Feeding behavior and ecology of shallow-water unstalked crinoids (echinodermata) in the Caribbean Sea

The feeding behavior, living position, and skeletal morphology of 8 species of reef-dwelling Caribbean comatulid crinoids are intimately related to the regime of water movement prevailing in the microhabitat. These adaptations are related to the dependence of the crinoid suspension-feeding mechanism on externally produced water movements for a continuous food supply. Greater numbers of co-occurring comatulid species (6 to 7) and larger populations have been found off Colombia and Panamá than off Curaçao and Jamaica (4 species). It is suggested that these differences may be related to increased or diversified primary productivity close to the larger land masses. Overal food availability as determined by primary productivity may, thus, be an important factor controlling the regional diversity and abundance of these species.     

Multiple mating and the evolution of social behavior in the hymenoptera

Summary The data on the frequency of mating by queens of eusocial Hymenoptera are reviewed.It is pointed out that the issue of sperm clumping is probably irrelevant to the evolution of eusociality.The hypothesis is presented that multiple mating is an adaptation for maintaining large colonies. In ants there is a significant relation between the size of the colony and the frequency of mating.The effect of multiple mating on the spread of a gene for worker behavior is explored. If a female mates twice, the effective number of matings is less than two except in the case of identical sperm contribution by the males.Sperm bias is defined as the contribution of unequal amounts of sperm by the males that mate with a queen. Sperm bias can be produced as a sampling phenomenon, by inter-male competition for females and by sperm competition.The relation between the ergonomic efficiency of the workers at the production of reproductives and the number of matings that is consistent with the evolution of eusociality is derived. If workers are only about 10% more efficient at producing reproductives within a eusocial colony than they are solitarily, then two matings by the queen will still produce a selective advantage to eusocial behavior.     

Field observations on the feeding behavior of salps (Tunicata: Thaliacea)

Observations of living salps by SCUBA diving in the Florida Current and Gulf of California (Mexico) indicate that they filter feed with a continuously renewed mucus net. Ninety-one percent of 1420 salps (6 species) examined were feeding in this manner. Particles collected range from about 1 mm to less than 1 μm. Compact fecal pellets appear to contain much undigested material and may carry significant amounts of carbon out of surface waters.     

Courtship and spawning in the emperor angelfish Pomacanthus imperator,with comments on reproduction by other pomacanthid fishes

Courtship and spawning are described for Pomacanthus imperator and 4 Centropyge spp. at Enewetak Atoll, Marshall Islands, observed from 15 August to 15 September, 1981. In all species, courtship and spawning occur at dusk, continue throughout most of the lunar month, are preceded by male display to the female, and culminate in the pair's shedding gametes into the water column. The species differ in ascent height, details of courtship behavior, spawning location relative to prominent reef topography and degree and type of sexual dichromatism. Social organization in all species appears based on male defense of harems of 2 to 5 females. Observed behavior is compared to that of confamilials, and discussed relative to proposed theories concerning lunar periodicity of spawning activity, sexual dichromatism and the adaptive significance of spawning ascent behavior.     

Diving behavior of immature hawksbills (Eretmochelys imbricata) in a Caribbean cliff-wall habitat

Time-depth recorders were attached to immature hawksbills (Eretmochelys imbricata Linnaeus, 1766) residing at the northwestern cliffs of Mona Island, Puerto Rico. Data on diving profiles obtained from four turtles of 32.0 to 53.4 cm straight carapace length revealed strong similarities in behavioral patterns. During daylight hours, turtles were active an average 8.4 h per day, surfacing 3.6% of the time. Length of foraging dives correlated with turtle size, with mean durations ranging from 8.6 to 14.0 min. Foraging dives, with a mean depth of 4.7 m, were associated with feeding on encrusting sponges. At night, turtles were mostly inactive, surfacing 1.8% of the time and with individual mean submergence intervals of between 30.4 and 37.1 min. From the surfacing behavior of turtles making deep and long dives, it is inferred that dives were aerobic, with the turtles making use of oxygen stores in addition to that of the lung.     

Cooperative behavior and social organization of the Swallow-tailed Manakin (Chiroxiphia caudata)

Summary The mating system of the Swallow-tailed Manakin (Chiroxiphia caudata) is a type of non-resource based polygyny in which males aggregate at traditional sites or leks to perform cooperative displays. Each lek and all its contained courts are used communally by a group of 4–6 males. Within the group a linear dominance hierarchy exists. Position in the hierarchy persists within and between years and at all courts and is inherited in linear sequence. The dominant male of the group behaves as a sentinel calling repeatedly from a high perch in an attempt to attract females to a court.When a female arrives, two or three males engage in a cooperative precopulatory dance, the Jump Display. This is followed by a Solo Precopulatory Display performed by a single male who, if successful, will copulate with the female. With rare exception, the dominant male performs all Solo Displays and all copulations.Display sequences that include both a Jump Display and Solo Precopulatory Display are more likely to lead to copulation than those consisting of only one part. Thus, the subordinates who help the dominant perform the dance are expending energy that increases his fitness without receiving any immediate benefit themselves. Several factors that may have contributed to the evolution of the mating system and cooperative displays of this species are considered.     

