Tag

Stabilizing Selection

All articles tagged with #stabilizing selection

biological-anthropology12 days ago•46 min saved

Cranial evolution in Homo shaped by constraints and neutral change, not steady directional selection

A morphometric analysis of fossil and modern Homo skulls shows brain- and face-related cranial changes were not driven by gradual directional selection for larger brains or smaller faces. Instead, neutral processes and stabilizing selection best explain the observed variation in both Homo sapiens and Homo neanderthalensis, with some axes hinting at limited selection. The results highlight environmental and cultural constraints (e.g., cooking, tool use) as key factors shaping cranial evolution rather than continuous, linear directional pressures, and suggest releases from stabilizing selection during major transitions may have fueled later diversification.

via Nature|

#biological-anthropology #cranial-morphology #encephalization

science1 month ago•73 min saved

Tail-specific genetics: rare variants sculpt trait extremes under selection

A large study across 74 quantitative traits in UK Biobank and replication cohorts shows that while complex traits are broadly polygenic, the tails of their distributions are enriched for rare, large‑effect alleles. Using POPout and family‑based STANDout tests, researchers find widespread tail departures from common-variant expectations, replicated across ancestries and repeated measurements. Incorporating sequencing‑identified rare variants markedly reduces these tail deviations, indicating rare alleles drive trait extremes. Forward simulations support stabilizing selection as a mechanism, with lifetime reproductive success providing empirical support for selection. These results imply tail architecture is distinct from the population-wide polygenic pattern and have implications for rare-variant discovery and improving prediction of complex traits and diseases.

via Nature|

#genetics #polygenic-risk-scores #rare-variants