Home About us Contact
|
Home About us Contact | ||
|
|
||
Prey Animals (prey + animals)
Selected AbstractsFirst Documentation of Cultural Transmission of Predator Recognition by Larval AmphibiansETHOLOGY, Issue 6 2007Maud C. O. Ferrari Predation is a pervasive selective agent shaping a prey's behaviour, morphology and life history. To survive, prey animals have to respond adaptively to predation threats and this can be achieved through learned predator recognition. Cultural transmission of predator recognition is likely a widespread means of learning in social animals, including mammals, birds and fishes. However, no studies have investigated the cultural transmission of predator recognition in amphibians. In our study, we examined whether naïve woodfrog (Rana sylvatica) tadpoles can acquire the recognition of the odour of a predatory tiger salamander (Ambystoma tigrinum) from experienced conspecifics. After conditioning some tutors to recognize salamander odour, we paired naïve observer tadpoles with either a salamander-naïve or salamander-experienced tutor and exposed the pairs to either salamander odour or a water control. Observers were subsequently tested alone for a response to salamander odour. We found that when given salamander odour, observer tadpoles that were paired with a salamander-experienced tutor successfully learned to recognize the salamander odour as a threat, whereas the observers paired with salamander-naïve tutors did not. Likewise, tadpoles exposed to the water control did not learn to recognize the salamander regardless of whether they were paired with a naïve or experienced tutor. This is the first study demonstrating cultural transmission of predator recognition in an amphibian species. [source] WARNING DISPLAYS IN SPINY ANIMALS: ONE (MORE) EVOLUTIONARY ROUTE TO APOSEMATISMEVOLUTION, Issue 12 2005Michael P. Speed Abstract To date, theoretical or laboratory simulations of aposematic evolution in prey animals have focused narrowly on internally stored chemical defense as the source of unprofitability and ignore aposematic advertisement of physical defenses such as spines (and defensive hairs, claws, etc.). This has occurred even though aposematism in spiny animals has been recognized since the 19th century. In this paper we present the first detailed theoretical consideration of aposematism in spiny animals, focusing on questions of initial evolution, costs of display, and coevolution of displays with defenses. Using an individual-based evolutionary model, we found that spines (or similar physical defenses) can easily evolve without aposematism, but when spines do evolve, aposematic displays can also easily evolve if they help to make the prey animal distinctive and if they draw attention to the physical threat. When aposematic displays evolve, they cause reduced investment in costly spines, so that, in addition to signaling unprofitability, aposematic display may enhance the cost-effectiveness of antipredator defenses (one exception to this conclusion is if the display is itself as costly as the defense). For animals with stinging spines, combining physical and chemical defense, the evolution of aposematic display may lead to reduced investment in the toxin compared to the spine. This occurs because spines act as both secondary (repellent) defenses and as primary defenses (their own visible, honest advertisement), whereas internally stored toxins only (generally) act as repellent secondary defenses. We argue that conspicuous aposematism in spines functions as an attention-getting mechanism, whereas conspicuous aposematic display in purely toxic animals may be explained by signal reliability arguments. Finally, one (more) route by which aposematism may initially evolve is by spiny rather than purely chemically defended species, spreading to species with other forms of secondary defense as the signal becomes common. [source] Estimating age and season of death of pronghorn antelope (Antilocapra americana Ord) by means of tooth eruption and wearINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 3 2001Patrick M. Lubinski Abstract Age and season of death information for prey animals at archaeological sites can address issues such as season of site occupation and prey hunting or harvesting strategies. Unfortunately, adequate reference information for estimating age and season is lacking for many wild species, including pronghorn antelope. To address this problem, new methods of scoring tooth eruption and wear have been developed and have been applied to a sample of over 500 pronghorn mandibles to obtain improved eruption and wear schedules. One implication of this study is that ,age class discreteness' is an unreliable method for demonstrating mass mortality of prey. This study provides a much larger comparative sample than previously available, although larger known-age mandible samples are still needed for pronghorn and many other wild species. Copyright © 2001 John Wiley & Sons, Ltd. [source] Fight or flight: antipredator strategies of baleen whalesMAMMAL REVIEW, Issue 1 2008JOHN K. B. FORD ABSTRACT 1The significance of killer whale Orcinus orca predation on baleen whales (Mysticeti) has been a topic of considerable discussion and debate in recent years. Discourse has been constrained by poor understanding of predator-prey dynamics, including the relative vulnerability of different mysticete species and age classes to killer whales and how these prey animals avoid predation. Here we provide an overview and analysis of predatory interactions between killer whales and mysticetes, with an emphasis on patterns of antipredator responses. 