scholarly journals Adaptive significance of death feigning posture as a specialized inducible defence against gape-limited predators

2006 ◽  
Vol 273 (1594) ◽  
pp. 1631-1636 ◽  
Author(s):  
Atsushi Honma ◽  
Shintaro Oku ◽  
Takayoshi Nishida

Death feigning is fairly common in a number of taxa, but the adaptive significance of this behaviour is still unclear and has seldom been tested. To date, all proposed hypotheses have assumed that prey manage to escape predation by sending a death-mimicking signal, although death-feigning postures are markedly different from those of dead animals. Moreover, the efficacy of this technique may largely depend on the foraging mode of the predator; death feigning seldom works with sit-and-wait predators that make the decision to attack and consume prey within a very brief time. We examined whether death feigning in the pygmy grasshopper Criotettix japonicus Haan was an inducible defence behaviour against the frog Rana nigromaculata , a sit-and-wait, gape-limited predator. The characteristic posture assumed by the grasshopper during death feigning enlarges its functional body size by stretching each of three body parts (pronotum, hind legs and lateral spines) in three different directions, thereby making it difficult for the predator to swallow the prey. Our result is the first consistent explanation for why death-mimicking animals do not always mimic the posture of dead animals.

1973 ◽  
Vol 39 (2) ◽  
pp. 255-261 ◽  
Author(s):  
A. Roberto Frisancho ◽  
Jorge Sanchez ◽  
Danilo Pallardel ◽  
Lizandro Yanez

1962 ◽  
Vol 3 (2) ◽  
pp. 169-180 ◽  
Author(s):  
Forbes W. Robertson

1. Mass selection for both high- and low-ratio of wing to thorax length has been carried out on a population of Drosophila melanogaster. The response to selection was immediate and sustained. When the experiment was stopped after ten generations, the wing area in the two selected lines differed by about 30%. The heritability estimate worked out at 0·56 ± 0·08.2. Thorax length remained comparatively unchanged during selection nor was there any change in wing shape. There was some evidence of assymetry of response since there was a relatively greater change in favour of smaller rather than larger size.3. The tibia length of all pairs of legs showed correlated changes so that the lines with larger or smaller wing sizes had also larger and smaller legs.4. The normal allometric relation between wing and thorax length, associated with variation in body-size, apparently also changed, so that for a given change in thorax length there was a greater or smaller proportional change in wing size in the high- or low-ratio lines.5. The changes in relative wing size are due to changes in cell number.6. It is suggested that the genetic changes due to selection act in the early pupal period when the imaginal discs are undergoing differentiation and proliferation to form imaginal hypoderm and appendages.7. Tests of genetic behaviour failed to show any departure from additivity in crosses which involved the unselected population and the high-ratio line. But highly significant departures existed in the cross to the low-ratio line. Relatively smaller wing size behaves as largely recessive. Stability of the normal wing/thorax ratio involves dominance and probably also epistasis. The genetic properties of the relative size of the appendage are apparently similar to those which characterize body-size as a whole.8. It is suggested that selection provides a valuable tool for studying the constancy or lability of the growth patterns which determine morphology.


2010 ◽  
Vol 31 (4) ◽  
pp. 558-562 ◽  
Author(s):  
Rodica Plăiaşu ◽  
Tibor Hartel ◽  
Raluca Ioana Băncilă ◽  
Dan Cogălniceanu ◽  
Joost Smets

AbstractBody condition is important because it is correlated with population and habitat quality parameters. Since the direct measurements are either lethal or unreliable, a wide range of non-lethal body condition indices has been proposed. The aim of our study was to apply and compare three body condition indices (Fulton's index, relative body condition mass index and residual index) using body size indicator – body mass data for 24 populations of the yellow bellied toad (Bombina variegata). The condition index should be independent of body size indicator, in this case snout vent length (SVL). Therefore we tested all three indices for the statistical independence of SVL and for the normality of distribution. Fulton's index violated the independence assumption, whereas the relative body condition mass index did not have a normal distribution. Residual index was found both independent of SVL and normally distributed. Moreover, the residual index highlighted biological significant differences on the basis of altitude and season. Our results recommend the residual index as a useful tool in amphibian monitoring and conservation.


2002 ◽  
Vol 10 (1-2) ◽  
pp. 27-55 ◽  
Author(s):  
Felix K. Ameka

Different languages present a variety of ways of talking about emotional experience. Very commonly, feelings are described through the use of ‘body image constructions’ in which they are associated with processes in, or states of, specific body parts. The emotions and the body parts that are thought to be their locus and the kind of activity associated with these body parts vary cross-culturally. This study focuses on the meaning of three ‘body image constructions’ used to describe feelings similar to, but also different from, English ‘jealousy’, ‘envy’, and ‘covetousness’ in the West African language Ewe. It is demonstrated that a ‘moving body’, a pychologised eye, and red eyes are scripted for these feelings. It is argued that the expressions are not figurative and that their semantics provide good clues to understanding the cultural construction of emotions both emotions and the body.


Author(s):  
Hjördís Sigursteinsdóttir ◽  
Hafdís Skúladóttir ◽  
Thórey Agnarsdóttir ◽  
Sigrídur Halldórsdóttir

Background: Middle managers have not received enough attention within the healthcare field, and little is known how stressful factors in their work environment coupled with a lack of adequate sleep are related to musculoskeletal pain. The aim of this study was to examine the correlation between stressful factors in the work environment, lack of adequate sleep, and pain/discomfort in three body areas. Methods: Questionnaire was sent electronically to all female nursing unit managers (NUM) in Iceland through the outcome-survey system. The response rate was 80.9%. Results: NUM who had high pain/discomfort in the neck area also had very high pain/discomfort in the shoulder area and pain in the lower back. The results also revealed positive a medium-strong correlation between mental and physical exhaustion at the end of the workday and musculoskeletal pain. Stress in daily work, mental strain at work, and being under time-pressures had hardly any correlation with pain/discomfort in the three body parts. Adequate sleep had a significant negative correlation with all stressful factors in the work environment and all three body parts under review. Conclusion: The results will hopefully lead to a better consideration of stressful factors in the work environment, sleep, and musculoskeletal pain in middle managers.


Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1309
Author(s):  
János L. Korponai ◽  
Csilla Kövér ◽  
Charo López-Blanco ◽  
István Gyulai ◽  
László Forró ◽  
...  

The body size of aquatic invertebrates is, to a great extent, dependent on ambient temperature, but size distributions are also determined by other factors like food supply and predation. The effect of temperature on organisms is formulated in the temperature–size hypothesis, which predicts a smaller body size with increasing temperature. In this study, the effect of temperature on the subfossil remains of three littoral Cladocera (Alona affnis, A. quadrangularis, and Chydorus cf. sphaericus) was investigated. Exoskeletal remains of these species can be found in large numbers in lacustrine sediments and over a wide north–south range in Europe. The total length of both headshield and postabdomen for A. affinis and A. quadrangularis and carapace length for C. cf. sphaericus were measured to observe their response to changes in latitude and temperature. A different response to ambient temperature in the growth of body parts was observed. The size of the headshields of both Alona species and of the carapace of Chydorus was significantly larger in colder regions as opposed to warm ones. It turned out that the postabdomen was not a good predictor of ambient temperature. While the sizes of all remains increased with latitude, the sizes of the Alona remains was smaller in the mountain lakes of the Southern Carpathians than in other cold lakes, in this case in Finland, a fact indicative of the importance of other factors on size distribution. This study demonstrates that a morphological response to climate is present in littoral cladocerans, and, therefore, changes in the length of headshield and carapace may be used as a proxy for climate changes in paleolimnological records.


1974 ◽  
Vol 19 (1) ◽  
pp. 47-65 ◽  
Author(s):  
G. Wiener ◽  
Susan Hayter

SUMMARYBody weight was studied from birth to 5½ years of age and six linear measures of body size from birth to 4¼ years for sheep of five breeds, Scottish Blackface, Cheviot, Welsh Mountain, Lincoln Longwool and Southdown, and of crosses of these breeds with each other and with the Tasmanian Merino, but not in all possible combinations. The sheep were run as a single flock. Numbers ranged from 753 at birth to 150 at the end of the experimental period.There were marked differences among the breeds and crosses in all aspects of body size and some differences in rate of maturity. They also differed in conformation independently of body weight. Crosses of the hill breeds with the Lincoln and probably with the Southdown were heavier than the average of the parental breeds and larger in some linear body measurements from about weaning onwards. The weights of crosses of Blackface and Cheviot with Lincoln eventually exceeded those of the heavier parent of the cross. For the crosses among the three hill breeds only the Blackface Cheviot cross showed significant deviations from mid-parent values for weight and size.Maternal effects were important for all traits studied from birth to weaning and for weight up to a year old. In relation to mature size, Welsh dams produced the biggest and Lincoln the smallest lambs. The data did not permit Southdown maternal effects to be estimated. The effects of birth type and rearing were apparent for late maturing body parts up to a year old and for weight up to 3 years. Males, measured only from birth to weaning, were heavier and generally larger than females.Residual correlations between the various measures of size varied from 0·1 to 0·7.


1963 ◽  
Vol 5 (1) ◽  
pp. 77-86 ◽  
Author(s):  
C. S. Taylor ◽  
W. C. Rollins

SUMMARYThe variation and covariation of 12 linear body measurements within 60 pairs of monozygotic twin heifers is analysed in terms of a twin's mean size over a two-year period.Possibly all the covariation, and two thirds, on average, of the variation can be accounted for by a single factor common to all the measurements.Interpretation of this factor shows that a twin is a more or less proportional replicate of its identical co-twin. This proportionality, however, is somewhat distorted because of relatively greater differences in the later maturing body parts.Finally it is shown that the predominant differences in both size and shape can simultaneously be described as twin lagging behind identical co-twin by 0±11·8 days' growth.


2020 ◽  
Author(s):  
Jonathan H. Massey ◽  
Jun Li ◽  
David L. Stern ◽  
Patricia J. Wittkopp

AbstractUnderstanding the genetic basis of species differences is a major goal in evolutionary biology. Pigmentation divergence between Drosophila species often involves genetic changes in pigmentation candidate genes that pattern the body and wings, but it remains unclear how these changes affect pigmentation evolution in multiple body parts between the same diverging species. Drosophila elegans and D. gunungcola show pigmentation differences in the thorax, legs, and wings, with D. elegans exhibiting male-specific wing spots and D. gunungcola lacking wing spots with intensely dark thoraces and legs. Here, we performed QTL mapping to identify the genetic architecture of these differences. We find a large effect QTL on the X chromosome for all three body parts. QTL on Muller Element E were found for thorax pigmentation in both backcrosses but were only marginally significant in one backcross for the legs and wings. Consistent with this observation, we isolated the effects of the Muller Element E QTL by introgressing D. gunungcola alleles into a D. elegans genetic background and found that D. gunungcola alleles linked near the pigmentation candidate gene ebony caused intense darkening of the thorax, minimal darkening of legs, and minimal shrinking of wing spots. D. elegans ebony mutants showed changes in pigmentation consistent with Ebony having different effects on pigmentation in different tissues. Our results suggest that multiple genes have evolved differential effects on pigmentation levels in different body regions.


Sign in / Sign up

Export Citation Format

Share Document