Cooperative defence and other benefits among exposed spiny lobsters: inferences from group size and behaviour

Caribbean spiny lobsters show strikingly coordinated queuing behaviour and resting, outward-facing radial formations, especially during mass migrations when large numbers cross shelter-poor substrate in daylight. The close association of individual lobsters during these behaviours could be due to chance or some benefit of association such as dilution (and associated selfish-herd effects), group vigilance, cooperative defence, and/or drag reduction during migration. To infer probable beneficial functions, we examined the frequency distributions of individuals and groups using a seven-year set of field data and additional behavioural observations in large seawater enclosures. Group size distributions were not significantly aggregated in dens during the non-migratory period but became highly aggregated during migration. The group size distributions of lobsters initially leaving dens and those observed moving in the open were statistically different from one another, indicating that group sizes at each of these steps in the migration are not simply the result of previous group sizes. The distribution of group sizes suggests that, during movement in the open, dilution, vigilance, cooperative defence, and/or drag reduction may all favour the formation of queues. During resting in the open, dilution, vigilance, and cooperative defence may continue to favour individuals that remain in formation within the group.

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Heritability of the Effect of Corticosteroids on Intraocular Pressure

Acta geneticae medicae et gemellologiae ◽

10.1017/s1120962300025658 ◽

1970 ◽

Vol 19 (1-2) ◽

pp. 264-267 ◽

Cited By ~ 4

Author(s):

F.H. Reuling ◽

J.T. Schwartz

Keyword(s):

Intraocular Pressure ◽

Clinical Signs ◽

Topical Steroids ◽

Frequency Distributions ◽

Steroid Response ◽

Large Numbers ◽

Wide Range ◽

Allele Pair ◽

High Level ◽

Genetically Determined

In the late 1950's and early 1960's, it became evident that some glaucoma patients developed elevations of intraocular pressure, which were difficult to control, following prolonged use of systemic or ocular medications containing corticosteroids (Chandler, 1955, Alfano, 1963; Armaly, 1963). In addition, some patients without glaucoma, when treated with steroids for long periods of time, developed clinical signs of chronic simple glaucoma (McLean, 1950; François, 1954; Covell, 1958; Linner, 1959; Goldman, 1962). Fortunately, the elevation of intraocular pressure was reversible if the drug was discontinued.Over the past decade, extensive investigation of the “steroid response” has been undertaken. For this presentation, the steroid response may be considered as a gradual elevation of intraocular pressure, occurring over several weeks, in an eye being medicated with corticosteroid drops several times a day. The elevation in pressure is usually accompanied by a reduction in the facility of aqueous outflow. When relatively large numbers of subjects were tested with topical steroids, so that a wide range of responsiveness could be observed, a variation in individual sensitivity was demonstrated. Frequency distributions of intraocular pressure or change in pressure following steroids showed a skew toward the high side. On the basis of trimodal characteristics which they observed in such frequency distributions, Becker and Hahn (1964), Becker (1965) and Armaly (1965, 1966) considered the possible existence of several genetically determined subpopulations. These investigators distinguished three subpopulations on the basis of low, intermediate, and high levels of pressure response. It was hypothesized that these levels of response characterized three phenotypes, corresponding to the three possible genotypes of an allele pair, wherein one member of the pair determined a low level of response, and the other member determined a high level of response (Armaly, 1967).

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Size Distributions and Growth of the Fan-shell Pinna bicolor Gmelin (Mollusca : Eulamellibranchia) in South Australia

Marine and Freshwater Research ◽

10.1071/mf9790025 ◽

1979 ◽

Vol 30 (1) ◽

pp. 25 ◽

Cited By ~ 27

Author(s):

AJ Butler ◽

FJ Brewster

Keyword(s):

South Australia ◽

Adductor Muscle ◽

Size Distributions ◽

Limited Data ◽

Length Frequency ◽

Age Classes ◽

Frequency Distributions ◽

Growth And Survival ◽

Random Samples ◽

Variable Success

Fourteen random samples of Pinna bicolor were collected over a period of 31 months from 6 m depth in Gulf St Vincent off Edithburgh, South Australia. The length-frequency distributions suggest that: P. bicolor larvae settle in spring but with variable success; growth of newly settled young is rapid over summer; by age 1 year their modal shell length is about 20 cm; by age 2 it is about 26 cm; they may survive substantially longer than 3 years so that a length-class of mode c. 35 cm is always present and is composed of several age-classes not necessarily equally represented. These suggestions are corroborated by limited data on adductor muscle scars, the development of epibiota on the shells, and the growth and survival of tagged animals over 9 months.

