New Journal of Zoology Podcast

12 01 2016

A new episode of the Journal of Zoology podcast is now available and you can listen to it here.

JZO Winter 2016 podcast logoIn this episode, Anthony Russell talks to us about the mystery of the ‘dead bird’ posture in dinosaur fossils and how studying the anatomy of extant birds such as domestic chickens can elucidate it, we will learn from Tiana Kohlsdorf about the ecological significance of animals’ locomotor performance, such running speed and grip, and how it varies between different substrates and habitats, and we are told by Stéphanie Périquet how increased abundance of lions alters the diet and foraging strategies of spotted hyaenas, as demonstrated by their study in the Hwange National Park in Zimbabwe.

You may subscribe to iTunes to receive the latest Journal of Zoology podcasts.





Author Spotlight: Investigating the ‘dead bird’ posture of non-avialan dinosaurs

11 12 2015

Opisthotonic head displacement in the domestic chicken and its bearing on the ‘dead bird’ posture of non-avialan dinosaurs

A. P. Russell & A. D. Bentley

The research undertaken in this study, published in Journal of Zoology, seeks to examine the intervertebral movement that occurs in dead chickens when the head is drawn back into the “dead bird” (opisthotonic) posture seen in many dinosaur fossils. This posture is highly evocative because it suggests that the animals suffered death throes, thus potentially having implications for how the dinosaur died.

ADAM BENTLEY

Adam Bentley

Our work was initiated by my co-author, Adam Bentley, who, at the time, was an undergraduate student seeking a suitable final year research project. He was fascinated by a recent publication that attempted to evaluate all of the theories that had been advanced to explain this phenomenon in dinosaurs, and to arrive at the most plausible of these. That publication favoured the clinical condition of opisthotonus, resulting from neuromuscular trauma at the time of death. In discussing with Adam the various publications that had considered the opisthotonic posture (and its causes) in dinosaurs, we realized that nobody had systematically documented the vertebral movements associated with this. Given that birds are living dinosaurs, and that chickens are readily available in grocery stores (Asian ones being particularly good sources of chickens with the head and neck still attached), we set out to design a project that would yield statistically robust data and provide us with solid anatomical information.

ANTHONY RUSSELL

Anthony Russell

The key to being able to conduct the project successfully was the presence in my lab of a state-of-the-art digital radiography system that allowed us to pose and image the chicken carcasses in repeatable positions that mimicked the head retraction process. We began by determining the carriage of the head “at rest” (when the chicken is standing), and then established five equally-spaced stages of displacement to the fully retracted position with the top of the head resting on the hip girdle. We were able to document 15 chickens in this way (ten of which constituted our test group), and we recorded the angles of 11 neck joints for all of the stations along the cervical retraction pathway. We then repeated these procedures for protraction of the neck (a movement we dubbed protonic displacement), to determine the relative mobility of the joints when the head was forced forward and downward. The patterns here turned out to be quite different from those seen in neck retraction. Overall, for our sample of 10 chickens we were able to record displacement data for 11 joints in 14 positions, yielding 1540 angles for analysis.

This work was time consuming and challenging, but the outcome was very revealing. We found that certain neck joints are highly flexible whereas others are highly restricted in their movements. Although our research cannot answer questions as to why, in any given instance, a particular dinosaur fossil may have assumed the opisthotonic posture, our findings provide us with information about how to explore the anatomy of the neck vertebrae of dinosaurs (and other fossils) to see if such displacement was physically possible (because it has been reported that it is confined to certain groups of amniote vertebrates). It also raises questions about scale. Chickens are relatively small, and their head and neck relatively easily displaced by modest external forces. At larger sizes (as is typical of dinosaur fossils and even large birds, such as ostriches) the head and neck are bulkier and offer greater resistance to displacement (especially in terrestrial as opposed to aquatic situations). Thus, circumstantial evidence relating to the conditions of preservation and burial of each specimen remains important for determining why that particular animal expresses the opisthotonic posture. The form of the neck facilitates such displacement, but whether perimortem physiological symptoms, or postmortem decay phenomena, were responsible must be determined by examining “the scene of the crime”.

