The abilities of these salamanders to inherit antipredatory behavior, to assess risk even without experience, and to generalize defensive responses to predators means that conditioning is not necessary before the reintroduction of captive individuals.
(PRWEB) September 11, 2013
How a species reacts to potential predators plays a role in how conservationists might manage the species. For managing endangered species, such as the Barton Springs Salamander, this information can be useful. Researchers conducted experiments to test this amphibian’s response to various fish predators.
The journal Herpetologica presents a study in which Barton Springs Salamanders were exposed to three different species of fish predators—the Western Mosquitofish, Redbreasted Sunfish, and Largemouth Bass—and a blank water control. Two of these fish species were native to the watershed; the sunfish was introduced.
Many amphibian populations are in decline due to destruction of habitat, pathogens, and the introduction of nonnative predatory fishes. The Barton Springs Salamander, native to central Texas, is a federally endangered species that is also placed on the International Union for Conservation of Nature’s Red List.
A prey species may distinguish its predators through either a learned or an innate recognition. The learned response comes from encounters with potentially dangerous predators, while the innate recognition is genetically inherited. The current study used captive-bred salamanders that had never been exposed to the predators before and could not have a learned response.
In response to chemical cues from their predators, the salamanders decreased their activity in the presence of all three fish species, but showed no reaction to the water control. An additional test, using small nonpredatory guppies, garnered no reaction from the salamanders, showing that the antipredator behavior was not a generalized reaction to all fish species. While the responses to the mosquitofish and sunfish were the same, the salamanders displayed a heightened reaction to the largemouth bass.
Because the largemouth bass is a voracious predator, researchers speculate that the salamanders’ stronger reaction to this fish may be evidence that the salamander is capable of risk assessment. The reaction to the non-native sunfish suggests that the salamanders can generalize predators based on common traits of traditional predators.
Additionally, this study shows that Barton Springs Salamanders also have innate antipredatory behaviors. Mosquitofish prey on eggs and larvae. An antipredator response to these fish would be an advantageous trait to inherit for early life stages. Since the test salamanders were captive-bred, it is possible that they retained this strong response into adulthood because they could not learn through experience that some predators become less dangerous to them as adults in the wild.
For an endangered prey species, time spent responding to predators is time not spent foraging or mating. So the ability to differentiate the risk posed by predators could be an essential skill. For conservation managers, the abilities of these salamanders to inherit antipredatory behavior, to assess risk even without experience, and to generalize their defensive responses to introduced predators means that conditioning is not necessary before the reintroduction of captive individuals.
Full text of the article “Chemically-Mediated Predator Avoidance in the Barton Springs Salamander,” Herpetologica, Volume 69, Issue 3, 2013, is now available.
Herpetologica is a quarterly journal of The Herpetologists' League, containing original research articles on the biology of amphibians and reptiles. The journal serves herpetologists, biologists, ecologists, conservationists, researchers and others interested in furthering knowledge of the biology of amphibians and reptiles. To learn more about the society, please visit: http://www.herpetologistsleague.org/en/index.php