Crypsis, conspicuousness, mimicry and polyphenism as antipredator defences of foraging octopuses on Indo-Pacific coral reefs, with a method of quantifying crypsis from video tapes

We tested the hypothesis that soft-bodied octopuses, which spend most of their lives in dens, remain highly cryptic as their primary defence against predation while they forage. We videotaped foraging octopuses on two widely dispersed Pacific coral reefs and developed a rigorous method to analyse the degree of crypsis from videotapes. Five ranks were assigned (two of‘ highly cryptic’, one of ‘moderately cryptic’, and two of ‘conspicuous’) to assess each octopus's body pattern match to its background, using the criteria of brightness, colour, shape and skin patterning. The data do not support the hypothesis. In Tahiti, octopuses were highly cryptic only 54%, moderately cryptic 24% and conspicuous 22% of the time. In Palau, the respective calculations were 31 %, 19% and 50%. A major feature of their behaviour was their remarkable ability to instantly change their body pattern, or phenotype, by direct neural control of the skin. Six chronic and nine acute categories of body patterns were observed. On average, octopuses changed their phenotype 2.95 times/minute, or 177 times per hour, based upon 7.5 hours of videotaped foraging. This rapid neurally controlled polyphenism was used most often to adjust their appearance as they foraged slowly across highly diverse substrates, thus implementing appropriate mechanisms of crypsis over each (e.g. general background resemblance, deceptive resemblance, disruptive coloration). However, when crawling rapidly, or swimming for short distances, octopuses often engaged a second antipredator lactic that was conspicuous: mimicking fishes or showing bold disruptive patterns that rendered them visibly different from an octopus. Nevertheless, sometimes they were simply conspicuous even when moving slowly, particularly in Palau, where the octopuses were larger, there was a high degree of mating“, and fewer signs of predation were evident. The results suggest that, while foraging, the overall strategy is to use polyphenism to produce ‘apparent rarity’ of any single phenotype (or search image) through mechanisms of crypsis, conspicuousness and mimicry, all of which are guided by keen vision in this marine invertebrate.     

Hybridization and population genetics of two macaque species in Sulawesi, Indonesia

This study investigates hybridization and population genetics of two species of macaque monkey in Sulawesi, Indonesia, using molecular markers from mitochondrial, autosomal, and Y-chromosome DNA. Hybridization is the interbreeding of individuals from different parental taxa that are distinguishable by one or more heritable characteristics. Because hybridization can affect population structure of the parental taxa, it is an important consideration for conservation management. On the Indonesian island of Sulawesi an explosive diversification of macaques has occurred; seven of 19 species in the genus Macaca live on this island. The contact zone of the subjects of this study, M. maura and M. tonkeana, is located at the base of the southwestern peninsula of Sulawesi. Land conversion in Sulawesi is occurring at an alarming pace; currently two species of Sulawesi macaque, one of which is M. maura, are classified as endangered species. Results of this study indicate that hybridization among M. maura and M. tonkeana has led to different distributions of molecular variation in mitochondrial DNA and nuclear DNA in the contact zone; mitochondrial DNA shows a sharp transition from M. maura to M. tonkeana haplotypes, but nuclear DNA from the parental taxa is homogenized in a narrow hybrid zone. Similarly, within M. maura divergent mitochondrial DNA haplotypes are geographically structured but population subdivision in the nuclear genome is low or absent. In M. tonkeana, mitochondrial DNA haplotypes are geographically structured and a high level of nuclear DNA population subdivision is present in this species. These results are largely consistent with a macaque behavioral paradigm of female philopatry and obligate male dispersal, suggest that introgression between M. maura and M. tonkeana is restricted to the hybrid zone, and delineate one conservation management unit in M. maura and at least two in M. tonkeana.     

