scholarly journals Primates follow the ‘island rule’: implications for interpreting Homo floresiensis

2007 ◽  
Vol 3 (4) ◽  
pp. 398-400 ◽  
Author(s):  
Lindell Bromham ◽  
Marcel Cardillo
Keyword(s):  
Primate Species ◽  
Small Animals ◽  
Island Rule ◽  
Size Change ◽  
Island Endemic ◽  
Large Animals

When the diminutive skeleton of Homo floresiensis was found on the Indonesian island of Flores, it was interpreted as an island dwarf, conforming to the ‘island rule’ that large animals evolve smaller size on islands, but small animals tend to get larger. However, previous studies of the island rule have not included primates, so the extent to which insular primate populations undergo size change was unknown. We use a comparative database of 39 independently derived island endemic primate species and subspecies to demonstrate that primates do conform to the island rule: small-bodied primates tend to get larger on islands, and large-bodied primates get smaller. Furthermore, larger species undergo a proportionally greater reduction in size on islands.

scholarly journals Plants obey (and disobey) the island rule

2019 ◽  
Vol 116 (36) ◽  
pp. 17632-17634 ◽  
Author(s):  
M. Biddick ◽  
A. Hendriks ◽  
K. C. Burns
Keyword(s):  
Leaf Area ◽  
Seed Size ◽  
Functional Traits ◽  
Small Animals ◽  
Island Rule ◽  
Southwest Pacific ◽  
Plant Stature ◽  
Large Animals

The island rule predicts that small animals evolve to become larger on islands, while large animals evolve to become smaller. It has been studied for over half a century, and its validity is fiercely debated. Here, we provide a perspective on the debate by conducting a test of the island rule in plants. Results from an extensive dataset on islands in the southwest Pacific illustrate that plant stature and leaf area obey the island rule, but seed size does not. Our results indicate that the island rule may be more pervasive than previously thought and that support for its predictions varies among functional traits.

EMPTY BODY WEIGHTS, CARCASS WEIGHTS AND OFFAL PROPORTIONS IN BULLS AND STEERS OF DIFFERENT MATURE SIZE

1984 ◽  
Vol 64 (1) ◽  
pp. 53-57 ◽  
Author(s):  
S. D. M. JONES ◽  
R. E. ROMPALA ◽  
J. W. WILTON ◽  
C. H. WATSON
Keyword(s):  
Body Weight ◽  
Small Animal ◽  
High Energy ◽  
Carcass Weight ◽  
Small Animals ◽  
Beef Steers ◽  
Body Weights ◽  
Breed Crosses ◽  
Large Animals ◽  
Animal Size

Empty body weights, carcass weights and offal proportions were compared in 33 young beef bulls and 33 beef steers of different mature body size (35 small or mainly British breed crosses, 31 large or Continental crosses). All cattle were fed a high energy diet based on corn silage and high moisture corn from weaning to slaughter. Slaughter was carried out once 6 mm of fat had been attained at the 11/12th ribs, determined ultrasonically. Feed was removed 24 h and water 16 h prior to slaughter. The offal components were all weighed fresh and the alimentary components emptied of digesta. Bulls weighed 8.0% heavier (P < 0.05) than steers at slaughter, while large animals were 38.7% heavier (P < 0.0001) than small animals. Bulls and large animals had carcasses that dressed out 1.5% heavier than steers and small animals. To eliminate the effect of gutfill, carcass weights and offal components were expressed as a proportion of empty body weight. Bulls had a higher proportion of warm carcass weight and lower proportions of liver, spleen, heart, lungs, rumen, abomasum, large intestine and front feet relative to empty body weight than steers. Large animals had a greater proportion of warm carcass weight and hind feet, and a lower proportion of head, hide, liver, kidneys, omasum and small intestine relative to empty body weight than small animals. All castration by size interactions for liveweight, carcass weight, empty body weight and offal proportions were not significant. Castration and small animal size both increased the proportion of noncarcass parts relative to empty body weight in animals slaughtered at similar finish. Key words: Body, carcass, offal, bull, steer, maturity

Theoretical and empirical scaling patterns and topological homology in bone trabeculae.

