scholarly journals The trade-off between color and size in lizards' conspicuous tails

2021 ◽  
Author(s):  
Raiane dos Santos Guidi ◽  
Vinicius de Avelar Sao-Pedro ◽  
Holda Ramos-Silva ◽  
Gabriel Correa Costa ◽  
Daniel Marques Almeida Pessoa
Keyword(s):  
Body Size ◽  
Natural Environment ◽  
Body Part ◽  
The Body ◽  
Trade Off ◽  
Red Color ◽  
Color Signals ◽  
Free Ranging

A tail of conspicuous coloration is hypothesized to be an advantageous trait for many species of lizards. Predator attacks would be directed to a non-vital, and autotomizable, body part, increasing the chance of survival. However, as body size increases it also increases the signaling area that could attract predators from greater distances, increasing the overall chance of predation. Here, we test the hypothesis that there is a trade-off between tail color and size, affecting predation probabilities. We used plasticine replicas of lizards to study the predation patterns of small and large lizards with red and blue tails. In a natural environment, we exposed six hundred replicas subjected to the attack of free-ranging predators. Large red-tailed models were attacked more quickly, and more intensely, by birds. Mammals and unidentified predators showed no preference for any size or colors. The attacks were not primarily directed to conspicuous tails when compared to the body or the head of our replicas. Our study suggests that red color signals in large lizards could enhance their detection by visually oriented predators (i.e., birds). The efficacy of conspicuous tails as a decoy may rely on associated behavioral displays, which are hard to test with static replicas.

Studies on the growth and longevity of the yellow-bellied toad, Bombina variegata, in natural environments

1993 ◽  
Vol 14 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Barbara Plytycz ◽  
Janusz Bigaj
Keyword(s):  
Body Size ◽  
Body Length ◽  
Cross Sections ◽  
Natural Environment ◽  
Early Life ◽  
Dorsal Surface ◽  
The Body ◽  
Natural Environments ◽  
Bombina Variegata ◽  
Different Parts

AbstractYellow-bellied toads were studied in their natural environment in a mountain locality in southeastern Poland. 608 specimens were captured, marked by yellow skin autografts placed in different parts of their dorsal surface according to body length, and released. Some of them were recaptured and measured from one to nine years later to estimate their growth and longevity. Yellow-bellied toads grew rapidly in early life; thereafter their growth was very limited. Body size was not an accurate age indicator of an individual of this species. The body length 51-55 mm was maximal in this locality. Yellow-bellied toads were long-lived in nature, some individuals surviving for much more than ten years, and perhaps even more than 20 years. The skeletochronological technique (counting the growth lines in phalangeal cross-sections of the clipped toes of some marked individuals) underestimated the actual age of these animals.

Niche partitioning within a population of sea snakes is constrained by ambient thermal homogeneity and small prey size

2020 ◽  
Vol 129 (3) ◽  
pp. 644-651 ◽  
Author(s):  
Claire Goiran ◽  
Gregory P Brown ◽  
Richard Shine
Keyword(s):  
Body Size ◽  
Habitat Use ◽  
New Caledonia ◽  
Niche Partitioning ◽  
Thermal Conditions ◽  
The Body ◽  
Small Prey ◽  
Sea Snakes ◽  
Local Extirpation ◽  
Free Ranging

Abstract In many populations of terrestrial snakes, the phenotype of an individual (e.g. body size, sex, colour) affects its habitat use. One cause for that link is gape limitation, which can result in larger snakes eating prey that are found in different habitats. A second factor involves thermoregulatory opportunities, whereby individuals select habitats based upon thermal conditions. These ideas predict minimal intraspecific variation in habitat use in a species that eats small prey and lives in a thermally uniform habitat, such as the sea snake Emydocephalus annulatus, which feeds on tiny fish eggs and lives in inshore coral reefs. To test that prediction, we gathered data on water depths and substrate attributes for 1475 sightings of 128 free-ranging E. annulatus in a bay near Noumea, New Caledonia. Habitat selection varied among individuals, but with a preference for coral-dominated substrates. The body size and reproductive state of a snake affected its detectability in deep water, but overall habitat use was not linked to snake body size, colour morph, sex or pregnancy. A lack of ontogenetic shifts in habitat use allows extreme philopatry in E. annulatus, thereby reducing gene flow among populations and, potentially, delaying recolonization after local extirpation events.

