March 17, 2023                                                    feature

Diversification of the ruminant skull—from microevolutionary processes to macroevolutionary patterns

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2023-03-18 02:00:06

March 17, 2023 feature

Evolutionary biologists aim to form fundamental connections between microevolutionary processes and macroevolutionary patterns based on comparative datasets of population-level variation. In a new report on Science Advances, Daniel R. Rhoda and a team of scientists in evolutionary biology at the University of Chicago and the Jackson Laboratory in the U.S., analyzed a previously published dataset of ruminant (mammalian) crania.

The results were biased via highly conserved craniofacial evolutionary allometry (CREA), where larger species demonstrated proportionally longer faces. The outcomes highlighted the feature as an evolutionary line of least resistance, facilitating morphological diversification aligned with the browser-grazer spectrum. The results show how constraints at the population level can produce highly directional patterns of phenotypic evolution at the macroevolutionary scale. The work sheds light on exploring the role of craniofacial evolutionary allometry across mammalian clades. Craniofacial evolutionary allometry (CEA)

Natural selection affects phenotypic variation in a population, where the development of the population responds to selection. The direction of the greatest amount of variation is known as the line of least resistance (LLR) and represents the potential direction of greatest evolutionary change. If the selection is aligned with the line of least resistance, biologists expect populations to evolve in a direct path towards an adaptive peak. However, if the selection is oriented elsewhere, the response to selection will be realigned towards the line of least resistance. As a result of this, interactions between the adaptive landscape and limits of variation within a species at the population level determine the path of phenotypic evolution.

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