Body Size Change of Carcharocles Megalodon Through Time in Comparison with Contemporaneous Marine Mega-Fauna

2014 ◽  
Vol 13 ◽  
pp. 90-90
Author(s):  
Meghan A. Balk ◽  
Catalina Pimiento
Keyword(s):  
2017 ◽  
Author(s):  
Nora Soto ◽  
◽  
Yurena Yanes ◽  
David Lubell
Keyword(s):  

2015 ◽  
Vol 27 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Brittney Bernardoni ◽  
Tamara A. Scerpella ◽  
Paula F. Rosenbaum ◽  
Jill A. Kanaley ◽  
Lindsay N. Raab ◽  
...  

We prospectively evaluated adolescent organized physical activity (PA) as a factor in adult female bone traits. Annual DXA scans accompanied semiannual records of anthropometry, maturity, and PA for 42 participants in this preliminary analysis (criteria: appropriately timed DXA scans at ~1 year premenarche [predictor] and ~5 years postmenarche [dependent variable]). Regression analysis evaluated total adolescent interscan PA and PA over 3 maturity subphases as predictors of young adult bone outcomes: 1) bone mineral content (BMC), geometry, and strength indices at nondominant distal radius and femoral neck; 2) subhead BMC; 3) lumbar spine BMC. Analyses accounted for baseline gynecological age (years pre- or postmenarche), baseline bone status, adult body size and interscan body size change. Gymnastics training was evaluated as a potentially independent predictor, but did not improve models for any outcomes (p < .07). Premenarcheal bone traits were strong predictors of most adult outcomes (semipartial r2 = .21-0.59, p < .001). Adult 1/3 radius and subhead BMC were predicted by both total PA and PA 1-3 years postmenarche (p < .03). PA 3-5 years postmenarche predicted femoral narrow neck width, endosteal diameter, and buckling ratio (p < .05). Thus, participation in organized physical activity programs throughout middle and high school may reduce lifetime fracture risk in females.


Author(s):  
Maggie Hantak ◽  
Bryan McLean ◽  
Daijiang Li ◽  
Robert Guralnick

Anthropogenically-driven climate warming is a hypothesized driver of animal body size reductions. Less understood are effects of other human-caused disturbances on body size, such as urbanization. We compiled 140,499 body size records of over 100 North American mammals to test how climate and urbanization, and their interactions with species traits, impact body size. We tested three hypotheses of body size change across urbanization gradients; urban heat island effects, fragmentation, and resource availability. Our results unexpectedly demonstrate urbanization is more tightly linked with body size changes than temperature, most often leading to larger individuals, thus supporting the resource availability hypothesis. In addition, life history traits, such as thermal buffering, activity time, and average body size play critical roles in mediating the effects of both climate and urbanization on intraspecific body size trends. This work highlights the value of using digitized, natural history data to track how human disturbance drives morphological change.


2019 ◽  
Vol 15 (10) ◽  
pp. 20190481 ◽  
Author(s):  
José Alexandre F. Diniz-Filho ◽  
Lucas Jardim ◽  
Thiago F. Rangel ◽  
Phillip B. Holden ◽  
Neil R. Edwards ◽  
...  

According to the island rule, small-bodied vertebrates will tend to evolve larger body size on islands, whereas the opposite happens to large-bodied species. This controversial pattern has been studied at the macroecological and biogeographical scales, but new developments in quantitative evolutionary genetics now allow studying the island rule from a mechanistic perspective. Here, we develop a simulation approach based on an individual-based model to model body size change on islands as a progressive adaptation to a moving optimum, determined by density-dependent population dynamics. We applied the model to evaluate body size differentiation in the pigmy extinct hominin Homo floresiensis, showing that dwarfing may have occurred in only about 360 generations (95% CI ranging from 150 to 675 generations). This result agrees with reports suggesting rapid dwarfing of large mammals on islands, as well as with the recent discovery that small-sized hominins lived in Flores as early as 700 kyr ago. Our simulations illustrate the power of analysing ecological and evolutionary patterns from an explicit quantitative genetics perspective.