2Responses of baleen whales to predatory advances and attacks by killer whales appear to fall into two distinct categories, which we term the fight and flight strategies. The fight strategy consists of active physical defence, including self-defence by single individuals, defence of calves by their mothers and coordinated defence by groups of whales. It is documented for five mysticetes: southern right whale Eubalaena australis, North Atlantic right whale Eubalaena glacialis, bowhead whale Balaena mysticetus, humpback whale Megaptera novaeangliae and grey whale Eschrichtius robustus. The flight strategy consists of rapid (20,40 km/h) directional swimming away from killer whales and, if overtaken and attacked, individuals do little to defend themselves. This strategy is documented for six species in the genus Balaenoptera. 3Many aspects of the life history, behaviour and morphology of mysticetes are consistent with their antipredator strategy, and we propose that evolution of these traits has been shaped by selection for reduced predation. Fight species tend to have robust body shapes and are slow but relatively manoeuvrable swimmers. They often calve or migrate in coastal areas where proximity to shallow water provides refuge and an advantage in defence. Most fight species have either callosities (rough and hardened patches of skin) or encrustations of barnacles on their bodies, which may serve (either primarily or secondarily) as weapons or armour for defence. Flight species have streamlined body shapes for high-speed swimming and they can sustain speeds necessary to outrun pursuing killer whales (>15,20 km/h). These species tend to favour pelagic habitats and calving grounds where prolonged escape sprints from killer whales are possible. 4The rarity of observed successful attacks by killer whales on baleen whales, especially adults, may be an indication of the effectiveness of these antipredator strategies. Baleen whales likely offer low profitability to killer whales, relative to some other marine mammal prey. High-speed pursuit of flight species has a high energetic cost and a low probability of success while attacks on fight species can involve prolonged handling times and a risk of serious injury. [source] Innovation and evolution at the edge: origins and fates of gastropods with a labral toothBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2001GÉERAT J. VERMEIJ I combined data from the taxonomy, phytogeny, functional morphology, biogeography, and fossil record of gastropods to probe the origins, distribution, and fates of predatory gastropod clades characterized by the presence of a labral tooth, a downwardly projecting tooth or spine formed at the edge of the outer lip of the shell. A labral tooth occurs in at least 608 species, of which 251 are Recent. Studies of the type and position of the labral tooth, along with other characters, indicate that the labral tooth has evolved independently at least 58 times, beginning in the Campanian epoch of the late Cretaceous. The labral tooth plays a more or less active part in predation on relatively large prey animals that are protected by a hard skeleton. In the Recent fauna, tooth-bearing species are overwhelmingly warm-temperate to tropical in distribution (240 of 251 species; 96%). Within Muricidae (excluding Coralliophilinae), however, there is no discernible latitudinal gradient in the number of tooth-bearing species relative to total regional diversity. First appearances of clades with a labral tooth are overwhelmingly concentrated in the late Oligocene to Pleistocene interval, with the largest number appearing during the early Miocene (12 clades). The temporal pattern differs significantly from that expected on the basis of the number of faunas available per time interval, and is therefore not an artifact of sampling or fossil preservation. The most consistent factor associated with, and permitting the repeated evolution of, the labral tooth is high planktonic primary productivity. Two factors may account for the link between primary productivity and the evolution of labral téeth: (1) the general economic opportunity afforded by ready availability of an access to nutrients, and (2) the greater abundance and sizes range of available suspension-féeding prey animals. Incumbency,the presence of already well-adapted species,often controls evolutionary opportunity. The complementary distributions of major tooth-bearing clades in many parts of the world point to the role of well-adapted incumbents in limiting the adaptive exploration by other clades that could in principle evolve a labral tooth. The elimination of incumbents by extinction, however, does not provide opportunities for other clades to fill the adaptive void. [source] | ||||||||||