Anthony Russell





Editorial Board Member’s Choice

4 11 2015

By Maria Luisa da Silva

Agonistic sounds and swim bladder morphology in a malapterurid electric catfish

K. S. Boyle, G. Bolen & E. Parmentier, 2015, Journal of Zoology, 296: 249-260.

I was glad to read this article about sound production in fish, because it is a field that must be better studied and this study represents an effort to cover the lack of information. The difficulties to study behaviour in fish start because they live in the water and we are terrestrial, so this team of researchers from University of Liège, Belgium, kept some individuals of Malapterurus beninensis in several aquaria and recorded their agonistic sounds. Many fish species produce sounds and sometimes it is a mystery which structure is responsible for the sound emission. The movement of the protactor muscle linked at “elastic spring apparatus” (ESA) during the production of low frequency drumming sounds in doradid catfish has already been described, and the authors present a detailed sound analysis of broadband clicks trains, unusual emissions among catfish families, with high-quality spectrograms and oscillograms.

The sounds that the authors observed M. beninensis to make were ratchet, click train and mouth sounds. Mouth sounds were single event, of low frequency and coincided with a bite-like motion, whereas ratchet and click sounds were high-frequency and occured in trains. This species also produced bubble sounds, however they did not coincide with behavioural interactions and seemed to be by-products of air released from the orobranchial chamber or the swim bladder. The authors also show impressive images of the swim bladder obtained by computerized tomography and histological and ultrastructure analysis. What is particularly interesting is that this structure has evolved several times among Siluriformes, especially in a group that also uses electrical signals for defence. However, the scope for answering questions like the authors proposed – ‘What is the evolutionary function of the ESA morphology in Malapteruridae?’ – it is limited in laboratory experiments to analyse and to interpret natural behaviour associated with sound production. If it is possible to study this species in a semi-captive, almost natural condition, with some control and maybe with waterproof cameras to identify which individual produce the sound, we might be better able to answer evolutionary questions about sound production in these fish.





New Journal of Zoology Podcast

21 09 2015

A new episode of the Journal of Zoology podcast is now available and you can listen to it here.

Journal of Zoology PodcastIn this episode, Raoul Manenti talks to us about how density and resource competition affects intraspecific aggression in a cannibalistic salamander that lives in caves, we will here from Rob Slotow about reintroduced lions and how resource selection models could help mitigate conflicts between them and the local people, and Inigo Zuberogoitia tells us about nest site selection behaviour and decision making in peregrine falcons.

You may subscribe in iTunes to receive the latest Journal of Zoology podcasts.

Elina Rantanen





Author Spotlight: The metabolic machinery putting the “fight” in Siamese fighting fish

20 07 2015

Biochemical correlates of aggressive behavior in the Siamese fighting fish

M. D. Regan, R. S. Dhillon, D. P. L. Toews, B. Speers-Roesch, M. A. Sackville, S. Pinto, J. S. Bystriansky and G. R. Scott

 

Aggressive interactions between individuals of the same species can result in the evolution of exaggerated body traits that improve success in these interactions, and subsequently, access to resources such as food and mates. Although conspicuous morphological adaptations such as antlers are usually what come to mind, metabolic processes that occur hidden within cells are required to sustain aggressive behaviour, so their enhancement may also be important for a successful outcome.

Siamese fighting fish, Betta splendens

Siamese fighting fish, Betta splendens; photo by Dave Toews

With this in mind, we designed a study to examine the intersection of aggressive behaviour and metabolic biochemistry using the Siamese fighting fish, a staple of the world’s pet shops. Male Siamese fighting fish are notoriously aggressive towards one another, fighting over access to territory and females. Because such aggressive behaviour is energetically costly, we hypothesized that more aggressive fish, which win more fights, would have a greater ability to generate cellular energy in their muscles than less aggressive fish, which tend to lose.

