Individual and age-related variation of cellular brain composition in a squamate reptile

Within-species variation in the number of neurons, other brain cells and their allocation to different brain parts is poorly studied. Here, we assess these numbers in a squamate reptile, the Madagascar ground gecko ( Paroedura picta ). We examined adults from two captive populations and three age groups within one population. Even though reptiles exhibit extensive adult neurogenesis, intrapopulation variation in the number of neurons is similar to that in mice. However, the two populations differed significantly in most measures, highlighting the fact that using only one population can underestimate within-species variation. There is a substantial increase in the number of neurons and decrease in neuronal density in adult geckos relative to hatchlings and an increase in the number of neurons in the telencephalon in fully grown adults relative to sexually mature young adults. This finding implies that adult neurogenesis does not only replace worn out but also adds new telencephalic neurons in reptiles during adulthood. This markedly contrasts with the situation in mammals, where the number of cortical neurons declines with age.

Global wildlife trade across the tree of life

Wildlife trade is a multibillion dollar industry that is driving species toward extinction. Of >31,500 terrestrial bird, mammal, amphibian, and squamate reptile species, ~24% (N = 7638) are traded globally. Trade is strongly phylogenetically conserved, and the hotspots of this trade are concentrated in the biologically diverse tropics. Using different assessment approaches, we predict that, owing to their phylogenetic replacement and trait similarity to currently traded species, future trade will affect up to 4064 additional species—totaling 11,702 species at risk of extinction from trade. Our assessment underscores the need for a strategic plan to combat trade with policies that are proactive rather than reactive, which is especially important because species can quickly transition from being safe to being endangered as humans continue to harvest and trade across the tree of life.

Late Pleistocene Squamate Reptiles from the Baranica Cave near Knjazevac (Eastern Serbia)

The Late Pleistocene layers (2-4) of the Baranica Cave near Knjazevac (Eastern Serbia) contain rich and diverse vertebrate fauna, as well as several Palaeolithic artefacts. The squamate reptile fauna contains three lizard and six ophidian (snakes) taxa (Lacerta agilis, Lacertidae indet., Anguis fragilis, Zamenis cf. longissimus, Coronella austriaca, Coronella cf. austriaca, cf. Natrix sp., Vipera cf. berus, Vipera sp.). This is only the second of Late Pleistocene herpetofauna described from Serbia. It consists of the forms mainly characteristic for cold and temperate semi-open regions.

Microsatellite landscape evolutionary dynamics across 450 million years of vertebrate genome evolution

The evolutionary dynamics of simple sequence repeats (SSRs or microsatellites) across the vertebrate tree of life remain largely undocumented and poorly understood. In this study, we analyzed patterns of genomic microsatellite abundance and evolution across 71 vertebrate genomes. The highest abundances of microsatellites exist in the genomes of ray-finned fishes, squamate reptiles, and mammals, while crocodilian, turtle, and avian genomes exhibit reduced microsatellite landscapes. We used comparative methods to infer evolutionary rates of change in microsatellite abundance across vertebrates and to highlight particular lineages that have experienced unusually high or low rates of change in genomic microsatellite abundance. Overall, most variation in microsatellite content, abundance, and evolutionary rate is observed among major lineages of reptiles, yet we found that several deeply divergent clades (i.e., squamate reptiles and mammals) contained relatively similar genomic microsatellite compositions. Archosauromorph reptiles (turtles, crocodilians, and birds) exhibit reduced genomic microsatellite content and the slowest rates of microsatellite evolution, in contrast to squamate reptile genomes that have among the highest rates of microsatellite evolution. Substantial branch-specific shifts in SSR content in primates, monotremes, rodents, snakes, and fish are also evident. Collectively, our results support multiple major shifts in microsatellite genomic landscapes among vertebrates.