scholarly journals Sized-related changes in winter condition of male calves in reindeer

Rangifer ◽  
1987 ◽  
Vol 7 (1) ◽  
pp. 2 ◽  
Author(s):  
T. Helle ◽  
E. Pulliainen ◽  
J. Aspi
Keyword(s):  
Body Size ◽  
Food Competition ◽  
The Body ◽  
Carcass Weight ◽  
Length Ratio ◽  
Late Winter ◽  
Winter Condition ◽  
Selection For ◽  
Snow Conditions ◽  
Free Ranging

<p>Size-related changes in body condition of free-ranging male calves of semi-domesticated reindeer were studied in northern Finland from October 1983 to February 1984. In October-November, back fat depth or muscle fat percent correlated positively with the body size (=back length). In January, the highest means especially for muscle fat percent were found among medium-sized calves. Carcass weight and weight/back length ratio correlated positively with size, excluding February sample, where correlation for carcass weight was non-significant and for weight/back length ratio negative. Weight in the autumn correlated negatively with weight in February. Therefore, normalizing selection for body size (working against small and large phenotypes) is expected to occur in late winter. Small calves may be at greater mortality risk because of lower initial body reserves. Large calves commonly disperse during the rutting season and they may suffer most from increased food competition later in winter. Using of medium-sized calves for breeding might be the safest policy on ranges characterized by short food supply and difficult snow conditions.</p><p>Koon vaikutus poron urosvasojen talviseen kuntoon.</p><p>Abstract in Finnish / Tiivistelm&auml;: Koon vaikutusta vapaana laiduntavien poron urosvasojen kuntoon tutkittiin Pohjois-Suomessa loka-helmikuussa talvella 1983-84. Loka-marraskuussa selk&auml;rasvan paksuus tai lihaksen rasvaprosentti riippui vasan koosta ( = sel&auml;n pituus). Tammikuussa sen sijaan lihaksen rasvaprosentti oli korkein keskikokoisilla vasoilla. Ruhopaino sek&auml; ruhopaino/sel&auml;n pituus oli yleensa riippuvainen koosta. Helmikuussa ruhopainon riippuvuus koosta ei ollut en&auml;&auml; tilastollisesti merkitsev&auml;, ja koon ja ruhopainon/sel&auml;npituuden v&auml;linen korrelaatio oli negatiivinen. Eniten painoa menettiv&auml;t (%) loka-helmikuun v&auml;lill&auml; suurikokoisimmat vasat. Havainnot viittaavat siihen, ett&auml; talvella esiintyv&auml; kuolleisuus on normalisoivaa koon suhteen (karsii pieni&auml; ja suuria fenotyyppej&auml;). Pienten vasojen kuolleisuusriski on suuri alunperinkin v&auml;h&auml;isen varastoravinnon vuoksi. Suuret vasat puolestaan erkaantuvat usein emist&auml;&auml;n jo rykim&auml;aikana, ja joutuvat k&auml;rsim&auml;&auml;n eniten talven mittaan kiristyv&auml;st&auml; ravintokilpailusta. Niukoilla laitumilla siitokseen on turvallisinta s&auml;&auml;st&auml;&auml; keskikokoisia vasoja.</p><p>Sammenhengen mellom st&oslash;rrelse og vinterkondisjon hos hankalver av reinsdyr.</p><p>Abstract in Norwegian / Sammendrag: St&oslash;rrelses-relaterte forandringer i kroppskondisjon hos fritt beitende han-kalver av semidomestiserte rein er studert i Nord-Finland fra oktober 1983 til februar 1984. I oktober - november korrelerte tykkelsen av ryggfettet eller muskelfett-prosenten positivt med kroppsst&oslash;rrelsen (= rygglengden). I januar ble de h&oslash;yeste middelverdier, s&aelig;rlig for muskelfett-prosenten, funnet hos kalver av middels st&oslash;rrelse. Skrott-vekter og vekt/rygglengde-forholdet korrelerte positivt med kroppsst&oslash;rrelse bortsett fra februar-pr&oslash;vene, der korrellasjonen for skrott-vekt var ikke-signifikant og for vekt/rygglengde-forholdet var negativt. Vekt om h&oslash;sten korrelerte negativt med vekt i februar. Derfor ventes et normaliserende utvalg for kroppsvekt (som arbeider mot sm&aring; og store fenotyper) &aring; skje p&aring; senvinteren. Sm&aring; kalver er utsatt for st&oslash;rre d&oslash;dsrisiko p&aring; grunn av lavere kroppsreserver. Store kalver streifer vanligvis under brunsttiden og kan komme til &aring; lide under &oslash;kt n&aelig;ringskonkurranse p&aring; senvinteren. Bruk av middels store kalver i avlen kan v&aelig;re den sikreste metode p&aring; beiter som karakteriseres av d&aring;rlige n&aelig;ringstilgang og vanskelige sn&oslash;forhold.</p>