Character displacement, frequency-dependent selection, and divergence of shell colour in land snails Mandarina (Pulmonata)

Endemic land snails of the genus Mandarina of the oceanic Bonin Islands offer an exceptional example of habitat and character divergence among closely related species. In this study, microhabitat differences between sympatric ground-dwelling species were studied by distinguishing habitats on the basis of vegetation and types of litter. In all sites where two ground species coexisted, segregation occurred with each species showing preference for the microhabitat in which they were found. When they were in sympatry, one species was predominant in relatively wet and sheltered sites and the other in relatively dry and exposed sites. Although most species can live in both types of habitat, occupation by one species is inhibited by occupation by another. This suggests that competitive interaction between sympatric species caused segregation. Except for populations that have undergone interspecific hybridization, no examples were found of sympatric populations of two ground species sharing a similar shell colour. Species that were predominant in relatively wet and sheltered sites possessed shells with dark coloration and their colour patterns were mostly of one type. Species that were predominant in relatively dry and exposed sites possessed shells with bright coloration and their color patterns were polymorphic. Most populations from areas in which single species were distributed had shells with medium coloration. Microhabitat differentiation between sympatric species possibly caused diversification of shell colour, because bright shells are advantageous in sites where snails are largely exposed, and dark shells are advantageous in sites in where they are mostly sheltered from sunlight. In addition, frequency-dependent selection by predators hunting by sight may have operated to maintain colour polymorphism in the populations which are restricted to exposed habitats by competition with other sympatric species. This reveals the importance of interaction among closely related species as a cause of diversification in ecological and morphological traits.     

Seasonal changes in environmental variables,biomass, production and nutrient contents in two contrasting tropical intertidal seagrass beds in South Sulawesi,Indonesia

Seasonal dynamics were studied by monthly monitoring of biological and environmental variables in permanent quadrats in two contrasting intertidal seagrass beds in South Sulawesi, Indonesia, from February 1991 to January 1992. Datasets were analysed with canonical correlation analysis for correlations between environmental and biological variables. Considerable variation in biomass, production and plant tissue nutrient contents in a monospecific seagrass bed of Enhalus acoroides, growing on a coastal terrigenous mudbank (Gusung Tallang), was assumed to be related to riverine influences of the nearby Tallo River. The variation in seagrass variables at this site could, however, not be significantly correlated to seasonal patterns in rainfall, salinity, tides, nutrient availability, water motion or turbidity. A seasonal cycle in biomass, production and nutrient contents in a mixed seagrass bed of Thalassia hemprichii and E. acoroides, growing on carbonate sand on the reef flat of an offshore coral island (Barang Lompo), was found to be largely determined by tidal exposure and water motion. Exposure of the intertidal seagrass bed during hours of low water during spring tides showed a gradual shift from exposure during the night (January-June) to exposure during daylight (July-December). Daylight exposure resulted in a significant loss of above-ground plant biomass through desiccation and burning of leaves. The observed seasonal dynamics of the seagrass bed on reef sediment contrast with reports from the Caribbean, where the effect of tidal exposure on comparable shallow-water seagrass communities is relatively insignificant due to a small tidal amplitude.     

New species of the fleas Farhangia and Nestivalius,from endemic rodents in Sulawesi,Indonesia

The fleas (Siphonaptera: Pygiopsyllidae) Farhangia quattuordecimdentata sp. n. and Farhangia sedecimdentata sp. n. are described from pygmy squirrels (Prosciurillus spp.), and Nestivalius sulawesiensis sp. n. from murine rodents, all from Sulawesi, Indonesia. Both new species of Farhangia were collected in Central Sulawesi (Sulawesi Tengah); F. quattuordecimdentata sp. n. was recovered mainly from P. murinus, whereas F. sedecimdentata sp. n. was recovered mainly from P. leucomus. These new species are compared with the two previously described species of Farhangia: F. celebensis (Ewing) from P. murinus in North Sulawesi (Sulawesi Utara) and F. sciuri (Ewing) from the tree squirrel Callosciurus prevosti in Sabah (Borneo). Nestivalius sulawesiensis sp. n. was collected from six species of endemic murine rodents in both North and Central Sulawesi. It is compared to the morphologically similar N. pomerantzi (Traub) from Mindanao, which parasitizes murine hosts that are endemic to the Philippines.     

Relationships between densities of previous and simultaneous foragers and the foraging behaviour of three bumblebee species

1. The local insect composition may be as important as the local floral composition for bumblebees' foraging behaviour. However, little is known about how the local abundance of insects affects the foraging patterns of individuals. 2. Using field observations, we studied the relationships between the local density of previous and simultaneous foragers and the local foraging behaviour of Bombus pascuorum, Bombus lucorum/B. terrestris and Bombus lapidarius while pollinating Centaurea jacea. 3. The number of bumblebees foraging in the plots was positively related to the number of new individuals arriving at these plots. The number of inflorescences contacted and the duration of visits were negatively related to the number of simultaneous foragers, but only in B. lucorum/B. terrestris. The effects of previous foragers on the behaviour of other bumblebees were species‐specific and variable in their direction. Such contrasting effects can be explained in terms of bumblebee species' abundances and functional similarity. In some cases, the effect of previous foragers increased with Centaurea density. 4. The local abundance of previous and simultaneous foragers affected the foraging behaviour of particular bumblebee individuals in complex ways. Future studies on local foraging behaviour might benefit from including the abundance of co‐foragers.     

