Carving out turf in a biodiversity hotspot: multiple, previously unrecognized shrew species co‐occur onJavaIsland,Indonesia

Abstract

In theory, competition among species in a shared habitat results in niche separation. In the case of small recondite mammals such as shrews, little is known about their autecologies, leaving open questions regarding the degree to which closely related species co-occur and how or whether ecological niches are partitioned. The extent to which species are able to coexist may depend on the degree to which they exploit different features of their habitat, which may in turn influence our ability to recognize them as species. We explored these issues in a biodiversity hotspot, by surveying shrew (genus Crocidura) diversity on the Indonesian island of Java. We sequenced portions of nine unlinked genes in 100-117 specimens of Javan shrews and incorporated homologous data from most known Crocidura species from other parts of island South-East Asia. Current taxonomy recognizes four Crocidura species on Java, including two endemics. However, our phylogenetic, population genetic and species delimitation analyses identify five species on the island, and all are endemic to Java. While the individual ranges of these species may not overlap in their entirety, we found up to four species living syntopically and all five species co-occurring on one mountain. Differences in species' body size, use of above ground-level habitats by one species and habitat partitioning along ecological gradients may have facilitated species diversification and coexistence.

How many species of mammals are there?

“…While the addition of > 300 species each of rodents and bats is unsurprising given their existing diversity, these clades may reasonably contain disproportionally high levels of cryptic diversity (e.g., Ruedi and Mayer 2001;Belfiore et al 2008), and thus the application of genetic sequence data may continue to yield greater insights. Within Eulipotyphla (most particularly in shrews), we expect that the discovery of new species will continue given their rate of recent discoveries and frequency of morphological crypsis (Esselstyn et al 2013). The species richness in Sorex (86 species) and Crocidura (197 species) suggests that genus-level revisions are needed and, when conducted, are likely to yield further taxonomic rearrangements (Castiglia et al 2017;Matson and Ordóñez-Garza 2017).…”

Sun skink landscape genomics: assessing the roles of micro‐evolutionary processes in shaping genetic and phenotypic diversity across a heterogeneous and fragmented landscape

“…; Brown & Siler ; Esselstyn et al . ). Thus, it is notable that this study has revealed predicted patterns of genetic variability in which, despite the species’ presence in virtually all terrestrial habitats of South‐East Asia, the genetic signal of landscape fragmentation and oceanic barriers to gene flow are detectable at a finer genomic level.…”

“…Thus, our failure to detect isolation by environment along with the observed low population structure makes sense given the wide geographical range and apparent generalist ecological preferences exhibited by this species. Interestingly, in several recent mainland versus adjacent island archipelago comparisons of genetic diversity of widespread vertebrates, the expectation of a genetically homogenous continental population as compared to more genetically structured or fragmented island archipelago populations has not been observed (Stuart et al 2006;Brown et al 2010;Esselstyn et al 2013). Thus, it is notable that this study has revealed predicted patterns of genetic variability in which, despite the species' presence in virtually all terrestrial habitats of South-East Asia, the genetic signal of landscape fragmentation and oceanic barriers to gene flow are detectable at a finer genomic level.…”

Phylogeny, phylogeography and geographical variation in theCrocidura monax(Soricidae) species complex from the montane islands of Tanzania, with descriptions of three new species

“…Laboratory protocols followed those of Esselstyn et al . (, ). We first sequenced 684 bp from the 3′ end of cytochrome b (CytB) in 267 specimens ().…”

“…We extracted, amplified and sequenced various fragments of DNA from montane populations of the Crocidura monax species complex and several potentially related taxa. Laboratory protocols followed those of Esselstyn et al (2009Esselstyn et al ( , 2013. We first sequenced 684 bp from the 3′ end of cytochrome b (CytB) in 267 specimens (Appendix).…”