Predator defense

Blanchard DC, Griebel G, Blanchard RJ (2001a) Mouse defensive behavior pharmacological and behavioral assays for anxiety and panic. Neurosci Biobehav Rev 25 205-218 Blanchard DC, Hynd AL, Minke KA, Minemoto T, Blanchard RJ (2001b) Human defense behaviors to threat scenarios show parallels to fear- and anxiety-related defense patterns of non-human mammals. Neurosci Biobehav Rev 25 761-770 Blanchard DC, Griebel G, Blanchard RJ (2003) The mouse defense test battery pharmacological and behavioral assays for anxiety and panic. Eur J Pharmacol 463 97-116 Blanchard RJ, Blanchard DC (1989) Anti-predator defense behaviors in a visible burrow system. J Comp Psychol 103 70-82... 

Paul, V.J. and Van Alstyne, K.L., Use of ingested algal diterpenoids by Elysia halimedae Macnae (Opisthobranchia Ascoglossa) as anti-predator defenses, J. Exp. Mar. Biol. Ecol., 119, 15, 1988. 

Gut pigment Molecular methods Microzooplankton Phaeocystis antarctica Predator defense... 

Field studies are necessary to validate anti-predator responses of prey fishes in the chemically complex natural environment. While several of the early trap experiments demonstrated the effectiveness of alarm cues in the field (i.e., Mathis and Smith, 1992), the more complicated recent studies often demonstrate no preferential avoidance between familiar and unfamiliar cues or, alternatively, results are contradictory to predictions. Trap experiments have therefore brought into question previous knowledge based primarily on laboratory studies (i.e., visual compensation model). Anti-predator defense strategies of fishes are clearly context-dependent. To decipher and explore the complexities of this dependent response further, field studies investigating the various biotic and abiotic factors affecting a fish s response are required. 

Anti-predator adaptations are often mediated or induced by chemical cues (Kats and Dill, 1998), especially in aquatic systems where visual cues are limited (Smith, 1992). Chemical cues function well in this medium as a large number of compounds can dissolve in water allowing for the production of a great number of possible signals (Hara, 1994). Research, in the past decade, has indicated that the assessment of these chemical cues is highly sophisticated (reviews Chivers and Mirza, 2001). Logically, the ability to accurately assess the risk of predation would be beneficial as each anti-predator defense has an innate cost to the user and the effectiveness of each response option is dependent on the context of the encounter and the specific predator. 

Amphibians are vulnerable to predation and show diverse predator defenses. We hypothesized that the common red-backed salamander should try to evade two common terrestrial predators, the garter snake and the spotted salamander, by avoiding locations containing their scent. When given a choice of clean substrates or those soiled by these predators, the red-backed salamander avoided the soiled substrates. To test whether they avoided the waste products and not the predator scent, we gave test subjects a choice between substrates soiled by predators and those soiled by red-backed salamanders. Salamanders pref-ered conspecific substrates to predator substrates, and in combination with other findings, our data show that red-backed salamanders probably reduce the likelihood of predation by avoiding locations with the chemical traces of predators. 

Many organisms rely on anti-predator defenses after contact with a predator (Brodie, Formanowicz Brodie, 1991). Because energetic costs and mortality risks are increased during contact, some species avoid these interactions whenever possible. A number of animals chemically detect and avoid predators, including invertebrates (Parker Shulman, 1986 Alexander Covich, 1991 Turner, 1996), fish (Keefe, 1992 Smith, 1992 Mathis Smith, 1993), reptiles (Thoen, Bauwens Verheyen, 1986 Dial, 1989 Cooper, 1990), and mammals (Weldon, 1990). In anuran amphibians, tadpoles commonly avoid the waterborne odors of predators (Petranka, Kats Sih, 1987 Flowers Graves, 1997 Kie-secker, Chi vers Blaustein, 1997), and among caudate amphibians, both larval and adult... 

The lower activity levels at night during the goldfish-fed snake trials were probably normal, low-level activity rather than freeze responses. The latter term implies immobility and certainly a reduction in activity below normal levels, which in the absence of a significant avoidance response was unlikely to have occurred. Some of the salamanders in our study may have momentarily shifted into an anti-predator defense mode upon initial exposure to snake odors, but quickly shifted back into an avoidance mode once contact with the predator appeared less imminent. This ambivalence in some salamanders may also have contributed to the 18 minute delay to peak activity. 

