The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Syncytins are envelope genes from endogenous retroviruses that have been captured during evolution for a function in placentation. They have been found in all placental mammals in which they have been searched, including marsupials. Placental structures are not restricted to mammals but also emerged in some other vertebrates, most frequently in lizards, such as the viviparous Scincidae. Here, we performed high-throughput RNA sequencing of a placenta transcriptome and screened for the presence of retroviral genes with a full-length ORF. We identified one such gene, which we named "," that has all the characteristics expected for a syncytin gene. It encodes a membrane-bound envelope protein with fusogenic activity ex vivo, is expressed at the placental level as revealed by in situ hybridization and immunohistochemistry, and is conserved in all species tested, spanning over 25 My of evolution. Its cognate receptor, required for its fusogenic activity, was searched for by a screening assay using the GeneBridge4 human/Chinese hamster radiation hybrid panel and found to be the MPZL1 gene, previously identified in mammals as a signal-transducing transmembrane protein involved in cell migration. Together, these results show that syncytin capture is not restricted to placental mammals, but can also take place in the rare nonmammalian vertebrates in which a viviparous placentotrophic mode of reproduction emerged. It suggests that similar molecular tools have been used for the convergent evolution of placentation in independently evolved and highly distant vertebrates.

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Analysis of placentation in the final stages of development in Mabuya mabouya shows that the placenta is formed by the apposition of the chorioallantois to the uterine mucosa implicating the entire embryonic chamber, because the allantoic vesicle invades all the exocoelom. The chorioallantoic placenta presents the features proper of a type IV allantoplacenta. However, in the mesometrial area peripheral to the placentome, we found that the paraplacentome is an additional zone specialized for histotrophic transfer, and is separated from the rest of the embryonic chamber by a chorionic invagination formed of polymorphic cells. The chorionic areolae are components of the embryonic hemisphere; they are in apposition to an endometrium with columnar epithelial cells and several glands that secrete toward the cavity of the areolae. They are observed only in the preparturition stage, probably operating in maternal-fetal transfer of nutrients during the last embryonic growth stage. The mesometrial hemisphere possesses specializations related to histotrophic nutrition (placentome, paraplacentome, and chorionic areolae), while in the abembryonic hemisphere there is an allantoplacenta of mixed function, with capacity for histotrophic nutrition and for gas exchange. The absorptive plaques are small rounded areas constituted by chorionic cells similar to the paraplacentomal chorionic cells, in intimate apposition with a secretory uterine epithelium. Separating the absorptive plaques are respiratory segments histologically similar to the type I allantoplacenta. The additional histotrophic areas found for this species demonstrate the great specialization of this allantoplacenta, and support the highest degree of matrotrophy among reptiles reached in the Neotropical Mabuya.

Topological and histological analyses of Mabuya mabouya embryos at different developmental stages showed an extraembryonic membrane sequence as follows: a bilaminar omphalopleure and progressive mesodermal expansion around the whole yolk sac at gastrula stages; mesodermal split and formation of an exocoelom in the entire embryonic chamber at neurula stages; beginning of the expansion of the allantois into the exocoelom to form a chorioallantoic membrane at pharyngula stages; complete extension of the allantois into the exocoelom between limb-bud to preparturition stages. Thus, a placental sequence could be enumerated: bilaminar yolk sac placenta; chorioplacenta; allantoplacenta. All placentas are highly specialized for nutrient absorption from early developmental stages. The bistratified extraembryonic ectoderm possesses an external layer with cuboidal cells and a microvillar surface around the whole yolk sac, which absorbs uterine secretions during development of the bilaminar yolk sac placenta and chorioplacenta. During gastrulation, with mesodermal expansion a dorsal absorptive plaque forms above the embryo and several smaller absorptive plaques develop antimesometrially. Both structures are similar histologically and are active in histotrophic transfer from gastrula stages until the end of development. The dorsal absorptive plaque will constitute the placentome and paraplacentome during allantoplacental development. At late gastrula-early neurula stages some absorptive plaques form chorionic concavities or chorionic bags that are penetrated by a long uterine fold and seem to have a specialized histotrophic and/or metabolic role. The extraembryonic mesoderm does not ingress into the yolk sac and neither an isolated yolk mass nor a yolk cleft are formed. This derived pattern of development may be related to the drastic reduction of the egg size and obligatory placentotrophy from early developmental stages. Our results show new specialized placentotrophic structures and a novel arrangement of extraembryonic membrane morphogenesis for Squamata.