Search for: All records

Zoonotic diseases, including those carried by mammalian hosts, pose a significant threat to human health worldwide and substantial investment in wildlife disease surveillance is aimed at identifying the risk of spillover from wildlife to human populations where they interact. However, host species diversity is highest in the most intact habitats away from human habitation and most of the potential host species within these habitats are unsampled for infections. This is particularly true in biodiverse tropical ecosystems where the prevalence and identity of infections are the least known. We screened for presence of trypanosomes in 2,335 specimens from 66 species of rodents and shrews sampled from 11 mountain areas on the tropical island of Sulawesi, Indonesia. Our sampling spanned from the edge of human occupation into the most intact forests available on the island with sampling elevations ranging from 220 to 2,700 m. The two most common Trypanosoma species we detected were a native species from the Theileri clade (19.0 % of samples) and an introduced species from the Lewisi clade (5.1 % of murid rodent samples). Both species were detected at all elevations, extending from village edges to mountain peaks, but both reached their highest prevalence above 2,000 m elevation in the most intact forest away from human habitation. If these patterns with trypanosome infections are typical of other zoonotic diseases, wildlife disease surveillance would need to shift resources to study host-pathogen dynamics in more remote ecosystems. Sampling focused on the breadth of biodiversity, such as collected by and housed in natural history collections, is needed to further our understanding of zoonotic diseases and their prevalence. 

Communities that occupy similar environments but vary in the richness of closely related species can illuminate how functional variation and species richness interact to fill ecological space in the absence of abiotic filtering, though this has yet to be explored on an oceanic island where the processes of community assembly may differ from continental settings. In discrete montane communities on the island of Sulawesi, local murine rodent (rats and mice) richness ranges from 7 to 23 species. We measured 17 morphological, ecological, and isotopic traits – both individually and as five multivariate traits – in 40 species to test for the expansion or packing of functional space among nine murine communities. We employed a novel probabilistic approach for integrating intraspecific and community‐level trait variance into functional richness. Trait‐specific and phylogenetic diversity patterns indicate dynamic community assembly due to variable niche expansion and packing on multiple niche axes. Locomotion and covarying traits such as tail length emerged as a fundamental axis of ecological variation, expanding functional space and enabling the niche packing of other traits such as diet and body size. Though trait divergence often explains functional diversity in island communities, we found that phylogenetic diversity facilitates functional space expansion in some conserved traits such as cranial shape, while more labile traits are overdispersed both within and between island clades, suggesting a role of niche complementarity. Our results evoke interspecific interactions, differences in trait lability, and the independent evolutionary trajectories of each of Sulawesi's six murine clades as central to generating the exceptional functional diversity and species richness in this exceptional, insular radiation. 

Abstract It remains unclear how variation in the intensity of sperm competition shapes phenotypic and molecular evolution across clades. Mice and rats in the subfamily Murinae are a rapid radiation exhibiting incredible diversity in sperm morphology and production. We combined phenotypic and genomic data to perform phylogenetic comparisons of male reproductive traits and genes across 78 murine species. We identified several shifts towards smaller relative testes mass (RTM), presumably reflecting reduced sperm competition. Several sperm traits were associated with RTM, suggesting that mating system evolution selects for convergent suites of traits related to sperm competitive ability. We predicted that sperm competition would also drive more rapid molecular divergence in species with large testes. Contrary to this, we found that many spermatogenesis genes evolved more rapidly in species with smaller RTM due to relaxed purifying selection. While some reproductive genes evolved rapidly under recurrent positive selection, relaxed selection played a greater role in underlying rapid evolution in small testes species. Our work demonstrates that postcopulatory sexual selection can impose strong purifying selection shaping the evolution of male reproduction and that broad patterns of molecular evolution may help identify genes that contribute to male fertility. 