Vertical patterns and duration of surface wetness in an old-growth tropical montane forest, Indonesia

In tropical montane forests, the wetness of leaf surfaces is an important parameter which may influence gas exchange, growth and vitality of leaves, and forest productivity. Thirty surface wetness sensors were operated during May–August 2004 in a vertical profile inside an old-growth lower montane rain forest of Central Sulawesi, Indonesia, with the objective to analyse spatial and temporal patterns of surface wetness and to relate wetness duration to the microclimate inside the stand. The canopy was wet during 25–30% of time in this study period. In a dry period, however, surface wetness lasted for only 5% of the time, whereas the canopy was wet during 45–55% of the time in a rainy period. In the lower shade canopy, surface wetness continuously existed for periods of up to 22 h and more, although rainfall occurred only during afternoon thunderstorms of limited duration. The long duration of surface wetness has implications for forest interception models, which assume a complete drying of the canopy between subsequent rainfall events. In periods with rainfall, leaf wetness typically occurred in the afternoon, evening and first half of the night because intercepted water persisted on the leaves until about midnight. In dry periods, in contrast, surface wetness was mainly caused by dewfall in the second half of the night, and it occurred mainly in the uppermost canopy where radiative heat losses resulted in a substantial under-cooling of the leaves. Ecophysiological and hydrological importance is suggested by the long duration of surface wetting in this stand with possible implications for gas exchange, leaf growth, leaf colonization by epiphylls and the forest water balance.     

Do caterpillars disperse their damage?: larval foraging behaviour of two specialist herbivores,Euphydryas phaeton (Nymphalidae) and Pieris rapae (Pieridae)

Abstract. 1. To examine ecological and evolutionary aspects of caterpillar foraging behaviour, this study focused on observation of the individual foraging behaviour of two lepidopteran species, Pieris rapae L. and Euphydryas phaeton (Drury), on their respective host plants.
2. Periodic observations over the course of a day showed that the larvae move considerable distances, forage on the upper surfaces of leaves, and often immediately leave areas from which they have fed, leaving a pattern of dispersed herbivory.
3. Differences in foraging behaviour were not found between the two species, even though one species is aposematic and the other is cryptically coloured, but there were significant differences in the foraging patterns of P.rapae on the two host plants, broccoli and radish.     

Forest aboveground biomass along an elevational transect in Sulawesi,Indonesia, and the role of Fagaceae in tropical montane rain forests

Aim This study investigates how estimated tree aboveground biomass (AGB) of tropical montane rain forests varies with elevation, and how this variation is related to elevational change in floristic composition, phylogenetic community structure and the biogeography of the dominant tree taxa. Location Lore Lindu National Park, Sulawesi, Indonesia. Methods Floristic inventories and stand structural analyses were conducted on 13 plots (each 0.24 ha) in four old‐growth forest stands at 1050, 1400, 1800 and 2400 m a.s.l. (submontane to upper montane elevations). Tree AGB estimates were based on d.b.h., height and wood specific gravity. Phylogenetic diversity and biogeographical patterns were analysed based on tree family composition weighted by AGB. Elevational trends in AGB were compared with other Southeast Asian and Neotropical transect studies (n = 7). Results AGB was invariant from sub‐ to mid‐montane elevation (309–301 Mg ha^?1) and increased slightly to 323 Mg ha^?1 at upper montane elevation. While tree and canopy height decreased, wood specific gravity increased. Magnoliids accounted for most of the AGB at submontane elevations, while eurosids I (including Fagaceae) contributed substantially to AGB at all elevations. Phylogenetic diversity was highest at upper montane elevations, with co‐dominance of tree ferns, Podocarpaceae, Trimeniaceae and asterids/euasterids II, and was lowest at lower/mid‐montane elevations, where Fagaceae contributed > 50% of AGB. Biogeographical patterns showed a progression from dominant tropical families at submontane to tropical Fagaceae (Castanopsis, Lithocarpus) at lower/mid‐montane, and to conifers and Australasian endemics at upper montane elevations. Cross‐continental comparisons revealed an elevational AGB decrease in transects with low/no presence of Fagaceae, but relatively high AGB in montane forests with moderate to high abundance of this family. Main conclusions AGB is determined by both changes in forest structure and shifts in species composition. In our study, these two factors traded off so that there was no net change in AGB, even though there were large changes in forest structure and composition along the elevational gradient. Southeast Asian montane rain forests dominated by Fagaceae constitute important carbon stocks. The importance of biogeography and species traits for biomass estimation should be considered by initiatives to reduce emissions from deforestation and forest degradation (REDD) and in taxon choice in reforestation for carbon offsetting.     

