environment, which allows higher density of individuals. The results described here for soft-sediment marine cave bottoms are in contrast to previous observations in hard benthic marine cave communities, where small-scale variability was similar for interior and exterior cave habitats. The results of this study show that even in the absence of endemic cave taxa, the species assemblage at each cave was clearly different from that present in the exterior habitat and also from that present in other cave sediments. This high variability and strong individuality observed in soft-bottom marine caves suggest that there are many and complex factors controlling these communities.

Pair formation in the herbivorous rabbitfish Siganusdoliatus

This study investigated the basis of pair formation in the abundant herbivorous rabbitfish Siganus doliatus on Orpheus Island, Great Barrier Reef. Pair formation was the most common social system in S. doliatus, with 67.4% of all individuals occurring in pairs. Pairs were stable (i.e. individuals remained with the same partner throughout the study) and pair members were found within 5 m of each other 82.9% of the time. Of the examined pairs, 25% were homosexual resulting in a proportion of heterosexual pairs (75%) that was significantly lower than expected if pairs were formed solely for reproductive reasons. Therefore, although reproduction appears to be the main driver of pair formation in S. doliatus, other factors are likely to influence this behaviour. The high density of individuals on the reef crest (5.7 ± 0 .9 individuals 200 m(-2); mean ± s.e.) and extensively overlapping home ranges of pairs indicated that the defence of territories plays no role in pair formation. Instead, it appears that pair formation in S. doliatus is driven, in part, by other, non-reproductive, ecological factors. It is suggested that pair formation allows for increased vigilance against predation and enables S. doliatus to execute a novel feeding behaviour.

The effects of protection from fishing on species richness: distinguishing between alternative explanations

Marine reserves that prohibit fishing often result in greater densities of individuals and more species than adjacent fished areas. However, simple conclusions about their effects on species richness are confounded, because more species are expected to occur wherever there are more individuals. Here, there is an important distinction between the number of species per sampling unit (species density), and species richness measured as the number of species per given number of individuals. When conservation of species richness is an important goal, analyses need to discriminate between the alternative explanations for differences in the number of species. We used rarefaction to test whether species richness was higher in two 'no-take' marine reserves after controlling for differences in the density of individuals. We surveyed each reserve in three different years. There was a higher density of individuals and species in each reserve than in adjacent fished areas. However, rarefaction analyses indicated that effects on species richness were weak after controlling for the number of individuals: slightly higher species richness was recorded inside each reserve in one of three surveys, but the difference was small, and was apparent only when the maximum number of individuals was approached. Our results therefore indicate that patterns in species density were not reflected by patterns in species richness-the application of rarefaction methods is needed to determine the responses of species richness to protection elsewhere. The distinction between species density and species richness will not be important in all situations, but when it is important, inferences about species richness cannot be reliably deduced from measurements of species density.

Adaptive non-parametric identification of dense areas using cell phone records for urban analysis

Pervasive large-scale infrastructures (like GPS, WLAN networks or cell-phone networks) generate large datasets containing human behavior information. One of the applications that can benefit from this data is the study of urban environments. In this context, one of the main problems is the detection of dense areas, i.e., areas with a high density of individuals within a specific geographical region and time period. Nevertheless, the techniques used so far face an important limitation: the definition of dense area is not adaptive and as a result the areas identified are related to a threshold applied over the density of individuals, which usually implies that dense areas are mainly identified in downtowns. In this paper, we propose a novel technique, called AdaptiveDAD, to detect dense areas that adaptively define the concept of density using the infrastructure provided by a cell phone network. We evaluate and validate our approach with a real dataset containing the Call Detail Records (CDR) of fifteen million individuals.

Recognizing Sets in Evolutionary Multiobjective Optimization

Among Evolutionary Multiobjective Optimization Algorithms (EMOA) there are many which find only Paretooptimal solutions. These may not be enough in case of multimodal problems and non-connected Pareto fronts, where more information about the shape of the landscape is required. We propose a Multiobjective Clustered Evolutionary Strategy (MCES) which combines a hierarchic genetic algorithm consisting of multiple populations with EMOA rank selection. In the next stage, the genetic sample is clustered to recognize regions with high density of individuals. These regions are occupied by solutions from the neighborhood of the Pareto set. We discuss genetic algorithms with heuristic and the concept of well-tuning which allows for theoretical verification of the presented strategy. Numerical results begin with one example of clustering in a single-objective benchmark problem. Afterwards, we give an illustration of the EMOA rank selection in a simple two-criteria minimization problem and provide results of the simulation of MCES for multimodal, multi-connected example. The strategy copes with multimodal problems without losing local solutions and gives better insight into the shape of the evolutionary landscape. What is more, the stability of solutions in MCES may be analyzed analytically.