Abstract We describe 3 new species of shrews (Eulipotyphla, Soricidae, Crocidura) from West Sumatra, Indonesia. Two of these taxa were found above 1,800 m on Mt. Singgalang. The third taxon was found above 1,660 m on Mt. Talamau, 65 km northwest of Mt. Singgalang. We also resurrect Crocidura aequicauda based on 2 specimens from Mts. Tujuh and Kerinci, which lie near the border between West Sumatra and Jambi provinces. Several methodological approaches support our findings: linear cranial morphometrics, landmark-based 2D geometric morphometrics, and molecular phylogenetics using both mtDNA and 6 nuclear exons. A multilocus species-tree analysis places the 3 new species and C. aequicauda in a clade with the Javan endemics C. monticola and C. umbra. Although the 2 taxa from Mt. Singgalang are recovered as sister species, 1 is nearly twice the size of the other, and they are divergent in several other morphological characters, such as tail length, cranium size, and pelage color and texture. Recently diverged yet morphologically disparate sister taxa living syntopically in an isolated habitat “island,” like the montane forests of Mt. Singgalang, is unusual in mammals but documented in other Crocidura on neighboring Java and Borneo; these 2 new taxa represent the first known case of this phenomenon on Sumatra. Our results bring the number of Sumatran Crocidura to 10, 9 of which are endemic to the island. All 3 of the new species appear to be endemic to a single mountain and were not detected in similar surveys of nearby mountains. If this local endemism pattern is common, it would indicate that Sumatra’s mammal diversity may be severely underestimated, largely due to the paucity of small-mammal surveys and museum specimens. 

Abstract Crunomys and Maxomys are closely related murine genera from forested regions of Southeast Asia and western portions of the Indo-Australian Archipelago. Previous phylogenetic analyses suggested that a taxonomic reappraisal is necessary for these genera, but limited taxon sampling prevented formal changes. We produced a mitochondrial DNA dataset that includes 376 individuals representing all 22 recognized species and a nuclear dataset comprising thousands of ultraconserved elements missing only 1 recognized species. Our phylogenetic inferences consistently show that Crunomys is nested within Maxomys. We transfer all Maxomys species to the older genus Crunomys to resolve the paraphyly. We also conducted a morphological analysis of species from Sulawesi and described a new species of Crunomys from the eastern peninsula of the island. We identify 43 geographically defined mitochondrial haplogroups across all species of Crunomys, many of which also are inferred as distinct in a multilocus species delimitation analysis. Historical biogeographic reconstructions consistently inferred multiple dispersal events to and from oceanic islands and among continental shelf islands and mainland Southeast Asia. On both large continental shelf islands like Borneo and large oceanic islands like Sulawesi, in situ divergence produced high levels of diversity. 

Abstract Faunivorous mammals with simple guts are thought to rely primarily on endogenously produced enzymes to digest food, in part because they lack fermentation chambers for facilitating mutualistic interactions with microbes. However, variation in microbial community composition along the length of the gastrointestinal tract has yet to be assessed in faunivorous species with simple guts. We tested for differences in bacterial taxon abundances and community compositions between the small intestines and colons of 26 individuals representing four species of shrew in the genus Crocidura. We sampled these hosts from a single locality on Sulawesi Island, Indonesia, to control for potential geographic and temporal variation. Bacterial community composition differed significantly between the two gut regions and members of the family Mycoplasmataceae contributed substantially to these differences. Three operational taxonomic units (OTUs) of an unclassified genus in this family were more abundant in the small intestine, whereas 1 OTU of genus Ureaplasma was more abundant in the colon. Species of Ureaplasma encode an enzyme that degrades urea, a metabolic byproduct of protein catabolism. Additionally, a Hafnia–Obesumbacterium OTU, a genus known to produce chitinase in bat gastrointestinal tracts, was also more abundant in the colon compared to the small intestine. The presence of putative chitinase- and urease-producing bacteria in shrew guts suggests mutualisms with microorganisms play a role in facilitating the protein-rich, faunivorous diets of simple gut mammals. 

Abstract Albinism, a congenital disorder that results in a lack of melanin deposition, is common in domesticated animals but rare in nature. Among the ∼2500 species of rodents worldwide, only 67 have published reports of albinism. Here we report the capture of an albino murid (Muridae: Rodentia) from Mt. Singgalang in West Sumatra, Indonesia. The specimen is an adolescent but sexually mature maleMaxomys hylomyoides, a montane Sumatran endemic. To our knowledge, this specimen represents the first reported albino rodent from Indonesia and Sundaland, and only the second from Southeast Asia.