Anthropological Science Advance Publications

The effective population size (Ne) quantifies the rate at which genetic diversity is eroded by genetic drift, a fundamental process of evolutionary change, and also provides an insight into the demographic history and dynamics of modern human populations. The main interest of this study was to reconstruct the recent effective population size, by using inferred long segments of identity by descent (IBD), and to estimate the effective/census size ratio in the Lithuanian population. We used Illumina 770K HumanOmniExpress-12v1.0 array data of 295 unrelated individuals of the Lithuanian population. IBDseq v. r1206 and IBDNe v. 04Sep15.e78 software packages were used to detect IBD segments and to estimate Ne, respectively. We estimated the effective population size in Lithuania 50 generations (g) ago to be 11900, whereas for g = 0 (1991) the effective population was 417000 (95% confidence interval, CI [218000; 1150000], and the census size was 3701968. We evaluated the ratio of effective size to census (N) size. The estimates of Ne were approximately one-tenth of the census size. We conclude that natural levels of fluctuations in the Lithuanian population size probably caused the small values of Ne/N. Because of extrapolation of slowing growth rates and migration of the Lithuanian population, this estimate might be correct, as the census size is expected to be several times larger than the Ne.

The African primate fossil record is very poor between the mid-Middle and mid-Late Miocene. Nakali (~10–9.8 Ma) is one of the rare African localities that have yielded primate fossils from this period, including a new genus of great ape, Nakalipithecus nakayamai, and another large-bodied hominoid species. The Nakali primate fauna also includes small-bodied ‘apes’ and Old World monkeys (mostly colobines). In this article, we describe a new specimen of a small-bodied ‘ape’ discovered from Nakali, which is assigned to nyanzapithecines. Nyanzapithecines are characterized by their derived dental morphology, and the previously known nyanzapithecines range in chronological age between the Late Oligocene and early Middle Miocene (~25–13.7 Ma). The new nyanzapithecine specimen from Nakali is therefore the latest occurrence of this group in the African fossil record, extending its chronological range by almost 4 million years younger.