Biology subjects

Johns, P.

Publications and source records attributed to Johns, P..

6 recordsLinked to original sources

bioRxiv2025

Large-scale identification of microsatellite loci from multiple otter (Mammalia, Carnivora, Lutrinae) species using whole genome sequence data

The development of molecular studies on elusive, rare, and/or poorly known species faces challenges due to the lack of suitable markers. Species-specific microsatellite markers minimize bias, offer better performance, and are cost-effective, aiding the development of population genetic studies. The use of whole-genome sequences allows for the development of species-specific microsatellite markers and their survey in closely related species, enabling the discovery of shared markers that can facilitate comparative studies. Lutrinae includes 14 extant species of otters. Despite their worrisome conservation status, due to inherent characteristics of these species that make their study difficult by traditional methods, many of them lack reliable population genetic data, limiting conservation efforts. In this study, we employed a multi-taxon approach to identify a large number of novel microsatellite loci for 11 of the 14 otter species, assessing whether the identified loci were shared among different taxa. We identified a total of 23,320 microsatellite loci across 11 species, which were reduced to 12,573 after stringent filtering criteria. Primer design was completed successfully for 420 and 259 unique loci, considering two minimum melting temperatures. We validated marker efficiency by testing the 81 loci designed for two Asian species. Of these, 51 loci yielded reliable microsatellite genotypes in both species, with 34 showing allelic variation in at least one of them. These results demonstrate that these markers are applicable in empirical genotyping for both their target and closely related ones.

genomics↗

bioRxiv2025

Agonistic interactions between slender mudskippers (Periophthalmus gracilis) in Singapore

Mudskippers engage in frequent territorial interactions. Few studies of mudskipper agonistic behavioral sequences exist. The slender mudskipper (Periophthalmus gracilis) inhabits intertidal zones of mangrove forests across Southeast Asia. Here, we describe common behavioral sequences of winners and losers among unmanipulated, wild slender mudskipper interactions in Singapore. Winning mudskippers showed more approach behaviors than losers, such as "Crawl towards", and more behaviors that may indicate aggression, such as "Pectoral wave", "Flag", and "Head up". Losers showed more evasive behaviors, like "Jump" and "Crawl away". We found evidence of agonistic behavioral matching. Larger mudskippers won contests more frequently than smaller mudskippers.

animal behavior and cognition↗

bioRxiv2023

Agonism between family groups of cooperative breeding smooth-coated otters (Lutrogale perspicillata)

Intraspecific agonistic interactions are common in the animal kingdom and have significant consequences for animals. With a growing population and limited resources, these interactions have been observed more frequently among smooth-coated otters in Singapore. However, little is known about the behavioral patterns of these interactions and the factors that may affect their outcomes. To address this, we analyzed intraspecific agonistic interactions through publicly available videos from citizen scientists. Our analysis revealed different behavioral patterns and typical behaviors between winning and losing family groups in different environments. We also found suggestive evidence that larger family groups with more individuals than opponents have an advantage in these interactions. The environment in which an interaction occurs may also affect its intensity.

animal behavior and cognition↗

bioRxiv2023

Land use and oriental pied hornbill occurrence in Singapore

Oriental pied hornbills (Anthracoceros albirostris) disappeared from Singapore in the 1800s but were reintroduced in the 2000s. Since then, they have multiplied and even thrived in Singapore, spreading throughout much of the country. Because Singapore is extremely urban and densely populated, here we examine where hornbills have been seen as a function of land-use. We combine citizen science data from eBird and iNaturalist with GIS information to model hornbill sightings. We find that the percent Park and Beach cover have strong positive effects on the probability of hornbill sightings, and that percent Park cover has a positive interaction with percent Built-up and Sea cover. Our results are broadly consistent with sightings of oriental pied hornbills in the region.

ecology↗

bioRxiv2022

Aggressive interactions between smooth-coated otters and water monitor lizards in Singapore

Smooth-coated otters (Lutrogale perspicillata) and Malayan water monitor lizards (Varanus salvator) occupy similar habitats and and interact regularly in Singapores waterways. These interactions have a range of potential outcomes and are sometimes lethal. Few formal behavioral studies exist for either species. We analyzed interactions between otters and monitor lizards by gleaning data from publicly available videos from citizen scientists to examine what factors influence aggressive and defensive behaviors, and what influences vigilance in otters. Behavioral sequence analysis revealed no obvious monitor lizard behavior that predicted otter aggression towards monitors. We found that the presence and number of otter pups is positively associated with otter aggression. Otters also tended to be more vigilant in groups with more pups, and more vigilant on land than water. Monitor lizards displayed aggressive and defensive behaviors more frequently than did otters, regardless of whether the otters were aggressive towards lizards. These observations suggests that otters vary their aggression and vigilance levels depending on the context of each interaction.

animal behavior and cognition↗

bioRxiv2021

Multiple reproductive females in family groups of smooth-coated otters

Smooth-coated otters (Lutrogale perspicillata) are inhabitants of the waterways of India and Singapore. Otter families typically consist of a single mating pair with mature, nonbreeding siblings living in family groups, or "romps". We note here the presence of multiple reproductive female otters within some romps, as well as the possible existence of simultaneous litters by different mothers. This phenomenon has not been recorded among L. perspicillata before. Here we address possible influences leading to multiple reproductive females within romps of smooth-coated otters, including inclusive fitness, incomplete suppression of reproduction, and existing in an urban environment. The numerous, recurring observations of multiple reproductive females warrant further investigation; while uncommon, this phenomenon is not as rare as once thought.

animal behavior and cognition↗