scholarly journals Comparison of Dolphins' Body and Brain Measurements with Four Other Groups of Cetaceans Reveals Great Diversity

2016 ◽  
Vol 88 (3-4) ◽  
pp. 235-257 ◽  
Author(s):  
Sam H. Ridgway ◽  
Kevin P. Carlin ◽  
Kaitlin R. Van Alstyne ◽  
Alicia C. Hanson ◽  
Raymond J. Tarpley
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Body Length ◽  
Brain Volume ◽  
Brain Size ◽  
The Other ◽  
Vascular Networks ◽  
Data Set ◽  
Brain Mass ◽  
Endocranial Volume

We compared mature dolphins with 4 other groupings of mature cetaceans. With a large data set, we found great brain diversity among 5 different taxonomic groupings. The dolphins in our data set ranged in body mass from about 40 to 6,750 kg and in brain mass from 0.4 to 9.3 kg. Dolphin body length ranged from 1.3 to 7.6 m. In our combined data set from the 4 other groups of cetaceans, body mass ranged from about 20 to 120,000 kg and brain mass from about 0.2 to 9.2 kg, while body length varied from 1.21 to 26.8 m. Not all cetaceans have large brains relative to their body size. A few dolphins near human body size have human-sized brains. On the other hand, the absolute brain mass of some other cetaceans is only one-sixth as large. We found that brain volume relative to body mass decreases from Delphinidae to a group of Phocoenidae and Monodontidae, to a group of other odontocetes, to Balaenopteroidea, and finally to Balaenidae. We also found the same general trend when we compared brain volume relative to body length, except that the Delphinidae and Phocoenidae-Monodontidae groups do not differ significantly. The Balaenidae have the smallest relative brain mass and the lowest cerebral cortex surface area. Brain parts also vary. Relative to body mass and to body length, dolphins also have the largest cerebellums. Cortex surface area is isometric with brain size when we exclude the Balaenidae. Our data show that the brains of Balaenidae are less convoluted than those of the other cetaceans measured. Large vascular networks inside the cranial vault may help to maintain brain temperature, and these nonbrain tissues increase in volume with body mass and with body length ranging from 8 to 65% of the endocranial volume. Because endocranial vascular networks and other adnexa, such as the tentorium cerebelli, vary so much in different species, brain size measures from endocasts of some extinct cetaceans may be overestimates. Our regression of body length on endocranial adnexa might be used for better estimates of brain volume from endocasts or from endocranial volume of living species or extinct cetaceans.

scholarly journals Do Different Methods Yield Equivalent Estimations of Brain Size in Birds?

2020 ◽  
Vol 95 (2) ◽  
pp. 113-122
Author(s):  
Diego Ocampo ◽  
César Sánchez ◽  
Gilbert Barrantes
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Brain Mass ◽  
Wide Range ◽  
Evolutionary Studies ◽  
Relative Brain Size ◽  
Using Data ◽  
Endocranial Volume ◽  
The Brain ◽  
Size Estimates

The ratio of brain size to body size (relative brain size) is often used as a measure of relative investment in the brain in ecological and evolutionary studies on a wide range of animal groups. In birds, a variety of methods have been used to measure the brain size part of this ratio, including endocranial volume, fixed brain mass, and fresh brain mass. It is still unclear, however, whether these methods yield the same results. Using data obtained from fresh corpses and from published sources, this study shows that endocranial volume, mass of fixed brain tissue, and fresh mass provide equivalent estimations of brain size for 48 bird families, in 19 orders. We found, however, that the various methods yield significantly different brain size estimates for hummingbirds (Trochilidae). For hummingbirds, fixed brain mass tends to underestimate brain size due to reduced tissue density, whereas endocranial volume overestimates brain size because it includes a larger volume than that occupied by the brain.

scholarly journals The pattern of brain-size change in the early evolution of cetaceans

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257803
Author(s):  
David A. Waugh ◽  
J. G. M. Thewissen
Keyword(s):  
Body Mass ◽  
Middle Miocene ◽  
Brain Size ◽  
Occipital Condyle ◽  
Sudden Increase ◽  
Size Change ◽  
Brain Mass ◽  
Single Method ◽  
Relative Brain Size ◽  
Endocranial Volume