1998 ◽  
Vol 201 (4) ◽  
pp. 573-590
Author(s):  
S M Swartz ◽  
A Parker ◽  
C Huo
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Cancellous Bone ◽  
Structural Design ◽  
Theoretical Models ◽  
Small Animals ◽  
Bone Trabeculae ◽  
Large Animals ◽  
Vertebrate Skeleton ◽  
Area And Volume

Trabecular or cancellous bone is a major element in the structural design of the vertebrate skeleton, but has received little attention from the perspective of the biology of scale. In this study, we investigated scaling patterns in the discrete bony elements of cancellous bone. First, we constructed two theoretical models, representative of the two extremes of realistic patterns of trabecular size changes associated with body size changes. In one, constant trabecular size (CTS), increases in cancellous bone volume with size arise through the addition of new elements of constant size. In the other model, constant trabecular geometry (CTG), the size of trabeculae increases isometrically. These models produce fundamentally different patterns of surface area and volume scaling. We then compared the models with empirical observations of scaling of trabecular dimensions in mammals ranging in mass from 4 to 40x10(6)g. Trabecular size showed little dependence on body size, approaching one of our theoretical models (CTS). This result suggests that some elements of trabecular architecture may be driven by the requirements of maintaining adequate surface area for calcium homeostasis. Additionally, we found two key consequences of this strongly negative allometry. First, the connectivity among trabecular elements is qualitatively different for small versus large animals; trabeculae connect primarily to cortical bone in very small animals and primarily to other trabeculae in larger animals. Second, small animals have very few trabeculae and, as a consequence, we were able to identify particular elements with a consistent position across individuals and, for some elements, across species. Finally, in order to infer the possible influence of gross differences in mechanical loading on trabecular size, we sampled trabecular dimensions extensively within Chiroptera and compared their trabecular dimensions with those of non-volant mammals. We found no systematic differences in trabecular size or scaling patterns related to locomotor mode.

scholarly journals Evolutionary cascades induced by large frugivores

2017 ◽  
Vol 114 (45) ◽  
pp. 11998-12002 ◽  
Author(s):  
Jedediah F. Brodie
Keyword(s):  
Tropical Forests ◽  
Fruit Size ◽  
Peninsular Malaysia ◽  
Fruit Color ◽  
Small Animals ◽  
Fruit Traits ◽  
Frugivorous Birds ◽  
Large Animals ◽  
Evolutionary Consequences ◽  
Morphologic Changes

Large, fruit-eating vertebrates have been lost from many of the world’s ecosystems. The ecological consequences of this defaunation can be severe, but the evolutionary consequences are nearly unknown because it remains unclear whether frugivores exert strong selection on fruit traits. I assessed the macroevolution of fruit traits in response to variation in the diversity and size of seed-dispersing vertebrates. Across the Indo-Malay Archipelago, many of the same plant lineages have been exposed to very different assemblages of seed-dispersing vertebrates. Phylogenetic analysis of >400 plant species in 41 genera and five families revealed that average fruit size tracks the taxonomic and functional diversity of frugivorous birds and mammals. Fruit size was 40.2–46.5% smaller in the Moluccas and Sulawesi (respectively), with relatively depauperate assemblages of mostly small-bodied animals, than in the Sunda Region (Borneo, Sumatra, and Peninsular Malaysia), with a highly diverse suite of large and small animals. Fruit color, however, was unrelated to vertebrate diversity or to the representation of birds versus mammals in the frugivore assemblage. Overhunting of large animals, nearly ubiquitous in tropical forests, could strongly alter selection pressures on plants, resulting in widespread, although trait-specific, morphologic changes.

scholarly journals WHAT IS THE LENGTH OF A SNAKE?

