Geometric causes of species rarity
Understanding the limits of species distributions is a central objective of biogeography and macroecology and has become increasingly important as climate change drives rapid shifts in geographic ranges. Species range sizes follow a highly skewed frequency distribution, with most species occupying ranges orders of magnitude smaller than those of the most widespread species. Range sizes also…
The rarity of species across the globe can be attributed to the geometric patterns formed by dispersal barriers within continents, according to a new study. This finding sheds light on the skewed distribution of species range sizes, where most species have much smaller ranges than the few most widespread ones. The study reveals that small-ranged species are disproportionately concentrated near continental margins and other geographic boundaries, a pattern that remains unexplained by any universally accepted theory.
The researchers have developed a simple geometric model that demonstrates how range size patterns emerge from the random placement of dispersal barriers within continental domains. This model accurately predicts both the frequency distribution and the spatial distribution of range sizes across amphibians, birds, and mammals. Consequently, it offers a fundamental explanation for the global patterns of species rarity that can be further refined by taking into account elevational barriers and spatial variation in species richness.
The study suggests that the geometry of dispersal barriers and the geographic domain play a crucial role in constraining species range size, with proximity to domain boundaries being a key factor in determining species rarity. These insights have significant implications for understanding the evolutionary potential and vulnerability to extinction of species.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