Thick brachiopod shell concentrations from prodelta and siliciclastic ramp in a Tortonian Atlantic–Mediterranean strait (Miocene, Guadix Basin, southern Spain)

Carbonate production by brachiopods in shallow-water habitats is generally expected to be not sufficiently high and temporally persistent to allow them to form very thick and densely packed shell concentrations. The formation of thick brachiopod concentrations requires long-term persistence of populations with high density of individuals, and such circumstances are assumed to be rare especially during the Cenozoic. However, here we show that the large-sized brachiopod Terebratula terebratula, the most common species in benthic assemblages with epifaunal bivalves and irregular echinoids, formed several decameter- to meter-thick, densely packed concentrations in shallow siliciclastic, high-energy environments, in a seaway connecting the Atlantic Ocean with the Mediterranean Sea during the Latest Tortonian (Late Miocene, Guadix Basin, southern Spain). This brachiopod formed (1) meter-scale, thick, parautochthonous concentrations in a prodelta setting and (2) thin, mainly allochthonous, tide- and storm-reworked concentrations in megaripples and dunes. The abundance of brachiopods at the spatial scale of the Guadix Basin seems to be mainly related to intermediate levels of sedimentation rate and current velocity because abundance and thickness of shell concentrations decline both (1) in onshore direction towards delta foresets with high sedimentation rate generated by debris flows and (2) in offshore direction with increasing levels of tide- and storm-induced substrate instability. Although brachiopods in dune and megaripple deposits are more fragmented, disarticulated, and sorted, and have a higher pedicle/brachial valve ratio than in prodelta deposits, taphonomic damage is still relatively high in prodelta deposits. Terebratula terebratula thus formed thick concentrations in spite of that disintegration processes were relatively intense along the whole depositional gradient. Therefore, population dynamic of this species was probably characterized by production maxima that were comparable to some Cenozoic molluscs in terms of their productivity potential to form thick shell concentrations in shallow subtidal environments. We suggest that temporal changes in brachiopod carbonate production have a significant spatial and phylogenetic component because multiple large-sized species of the family Terebratulidae, which underwent radiation during the Cenozoic, attained high abundances and formed shell concentrations in temperate regions.

Social context-dependent immune gene expression in bumblebees (Bombus terrestris)

Social insects are prone to attack by parasites as they provide numerous resources of food and brood, homeostatic nest conditions and a high density of individuals, enhancing the transmission of parasites. The defence of social insects might occur at different levels, the individual and the group. Individual defence occurs in part via the innate immune system resulting in the expression of antimicrobial substances. Group level defences, summarised as ‘social immunity’, represent a suite of behavioural and organisational features. Here, all effects contributing to social immunity except for the social context were removed from bumblebee (Bombus terrestris) workers, kept either in groups or solitarily. The gene expression of six effector molecules of the immune system was monitored in both groups and in controls from the same source colonies. The social treatment has a highly significant effect on immune gene expression, with groups exhibiting higher levels of two antimicrobial peptides (AMPs) and two lysozymes. Phenoloxidase is affected at the regulatory level, with a strong upregulation of its suppressor Spn27A in groups suggesting a trade-off with antimicrobial activity. AMPs are strongly upregulated in groups, whereas lysozymes are strongly downregulated in solitary treatments suggesting another trade-off. Clearly, social immunity impacts elements of individual immunity.

When landscape modification is advantageous for protected species. The case of a synanthropic tarantula, Brachypelma vagans