2008 ◽  
pp. 1-3 ◽  
Author(s):  
Jesus A. Rivas ◽  
Rafeal E. Ascanio ◽  
Maria D. C. Munoz
Keyword(s):  
Large Range ◽  
Small Animals ◽  
Live Animal ◽  
Actual Length ◽  
Total Length ◽  
Large Animals ◽  
The Way

The way that herpetologists have traditionally measuredlive snakes is by stretching them on a ruler andrecording the total length (TL). However, due to the thinconstitution of the snake, the large number of intervertebraljoints, and slim muscular mass of most snakes,it is easier to stretch a snake than it is to stretch anyother vertebrate. The result of this is that the length ofa snake recorded is infl uenced by how much the animalis stretched. Stretching it as much as possible is perhapsa precise way to measure the length of the specimenbut it might not correspond to the actual length ofa live animal. Furthermore, it may seriously injure a livesnake. Another method involves placing the snake in aclear plexiglass box and pressing it with a soft materialsuch as rubber foam against a clear surface. Measuringthe length of the snake may be done by outlining itsbody with a string (Fitch 1987; Frye 1991). However, thismethod is restricted to small animals that can be placedin a box, and in addition, no indications of accuracy of thetechnique are given. Measuring the snakes with a fl exibletape has also been reported (Blouin-Demers 2003)but when dealing with a large animals the way the tapeis positioned can produce great variance on the fi nal outcome.In this contribution we revise alternative ways tomeasuring a snake and propose a method that offers repeatableresults. We further analyze the precision of thismethod by using a sample of measurements taken fromwild populations of green anacondas (Eunectes murinus)with a large range of sizes.

scholarly journals Shear-sensitive adhesion enables size-independent adhesive performance in stick insects

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191327 ◽  
Author(s):  
David Labonte ◽  
Marie-Yon Struecker ◽  
Aleksandra V. Birn-Jeffery ◽  
Walter Federle
Keyword(s):  
Body Weight ◽  
Adhesive Force ◽  
Whole Body ◽  
Small Animals ◽  
Shear Forces ◽  
Stick Insects ◽  
Adhesive Pads ◽  
The Difference ◽  
Large Animals ◽  
Adhesive Performance

The ability to climb with adhesive pads conveys significant advantages and is widespread in the animal kingdom. The physics of adhesion predict that attachment is more challenging for large animals, whereas detachment is harder for small animals, due to the difference in surface-to-volume ratios. Here, we use stick insects to show that this problem is solved at both ends of the scale by linking adhesion to the applied shear force. Adhesive forces of individual insect pads, measured with perpendicular pull-offs, increased approximately in proportion to a linear pad dimension across instars. In sharp contrast, whole-body force measurements suggested area scaling of adhesion. This discrepancy is explained by the presence of shear forces during whole-body measurements, as confirmed in experiments with pads sheared prior to detachment. When we applied shear forces proportional to either pad area or body weight, pad adhesion also scaled approximately with area or mass, respectively, providing a mechanism that can compensate for the size-related loss of adhesive performance predicted by isometry. We demonstrate that the adhesion-enhancing effect of shear forces is linked to pad sliding, which increased the maximum adhesive force per area sustainable by the pads. As shear forces in natural conditions are expected to scale with mass, sliding is more frequent and extensive in large animals, thus ensuring that large animals can attach safely, while small animals can still detach their pads effortlessly. Our results therefore help to explain how nature’s climbers maintain a dynamic attachment performance across seven orders of magnitude in body weight.

