scholarly journals Testing size–frequency distributions as a method of ontogenetic aging: a life-history assessment of hadrosaurid dinosaurs from the Dinosaur Park Formation of Alberta, Canada, with implications for hadrosaurid paleoecology

Paleobiology ◽  
2020 ◽  
Vol 46 (3) ◽  
pp. 379-404
Author(s):  
Mateusz Wosik ◽  
Kentaro Chiba ◽  
François Therrien ◽  
David C. Evans
Keyword(s):  
Life History ◽  
Body Size ◽  
Frequency Distribution ◽  
Growth Rates ◽  
Long Bone ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Combining Data ◽  
Dinosaur Park Formation

AbstractHadrosaurid dinosaurs, the dominant large-bodied terrestrial herbivores in most Laurasian Late Cretaceous ecosystems, have an exceptional fossil record consisting of many species known from partial ontogenetic series, making them an ideal clade with which to conduct life-history studies. Previous research considered the Dinosaur Park Formation (DPF) of Alberta as an attritional, or time-averaged, sample and interpreted size–frequency distribution of long bones collected from the DPF with three size classes to suggest that hadrosaurids from the DPF attained near-asymptotic body size in under 3 years. This conflicted with previously published osteohistological estimates of 6+ years for penecontemporaneous hadrosaurids from the Two Medicine Formation (TMF) of Montana, suggesting either extreme variation in hadrosaurid growth rates or that size–frequency distributions and/or osteohistology and growth modeling inaccurately estimate ontogenetic age.We tested the validity of the previously proposed size–age relationship of hadrosaurids from the DPF by significantly increasing sample size and combining data from size–frequency distributions and osteohistology across multiple long-bone elements. The newly constructed size–frequency distributions typically reveal four relatively distinct size–frequency peaks that, when integrated with the osteohistological data, aligned with growth marks. The yearling size class was heavily underrepresented in the size–frequency distribution. If not due to preservation, this suggests that either juvenile (<2 years of age) hadrosaurids from the DPF had increased survivorship following an initially high nestling mortality rate or that yearlings were segregated from adults. A growth-curve analysis revealed asymptotic body size was attained in approximately 7 years, which is consistent with hadrosaurids from the TMF. The data suggest size–frequency distributions of attritional samples underestimate age and overestimate growth rates, but when paired with osteohistology can provide unique life-history insights.

scholarly journals 2.2.2 The Size Frequency Distribution and Rate of Production of Microcraters

1976 ◽  
Vol 31 ◽  
pp. 227-231
Author(s):  
D. A. Morrison ◽  
E. Zinner
Keyword(s):  
Frequency Distribution ◽  
Lunar Surface ◽  
Particle Flux ◽  
Surface Orientation ◽  
Submicron Particle ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Crater Size ◽  
Size Frequency ◽  
Micron Diameter

AbstractCrater size frequency distributions vary to a degree which probably cannot be explained by variations in lunar surface orientation of the crater detectors or changes in micrometeoroid flux. Questions of sample representativity suggest that high ratios of small to large craters of micrometeoroids (e.g., a million 1.0 micron craters for each 500 micron crater) should be the most reliable. We obtain a flux for particles producing 0.1 micron diameter craters of approximately 300 per cm2 per steradian per year. We observe no anisotropy in the submicron particle flux between the plane of the ecliptic and the normal in the direction of lunar north. No change in flux over a 106 year period is indicated by our data.

The Slippery Slope: Towards an Understanding of the Body Size Frequency Distribution

Oikos ◽  
1997 ◽  
Vol 78 (1) ◽  
pp. 195 ◽  
Author(s):  
Natasha Loder ◽  
Tim M. Blackburn ◽  
Kevin J. Gaston
Keyword(s):  
Body Size ◽  
Frequency Distribution ◽  
The Body ◽  
Slippery Slope ◽  
Size Frequency Distribution ◽  
Size Frequency

scholarly journals Size-frequency distribution of coral assemblages in insular shallow reefs of the Mexican Caribbean using underwater photogrammetry

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8957 ◽  
Author(s):  
Roberto C. Hernández-Landa ◽  
Erick Barrera-Falcon ◽  
Rodolfo Rioja-Nieto
Keyword(s):  
Species Richness ◽  
Frequency Distribution ◽  
Dominant Species ◽  
Coral Cover ◽  
Sampling Area ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Reef Health ◽  
Minimum Sampling Area