Changes in photosynthesis,xanthophyll cycle,and sugar accumulation in two North Australia tropical species differing in leaf angles

Two tropical species of North Australia, Acacia crassicarpa and Eucalyptus pellita, have similar leaf size and leaf structure but different leaf angles. A. crassicarpa with near vertical leaf angle directly reduced photon absorption and leaf temperature (T _l) and had relatively high photosynthetic activity (P _max) and low xanthophyll cycle activity. In contrast, E. pellita with a small leaf angle exhibited high T _l, low P _max, and high activity of xanthophyll cycle which was useful for the dissipation of excessive energy and reduction of photoinhibition. In the dry season, contents of soluble sugars including pinitol, sucrose, fructose, and glucose in A. crassicarpa increased whereas larger amounts of only fructose and glucose were accumulated in E. pellita. Different sugar accumulation may be involved in osmotic adjustment of leaves during water stress that makes photosynthesis more efficient. The leaf angle may be critical for developing different protective mechanisms in these two tropical tree species that ensure optimal growth in the high irradiance and drought stress environment in North Australia.     

Free-ranging livestock influence species richness,occupancy, and daily behaviour of wild mammalian species in Baluran National Park,Indonesia

In some developing countries, human activities in protected areas threaten wildlife populations and their habitats. This study was conducted to understand the influences of free-range livestock on the wild mammalian population in Baluran National Park, Indonesia. There were 3852 and 1156 cows and goats, respectively, and livestock occupied an area of approximately 55.96 km². The species richness and probability of occupancy in areas with and without livestock were assessed, and the spatial co-occurrence and overlap of daily activity patterns among mammalian species and livestock were measured. A total of 39 camera traps were installed from August 2015 to January 2016, collecting 23,021 independent photographs. In areas with livestock, the number of mammal species (eight) was lower than in areas without livestock (11 species). The most affected species were the large herbivores Bubalus bubalis and Bos javanicus, and a large carnivore Panthera pardus, all of which were absent in areas with livestock. Regardless of the feeding guild, the probability of occupancy of almost all species declined in areas with livestock, except the medium herbivores Paradoxurus hermaphroditus and Hystrix javanica that showed a higher probability of occupancy. The species whose probability of occupancy declined were the carnivores Cuon alpinus and Prionailurus bengalensis; the herbivores Rusa timorensis, Tracypithecus auratus and Muntiacus muntjak; and the omnivore Sus scrofa. In the presence of livestock, R. timorensis and S. scrofa changed their activities from diurnal to nocturnal. Livestock affected most wild mammals in several ways, including by reducing the species richness, lessening the probability of occupancy and changing the daily activity patterns of many animals. This research recommends a significant reduction in the size of the range area for domestic livestock.     

Fruit and seed ontogeny related to the seed behaviour of two tropical species of Caesalpinia (Leguminosae)

Caesalpinia echinata and C. ferrea var. ferrea have different seed behaviours and seed and fruit types. Comparison of the seed ontogeny and anatomy partly explained the differences in seed behaviour between these two species of Brazilian legumes; some differences were also related to fruit development. The seed coat in C. ferrea consisted of two layers of osteosclereids, as well as macrosclereids and fibres, to form a typical legume seed coat, whereas C. echinata had only macrosclereids and fibres. In C. echinata , the developing seed coat had paracytic stomata, a feature rarely found in legume seeds. These seed coat features may account for the low longevity of C. echinata seeds. The embryogeny was similar in both species, with no differences in the relationship between embryo growth and seed growth. The seeds of both species behaved as typical endospermic seeds, despite their different morphological classification (exendospermic orthodox seeds were described for C. echinata and endospermic orthodox seeds for C. ferrea ). Embryo growth in C. ferrea accelerated when the sclerenchyma of the pericarp was developing, whereas embryonic growth in C. echinata was associated with the conclusion of spine and secretory reservoir development in the pericarp. Other features observed included an endothelial layer that secreted mucilage in both species, a nucellar summit, which grew up into the micropyle, and a placental obturator that connected the ovarian tissue to the ovule in C. ferrea . © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 57–70.     

