Invasive ants reduce abundance of small rainforest skinks

Invasive ants are among the world’s most damaging invasive species, often directly or indirectly affecting native fauna. Insecticidal baits are the main method for suppressing or eradicating invasive ant populations, but their use must be considered against potential for unintended effects on native organisms. The invasive yellow crazy ant (Anoplolepis gracillipes) is widespread in the tropics, particularly on islands, where they have displaced a range of invertebrates. Effects of this ant on vertebrates, and in continental ecosystems generally, are less studied. We investigated the effects of yellow crazy ants and bait application on rainforest skinks and their invertebrate prey. We compared skink and skink prey abundance across four replicated rainforest site categories: high and low yellow crazy ant sites had both been baited but differed in yellow crazy ant activity; control sites had never had yellow crazy ants or been baited; and buffer sites had never had yellow crazy ants but had been baited. We recorded significantly lower abundance of two small skink species (Lygisaurus laevis and Saproscincus tetradactylus) in high yellow crazy ant sites compared to all other site categories. The differences persisted even after baiting reduced yellow crazy ant activity by 97.8% ± 0.04% (mean ± SD). A larger rainforest skink species (Carlia rubrigularis) was not negatively affected by yellow crazy ant invasion. Skink prey abundance was significantly lower in high yellow crazy ant sites compared to control sites and low yellow crazy ant sites, but not compared to buffer sites. These differences did not persist following baiting. We found no evidence that baiting negatively affects skinks or their invertebrate prey. Our data suggest that yellow crazy ants, but not the bait used to treat them, pose a direct threat to small rainforest skinks.

Seasonal variation in the diet and the morphometric parameters of the genus Pseudo-phoxinus sp. (Cyprinidae) in Eastern Algeria

The diet and the morphometric parameters of the Pseudophoxinus sp. (Cyprinidae) in the El Mellah ravine (M’sila, Algeria) were studied by determining body measurements and analyzing the contents of digestive tracts of 320 fish from December 2018 to November 2019. The obtained results show marked diversity within the fish species diets, which can be grouped into three main fractions: (i) a plant fraction; (ii) an animal fraction composed mainly of invertebrate prey; and (iii) fraction consisting of fish eggs (digested by males during the breeding season). The plant fraction was present in all the analyzed digestive tracts, mainly being composed of phytoplankton (algae), namely, Spirogyra sp., Melosira sp. and Navicula sp. with the total relative abundances of 38.7%, 34.4% and 4.1%, respectively. On the other hand, the animal fraction was represented by the Chironomus sp., Austrosimulium sp., and Ecdyonurus sp. dipterans with a total relative abundance of 7.3%, 6.7% and 5.9%, respectively. Pseudophoxinus sp. eggs can also be considered as part of this fraction with the total relative abundance of 2.9%. The age of the fish seems to have an influence on their feeding behaviour. The juveniles of Pseudophoxinus sp. in the study area had a purely phytophagous diet, while adults showed a phytophagous behaviour with an omnivorous tendency. The present study shows that not only the age of the fish but also the seasonal changes (climatic conditions and entry into the breeding season) may have a significant influence on the diet and morphometric parameters of Pseudophoxinus sp. in El Mellah ravine.

Rampant tooth loss across 200 million years of frog evolution

Teeth are present in most clades of vertebrates but have been lost completely several times in actinopterygian fishes and amniotes. Using phenotypic data collected from over 500 genera via micro-computed tomography, we provide the first rigorous assessment of the evolutionary history of dentition across all major lineages of amphibians. We demonstrate that dentition is invariably present in caecilians and salamanders, but teeth have been lost completely more than 20 times in frogs, a much higher occurrence of edentulism than in any other vertebrate group. The repeated loss of teeth in anurans is associated with a specialized diet of small invertebrate prey as well as shortening of the lower jaw, but it is not correlated with a reduction in body size. Frogs provide an unparalleled opportunity for investigating the molecular and developmental mechanisms of convergent tooth loss on a large phylogenetic scale.

Rampant tooth loss across 200 million years of frog evolution

Teeth have been broadly maintained across most clades of vertebrates but have been lost completely at least once in actinopterygian fishes and several times in amniotes. Using phenotypic data collected from over 500 genera via micro-computed tomography, we provide the first rigorous assessment of the evolutionary history of dentition across all major lineages of amphibians. We demonstrate that dentition is invariably present in caecilians and salamanders, but teeth have been lost completely more than 20 times in frogs, a much higher occurrence of edentulism than in any other vertebrate group. The repeated loss of teeth in anurans is associated with a specialized diet of small invertebrate prey as well as shortening of the lower jaw, but it is not correlated with a reduction in body size. Frogs provide an unparalleled opportunity for investigating the molecular and developmental mechanisms of convergent tooth loss on a large phylogenetic scale.

Malleefowl Leipoa ocellata incubation mounds as habitat for other vertebrates

Ecosystem engineers change the availability of resources for other species by forming new habitat or modifying existing habitat but, despite the diversity of avian ecosystem engineers, 80% of current literature focuses on mammals and invertebrates. Malleefowl Leipoa ocellata build large incubation mounds of soil and leaf-litter that are likely to provide habitat for invertebrates and vertebrates but use of their mounds by other vertebrates has never been quantified. Here, we examine vertebrate fauna visitation rates at Malleefowl mounds and non-mounds using camera-trap data collected by two citizen science projects. From 2012 to 2018, 20 active Malleefowl mounds and 16 non-mound sites were monitored over 31,913 hours and 225,144 hours, respectively. In total, we identified visits by 1724 birds, reptiles and mammals from 36 species. The mean number of vertebrate visits per 1000 hours of surveillance was around one and a half times and species richness five times that at mounds compared with non-mounds. Malleefowl mounds may enhance the availability of invertebrate prey for insectivorous birds and mammals, provide a favourable microclimate for reptiles to thermoregulate, and be signalling/social communication locations. Our results show that further research is warranted and suggest that conservation of Malleefowl may be important not only for the Malleefowl itself, but also for a suite of mallee birds and reptiles.