Effect of temperature on activity and social behavior of the adult tautog Tautoga onitis under laboratory conditions

Experiments were conducted on the effects of high, sublethal temperature on activity, social behavior, and feeding in the adult tautog Tautoga onitis held under controlled laboratory conditions. Norms of these behaviors were established during acclimation to temperatures at which these fish are commonly found. During acclimation, the fish were active and feeding throughout the day. A dominance hierarchy, based primarily on size, was established for each group, with subordinate fish being displaced from all areas of the aquarium. Under elevated temperature, changes in established norms of these behaviors were observed, with activity, feeding, aggression, and the spacing between fish showing a decrease. Following return to pre-rise temperatures, although aggression remained reduced, activity, interfish distance, and feeding approached levels established during acclimation. A comparison of these results with previous ones on young tautog is made and the significance of the findings is discussed.This work was supported, in part, by a grant from the U.S. Energy Research and Development Administration No. E(49-7) 3045.     

基于苋菜转录组的ARF基因家族鉴定及表达

ARFs(auxin response factors)是重要的生长素响应因子,在植物的生长发育过程中起着关键的作用.基于'大红'苋菜转录组数据,通过在线分析软件SMART和NCBI-Blastp的注释筛选苋菜ARF基因家族成员(AtrARF);利用生物信息学分析软件,对AtrARFs蛋白的理化性质、二级结构、亚细胞定...     

A test on social behavior as a cause of dispersal of spruce grouse

Summary Social behavior is one hypothesized cause for dispersal. We tested this hypothesis on spruce grouse (Dendragapus canadensis) in two years by removing adults in summer and monitoring emigration of juveniles in autumn. Despite the absence of adults, juveniles emigrated from the natal range at rates comparable to juveniles on control areas. Data on density and dispersal from earlier spruce grouse studies are reviewed, which show that emigration is constant despite substantial differences in density, and that a clear female sex bias occurs across a wide range of densities. Results do not support the hypothesis that social behavior influences dispersal nor do they support a prediction of the Oedipus hypothesis that no sex bias occurs in polygynous birds. Offprint requests to: D.M. Keppie     

The social and mating systems of two labrid fishes,Halichoeres maculipinna and H. garnoti,off the Caribbean coast of Panama

Large males of both species are territorial, particularly when spawning. Small Halichoeres maculipinna (but not H. garnoti) are territorial towards equal sized conspecifics, but not towards dissimilar sized conspecifics or any individuals of an abundant congener. Territoriality of small H. maculipinna may be related to the process of sex-change rather than defense of food. Both sexes of both species, but particularly H. maculipinna, migrate from feeding areas to spawning sites at the edges of reefs at specific times of day. In the two species a large male spawns both with females that live in his feeding area and with many others. Differences in the mating system of H. maculipinna in Panama and Florida seem related to habitat differences at those sites. The relative spatial distributions of feeding and spawning sites may affect (a) whether a female spawns with a large male with whom she feeds, and (b) the ability of large males to monopolize mates at the expense of small males. The spawning success of small males seems to depend on whether large males can penalize their participation in spawning rather than on the ability of small males to predict the occurrence of (and then interfere in) spawnings by large males. In both species, the male-specific color pattern is most intensely exhibited by large males during sexual interactions and tends to be lost when they are being aggressive towards conspecifics. The evolutionary development of such a color pattern in labroid fishes seems to be a response to intersexual rather than intrasexual interactions.     

Functional morphology of the gonads of the articulate brachiopodTerebratulina retusa

The reproductive anatomy, and ultrastructural features of the gonads of the articulate brachiopodTerebratulina retusa (Linnaeus), are documented based on collections made between October 1985 and October 1986 from the Firth of Lorn, west coast of Scotland. This species is dioecious, and maturity is achieved in both sexes at shell lengths greater than ~5.5 mm. There is no obvious external sexual dimorphism except for slight differences in the coloration of the gonads; testes are white/cream, ovaries are yellow/orange. The gonads occur as four palmate lobes, a pair in each valve. Gonads are formed within a mantle sinus (vascula genitalia), which is an anterior extension of the coelom, that opens posteriorly into the visceral cavity and to the exterior via a pair of metanephridia. The latter serve as gonoducts during spawning. Gametes are borne on genital lamellae formed from a reticulate lattice of connective tissue. The lamellae are an extension of the ileoparietal band and are fused along one margin to the inner mantle membrane. Developing oocytes are closely affixed to the genital lamellae and originate from a pool of proliferating germ cells at its base. Vitellogenic oocytes that are at an advanced stage are released from the genital lamellae, but are retained within thevascula genitalia. Liberated oocytes continue to accumulate yolk and eventually occlude thevascula genitalia, before being spawned. Coelomocytes were identified within the gonads. In spent females these cells appear to be phagocytic and involved in the resorption of necrotic material, while in the male they may serve as nutritive cells.     