Foraging activity and behaviour of two goatfish species (Perciformes: Mullidae) at Fernando de Noronha Archipelago, tropical West Atlantic

The goatfishes (Mullidae) include about 50 bottom-foraging fish species. The foraging activity of the yellow goatfish, Mulloidichthys martinicus, and the spotted goatfish, Pseudupeneus maculatus, was studied comparatively at Fernando de Noronha Archipelago, off coast of Northeast Brazil tropical West Atlantic. Pseudupeneus maculatus fed over a larger variety of substrate types, had lower feeding rate, roamed more per given time, spent less time in a feeding event, and displayed a more diverse repertoire of feeding modes than M. martinicus. The differences in the foraging activity and behaviour between the two species possibly minimize a potential resource overlap, as already recorded for other sympatric mullids. Pseudupeneus maculatus had lower feeding rate most likely because it feeds on larger items, and roamed over greater distance per time. Possibly this is because it foraged over a greater variety of substrate distributed over a larger area than that used by M. martinicus. Notwithstanding the overall morphological and behavioural similarity of goatfishes in general, they do differ in their substrate preferences and foraging activity, which indicates that these fishes should not be simply considered generalized bottom foragers.     

Morphology, echolocation and foraging behaviour in two sympatric sibling species of bat (Tylonycteris pachypus and Tylonycteris robustula) (Chiroptera: Vespertilionidae)

We studied the wing morphology, echolocation calls, foraging behaviour and flight speed of Tylonycteris pachypus and Tylonycteris robustula in Longzhou County, South China during the summer (June–August) of 2005. The wingspan, wing loading and aspect ratio of the two species were relatively low, and those of T. pachypus were lower compared with T. robustula . The echolocation calls of T. pachypus and T. robustula consist of a broadband frequency modulated (FM) sweep followed by a short narrowband FM sweep. The dominant frequency of calls of T. pachypus was 65.1 kHz, whereas that of T. robustula was 57.7 kHz. The call frequencies (including highest frequency of the call, lowest frequency of the call and frequency of the call that contained most energy) of T. pachypus were higher than those of T. robustula , and the pulse duration of the former was longer than that of the latter. The inter-pulse interval and bandwidth of the calls were not significantly different between the two species. Tylonycteris pachypus foraged in more complex environments than T. robustula , although the two species were both netted in edge habitats (around trees or houses), along pathways and in the tops of trees. Tylonycteris pachypus flew slower (straight level flight speed, 4.3 m s⁻¹) than T. robustula (straight level flight speed, 4.8 m s⁻¹). We discuss the relationship between wing morphology, echolocation calls, foraging behaviour and flight speed, and demonstrate resource partitioning between these two species in terms of morphological and behavioural factors.     

Identification of Entamoeba polecki with Unique 18S rRNA Gene Sequences from Celebes Crested Macaques and Pigs in Tangkoko Nature Reserve,North Sulawesi,Indonesia

Unique species of macaques are distributed across Sulawesi Island, Indonesia, and the details of Entamoeba infections in these macaques are unknown. A total of 77 stool samples from Celebes crested macaques (Macaca nigra) and 14 stool samples from pigs were collected in Tangkoko Nature Reserve, North Sulawesi, and the prevalence of Entamoeba infection was examined by PCR. Entamoeba polecki was detected in 97% of the macaques and all of the pigs, but no other Entamoeba species were found. The nucleotide sequence of the 18S rRNA gene in E. polecki from M. nigra was unique and showed highest similarity with E. polecki subtype (ST) 4. This is the first case of identification of E. polecki ST4 from wild nonhuman primates. The sequence of the 18S rRNA gene in E. polecki from pigs was also unique and showed highest similarity with E. polecki ST1. These results suggest that the diversity of the 18S rRNA gene in E. polecki is associated with differences in host species and geographic localization, and that there has been no transmission of E. polecki between macaques and pigs in the study area.     

