Exploring Rattus praetor (Rodentia, Muridae) as a possible species complex using geometric morphometrics on dental morphology

Abstract

Taxonomic uncertainties in the Rattus genus persist due to among-species morphological conservatism coupled with within-species environmental variation in morphology. As a result, this genus contains a number of possible cryptic species. One important example can be found in R. praetor, where morphological studies indicate it is a possible species complex. Genetic studies of R. praetor (limited to analysis of mitochondrial DNA) have been inconclusive, but do indicate such subdivision. Here we use geometric morphometrics to explore this possible species complex by analysing the dental traits of 48 specimens from New Guinea and neighbouring regions. We find separate molar morphologies for Bougainsville Island, central New Guinea and west New Guinea which cannot be easily explained by different environmental factors (climate, precipitation and altitude), strongly suggesting the existence of a number of evolutionarily distinct taxa within what is currently called R. praetor thus supporting previous suggestions that R. praetor is a species complex. Our findings demonstrate the potential of advanced morphological analyses in identifying separate species, contrary to the claims of morphological conservatism. Future analyses should combine geometric morphometrics with genetic analyses over the species range and include sub-fossil specimens from the Bismarck archipelago and Solomon Islands to resolve the evolutionary history of R. praetor.

Role of ecology in shaping external nasal morphology in bats and implications for olfactory tracking

“…Bats are attracted to odor lures in the field, with more captures recorded in odor-baited mist nets [20,56] and increased frugivore activity around fruit odor lures in open field areas [57]. Olfactory cues may play an role in the detection of ripe fruits or flowers over long distances [22,58], as well as facilitating foraging in cluttered habitats [29]. However, it may be that bats rely more on spatial memory to locate potential food resources [59] and then rely on olfactory cues for fine-scale localization and discrimination.…”

geoorigins: A new method andrpackage for trait mapping and geographic provenancing of specimens without categorical constraints

“…The large spiny rat R. praetor , is distributed across New Guinea and the neighbouring islands, including the Bismarck Archipelago and the Solomon Islands. Recent shape analyses of their teeth revealed geographic structure with a general east–west cline (Hulme‐Beaman et al., 2018). This presents an interesting dataset for future studies into human migration since R. praetor was introduced to remote Oceania by humans (White, Clark, & Bedford, 2000).…”

“…All specimens are of known origin, with known sampling locations and associated latitude and longitude data; therefore, all results presented here are in effect CCV exercises. For shape, we used two geometric morphometric datasets of dental morphology: 48 New Guinea large spiny rat Rattus praetor specimens (Hulme‐Beaman, Cucchi, Evin, Searle, & Dobney, 2018); and 553 common vole Microtus arvalis specimens (Cucchi et al., 2014). For these datasets we aligned, processed and generated Procrustes distances between shape configurations using r and the package shapes (Dryden, 2016).…”

The missing Myopus: plugging the gaps in Late Pleistocene small mammal identification in western Europe with geometric morphometrics

“…This study uses geometric morphometrics, which has never been applied on these two genera, despite its efficiency in identifying similar species in modern and fossil record (e.g. McGuire, 2011;Cucchi et al, 2014;Hulme-Beaman et al, 2018;Stoetzel et al, 2017;Navarro et al, 2018;Kolendrianou et al, 2020). Several modern populations were considered, both to establish differences in their dental morphologies and to evaluate the reliability of traditional criteria previously used to separate the two genera.…”