scholarly journals Environmentally- and human-induced body-size responses in Macropus robustus and Macropus rufus , two widespread kangaroo species with largely overlapping distributions

2017 ◽  
Vol 43 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Rachel A. Correll ◽  
Thomas A. A. Prowse ◽  
Gavin J. Prideaux
Keyword(s):  
Body Size ◽  
Macropus Rufus

A comparative study of macroscopic and microscopic dimensions of the intensine in five macropods (Marsupialia: Macropodidae). I. Allometric relationships.

1992 ◽  
Vol 40 (1) ◽  
pp. 91 ◽  
Author(s):  
R Osawa ◽  
PF Woodall
Keyword(s):  
Body Size ◽  
Confidence Limits ◽  
Surface Areas ◽  
Red Kangaroo ◽  
A Value ◽  
Grey Kangaroo ◽  
Macropus Rufus ◽  
Villous Height ◽  
Kleiber’S Law ◽  
Swamp Wallaby

Macroscopic and microscopic dimensions of the intestines in five macropod species (the red kangaroo, Macropus rufus; the eastern grey kangaroo, M. giganteus; the agile wallaby, M. agilis; the swamp wallaby, Wallabia bicolor; and the red-necked pademelon, Thylogale thetis) were investigated allometrically in relation to body mass. In general, the length of the small intestine changed in an area : volume (A:V) compensating manner, but the circumference showed negative allometry such that the overall change in surface areas, both ground and mucosal (including the contribution of villi), were isometric but also included the coefficient derived from 'Kleiber's Law' (0.75) in their 95 and 99% confidence limits, respectively. Villous height and width generally showed no significant correlations with body size, but villous density was lower in large individuals. The allometry coefficient for the length of the large intestine was generally near the A:V compensating value (0.5) in most intraspecific analyses but much higher in the interspecific analysis, suggesting that some factor other than body size might be important (possibly dietary fibre). Caecal length was significantly correlated with body size only in two largest species (M. rufus and M. giganteus) and the interspecific analysis gave a value near A:V compensation).

Adolescent Gender Differences in Weight, Activity, and Body-Size Perception

2012 ◽  
Author(s):  
Judith R. Mccalla ◽  
Katie E. Chipungu ◽  
Patrice G. Saab ◽  
Amanda J. Countryman ◽  
Erin N. Etzel ◽  
...  
Keyword(s):  
Gender Differences ◽  
Body Size ◽  
Size Perception ◽  
Body Size Perception

Maternal body size and condition determine calf growth rates in southern right whales

2018 ◽  
Vol 592 ◽  
pp. 267-281 ◽  
Author(s):  
F Christiansen ◽  
F Vivier ◽  
C Charlton ◽  
R Ward ◽  
A Amerson ◽  
...  
Keyword(s):  
Body Size ◽  
Growth Rates ◽  
Maternal Body ◽  
Calf Growth ◽  
Right Whales ◽  
Southern Right Whales

Trophic position scales positively with body size within but not among four species of rocky reef predators

2020 ◽  
Vol 640 ◽  
pp. 189-200 ◽  
Author(s):  
AM Olson ◽  
A Frid ◽  
JBQ dos Santos ◽  
F Juanes
Keyword(s):  
Body Size ◽  
Trophic Position ◽  
Stomach Contents ◽  
Rocky Reef ◽  
Morphometric Traits ◽  
Predator Species ◽  
Predatory Fishes ◽  
Average Size ◽  
Interspecific Comparisons ◽  
Large Predators

Intra- and interspecifically, larger-bodied predators generally occupy higher trophic positions (TPs). With widespread declines in large predators, there is a need to understand their size-based trophic roles to predict ecosystem-level responses. In British Columbia, Canada, we examined size-based trophic interactions between predatory fishes—3 rockfish species (genus Sebastes) and lingcod Ophiodon elongatus—and their prey, converting predator δ15N signatures to TP and analyzing stomach contents. Intraspecifically, TP scaled positively with predator length and gape width, but the rates of change varied by species. Interspecifically, TP did not scale positively with the observed mean sizes or known maximum sizes of species. Lingcod TP was lower than that of yelloweye and quillback rockfishes, which were 51 and 37%, respectively, smaller than lingcod. Yellowtail rockfish had the smallest average size, yet their mean TP did not differ significantly from that of lingcod. Neither species differences in some morphometric traits known to influence body size-TP relationships nor phylogenetic history explained these results. Most prey consumed were <20% of the predator’s size, which might partially explain the lack of a size-based trophic hierarchy among species. Currently, large size classes of rockfishes are being lost due to fisheries and perhaps climate-driven changes. Our findings on intraspecific size-TP relationships indicate that fishery removals of large individuals may diminish trophic structures. Interspecific comparisons of TP suggest that, along with size, species remain an important factor in understanding trophic dynamics. In addition, smaller-bodied predator species may have significant ecological roles to be considered in ecosystem-based fisheries management.

Ecology and biogeography in the introduction to “De bestiis marinis” by Georg Wilhelm Steller

2019 ◽  
Vol 46 (1) ◽  
pp. 63-74
Author(s):  
Stefano Mattioli
Keyword(s):  
Body Size ◽  
Phenotypic Plasticity ◽  
Geographical Distribution ◽  
Functional Traits ◽  
Marine Mammals ◽  
Main Part ◽  
Wide Distribution ◽  
Restricted Range ◽  
Direct Influence ◽  
Modern Biology

The rediscovery of the original, unedited Latin manuscript of Georg Wilhelm Steller's “De bestiis marinis” (“On marine mammals”), first published in 1751, calls for a new translation into English. The main part of the treatise contains detailed descriptions of four marine mammals, but the introduction is devoted to more general issues, including innovative speculation on morphology, ecology and biogeography, anticipating arguments and concepts of modern biology. Steller noted early that climate and food have a direct influence on body size, pelage and functional traits of mammals, potentially affecting reversible changes (phenotypic plasticity). Feeding and other behavioural habits have an impact on the geographical distribution of mammals. Species with a broad diet tend to have a wide distribution, whereas animals with a narrow diet more likely have only a restricted range. According to Steller, both sea and land then still concealed countless animals unknown to science.

Sign in / Sign up

Export Citation Format

Share Document