Body size frequency distributions in African mammals are bimodal at all spatial scales

Abstract Body size is a functional trait that influences the overall biology and ecology of an organism. Studying the shape of size–frequency distributions and size variability within different scales, approximates the influence of large-scale ecological and evolutionary processes on a species. In this study we examine the patterns of distribution and variability of body size among freshwater Cladocera across different taxonomic levels, geographic distribution and habitat association. Using extensive literature data, we show the global distribution of body size in freshwater Cladocera. Hierarchical models were used to assess the effect of different categorical variables on size variability. Our results show that almost all size–frequency distributions were skewed right in all categories. The hierarchical model showed that taxonomic affiliation contributes the most to size variability in our dataset, suggesting that size might be a conserved trait. Large genera (≥1mm) have larger estimated variability compared to smaller genera. In general, our observations on size–frequency distributions and size variability show a brief insight in the varying advantages of adaptive body size in this group of organisms in both biology (physiology) and ecology (competition and co-existence). Thus, body size is a trait important to the survival and continuing evolution of Cladocera.

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Body-size and growth-rate divergence among populations of threespine stickleback (Gasterosteus aculeatus) in Cook Inlet, Alaska, USA

Canadian Journal of Zoology ◽

10.1139/cjz-2017-0092 ◽

2017 ◽

Vol 95 (11) ◽

pp. 877-884 ◽

Cited By ~ 4

Author(s):

J.L. Rollins

Keyword(s):

Growth Rate ◽

Body Size ◽

Gasterosteus Aculeatus ◽

Isolation By Distance ◽

Size Variation ◽

Threespine Stickleback ◽

Divergent Evolution ◽

Cook Inlet ◽

Frequency Distributions ◽

Size Frequency

Body size is one of the most perceptible traits of organisms and is an important fitness proxy in evolutionary studies. Oceanic threespine stickleback (Gasterosteus aculeatus L., 1758) have colonized and adapted to numerous freshwater habitats throughout the Holarctic since the most recent glacial retreat, giving us natural “replicates” of both convergent and divergent evolution. I observed considerable body-size variation among 22 threespine stickleback populations within a small region surrounding Cook Inlet, Alaska, USA. Larger bodied populations tended to have bimodal size-frequency distributions, whereas most smaller bodied populations had unimodal distributions. Bimodal distributions suggested the presence of at least two age classes within large-bodied populations. I used a Bayesian approach to infer mean size of presumed age-1 and age-2+ fish from bimodal size-frequency distributions; I found significant differences in size among populations within ages and sexes, suggesting significant divergence in growth rate among populations. I did not find significant correlations between growth rates (age-specific size) and geographic distances among populations, drainage affiliation, or distance to the sea. Thus, historical processes like isolation by distance, gene flow, or recent common ancestry did not explain differences in growth among populations, suggesting a role for local adaptation or phenotypic plasticity in size divergence.

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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 ◽

10.1017/pab.2020.2 ◽

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.

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Scale effects on the body size frequency distributions of African birds: patterns and potential mechanisms

Global Ecology and Biogeography ◽

10.1111/j.1466-8238.2012.00793.x ◽

2012 ◽

Vol 22 (4) ◽

pp. 380-390 ◽

Cited By ~ 6

Author(s):

Bernard W. T. Coetzee ◽

Peter C. le Roux ◽

Steven L. Chown

Keyword(s):

Body Size ◽

Scale Effects ◽

The Body ◽

Frequency Distributions ◽

Size Frequency

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Patterns of demography for rocky-shore, intertidal invertebrates approaching their geographical range limits: tests of the abundant-centre hypothesis in south-eastern Australia

Marine and Freshwater Research ◽

10.1071/mf09317 ◽

2010 ◽

Vol 61 (11) ◽

pp. 1243 ◽

Cited By ~ 12

Author(s):

Eszter Z. Hidas ◽

David J. Ayre ◽

Todd E. Minchinton

Keyword(s):

Rocky Shore ◽

Spatial Scales ◽

Range Limits ◽

Range Limit ◽

Frequency Distributions ◽

South Eastern ◽

Size Frequency ◽

Eastern Australia ◽

Intertidal Invertebrates ◽

South Eastern Australia

The abundant-centre hypothesis predicts that species' abundances peak at the centre of their geographical ranges and decline gradually towards their range limits. We tested predictions of this hypothesis for three rocky-shore, intertidal invertebrates with planktonic larvae (the whelk, Morula marginalba, the snail, Afrolittorina pyramidalis, and the barnacle, Tesseropora rosea) by quantifying their patterns of abundance and size, and inferring pulses of recruitment from size-frequency distributions, at multiple spatial scales spanning a 600-km region in south-eastern Australia and encompassing roughly the southern third of their geographical ranges. At the regional scale, abundances for all species were, as predicted, dramatically lower at their range limits. This decline was not gradual, however, because there were large variations in abundance at smaller spatial scales, and abrupt declines at the south-eastern corner of Australia. Size did not change towards the range limit for any species, but size-frequency distributions suggested a decline in the frequency of recruitment events at the range limit for T. rosea. We conclude that the abundant-centre hypothesis is not an appropriate model for abundance distributions of benthic marine invertebrates with planktonic larvae, because of the vagaries of dispersal and recruitment interacting with complex current patterns along non-uniform coastlines.

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Spatial Dynamics of Body Size Frequency Distributions for North American Squamates

Evolutionary Biology ◽

10.1007/s11692-011-9132-9 ◽

2011 ◽

Vol 38 (4) ◽

pp. 453-464 ◽

Cited By ~ 11

Author(s):

Christian L. Cox ◽

Scott M. Boback ◽

Craig Guyer

Keyword(s):

Body Size ◽

North American ◽

Spatial Dynamics ◽

Frequency Distributions ◽

Size Frequency

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Snake body size frequency distributions are robust to the description of novel species

Ecosphere ◽

10.1002/ecs2.1348 ◽

2016 ◽

Vol 7 (5) ◽

Author(s):

Bryan Maritz ◽

Mimmie Kgaditse ◽

Graham John Alexander

Keyword(s):

Body Size ◽

Novel Species ◽

Frequency Distributions ◽

Size Frequency

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The geographical diversification in varanid lizards: the role of mainland versus island in driving species evolution

Current Zoology ◽

10.1093/cz/zoaa002 ◽

2020 ◽

Vol 66 (2) ◽

pp. 165-171

Author(s):

Xia-Ming Zhu ◽

Yu Du ◽

Yan-Fu Qu ◽

Hong Li ◽

Jian-Fang Gao ◽

...

Keyword(s):

Body Size ◽

Joint Effect ◽

Offspring Quality ◽

Frequency Distributions ◽

Island Species ◽

Size Frequency ◽

Wide Range ◽

Body Sizes ◽

Species Evolution

Abstract Monitor lizards (Varanidae) inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes, thus providing an ideal model for examining the role of mainland versus island in driving species evolution. Here we use phylogenetic comparative methods to examine whether a link exists between body size-driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes, body size, and life-history traits (offspring number and size). We predict that: 1) since body size drives rapid diversification in groups, a link exists between body size-driven diversification and body size-frequency distributions; 2) because of various environments on island, island species will have higher speciation, extinction, and dispersal rates, compared with mainland species; 3) as a response to stronger intraspecific competition, island species will maximize individual ability associated with body size to outcompete closely-related species, and island species will produce smaller clutches of larger eggs to increase offspring quality. Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards. There is a link between body size-driven diversification and body size-frequency distributions, and the speciation rate is maximized at medium body sizes. Island species will have higher speciation, equal extinction, and higher dispersal rates compared with mainland species. Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.

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