Landscape fragmentation usually has a considerable effect on the genetic and demographic viability of most species because it reduces population size and increases isolation among populations. This situation provokes loss of genetic diversity and increased inbreeding that can lead to population or species extinctions. Some studies also show that landscape fragmentation may have no effect on or even positive consequences for species genetic diversity. The protected tarantula, Brachypelma vagans, exhibits a particular situation in the Mexican Caribbean, which has experienced high lowland and coastal fragmentation because of recent increases in agricultural, urban and touristic development. This modified landscape structure creates favorable conditions for establishment of B. vagans populations in rural settlements. Populations of this tarantula have high densities of individuals, principally females and juveniles, and gene dispersion is assumed by the rare males. Within this context, we studied the influence of natural and anthropogenic fragmentation on the genetic diversity of six B. vagans populations (five continental, one insular), together with their spatial organization. Our approach used seven inter simple sequence repeat markers, which are highly polymorphic markers. The 76 loci selected revealed high genetic variability for continental populations and a low, but not critical situation, for the insular population. We detected a good level of gene exchange among continental populations, and an evident and recent isolation of the island population. This species exhibits a metapopulation structure in the lowlands with numerous local populations where mature females exhibit high birth site fidelity. We conclude that this protected species does not exhibit characteristics to warrant its current conservation status, and we propose complete revision of the ecological and genetic situation for B. vagans in particular, and for all species within the genus Brachypelma in general.

Ichthyofauna associated with Cymodocea nodosa meadows in the Canarian Archipelago (central eastern Atlantic): Community structure and nursery role

We carried out 84 trawls in 41 seagrass meadows composed of the phanerogam Cymodocea nodosa at three islands of the Canarian Archipelago, during June to September 2003, in order to describe the associated ichthyofauna (composition, richness, and abundance), to analyze the role that this habitat can play in fish recruitment, and to determine the potential relationship between the spatial structure of the seagrass meadow and the patterns of richness and abundance of the fish assemblage. A total of 8298 individuals were captured. The five most relevant species, in terms of abundance and frequency, were Spondyliosoma cantharus, Diplodus annularis, Syngnathus typhle, Mullus surmuletus, and Pagellus erythrinus. Gran Canaria had the largest species richness (36 species) and mean number of species per sample (8.69 ± 0.49; mean ± SE). Lanzarote had the largest number of individuals (64.83% of the total registered) and mean total abundance per sample (168.39 ± 30.91). High densities of individuals were registered (95.86 ± 13.5) and 92.91% of fishes were juveniles. Our data showed that the physical configuration of the seagrass meadows did not significantly affect the patterns of richness and abundance of the associated fish assemblage. In conclusion, the C. nodosa meadows exhibited a singular ichthyofauna and they contribute to the maintenance of the diversity of the coastal fish assemblages in the Canarian Archipelago. This habitat constitutes, during spring and summer, a nursery habitat for juvenile fishes of many species, several of them commercially targeted.

How anthropogenic disturbances affect the resilience of a keystone palm tree in the threatened Andean cloud forest?

To conserve tropical forests, it is crucial to characterise the disturbance threshold beyond which populations of tropical trees are no longer resilient. This approach is still not widely employed, especially with respect to the effects of moderate disturbances. Compensation effects, such as positive interactions among plants, are addressed even more rarely. We attempt to identify the extents to which the distribution of the keystone palm tree Ceroxylon echinulatum is regulated by various regimes of deforestation in a threatened tropical montane cloud forest in the North-West Andes of Ecuador. The demographic structure of this palm tree was examined in three habitats: old-growth forest, forest disturbed by selective logging, and deforested pasture. Patterns were related to stand structure, microclimate, and soil composition. Seedling desiccation owing to severe aboveground water stress led to the absence of juvenile palms in pastures, and thus was predictive of a near extinction of the species in this habitat. However, shade provided by dominant bunchgrass in pastures considerably reduced above- and belowground water stress by diminishing light intensity. Selective logging resulted in a higher density of individuals in disturbed forests than in old-growth forests, but was associated with a spoiled spatial structure. Therefore, the protection of residual old-growth forests is a prerequisite for the conservation of C. echinulatum, although secondary forests might act as provisional refuges that promote its resilience. The reduction of water stress by nurse grasses in pastures represents a promising approach to promote the resilience of tropical tree species and their associated communities after deforestation.

Preliminary Data on the Isolated Testudo Graeca Population from the "Cetatea Histria" Museum Complex, the Danube Delta Biosphere Reserve (Romania)

The land of the Cetatea Histria Museum Complex, the Danube Delta Biosphere Reserve, holds a large population of Testudo graeca, relatively well isolated due to the existing fence around the land of museum and the lack of suitable habitat in the vicinity. The relative high density of individuals in this area, 1.68 individuals / ha, and low recapture rates, 9.25%, suggests a large population size. The presence of juveniles and the lack of individuals with tick infestation or traces of human violence on carapace or plastron indicate a viable population which occupies an area with limited human activity.