Onsets of schooling behavior and social transmission in chub mackerel Scomber japonicus

Grouping behavior has various types of antipredator functions. Some of these functions require social transmission of information, such as the many-eyes effect, whereas others do not, such as the dilution and confusion effects. Functions of grouping behavior would enhance with social transmission among group members. We investigated and compared the onsets of schooling behavior and social transmission of information in chub mackerel Scomber japonicus. Onset of schooling behavior was observed in rearing tanks by calculating the degree of parallel swimming. Onset of social transmission was examined by using visual cues from conspecifics. A group of five individuals was put in each of three experimental chambers from which they could see a group of conspecifics in the neighboring chamber. A weak electric stimulus was given to one of these chambers, and information transfer among individuals was observed. We found that social transmission by visual cues started on 30 days posthatching (25.1 mm in standard length), which was 2 weeks after the onset of schooling behavior. The late onset of social transmission relative to schooling behavior might be attributed to different predation pressure with development, or by underdevelopment of optic tectum, as the volume of the optic tectum did not increase just after the onset of schooling behavior.     

Size and spacing of capercaillie leks in relation to social behavior and habitat

Summary Spring territories of 17 adult capercaillie (Tetrao urogallus L.) cocks were 10–79 ha in extent; they varied inversely in size with the relative proportion of mature forest within them. The number of resident cocks at leks increased with the amount of mature forest within a 1 km radius of each lek center. Leks in two areas (n=46) were regularly spaced with mean distances to nearest neighbors of 1.98 and 2.07 km, corresponding to the territorial space occupied by adult cocks of adjoining leks. In one area with intensive logging, interlek distance increased with decreasing amounts of mature forest between them. Spring home ranges of 18 adult females averaged 51.3 ha±8.2 SE. The spatial relationships did not fit recent models of interlek spacing based on female spacing behavior. Instead, the results suggested that spacing of leks may be related to the territorial requirements of males.     

Micromorphology and ultrastructure of Caribbean sclerosponges

Fine structural analysis of living tissue of the sclerosponges Ceratoporella nicholsoni (Hickson) and Stromatospongia norae Hartman, collected near Discovery Bay, Jamaica, between 1984 and 1986, was carried out using transmission and scanning electron microscopy (TEM and SEM). The thick dermal membrane of these sponges is covered by exopinacocytes having a T shape in sections perpendicular to the surface. A dense, complex glycocalyx is produced at the surface of these cells. Choanocyte chambers are diplodal and unusually small. The inhalant and exhalant canals of both species are characterized by the presence of valvules, made by transverse lamellipodial processes of the endopinacocytes lining them. An abundant and diversified bacterial community occupies almost 20% of the mesohyl. A single layer of active basopinacocytes lines the mesohyl at the interface between the living tissue and the aragonitic skeleton. Basopinacocytes are presumed to be precursors of the irregular fibrillar organic matrix found in the aragonitic skeleton. Sclerocytes and spongocytes are abundant in the vicinity of the siliceous spicules. Typical lophocytes releasing smooth collagen fibrils are common in the dermal membrane as well as in the choanosome where they can be grouped in bundles. Uniquely, C. nicholsoni elaborates rough intercellular fibrils characterized by periodically spaced thickenings. The endolithic algae Ostreobium sp. is present in the most apical zones of the aragonitic skeleton, but does not seem to interfere with its development. The striking micromorphological resemblances between both species are discussed and compared to demosponges.Contribution no. 472 from the Discovery Bay Marine Laboratory, University of the West Indies, Discovery Bay, Jamaica, West Indies     

Exploring the effects of individual traits and within-colony variation on task differentiation and collective behavior in a desert social spider

Social animals are extraordinarily diverse and ecologically abundant. In understanding the success of complex animal societies, task differentiation has been identified as a central mechanism underlying the emergence and performance of adaptive collective behaviors. In this study, we explore how individual differences in behavior and body size determine task allocation in the social spider Stegodyphus dumicola. We found that individuals with high body condition indices were less likely to participate in prey capture, and individuals’ tendency to engage in prey capture was not associated with either their behavioral traits or body size. No traits were associated with individuals’ propensity to participation in web repair, but small individuals were more likely to engage in standard web-building. We also discovered consistent, differences among colonies in their collective behavior (i.e., colony-level personality). At the colony level, within-colony variation in behavior (aggressiveness) and body size were positively associated with aggressive foraging behavior. Together, our findings reveal a subtly complex relationship between individual variation and collective behavior in this species. We close by comparing the relationship between individual variation and social organization in nine species of social spider. We conclude that intraspecific variation is a major force behind the social organization of multiple independently derived lineages of social spider.     