Most authors have identified two rapid increases in relative brain size (encephalization quotient, EQ) in cetacean evolution: first at the origin of the modern suborders (odontocetes and mysticetes) around the Eocene-Oligocene transition, and a second at the origin of the delphinoid odontocetes during the middle Miocene. We explore how methods used to estimate brain and body mass alter this perceived timing and rate of cetacean EQ evolution. We provide new data on modern mammals (mysticetes, odontocetes, and terrestrial artiodactyls) and show that brain mass and endocranial volume scale allometrically, and that endocranial volume is not a direct proxy for brain mass. We demonstrate that inconsistencies in the methods used to estimate body size across the Eocene-Oligocene boundary have caused a spurious pattern in earlier relative brain size studies. Instead, we employ a single method, using occipital condyle width as a skeletal proxy for body mass using a new dataset of extant cetaceans, to clarify this pattern. We suggest that cetacean relative brain size is most accurately portrayed using EQs based on the scaling coefficients as observed in the closely related terrestrial artiodactyls. Finally, we include additional data for an Eocene whale, raising the sample size of Eocene archaeocetes to seven. Our analysis of fossil cetacean EQ is different from previous works which had shown that a sudden increase in EQ coincided with the origin of odontocetes at the Eocene-Oligocene boundary. Instead, our data show that brain size increased at the origin of basilosaurids, 5 million years before the Eocene-Oligocene transition, and we do not observe a significant increase in relative brain size at the origin of odontocetes.

Measurement of weasel body size

1991 ◽  
Vol 69 (8) ◽  
pp. 2277-2279 ◽  
Author(s):  
Donald R. Johnson
Keyword(s):  
Principal Component Analysis ◽  
Body Size ◽  
Body Mass ◽  
Body Length ◽  
Reliable Method ◽  
Principal Component ◽  
The Other ◽  
Young Males ◽  
Adult Females ◽  
Juvenile Males

Body size of long-tailed weasels (Mustela frenata) and short-tailed weasels (Mustela erminea) collected in northern and central Idaho was indexed using cranial length, zygomatic width, cranial mass, body mass, and body length (total less tail) as size variables. In comparison with the other variables, body length had lower and sometimes nonsignificant correlations with principal component 1 (PC1) scores of principal component analysis, suggesting that its further use as an index of body size for these species is inappropriate. Young males (6–9 months of age) of one or both species, similar in body size to adult females, occurred in all regions sampled. Because body size alone is not a reliable method of separating juvenile males from adult females, specimens identified as male lacking the baculum or tag information independently confirming sex are possibly misclassified.

scholarly journals The domesticated brain: genetics of brain mass and brain structure in an avian species

2016 ◽  
Author(s):  
R. Henriksen ◽  
M. Johnsson ◽  
L. Andersson ◽  
P. Jensen ◽  
D. Wright
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Brain Size ◽  
Large Body ◽  
Brain Regions ◽  
Population Variation ◽  
Wild Progenitor ◽  
Brain Mass ◽  
Evolutionary Studies ◽  
Selection For

ABSTRACTAs brain size usually increases with body size it has been assumed that the two are tightly constrained and evolutionary studies have therefore often been based on relative brain size (i.e. brain size proportional to body size) instead of absolute brain size. The process of domestication offers an excellent opportunity to disentangle the linkage between body and brain mass due to the extreme selection for increased body mass that has occurred. By breeding an intercross between domestic chicken and their wild progenitor, we address this relationship by simultaneously mapping the genes that control inter-population variation in brain mass and body mass. Loci controlling variation in brain mass and body mass have separate genetic architectures and are therefore not directly constrained. Genetic mapping of brain regions in the intercross indicates that domestication has led to a larger body mass and to a lesser extent a larger absolute brain mass in chickens, mainly due to enlargement of the cerebellum. Domestication has traditionally been linked to brain mass regression, based on measurements of relative brain mass, which confounds the large body mass augmentation due to domestication. Our results refute this concept in chicken and confirm recent studies that show that different genetic architectures underlie these traits.

