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  • Author or Editor: Juan Yu x
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In: Tilburg Law Review

To better understand the importance of body size in hermaphroditic mating, we studied the mating behaviour of the pond snail Radix auricularia. This simultaneous hermaphrodite exhibits a positive correlation between body size and egg production and provides weak evidence for size-assortative mating. In addition to this mating pattern, the partner performing the male role was significantly smaller than the mounted partner, performing the female role. In this study, two laboratory experiments were done to test whether body size has (1) an effect on mate choice of the sperm donor, and (2) poses mechanical constraints. These snails did not display physical limitation in mating with a much larger or smaller partner. In the mate choice experiment, we found no evidence for significant preferences for large partners. Therefore, mate choice of sperm donor and mechanical constraints are not likely to contribute to the formation of size-assortatively mating pairs in this species, which contributes to understanding about how these processes work in hermaphrodites.

In: Animal Biology

Abstract

The Asian water monitor (Varanus salvator) is a large generalist predator and scavenger lizard. This species has a widespread distribution throughout South and Southeast Asia and is frequently encountered around the edges of urban settlements. Here, we present information on diet diversity and habitat utilisation of a population of Asian water monitors inhabiting the University of Malaysia Terengganu campus located on the east coast of mainland Malaysia. The stomach contents of 30 Asian water monitors were examined by stomach flushing, and 47.6% of stomach contents was mangrove crab, 26.2% was human waste and 26.2% was other natural foods consisting of fruits, fishes, leeches, snails, birds and insects. We then recorded the locations and habitats utilised by patrolling the campus area and found Asian water monitors preferred to use water and mangrove forest habitats that fringed and crisscrossed the campus. The broad diversity of stomach contents reflected food available at this location and indicates the opportunistic feeding habit of this species. Given that this species widely distributed in Southeast Asia, its broad diet diversity and habitat variations may promote the adaptation of Asian water monitor to different environments.

In: Animal Biology

Summary

The antagonistic activities of essential oils of Ajania potaninii and A. fruticulosa against Ditylenchus destructor were determined by the liquid soak method in 96-well microplates. The main constituents of A. potaninii essential oil were 1,8-cineole (22.19%), (+)-camphor (12.84%), (−)-verbenol (13.84%) and borneol (12.67%). The results showed that the essential oils of A. fruticulosa (EC50 = 0.17 mg ml−1) and A. potaninii (EC50 = 0.27 mg ml−1) have antagonistic activity against D. destructor. The results also showed that 1,8-cineole (EC50 = 0.49 mg ml−1), myrtenol (EC50 = 0.40 mg ml−1) (A. fruticulosa) and (−)-verbenol (EC50 = 1.09 mg ml−1) (A. potaninii) have antagonistic activity. 1,8-Cineole is a key element affecting the antagonistic activity that was found in both essential oils. Several main constituents found in the essential oils had antagonistic effects against D. destructor. These results provide the basis for future development and utilisation of a substance to control D. destructor.

In: Nematology