Mind the gap: a comparative study of migratory behavior in social amoebae

Social amoebae aggregate to form a multicellular slug that migrates some distance. Most species produce a stalk during migration, but some do not. We show that Dictyostelium giganteum, a species that produces stalk during migration, is able to traverse small gaps and utilize bacterial resources following gap traversal by shedding live cells. In contrast, we found that Dictyostelium discoideum, a species that does not produce stalk during migration, can traverse gaps only when in the presence of other species’ stalks or other thin filaments. These findings suggest that production of stalk during migration allows traversal of gaps that commonly occurs in soil and leaf litter. Considering the functional consequences of a stalked migration may be important for explaining the evolutionary maintenance or loss of a stalked migration.     

Biokinetics of plutonium,americium and californium in the marine isopod Cirolana borealis,with observations on its feeding and molting behavior

In a series of laboratory experiments carried out during 1982, the biokinetics of ²³⁷Pu (IV), ²³⁷Pu (V), ²⁴¹Am (III), and ²⁵²Cf (III) were studied in the benthic marine isopod Cirolana borealis Lilljeb. Following a 3 wk exposure to labelled seawater, isopods reached non-equilibrium concentration factors of 52±15, 54±12, 176±14, and 185±53 for Pu (IV), Pu (V), Am and Cf, respectively. Uptake of these radionuclides occurred to a great extent by surface adsorption, with the major fraction of the accumulated radionuclides being associated with exoskeleton and lesser percentages located in gut, digestive gland, muscle and haemolymph. The pattern of radiotracer depuration was in all cases biphasic, with the long-lived retention compartment retaining the largest fraction of whole-body radioactivity. Biological half-lives for radionuclide turnover in the long-lived compartment were 60±3 d, 87±5 d, 261±12 d and 288±60 d for Pu (IV), Pu (V), Am and Cf, respectively. Examination of radionuclide distribution among tissues following longterm depuration showed that the radionuclides were eliminated from internal tissues more rapidly than from the exoskeleton. Uptake and depuration studies indicated that the biokinetics of americium and californium were similar to each other, but that they differed significantly from those of oxidized and reduced plutonium. In general, these experimental results support previous reports that americium and californium are more bioavailable than plutonium in the marine waters. The fraction americium and californium assimilated into tissue from food was very low and did not exceed 5%. Unassimilated labelled food was often retained in the gut for more than 2 mo and released only infrequently in a loosely bound condition. In the event of contamination, this particular feeding-digestion strategy in highly mobile, scavenging isopods could act as a potential biological mechanism for the widespread dispersion of radioactive wastes.     

Effects of Artisanal Fishing on Caribbean Coral Reefs

Abstract:  Although the impacts of industrial fishing are widely recognized, marine ecosystems are generally considered less threatened by artisanal fisheries. To determine how coral reef fish assemblages and benthic communities are affected by artisanal fishing, we studied six Caribbean islands on which fishing pressure ranged from virtually none in Bonaire, increasing through Saba, Puerto Rico, St Lucia, and Dominica, and reaching very high intensities in Jamaica. Using stationary-point fish counts at 5 m and 15 m depth, we counted and estimated the lengths of all noncryptic, diurnal fish species within replicate 10-m-diameter areas. We estimated percent cover of coral and algae and determined reef structural complexity. From fish numbers and lengths we calculated mean fish biomass per count for the five most commercially important families. Groupers (Serranidae), snappers (Lutjanidae), parrotfish (Scaridae), and surgeonfish (Acanthuridae) showed order-of-magnitude differences in biomass among islands. Biomass fell as fishing pressure increased. Only grunts (Haemulidae) did not follow this pattern. Within families, larger-bodied species decreased as fishing intensified. Coral cover and structural complexity were highest on little-fished islands and lowest on those most fished. By contrast, algal cover was an order of magnitude higher in Jamaica than in Bonaire. These results suggest that following the Caribbean-wide mass mortality of herbivorous sea urchins in 1983–1984 and consequent declines in grazing pressure on reefs, herbivorous fishes have not controlled algae overgrowing corals in heavily fished areas but have restricted growth in lightly fished areas. In summary, differences among islands in the structure of fish and benthic assemblages suggest that intensive artisanal fishing has transformed Caribbean reefs.