The characterisation of changes in coral communities depends heavily on systematic monitoring programs and the collection of necessary metrics to assess reef health. Coral cover is the most used metric to determine reef health. The current organizational shift in coral requires the evaluation of complementary metrics, such as colony size and frequency distributions, which help to infer the responses of the coral populations to local stress or larger scale environmental changes. In this study, underwater digital photogrammetry techniques were used to assess the live cover of all coral colonies ≥3 cm2 and determine the size-frequency distribution of the dominant species in the shallow reefs of the Cozumel Reefs National Park (CRNP). In addition, the minimum sampling area (m2) needed to obtain a representative sample of the local species pool was estimated. Areas between 550 and 825 m2 per reef were photographed to generate high-resolution digital ortho-mosaics. The live area of the colonies was digitised to generate community matrices of species and abundance. EstimateS software was used to generate accumulation curves and diversity (Shannon H′) at increasing area intervals. Chi-Square tests (χ2, p = 0.05) were used to compare the observed vs estimated species richness. Spearman’s coefficients (rs), were calculated to correlate the increase in sampling area (m2) vs H′, and the Clench’s function was used to validate the observed richness (R2 = 1 and R > 90%). SIMPER analysis was performed to identify dominant species. Comparisons in terms of abundance, coral cover and size-frequencies were performed with Kruskal-Wallis (H test, p = 0.05), and paired Mann-Whitney (U test, p = 0.05). In order to obtain 90% of the species richness, a minimum sampling area of 374 m2is needed. This sampling area could be used in shallow Caribbean reefs with similar characteristics. Twelve (mainly non-massive) species: Agaricia agaricites, A humilis, A. tenuifolia, Eusmilia fastigiata, Meandrina meandrites, Montastrea cavernosa, Orbicella annularis, Porites astreoides, P. porites, Pseudodiploria strigosa, Siderastrea radians andS. siderea, were dominant in terms of abundance and coral cover. A significant increase (p < 0.05) in the number of colonies and live coral (m2) was observed from north to south of the study area. Furthermore, a wide intraspecific variation of size-frequency, even between adjacent reefs, was also observed. The size-frequency distributions presented positive skewness and negative kurtosis, which are related to stable populations, with a greater number of young colonies and a constant input of recruits. Considering the increase in disturbances in the Caribbean and the appearance of a new coral disease, digital photogrammetry techniques allow coral community characteristics to be assessed at high spatial resolutions and over large scales, which would be complementary to conventional monitoring programs.

scholarly journals SMALL CRATERS AND THEIR DIAGNOSTIC POTENTIAL

2017 ◽  
Vol XLII-3/W1 ◽  
pp. 23-27
Author(s):  
R. Bugiolacchi
Keyword(s):  
Power Function ◽  
Frequency Distribution ◽  
Central Area ◽  
Saturation Level ◽  
The Moon ◽  
Current Estimate ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Diagnostic Potential

I analysed and compared the size-frequency distributions of craters in the Apollo 17 landing region, comprising of six mare terrains with varying morphologies and cratering characteristics, along with three other regions allegedly affected by the same secondary event (Tycho secondary surge). I propose that for the smaller crater sizes (in this work 9&amp;ndash;30&amp;thinsp;m), a] an exponential curve of power &amp;minus;0.18D can approximate Nkm<sup>&amp;minus;2</sup> crater densities in a regime of equilibrium, while b] a power function D<sup>&amp;minus;3</sup> closely describes the factorised representation of craters by size (1&amp;thinsp;m). The saturation level within the Central Area suggests that c] either the modelled rates of crater erosion on the Moon should be revised, or that the Tycho event occurred much earlier in time than the current estimate. We propose that d] the size-frequency distribution of small secondary craters may bear the signature (in terms of size-frequency distribution of debris/surge) of the source impact and that this observation should be tested further.