Brain size/body weight in the dingo (Canis dingo): comparisons with domestic and wild canids

2017 ◽  
Vol 65 (5) ◽  
pp. 292 ◽  
Author(s):  
Bradley P. Smith ◽  
Teghan A. Lucas ◽  
Rachel M. Norris ◽  
Maciej Henneberg
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Cuon Alpinus ◽  
Size Relationship ◽  
Wild Canids ◽  
Free Ranging ◽  
The Impact ◽  
Endocranial Volume ◽  
The Brain

Endocranial volume was measured in a large sample (n = 128) of free-ranging dingoes (Canis dingo) where body size was known. The brain/body size relationship in the dingoes was compared with populations of wild (Family Canidae) and domestic canids (Canis familiaris). Despite a great deal of variation among wild and domestic canids, the brain/body size of dingoes forms a tight cluster within the variation of domestic dogs. Like dogs, free-ranging dingoes have paedomorphic crania; however, dingoes have a larger brain and are more encephalised than most domestic breeds of dog. The dingo’s brain/body size relationship was similar to those of other mesopredators (medium-sized predators that typically prey on smaller animals), including the dhole (Cuon alpinus) and the coyote (Canis latrans). These findings have implications for the antiquity and classification of the dingo, as well as the impact of feralisation on brain size. At the same time, it highlights the difficulty in using brain/body size to distinguish wild and domestic canids.

scholarly journals Ambient temperature correlates with geographic variation in body size of least horseshoe bats

2020 ◽  
Vol 66 (5) ◽  
pp. 459-465 ◽  
Author(s):  
Man Wang ◽  
Kelly Chen ◽  
Dongge Guo ◽  
Bo Luo ◽  
Weiwei Wang ◽  
...  
Keyword(s):  
Body Size ◽  
Geographic Variation ◽  
Body Mass ◽  
Body Length ◽  
Primary Productivity ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Heat Conservation ◽  
The Mean ◽  
Horseshoe Bats

Abstract Geographic variation in body size is common within many animal species. The causes of this pattern, however, remain largely unexplored in most vertebrate groups. Bats are widely distributed globally owing to their ability of powered flight. Most bat species encounter a variety of climatic conditions across their distribution range, making them an ideal taxon for the study of ecogeographic patterns in body size. Here, we used adult least horseshoe bats, Rhinolophus pusillus, to test whether geographic variation in body size was determined by heat conservation, heat dissipation, climatic seasonality, or primary productivity. We measured body mass and head-body length for 246 adult bats from 12 allopatric colonies in China. We quantified the ecological conditions inhabited by each colony, including mean maximum temperature of the warmest month, mean minimum temperature of the coldest month, temperature seasonality, precipitation seasonality, and annual net primary productivity (ANPP). Body mass and head-body length, 2 of the most reliable indicators of body size, exhibited marked differences between colonies. After controlling for spatial autocorrelation, the mean minimum temperature of the coldest month explained most of the variation in body size among colonies, regardless of sex. The mean maximum temperature, climatic seasonality, and ANPP had limited power in predicting body size of males or females in comparison with mean minimum temperature. These results support the heat conservation hypothesis and suggest adaptive responses of body size to cold climates in cave-dwelling bats.

scholarly journals Effects of Isometric Brain-Body Size Scaling on the Complexity of Monoaminergic Neurons in a Minute Parasitic Wasp

2017 ◽  
Vol 89 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Emma van der Woude ◽  
Hans M. Smid
Keyword(s):  
Body Size ◽  
Cognitive Abilities ◽  
Brain Volume ◽  
Brain Size ◽  
Parasitic Wasp ◽  
Body Volume ◽  
Neural Pathways ◽  
Trichogramma Evanescens ◽  
Monoaminergic Neurons ◽  
Large Animals

Trichogramma evanescens parasitic wasps show large phenotypic plasticity in brain and body size, resulting in a 5-fold difference in brain volume among genetically identical sister wasps. Brain volume scales linearly with body volume in these wasps. This isometric brain scaling forms an exception to Haller's rule, which states that small animals have relatively larger brains than large animals. The large plasticity in brain size may be facilitated by plasticity in neuron size, in the number of neurons, or both. Here, we investigated whether brain isometry requires plasticity in the number and size of monoaminergic neurons that express serotonin (5HT), octopamine (OA), and dopamine (DA). Genetically identical small and large T. evanescens appear to have the same number of 5HT-, OA-, and DA-like immunoreactive cell bodies in their brains, but these cell bodies differ in diameter. This indicates that brain isometry can be facilitated by plasticity in the size of monoaminergic neurons, rather than plasticity in numbers of monoaminergic neurons. Selection pressures on body miniaturization may have resulted in the evolution of miniaturized neural pathways that allow even the smallest wasps to find suitable hosts. Plasticity in the size of neural components may be among the mechanisms that underlie isometric brain scaling while maintaining cognitive abilities in the smallest individuals.

scholarly journals Using relative brain size to better understand trophic interactions and phenotypic plasticity of invasive lionfish (Pterois volitans)

