Salicylic acid-independent plant defence pathways

Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent pathways. Cross-talk between the salicylic acid-dependent and the salicylic acid-independent pathways provides great regulatory potential for activating multiple resistance mechanisms in varying combinations.     

Diet of age-0 tarpon (<Emphasis Type=Italic>Megalops atlanticus</Emphasis>) in anthropogenically-modified and natural nursery habitats along the Indian River Lagoon,Florida

As human development in coastal areas increases, the role of anthropogenically-created habitats in the life history of marine organisms is becoming increasingly important. We examined the diet of age-0 tarpon, Megalops atlanticus, in and around man-made mosquito control impoundments along the Indian River Lagoon in east-central Florida, with a particular focus on identifying dietary patterns associated with tarpon size and nursery habitat type (i.e., between perimeter pool habitats in established impoundments and newly-created restoration marsh habitats). Age-0 tarpon were found to consume a wide variety of prey organisms, and exhibited considerable dietary variation among study sites. Smaller juvenile tarpon consumed a limited number of small prey taxa, while larger individuals fed on a greater range of prey taxa and sizes. Overall, copepods and fishes were the dominant prey items; however, the consumption of these organisms varied considerably among size classes and sites. There was no clear difference in tarpon diet between the two types of habitat we examined. The ability of juvenile tarpon to utilize such a diverse range of prey organisms may allow populations to inhabit a variety of habitats, including man-made marshes. When natural systems have been degraded or destroyed, human-altered habitats can assume a nursery role for the species.     

What Doesn't Kill You Makes You Wary? Effect of Repeated Culling on the Behaviour of an Invasive Predator

As a result of being hunted, animals often alter their behaviour in ways that make future encounters with predators less likely. When hunting is carried out for conservation, for example to control invasive species, these behavioural changes can inadvertently impede the success of future efforts. We examined the effects of repeated culling by spearing on the behaviour of invasive predatory lionfish (Pterois volitans/miles) on Bahamian coral reef patches. We compared the extent of concealment and activity levels of lionfish at dawn and midday on 16 coral reef patches off Eleuthera, The Bahamas. Eight of the patches had been subjected to regular daytime removals of lionfish by spearing for two years. We also estimated the distance at which lionfish became alert to slowly approaching divers on culled and unculled reef patches. Lionfish on culled reefs were less active and hid deeper within the reef during the day than lionfish on patches where no culling had occurred. There were no differences at dawn when removals do not take place. Lionfish on culled reefs also adopted an alert posture at a greater distance from divers than lionfish on unculled reefs. More crepuscular activity likely leads to greater encounter rates by lionfish with more native fish species because the abundance of reef fish outside of shelters typically peaks at dawn and dusk. Hiding deeper within the reef could also make remaining lionfish less likely to be encountered and more difficult to catch by spearfishers during culling efforts. Shifts in the behaviour of hunted invasive animals might be common and they have implications both for the impact of invasive species and for the design and success of invasive control programs.