Population studies of juvenile Trochus niloticus on a reef flat on the north-eastern Queensland coast, Australia

1997 ◽  
Vol 48 (3) ◽  
pp. 211 ◽  
Author(s):  
Laura L. Castell
Keyword(s):  
Frequency Distribution ◽  
Growth Rates ◽  
Reef Flat ◽  
Population Studies ◽  
Size Frequency Distribution ◽  
Shell Width ◽  
The North ◽  
Size Frequency ◽  
North Eastern ◽  
Trochus Niloticus

Transects and quadrats were used to sample the distribution and density of Trochus niloticus, recruitment, growth rates of juveniles, and characteristics of the microhabitat, on an intertidal reef flat at Orpheus Island between 1993 and 1995. Individuals between 1·5 and 62 mm shell width (SW) were found in all parts of the reef flat. Their density averaged 0·178 and 0·115 individuals m-2 in 1993 and 1994, respectively. Juveniles were found in groups of 2–4 individuals m-2 more frequently than would occur by chance, but denser aggregations were rare. As juveniles increased in size, there was a change in microhabitat: from small rubble (<10 mm) to larger rocks and coral bench and from shallow pools (<10 mm deep) to deeper pools. The size–frequency distribution was bimodal during parts of the year, suggesting seasonality in recruitment. Growth rates ranged between 2·3 and 2·6 mm SW month-1. In relation to the seeding of cultured juveniles for population enhancement, the results indicate that seeding densities should be <5 individuals m-2. Shallow areas with abundant small rubble may represent favourable conditions for individuals of <15 mm SW, but deeper areas with larger rocks are better for individuals of 15 mm SW.

scholarly journals Variation in the distribution of Corbicula species (Mollusca: Bivalvia: Corbiculidae) after 25 years of its introduction in the Río de la Plata, Argentina

2017 ◽  
Vol 34 ◽  
pp. 1-6 ◽  
Author(s):  
Yamila Reshaid ◽  
Luciana Cao ◽  
Francisco Brea ◽  
María Ortiz Blanche ◽  
Santiago Torres ◽  
...  
Keyword(s):  
Frequency Distribution ◽  
Buenos Aires ◽  
Rio De La Plata ◽  
Río De La Plata ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
La Plata ◽  
Size Frequency ◽  
Population Structures

In 1981, Corbiculafluminea (Müller, 1774) and C.largillierti (Philippi, 1844) were recorded at the Río de la Plata River. During the 1980’s, C.largillierti was found on a continuous fringe in the shore of that river, while C.fluminea was only found North of Buenos Aires’ harbor. Ten years later, C.fluminea spread to Punta Indio, while C.largillierti remained restricted to tributary streams. The density and size frequency distribution of both species were compared with previous data from samples performed in the same area in 1985–1989. The aim of this research was to determine whether the densities of both species decreased; whether C.fluminea is still more abundant than C.largillierti; and whether the size frequency distributions indicate different population structures from those observed in the end of the 1980’s. Nine localities from the river shore were sampled, and each individual was identified and measured. The size of C.fluminea varied between 2 and 39 mm, showing the highest frequency of individuals between 20 and 25 mm; furthermore the density decreased 90% in 2015/2016. No specimens of C.largillierti were found. In conclusion, the populations of Corbicula inhabiting the Río de la Plata River are retracting.

scholarly journals Response of benthic foraminifera to ocean acidification in their natural sediment environment: a long-term culturing experiment

2013 ◽  
Vol 10 (6) ◽  
pp. 9523-9572 ◽  
Author(s):  
K. Haynert ◽  
J. Schönfeld ◽  
R. Schiebel ◽  
B. Wilson ◽  
J. Thomsen
Keyword(s):  
Ocean Acidification ◽  
Frequency Distribution ◽  
Growth Rates ◽  
Organic Content ◽  
Specific Response ◽  
Natural Sediment ◽  
Size Frequency Distribution ◽  
Saturation State ◽  
Carbonate Production ◽  
Size Frequency

