Small mammal assemblages and their ectoparasite prevalence (Acarina) in mangrove forests of Peninsular Malaysia

The mangrove forest is located in the coastal intertidal zone and plays a vital role in buffering against erosion from storm surges, currents, waves, and tides. This ecosystem also serves for ecotourism due to its heterogeneous habitats, which supported a high diversity of plants and animals. Small mammals are among the abundant but poorly recognised inhabitants in mangrove forests. Apart from their role as primary consumer and prey, they are host to various ectoparasites, which potentially become the primary vector for tick-borne diseases among visitors. Therefore, this study aims to determine the small mammal assemblages and their ectoparasite prevalence in mangroves forests of Peninsular Malaysia. The capture-release method was applied for small mammal sampling, and each captured individual was screened and collected for ectoparasites before released. DNA barcoding using CO1 genes was performed for small mammal species verification, whereby ectoparasite identification was based on morphological identification and molecular verification using 16S rDNA genes. A total of 94 small mammals from 6 species were captured across sites, dominated by Rattus tiomanicus (n=74). From this number, 15 individuals (16% prevalence) were infested by ticks, 22 individuals (23%) were infested by mites, whereas 4 individuals (4%) were infested by both ticks and mites. Five species of ticks and one mite species were identified; Amblyomma cordiferum, Ixodes granulatus, Haemaphysalis hystricis, Dermacentor auratus, Dermacentor atrosignatus, and Laelaps echidninus. This study reveals a relatively poor diversity of small mammals in the mangroves forest, of which highly infested with a diversity of ectoparasites, elucidating the relationship of hostectoparasite associations in the riparian zone. This information is crucial to inform visitors to these areas, ultimately safeguard against ectoparasite-borne disease.

BAIT PREFERENCES BY DIFFERENT SMALL MAMMAL ASSEMBLAGES FOR EFFECTIVE CAGE-TRAPPING

The ecological study of small mammals often uses the cage-trapping method, installed with baits. Capture rates vary according to different baits used. We want to determine the bait preferences by different small mammal groups. The cage-trapping approach used common domestic bait types available, namely, aromatic banana, sweet potato with peanut butter, oil palm fruit, dried salted fish, jackfruit, and roasted coconut flesh. Sampling was conducted in three different habitat categories, namely urban, semi-urban, and recreational forests, located in Selangor, Malaysia, for one year. A total of 537 small mammals from 15 species were sampled, which was then grouped into seven groups (i.e., Rattus sp., Maxomys sp., Sundamys sp., Leopaldamys sabanus, Suncus murinus, squirrels, and Tupaia glis). Bait preferences were significantly different among the different small mammal groups, i.e., F (6,35) = 5.621, p = 0.000, with bananas shown to be most preferred bait, followed by oil palm fruits and sweet potatoes. Non-metric multidimensional scaling (nMDS) analysis revealed that the Rattus species encompassed the most diverse bait preference, while S. murinus and L. sabanus were the most selective. Muridae preferred sweet potatoes with peanut butter over bananas, while Sciuridae and Tupaiidae preferred bananas, and Soricidae preferred dried salted fish. This study elucidates the most effective bait selection for different small mammal assemblages, serving as a guide to increase capture rates when sampling targeted population of small mammals. Apart from that, it is helpful for effective rodent pest control.

Tarsal morphology of ischyromyid rodents from the middle Eocene of China gives an insight into the group’s diversity in Central Asia

Ischyromyids are a group of large rodents with the earliest fossil record known from the late Paleocene (Clarkforkian) of North America; they are considered the earliest fossil representatives of Rodentia of modern aspect. Ischyromyids dominated early Paleogene small-mammal assemblages of North America and in the latest Paleocene migrated to western Europe and to Asia; in the latter they survived only to the beginning of the late Eocene, but were never abundant. Here we describe for the first time the calcanei of ischyromyids from the early middle Eocene of the Erlian Basin in Nei Mongol, northern China. These calcanei document the existence of three species. The morphology of the studied tarsal bones overall suggests ambulatory locomotion for these animals (‘slow cursors’), similar to that of the coypu and porcupines, but one form shows more marked cursorial capabilities. These differences show that Chinese ischyromyids, although rare, had attained greater taxonomic diversity by the middle Eocene in Nei Mongol than estimated from dental remains. We also address the question of the morphological and ecological divergence of these ischyromyids in relation to their North American counterparts, as well as the issue of a direct dispersal route from North America to Asia in the early Eocene.

Two alternate states: shrub, bird and mammal assemblages differ on either side of the Dingo Barrier Fence

ABSTRACT The 5500 km long dingo barrier fence (DBF) is a boundary at which the goal of dingo control programs shifts from management to elimination. Since 1980 ecologists have used the discrepancies in dingo densities across the DBF to study the ecological role of Australia’s largest terrestrial predator. We used drone imagery, ground based shrub and tree counts, and camera trap footage to test our hypothesis that there are alternate states in plant, bird and mammal assemblages on either side of the DBF. We found that shrubs and trees were twice as dense where dingoes were rare, and 28 % of shrub and tree species, 78 % of mammal species, and 14 % of bird species recorded were significantly more likely to occur on one side of the DBF than the other. We provide the first comprehensive snapshot of how flora and fauna assemblages differ across the DBF. This study adds to literature demonstrating that the removal of the dingo has led to profound shifts in the shrub, mammal and bird assemblages in arid Australia. Any expansion of dingo control in arid Australia must be considered against the far-reaching consequences for ecosystem assembly associated with the removal of a top predator.