2020 ◽  
Author(s):  
McKenna Becker
Keyword(s):  
Body Mass ◽  
Brain Size ◽  
Predation Pressure ◽  
Mass Ratio ◽  
Pterois Volitans ◽  
Predator Prey ◽  
Brain Mass ◽  
Body Mass Ratio ◽  
Relative Brain Size ◽  
The Brain

AbstractPredator-prey dynamics provide critical insight into overall coral reef health. It has been shown that predator-prey relationships link the relative brain size of predators to their prey. Predation pressure forces prey to use decision-making skills that require higher cognition by inspecting and identifying predators and then adjusting their behavior to achieve the highest chance for survival. However, the predation pressure that prey face outweighs the pressure predators face to find prey, resulting in prey having larger relative brain sizes than their predators. There is little data on the relative brain size of fishes with few natural predators such as Pterois volitans. This study compared the brain mass to body mass ratio of Pterois volitans, which have very few natural predators and thus very little predation pressure, to the brain mass to body mass ratio of their prey, possible predators, competitors, and taxonomically similar fish. Lionfish had a significantly smaller relative brain size than their predators, prey, and competitors, but was not significantly smaller than taxonomically similar fish. These results demonstrate that the morphological anti-predator adaptation of venomous spines causes little predation pressure. Thus, lionfish do not use the same cognitive skills as other prey or predators and, in turn, have smaller relative brain sizes.

Size Matters: Body Size is Correlated with Longevity in Speckled Cockroaches (Nauphoeta cineria).

2021 ◽  
Vol 14 ◽  
Author(s):  
Sami Badwan ◽  
James Harper
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Body Length ◽  
Individual Species ◽  
Time Of Death ◽  
Large Size ◽  
The Status ◽  
Males And Females ◽  
The Relationship ◽  
Individual Body

Background: A relationship between body size and longevity has long been appreciated within eukaryotes, especially vertebrates. Introduction: In general, large size is associated with increased longevity among species of mammals and birds but is associated with decreased longevity within individual species such as dogs and mice. In this study, we examined the relationship between measures of individual body size and longevity in a captive population of speckled cockroaches (Nauphoeta cineria). Method: Newly molted adults of both sexes were removed from a mass colony housed in multiple terraria and housed individually with food and water provided ad libitum for the duration of their lifespan. Thrice weekly, the status (i.e. live/dead) of individual cockroaches was noted for the duration of the study. Individuals found dead were weighed and measured to obtain body mass and morphometric measures and the age at the time of death was recorded. The relationship between body size and lifespan was assessed. Result: Contrary to what is commonly seen within vertebrates, large cockroaches were longer-lived than their smaller counterparts. Specifically, body mass, body length and pronotum width were all significantly correlated with the age at death in a mixed population of males and females (n = 94). In addition, we found that the longevity of a historically larger population in terms of both body mass and body length were significantly longer-lived than the population used in this study. Conclusion: These data indicate there is a significant interaction between body size and aging in this species and that increased size results in a survival advantage. There is evidence in the literature indicating that a positive relationship between size and longevity may be common in insects.

Can endocranial volume be used as an estimate of brain size in birds?

2002 ◽  
Vol 80 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Andrew N Iwaniuk ◽  
John E Nelson
Keyword(s):  
Positive Relationship ◽  
Brain Size ◽  
Reliable Estimate ◽  
Avian Brain ◽  
Brain Mass ◽  
Age Related ◽  
Significant Difference ◽  
Two Measures ◽  
Endocranial Volume ◽  
Size Data

Endocranial volumes of vertebrate skulls and brain masses are often used interchangeably in comparative analyses of brain size. We test whether endocranial volume can be used as a reliable estimate of brain size in birds by comparing endocranial volumes with brain masses across 82 species using absolute values and with respect to body size. The results of paired tests across all 82 species and within two orders, Passeriformes and Psittaciformes, did not yield a significant difference between the two measures. These results were supported by correlational analyses that showed a significant positive relationship between endocranial volume and brain mass. Unpaired tests within short-tailed shearwaters (Puffinus tenuirostris) and paired tests within budgerigars (Melopsittacus undulatus) also yielded no significant differences between endocranial volume and brain mass. Thus, a combination of interspecific and intraspecific comparisons indicates that endocranial volume does provide a reliable estimate of brain size. Although this may enable more rapid collection of avian brain size data, endocranial volume should be used with caution because it cannot account for seasonal and age-related variation and cannot be used to measure differences in brain structure.

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