Body Size Estimation in Anorexia Nervosa

1988 ◽  
Vol 153 (S2) ◽  
pp. 23-26 ◽  
Author(s):  
Andrew M. Whitehouse ◽  
Christopher P. L. Freeman ◽  
Annette Annandale
Keyword(s):  
Anorexia Nervosa ◽  
Body Size ◽  
Body Part ◽  
Normal Weight ◽  
The Body ◽  
Size Perception ◽  
Size Estimation ◽  
Significant Difference ◽  
Body Size Perception ◽  
Body Size Estimation

Clinicians who deal with patients with anorexia nervosa are well acquainted with their patients' inability to recognise their emaciation. The patients' insistence that they are normal weight or even overweight, against clear evidence to the contrary, led Bruch (1962) to state that the misperception reaches “delusional proportions”. Studies of body size perception in anorexia nervosa that have used the ‘body part’ method have invariably found that the patients overestimate their body size (Slade & Russell, 1973; Crisp & Kalucy, 1974; Pierloot & Houben, 1978; Garner et al, 1976; Button et al, 1977; Fries, 1977; Casper et al, 1979) but the majority have not found any significant difference in size estimation between patients and controls (Slade, 1985).

The Body Size of Headstarted and Wild Juvenile European Pond Turtles (Emys orbicularis)

2017 ◽  
Vol 25 (2) ◽  
pp. 161
Author(s):  
Sławomir Mitrus ◽  
Bartłomiej Najbar ◽  
Adam Kotowicz ◽  
Anna Najbar
Keyword(s):  
Body Size ◽  
The Body ◽  
Emys Orbicularis

scholarly journals First record of Pachycrocuta brevirostris (Gervais, 1850) from Ukraine on the background of the European occurrence of the species

2021 ◽  
Author(s):  
Adrian Marciszak ◽  
Yuriy Semenov ◽  
Piotr Portnicki ◽  
Tamara Derkach
Keyword(s):  
Body Size ◽  
First Record ◽  
The Body ◽  
Crocuta Crocuta ◽  
Early Pleistocene ◽  
Eastern Asia ◽  
South Eastern

AbstractCranial material ofPachycrocuta brevirostrisfrom the late Early Pleistocene site of Nogaisk is the first record of this species in Ukraine. This large hyena was a representative of the Tamanian faunal complex and a single specialised scavenger in these faunas. The revisited European records list ofP.brevirostrisdocumented the presence of this species in 101 sites, dated in the range of 3.5–0.4 Ma. This species first disappeared in Africa, survived in Europe until ca. 0.8–0.7 Ma, and its last, relict occurrence was known from south-eastern Asia. The main reason of extinction ofP.brevirostrisprobably was the competition withCrocuta crocuta. The cave hyena was smaller, but its teeth were proportionally larger to the body size, better adapted to crushing bones and slicing meat, and could also hunt united in larger groups.

scholarly journals Calculating the optimal hematocrit under the constraint of constant cardiac power

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michal Sitina ◽  
Heiko Stark ◽  
Stefan Schuster
Keyword(s):  
Blood Flow ◽  
High Performance ◽  
Animal Species ◽  
Normal Values ◽  
Mechanical Load ◽  
The Body ◽  
Trade Off ◽  
Cardiac Power ◽  
Optimal Value ◽  
Good Agreement

AbstractIn humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3–0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

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