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Habitat value of a developing estuarine brackish marsh for fish and macrocrustaceans

ICES Journal of Marine Science ◽

10.1016/s1054-3139(03)00013-4 ◽

2003 ◽

Vol 60 (2) ◽

pp. 278-289 ◽

Cited By ~ 13

Author(s):

H Hampel ◽

A Cattrijsse ◽

M Vincx

Keyword(s):

Carcinus Maenas ◽

Environmental Parameters ◽

Shore Crab ◽

Total Biomass ◽

Density Peak ◽

Frequency Distributions ◽

Species Dominance ◽

Large Numbers ◽

Mesopodopsis Slabberi ◽

Mysid Shrimp

Abstract Marsh creation receives worldwide attention in mitigating loss of coastal wetlands and in management retreat of estuaries. In the Westerschelde, the former Selena Polder, south from the marsh of Saeftinghe, developed into the Sieperda marsh after several dyke breaches. Soon after the tides regained access to the polder, a tidal creek was formed. After 10 years, a developing marsh system was found adjacent to a mature marsh system. This situation offered the opportunity to compare the utilization by nekton species of a natural mature marsh with a recently created developing marsh under similar circumstances. Between April and October 1999, both the mature Saeftinghe marsh and the developing Sieperda marsh were sampled every 6 weeks on 2 consecutive days. Each sampling occasion covered the whole tidal cycle. The most important environmental parameters (water height, temperature, salinity, turbidity and dissolved oxygen) were similar in both marsh creeks. A distinct difference in nekton community structure between the two marshes was observed. The total biomass and densities of nekton species were higher in Saeftinghe. In Saeftinghe, a density peak occurred in July and was mainly due to large numbers of the mysid, Neomysis integer. In Sieperda, maximum abundance of the mysid, Mesopodopsis slabberi, caused the peak density in September. This difference in species dominance was observed in all samples. Biomass peaked in July in the mature marsh and in October in the developing marsh. Mysid shrimp (N. integer) and fish (mainly Pomatoschistus microps) were the main contributors to the biomass Saeftinghe. Herring, sprat (Clupeidae) and shore crab (Carcinus maenas) were more important in Sieperda. For P. microps, distinct differences in length–frequency distributions were noted between the marshes. While creek morphology influences the abundance and species composition of visiting nekton, the age of a marsh and its maturity are believed to be the prime factors in determining the habitat function of creek systems of developing and mature marshes.

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A morphological study of variation in Tyrophagus (Acarina), with particular reference to populations infesting cheese

Bulletin of Entomological Research ◽

10.1017/s0007485300055565 ◽

1961 ◽

Vol 52 (3) ◽

pp. 501-529 ◽

Cited By ~ 6

Author(s):

Phyllis L. Robertson

Keyword(s):