Sexual dichromatism and differential conspicuousness in two populations of the common collared lizard (Crotaphytus collaris) from Utah and New Mexico, USA

The common collared lizard (Crotaphytus collaris) exhibits considerable geographical colour variation, particularly among males. Populations of this diurnal saxicolous iguanian inhabit patches of rocky habitat throughout the species’ broad distribution in North America and are anticipated to experience local differences in selective pressures that influence colouration. Specifically, while social interactions might favour conspicuous colouration, crypsis may be advantageous in interactions with visually orienting predator and prey species. To address the local relationship between lizard and substrate colouration we compared the reflectance spectra of two geographically distant and phenotypically divergent populations of collared lizards with the rocky substrates they inhabit. Our northern study population (C. c. auriceps in eastern Utah) occurs on red rocks, where males exhibit boldly coloured turquoise bodies and bright yellow heads. In contrast, our southern study population (C. c. fuscus in southern New Mexico) lives on grey and tan rocks, and males in this location exhibit subdued brown and tan dorsal colours. Spectral comparisons revealed that males in the northern population contrasted strongly with their local rocks, whereas males in the southern population matched their rock colours with reasonably good fidelity. This relationship held under a variety of lighting conditions. Females in both populations were less conspicuously coloured than males, although northern females contrasted more with their rocks than did southern females. In addition, sexual dichromatism was pronounced in the northern population but minimal in the southern population. Finally, sexual size and weight dimorphism was strong in the southern population while being virtually absent in the northern population. A comparison of the local predator and prey assemblages suggests that the conspicuous and sexually dichromatic colouration of the northern population may have evolved in response to reduced pressure from visually orienting predators as well as reduced dependence on saurian prey. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 77 , 67–85     

Biodiversity and distribution of epibiontic communities on Caridina ensifera (Crustacea,Decapoda, Atyidae) from Lake Poso: comparison with another ancient lake system of Sulawesi (Indonesia)

Fernandez‐Leborans, G. and von Rintelen, K. 2010. Biodiversity and distribution of epibiontic communities on Caridina ensifera (Crustacea, Decapoda, Atyidae) from Lake Poso: comparison with another ancient lake system of Sulawesi (Indonesia). — Acta Zoologica (Stockholm) 91 : 163–175 The epibiont communities of the shrimp Caridina ensifera, endemic to Lake Poso (Sulawesi, Indonesia), were analysed. Most of the epibiont species were ciliated protozoa belonging to three suctorian genera (Acineta, Podophrya and Spelaeophrya), three peritrich genera (Zoothamnium, Vorticella and Cothurnia), and a haptorid genus (Amphileptus). There was also a rotifer epibiont of the genus Embata. Epibionts were identified to species level. There were 14 to 1114 epibionts per shrimp. The distribution of the epibiont species on the surface of the basibiont was recorded, calculating the number on the different colonized individuals of C. ensifera. The most abundant species, Zoothamnium intermedium and Acineta sulawesiensis, were also the most widely distributed. There was a significant difference between the spatial distributions of the different epibiont species. The analysis of the number of the epibiont species throughout the anteroposterior axis of the shrimp showed a gradient from the anterior to the posterior end of the body. Data from Lake Poso were compared with those of the Malili lake system (Sulawesi), obtained from its endemic shrimp, Caridina lanceolata. Lake Poso had the highest mean diversity, while Lake Mahalona showed the highest maximum diversity. All lakes were correlated with respect to the mean number of epibionts on the anatomical units of the shrimp, which showed a similar general distribution. The distributions of the different epibiont species were compared between the lakes. The possible adaptations of the epibionts as well as the colonization patterns were discussed. From the statistical results and the analysis of the distributions, we propose that in these communities epibiont species have a pattern of colonization in which they follow a behaviour as a whole; each species has a differential distribution, with the species occupying the available substratum with the particular requirements of each functional group, but there is a trend towards maintaining an equilibrium among species and groups, compensating for diversity and number of individuals. In all lakes there was an epibiont distribution model comprising the maintenance of an anteroposterior axis gradient, which was supported by the fluctuation in diversity and number of individuals of the different functional groups of epibiont species. The functional role of the different groups of species seems to tend towards sustainability with little global variation among the lakes.