Disorders of sexual development (DSD) are associated with atypical chromosomal, gonadal, or phenotypic sex. It is likely that the number of cases of DSD are underestimated in the equine population. Monorchidism in the horse is very rare. This case report describes the clinical assessment of a phenotypic mare with stallion-like behavior which led to the diagnosis of a DSD. A 4-year-old Quarter Horse mare presented in good body condition, with normal external genitalia for a mare, and normal mammary glands with two bilaterally symmetric teats. No uterus, cervix, or gonads were detected on transrectal palpation. Transrectal ultrasonography revealed a single gonad in the right dorsal abdomen with the morphologic appearance of a testicle. Presurgical hormonal evaluation revealed elevated serum testosterone and anti-Müllerian hormone (AMH) concentrations. The right gonad was successfully removed via standing exploratory laparoscopy and submitted for histopathology. No gonad was identified on the left side during laparoscopy. Histopathologic examination confirmed that the excised gonad was a testicle. Cytogenetic and molecular analysis revealed a 64,XY, SRY-positive chromosomal constitution. Hormonal evaluation 5 weeks after surgery revealed low serum testosterone and AMH levels. A diagnosis of monorchidism was based on ultrasound examination, laparoscopic exploration of the abdomen, removal of a single gonad, and a subsequent decrease in serum testosterone and AMH concentrations to basal levels. In summary, a combination of clinical signs, endocrine evaluation, chromosomal and molecular analysis, and histopathology can be used in the diagnosis of DSD conditions.

There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost-effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.

Nature Communications 6: Article number: 7414 (2015); Published: 16 June 2015; Updated: 18 February 2016. The authors inadvertently omitted Kimiora L. Ward, who managed and contributed data, from the author list. This has now been corrected in both the PDF and HTML versions of the Article.