The research team

The research team; photo by Sheldon Pinto

The eight of us met in Hamilton, Ontario to run the behavioural experiments together in Dr. Graham Scott’s lab at McMaster University. These experiments involved pairing equally-sized male Siamese fighting fish in tanks and allowing them to “fight” one another from either side of a glass divider. The glass divider was necessary for the reason you probably guessed: these fish will do each other harm. Our goal with the experiments was to accurately quantify aggressive behaviour of the fish and then examine how the metabolic pathways supplying energy to the fish’s muscle cells varied with aggression, and ultimately, fighting success. We used behavioural assays to quantify aggression and estimate winners and losers, and biochemical assays to quantify reliance on, and capacity for, aerobic and anaerobic energy supply pathways.

Siamese fighting fish bouts aren’t on the level of, say, Ali vs. Frazier in ’75. But we’d be lying if we said excitement didn’t run high during each 20-minute encounter, with the fish striking at each other in fits and starts through the glass divider. At the end of each bout, muscle samples were taken from each fish on which we made our biochemical measurements of metabolic fuels, metabolic wastes, and enzyme activity rates.

Our results were very much in line with our predictions: winning fish were better able to supply energy to their muscles during fights than losing fish, and they were able to do this using two major strategies. First, the muscles of winning fish were better able to supply energy from aerobic pathways, which was matched with greater breathing frequency during fighting (Siamese fighting fish have the ability to breathe air). Second, the muscles of winners also made greater use of anaerobic energy supply pathways and accumulated more lactic acid as a result. Overall, fighting success appears to require muscles with a greater biochemical ability to supply energy, as well as an all-out exploitation of these metabolic pathways during fights.

Matthew Regan





Winner of the 2014 Journal of Zoology ‘Paper of the Year’ award

18 06 2015

Seeing through the skin: dermal light sensitivity provides cryptism in moorish gecko

D. Fulgione, M. Trapanese, V. Maselli, D. Rippa, F. Itri, B. Avallone, R. Van Damme, D. M. Monti, and P. Raia

The ability of some animals to rapidly change colour fascinates and astounds us in equal measure. Such colour change is enabled by specialized cells called melanophores in the animal’s skin, and this phenomenon has been observed for instance in octopuses, chameleons and fiddler crabs. This ability allows the animal to use its colour as camouflage and blend into their background that is heterogeneous or constantly changing, in order to conceal it from its predators or prey. However, the mechanisms by which animals perceive their surroundings to match their colour to the background are still not clear.

Moorish geckos Tarentola mauritanica are known to turn darker or lighter depending on the tone of their surroundings, and Domenico Fulgione and his co-authors from University of Naples Federico II and University of Antwerp wanted to examine whether these geckos match their skin tone to their surroundings via the nervous system, endocrine system or local cell response. In order to test this, the authors brought wild-caught moorish geckos into the lab and as treatments covered their eyes or their trunk, and then put them inside terrariums covered by either black or white paper and with a transparent lid. The team then observed whether the geckos were still able to change their colour to match the tone of their surroundings.

Surprisingly, the blindfolded individuals still changed their colour consistently with their background, whereas when the geckos had their trunk covered they did not change colour, even when they could see their surroundings. This and examinations of opsin levels in tissue samples from various parts of the geckos’ body led the authors to conclude that the moorish geckos have melanophores on their trunk that are light-sensitive and react to the light reflectance levels of their surroundings, leading to the observed skin colour change. Although a similar phenomenon has been observed in some non-amniotes such as tilapia and cuttlefish, this study has been the first to show evidence of such cryptic colour change triggered by dermal light perception in amniotes.

Elina Rantanen





New Journal of Zoology Podcast

30 04 2015

A new episode of the Journal of Zoology podcast is now available and you can listen to it here.

In this episode, we will hear from Pierre-Paul Bitton and Brendan Graham about the success of European starlings colonising North America and how this phenomenon may have been aided by their wing morphology, Madlen Ziege tells us how the burrow structure of European rabbits changes as they move from the countryside into cities, and we learn from Megan Owen how polar bears communicate via scent from their paws!

You may subscribe in iTunes to receive the latest Journal of Zoology podcasts.

Elina Rantanen








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