An excellent review by Roth and Eisner (63) summarized the chemical defense substances found in arthropods up to 1962. These authors listed 31 defense substances of known structure one anhydride, three carboxylic acids, nine aldehydes, one furan, three hydrocarbons, two ketones, one lactone, eight quinones, and three inorganic compounds. Many of these same compounds (unsaturated aldehydes and quinones) have been found in other arthropods since 1962 (38). The compounds are discharged when the animal is disturbed by predators, and there can be no doubt that the action of most of them... 

Interested readers can find information on geographic variation in aboveground architecture and leaf characters of Encelia farinosa in response to temperature and available water in Housman et al. (2002), and a discussion of chemical variation and defense against predation in a report by Wisdom (1985). 

Structural type. The possible function of flavonoids as antiherbivore defense com-ponnds was discnssed, bnt Mears (1980b) found no correlation between complexity of flavonoid profile and latitnde, as might be the case if complexity of profile increases as one goes from temperate to more tropical climates with concomitant increase in insect predators. Althongh the nnmber of samples stndied was not large, there was a relationship between latitnde and complexity of pigment profiles in taxa restricted to calcareons snbstrates. No driving force for this apparent relationship is evident. 

Wisdom, C. S. 1985. Use of chemical variation and predation as plant defenses by Encelia farinosa against a specialist herbivore. J. Chem. Ecol. 11 1553-1565. 

Machado, G. et al.. Chemical defense in harvestmen (Arachnida, Opiliones) do benzoquinone secretions deter invertebrate and vertebrate predators J. Chem. EcoL, 31, 2519, 2005. 

The seeds and vegetative part of plants contain several sorts of inhibitors of insect, fungal, mammalian, and endogenous proteinases. These inhibitors may be involved in plant defense mechanisms against predators and participate in the development of the plant itself. Peptidic proteinase inhibitors are well studied in the families Fabaceae, Poaceae, Asteraceae, and Solanaceae (37). Non-proteinaceous inhibitors of serine... 

One example for a chemically defended zooplankton species is the Antarctic pteropod Clione antarctica. This shell-less pelagic mollusk offers a potentially rich source of nutrients to planktivorous predators. Nonetheless fish do not prey on this organism, due to its efficient chemical defense. In a bioassay-guided structure elucidation, pteroenone 37 could be isolated and characterized as the main defensive principle of C. antarctica [82,83]. If embedded in alginate, this compound is a feeding-deterrent in nanomolar concentrations. This unusual metabolite is likely to be produced by C. antarctica itself and not accumulated from its food, since its major food sources did not contain any detectable quantities of 37. 

A re-examination of the defensive chemistry of I marginata revealed that the tridentatols (85-88) represent the transformation products of less active sulfate ester storage forms (81-84) [161]. Crushing the tissue as an attacking predator would do results in the rapid conversion of the sulfate esters within seconds after wounding. This suggests that this reaction plays a role in a wound-activated defense. 

A recent example demonstrates that corals rely on induced biosynthesis of terpenes as a dynamic defense strategy as well. The induction of terpenoid secondary metabolites was observed in the sea whip Pseudopterogorgia elisabethae [162]. Levels of pseudopterosins 89-92, a group of diterpene glycosides with anti-inflammatory and analgesic properties (Scheme 23) [163-165], are increased in response predation by the mollusk Cyphoma gibbosum. First bioassays indicate that these natural products are involved in the chemical defense. 

For the marine organisms that make the metabolites, some of these molecules are part of defense mechanisms that serve to promote the species survival by deterring predators or inhibiting the growth of competing organisms. 

While secondary metabolites of plants and animals have been the subject of many chemical investigations, their associations and roles in their host organism are at times controversial this is particularly so, when insufficient observations exist. Nevertheless, natural products provide fruitful areas of research [69]. There is little doubt that chemical defense against predators is an important aspect of survival. In the marine environment, early observations of nudi-branch- sponge relationships were reported and those relating to isocyano compounds are summarized in Table 6. 

Experimental data suggest that VN stimuli might also play a relevant role in prey-predator interactions by mediating affective responses to prey or predator chemical cues. For instance, one of the preferred prey for the snake Thamnophis sirtalis is earthworms. Halpern (1988) demonstrated that earthworm wash constitutes a VN stimulus that is rewarding for these snakes. On the other hand, it has been shown that rats display defensive reactions to a collar that has been worn by a cat, even if they have no previous experience with cats. For these defensive behavioral responses to occur, direct contact with the collar is needed (Dielenberg and McGregor 2001). 

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