#trait-continuum

#trait-continuum

Few transformations in the history of life have been as extreme as the embrace of the ocean by seagrass. Like whales and dolphins, modern seagrasses descend from land-dwelling ancestors.

Such sex 'distorters' have been discovered - and studied in great depth - in laboratory animals such as mice and flies, in which their effects can be detected through selective breeding. 'If you look, more often than not, you find them,' says Nitin Phadnis, an evolutionary geneticist at the University of Utah in Salt Lake City, who co-led the study.

Human breasts sit at an elevated temperature, protecting a newborn from hypothermia. What's more, the size and shape of the breast allows for broad contact surface - enhancing the heat transfer from mother to child. This could improve a newborn's chances of survival and provide an evolutionarily grounded explanation for the development of external breasts in humans.

The mirror spider can rapidly shift a patchwork of minuscule reflective plates underneath its abdomen's outer surface, altering the pattern of mirrorlike flashes. This uncommon display comes from common building blocks: Similar tilelike arrangements of plates and soft joints appear throughout the tree of life, from turtle shells to tropical fruit peels. Researchers have now compiled 100 examples of this pattern across animals, plants, microbes and viruses, which they describe in PNAS Nexus.

The study's authors researched 96 peer-reviewed studies documenting SSB to compile one of the most comprehensive datasets for primates to date. The study found that SSB are a "persistent and integral component of primate social [practices]." In fact, the prevalence of SSB across a variety of closely related primate species - and over several lines of descendants - "indicates a deep evolutionary root or multiple independent evolutionary origins," the study's authors wrote.