Close Association ◽

Distinct Species ◽

Linear Measurement ◽

Wide Distribution ◽

Ecological Data ◽

Plant Materials ◽

Frequency Distributions ◽

Ecological Zones ◽

Distribution And Ecology ◽

The Many

The difficulty of deciding the systematic status of variations within and between populations of Tyrophagus is considered in relation to the wide distribution of the genus and the many materials it infests.Variation within populations of what was thought to be one species infesting cheese is explained by the isolation of three closely similar forms which it is difficult, if not impossible, to separate by measurement alone. Frequency distributions overlap slightly for four linear measurement ratios on which separation is attempted, but differences between them are emphasised by differences in minute structural characters and they are therefore accepted as distinct species, identified as longior (Gervais, 1844), palmarum Oudemans, 1924, and putrescentiae (Schrank, 1781).Variation between populations attacking plant materials and other stored products in addition to cheese is accounted for to some extent by the recognition of three further Tyrophagus species, oudemansi Robertson, 1959, brevicrinatus Robertson, 1959, and tropicus Robertson, 1959.Within the species recognised, significant differences are recorded in dorsal hair characters and body proportions between populations on cheese produced in different geographical areas, and also between cheese populations and those infesting other materials, and these differences are thought to be at a racial level.T. longior, T. palmarum and T. putrescentiae are found to be distributed around the world, but as cheese pests they occupy somewhat different, although overlapping, geographical zones, since longior is a temperate-to-cool form, palmarum a temperate form and putrescentiae a subtropical or tropical form. The three are also found to occupy different, but overlapping ecological zones, making possible their association in mixed populations.Confusion in ecological data previously published on Tyrophagus is thought to be attributable in part to similarities in the morphology, geographical distribution and ecology of its species, and to their close association.

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Preliminary Field Data on Group Size, Diet and Activity in the Alaotran Gentle Lemur Hapalemur griseus alaotrensis

Folia Primatologica ◽

10.1159/000021647 ◽

1998 ◽

Vol 69 (5) ◽

pp. 325-330 ◽

Cited By ~ 25

Author(s):

Thomas Mutschler ◽

Anna T. Feistner ◽

Caroline M. Nievergelt

Keyword(s):

Group Size ◽

Field Data ◽

Hapalemur Griseus

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Modelling changes in the length-frequency distributions of fish larvae using field estimates of predator abundance and size distributions

Fisheries Oceanography ◽

10.1046/j.1365-2419.2001.00167.x ◽

2001 ◽

Vol 10 (2) ◽

pp. 217-234 ◽

Cited By ~ 13

Author(s):

A. R. Paradis ◽

P. Pepin

Keyword(s):

Fish Larvae ◽

Size Distributions ◽

Length Frequency ◽

Frequency Distributions ◽

Predator Abundance

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DISTRIBUCIÓN ESPACIAL DE Vatiga spp. (HEMIPTERA: TINGIDAE) EN EL CULTIVO DE YUCA

Acta Biológica Colombiana ◽

10.15446/abc.v21n1.46762 ◽

2015 ◽

Vol 21 (1) ◽

Cited By ~ 1

Author(s):

Antonio De Souza Silva

Keyword(s):

Spatial Distribution ◽

Negative Binomial Distribution ◽

Binomial Distribution ◽

Field Data ◽

Negative Binomial ◽

Plant Leaves ◽

Frequency Distributions ◽

Morisita Index ◽

Best Fit

RESUMENEl objetivo de este trabajo fue generar informacion acerca de cuál es el modelo de disposición espacial de Vatiga spp. en el cultivo de la yuca. Se realizaron muestreos en dos áreas comerciales de 2500 m2, divididas en 100 parcelas. Se contaron adultos y de ninfas de Vatiga spp. en las hojas basales y medias de la planta. En total, se realizaron doce muestreos quincenalmente, desde febrero hasta abril de 2014, época de mayor incidencia de esta plaga. De forma general, a través de los índices de dispersión (varianza/media, índice de Morisita y exponente K) y las distribuciones de frecuencia, se observa que la distribución espacial de Vatiga spp. es agregada, es decir, el padrón de distribución Binomial Negativa fue el que resultó de mejor ajuste a los datos obtenidos a campo, con el conteo de los individuos.ABSTRACTThe aim of this study was to generate information about which is the model of spatial distribution of Vatiga spp. in the cassava culture. Sampling was conducted in two commercial areas of 2,500 m2, divided into 100 plots. Adults and nymphs of Vatiga spp. were counted in the basal and medium plant leaves. In all, twelve samples were taken fortnightly from February to April 2014, when occurs the highest incidence of this pest. Based in the indices of dispersion (variance/mean, Morisita index and K exponent) and the frequency distributions, it was observed that the spatial distribution of Vatiga spp. is aggregate, it means that the standard Negative Binomial distribution was the best fit to the field data obtained, with the counting direction of individuals.

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