Influence of Temperature on Performance in Guinea Pigs

1957 ◽  
Vol 190 (3) ◽  
pp. 457-458 ◽  
Author(s):  
Charles G. Wilber
Keyword(s):  
Low Temperatures ◽  
Guinea Pigs ◽  
Peak Performance ◽  
Albino Rats ◽  
Small Animals ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Endocrine Factors ◽  
The Difference ◽  
Large Animals

Guinea pigs were forced to swim to total exhaustion in water at various temperatures. Small animals (400 gm) showed peak performance at about 40°C, large ones (1000 gm) at about 35°C. Large animals swam longer at low temperatures but shorter at high temperatures than did small ones. At 35°C all guinea pigs swam for an average of about 150 minutes. In general this species shows much less capacity for swimming than do albino rats. The difference may be related to diet or to endocrine factors.

scholarly journals Quantitative genetics of body size evolution on islands: an individual-based simulation approach

2019 ◽  
Vol 15 (10) ◽  
pp. 20190481 ◽  
Author(s):  
José Alexandre F. Diniz-Filho ◽  
Lucas Jardim ◽  
Thiago F. Rangel ◽  
Phillip B. Holden ◽  
Neil R. Edwards ◽  
...  
Keyword(s):  
Body Size ◽  
Quantitative Genetics ◽  
Evolutionary Genetics ◽  
Simulation Approach ◽  
Island Rule ◽  
Size Change ◽  
Evolutionary Patterns ◽  
New Developments ◽  
Size Evolution ◽  
Individual Based Simulation

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.

scholarly journals Ventilation/Perfusion Matching: Of Myths, Mice, and Men

Physiology ◽  
2019 ◽  
Vol 34 (6) ◽  
pp. 419-429 ◽  
Author(s):  
Alys R. Clark ◽  
Kelly S. Burrowes ◽  
Merryn H. Tawhai
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Air Flow ◽  
Small Animals ◽  
Flow Perfusion ◽  
Large Animals

Despite a huge range in lung size between species, there is little measured difference in the ability of the lung to provide a well-matched air flow (ventilation) to blood flow (perfusion) at the gas exchange tissue. Here, we consider the remarkable similarities in ventilation/perfusion matching between species through a biophysical lens and consider evidence that matching in large animals is dominated by gravity but in small animals by structure.

scholarly journals Locomotory stresses in the limb bones of two small mammals: the ground squirrel and chipmunk

1983 ◽  
Vol 103 (1) ◽  
pp. 131-154 ◽  
Author(s):  
A. A. Biewener
Keyword(s):  
Safety Factor ◽  
Ground Squirrel ◽  
High Speed ◽  
Bone Geometry ◽  
Direct Consequence ◽  
Material Strength ◽  
Small Animals ◽  
Limb Bones ◽  
Wide Range ◽  
Large Animals

Peak stresses acting in limb bones should increase with increasing size if the forces acting on the bones increase in direct proportion to the animal's body weight. This is a direct consequence of the scaling of limb bone geometry over a wide range in size in mammals. In addition, recent work has shown that the material strength of bone is similar in large and small animals. If the assumptions in this analysis are correct, large animals would have a lower safety factor to failure than small animals. The purpose of this study was to measure peak stresses acting in the limb bones of small animals during locomotion and compare the results with similar measurements available for larger animals. Locomotory stresses acting in the fore and hindlimb bones of two rodents, the ground squirrel (Spermophilus tridecemlineatus) and chipmunk (Tamais striatus), were calculated using ground force recordings and measurements of limb position taken from high speed x-ray cine films. Peak (compressive) stresses calculated to act in the bones of these animals (−31 to −86 MN/m2) are similar in magnitude to those determined for much larger mammals. The more proximal bones of the fore and hindlimb, the humerus and femur, were found to develop stresses (−31 to −42 MN/m2) significantly lower than those acting in the more distal bones of each limb: the radius, ulna and tibia (−58 to −86 MN/m2). All of the long bones from both species, except their femora, were found to be loaded principally in bending. The caudal cortices of each bone developed a peak compressive stress, whereas the cranial cortices were loaded in tension. Various features of the musculo-skeletal organization and manner of locomotion of these rodents are considered to explain how animals of different size maintain a uniform safety factor to failure.

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