Abstract. Calcifying foraminifera are expected to be endangered by ocean acidification, However, the response of a complete community kept in natural sediment and over multiple generations under controlled laboratory conditions has not been constrained to date. During six month incubation, foraminiferal assemblages were treated with pCO2 enriched seawater of 430, 907, 1865 and 3247 μatm pCO2. The fauna was dominated by Ammonia aomoriensis and Elphidium species, whereas agglutinated species were rare. After 6 months incubation, pore water alkalinity was much higher in comparison to the overlying seawater. Consequently, the saturation state of Ωcalc was much higher in the sediment than in the water column in all pCO2 treatments and remained close to saturation. As a result, the life cycle of living assemblages was largely unaffected by the tested pCO2 treatments. Growth rates, reproduction and mortality, and therefore population densities and size-frequency distribution of Ammonia aomoriensis varied markedly during the experimental period. Growth rates varied between 25 and 50 μm per month, which corresponds to an addition of 1 or 2 new chambers per month. According to the size-frequency distribution, foraminifera start reproduction at a diameter of 250 μm. Mortality of large foraminifera was recognized, commencing at a test size of 285 μm at a pCO2 ranging from 430 to 1865 μatm, and of 258 μm at 3247 μatm. The total organic content of living Ammonia aomoriensis has been determined to be 4.3% of dry weight. Living individuals had a calcium carbonate production rate of 0.47 g m−2 yr−1, whereas dead empty tests accumulated at a rate of 0.27 g m−2 a−1. Although Ωcalc was close to 1, some empty tests of Ammonia aomoriensis showed dissolution features at the end of incubation. In contrast, tests of the subdominant species, Elphidium incertum, stayed intact. This species specific response could be explained by differences in the elemental test composition, in particular the higher Mg-concentrations in Ammonia aomoriensis tests. Our results emphasize that the sensitivity to ocean acidification of endobenthic foraminifera in their natural sediment habitat is much lower compared to the experimental response of specimens isolated from the sediment.

scholarly journals Catchability of the southern rock lobster Jasus edwardsii. II. Effects of size

2002 ◽  
Vol 53 (8) ◽  
pp. 1149 ◽  
Author(s):  
P. E. Ziegler ◽  
C. R. Johnson ◽  
S. D. Frusher ◽  
C. Gardner
Keyword(s):  
Frequency Distribution ◽  
Rock Lobster ◽  
Size Frequency Distribution ◽  
Frequency Distributions ◽  
Size Classes ◽  
Size Frequency ◽  
Jasus Edwardsii ◽  
Behavioural Interactions ◽  
Males And Females ◽  
Relative Selectivity

For most of the year, the size-frequency distribution of trap-caught southern rock lobster, Jasus edwardsii, reflected size-specific catchability rather than the size-frequency distribution of the population in a scientific reserve in Tasmania, Australia. The size-frequency distributions of the population on the ground and of lobsters captured in traps were similar only during a few months, typically during moulting and mating. Small males and females were usually under-represented in traps. Catchability generally increased with size, but varied with sex and season. During moulting and mating, size-specific catchability and relative selectivity of larger animals were similar to or lower than for smaller animals. The relative pattern of catchability throughout the year was similar for most size classes within each sex. Negative associations between small and large lobsters in traps were stronger in winter than in summer, indicating strong behavioural interactions. These interactions could explain the lower catchability of smaller lobsters. Relative selectivity estimates using tag–recapture and size-specific catchability data provided generally similar results.

Effects of Predation and Trophic Conditions on the Reproduction of Tylototriton verrucosus (Caudata: Salamandridae) in Darjeeling

2011 ◽  
Vol 4 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Ritwik Dasgupta
Keyword(s):  
Frequency Distribution ◽  
Primary Productivity ◽  
Egg Size ◽  
Zooplankton Abundance ◽  
Trophic Conditions ◽  
Size Frequency Distribution ◽  
Size Frequency ◽  
High Predation ◽  
Hatchling Size ◽  
Predation Rates

The facts that small hatchlings emerged from small eggs laid under high predation levels prevailing at the lower altitudes of distribution of this species in Darjeeling while larger hatchlings emerged from larger eggs laid under lower levels of predation at higher altitudes, show that predation is not selected for large egg and initial hatchling size in this salamandrid species. Metamorphic size was small under high predation rates because this species relied on crypsis for evading predators. Egg and hatchling size are related inversely to levels of primary productivity and zooplankton abundance in lentic habitats. Hatchling sizes are related positively to egg size and size frequency distribution of zooplankton. Small egg and small hatchling size have been selected for at the lower altitudes of distribution of this salamandrid in Darjeeling because predation rates increased in step with improvement in trophic conditions at the lower altitudes.

SIZE FREQUENCY DISTRIBUTION BIASES IN HORSESHOE CRAB MOLT ASSEMBLAGES: IMPLICATIONS FOR THE FOSSIL RECORD

2016 ◽  
Author(s):  
Shelly J. Wernette ◽  
◽  
Scott Evans ◽  
Christine Hall ◽  
Mary L. Droser ◽  
...  
Keyword(s):  
Frequency Distribution ◽  
Fossil Record ◽  
Horseshoe Crab ◽  
Size Frequency Distribution ◽  
Size Frequency
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