Body Image ◽  
2015 ◽  
Vol 13 ◽  
pp. 75-85 ◽  
Author(s):  
Katri K. Cornelissen ◽  
Andre Bester ◽  
Paul Cairns ◽  
Martin J. Tovée ◽  
Piers L. Cornelissen

2003 ◽  
Vol 17 (2) ◽  
pp. 396-407 ◽  
Author(s):  
A. J. Webster ◽  
J. L. Gittleman ◽  
A. Purvis
Keyword(s):  

Worm ◽  
2012 ◽  
Vol 1 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Shuhei So ◽  
Yohei Garan ◽  
Kohji Miyahara ◽  
Yasumi Ohshima

2016 ◽  
Vol 3 (1) ◽  
pp. 150277 ◽  
Author(s):  
Michael S. Y. Lee ◽  
Kate L. Sanders ◽  
Benedict King ◽  
Alessandro Palci

The relationship between rates of diversification and of body size change (a common proxy for phenotypic evolution) was investigated across Elapidae, the largest radiation of highly venomous snakes. Time-calibrated phylogenetic trees for 175 species of elapids (more than 50% of known taxa) were constructed using seven mitochondrial and nuclear genes. Analyses using these trees revealed no evidence for a link between speciation rates and changes in body size. Two clades ( Hydrophis , Micrurus ) show anomalously high rates of diversification within Elapidae, yet exhibit rates of body size evolution almost identical to the general elapid ‘background’ rate. Although correlations between speciation rates and rates of body size change exist in certain groups (e.g. ray-finned fishes, passerine birds), the two processes appear to be uncoupled in elapid snakes. There is also no detectable shift in diversification dynamics associated with the colonization of Australasia, which is surprising given that elapids appear to be the first clade of venomous snakes to reach the continent.


2017 ◽  
Author(s):  
Logan Wiest ◽  
William E. Lukens ◽  
Daniel J. Peppe ◽  
Steven G. Driese ◽  
Jack Tubbs

Recent research has demonstrated that the Lilliput effect (reduction of body size in response to a mass extinction) affected all trophic levels in the marine realm following the Cretaceous-Paleogene (K-Pg) event. However, it is unclear if this size change was strictly a marine signal, or a global phenomenon that also affected continental ecosystems. Herein we present the results of an ichnological proxy for body size of soil-dwelling insects across the K-Pg boundary in Big Bend National Park, Texas, U.S.A. Quantitative efforts focused on Naktodemasis isp., which are characterized as unbranching burrows composed of ellipsoidal packets of backfill menisci. These traces were likely produced by beetle larvae or cicada nymphs based on previous comparison with structures generated in modern soils and laboratory experiments. As an approximation for the body size of the subterranean insects, this dataset indicates that a smaller Naktodemasis diameter (DN) is statistically correlated (α &lt; 0.05) with several edaphic factors including poor drainage and weak development (Entisols). Additionally, the DN in strata immediately superjacent to the highest Cretaceous-specific taxa is smaller by 23% (5.6 ± 1.8 mm) in comparison to DN within the subjacent Cretaceous interval (7.3 ± 2.7 mm). This abrupt shift occurs in a well-drained Inceptisol, and cannot be attributed to facies changes, drainage, or paleosol maturity. Furthermore, a reduced DN (6.6 ± 2.3 mm) persists above this anomalous shift for at least 20 stratigraphic meters within chron 29r. The cause for this negative response in body size within soil-dwelling biota may be attributed to plant-community shifts in taxonomic composition and ecological strategies, which would have caused fundamental alterations to the diet of the herbivorous, subterranean insects. This study provides empirical evidence that the Lilliput effect was not restricted to marine environments during the aftermath of the K-Pg event.


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