Phylogenetic conservatism of dietary niches in Neotropical leaf-nosed bats
This study demonstrates that phylogenetic niche conservatism in the dietary habits of Neotropical leaf-nosed bats is evident but varies significantly depending on whether niche breadth or position is assessed and at which phylogenetic scale (family, subfamily, or species) the analysis is conducted.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Every living thing carries a unique set of requirements and habits that define how it lives, what it eats, and where it fits in the world. Scientists call this the ecological niche. For a long time, researchers focused mostly on the physical side of this niche: the temperature a species can tolerate, the rainfall it needs, or the altitude it can survive in. But there is another side, just as important: the biological side. This includes what an animal eats and who it interacts with. A key question in evolutionary biology is whether these habits are passed down from ancestors to descendants, like a family recipe that never changes. This tendency for lineages to keep their ancestral ways over millions of years is known as phylogenetic niche conservatism. While scientists have studied this for physical traits like climate tolerance for decades, they have barely scratched the surface when it comes to diet. Understanding whether dietary habits are conserved helps explain why certain animals live where they do, how they respond to climate change, and how the incredible variety of life on Earth came to be.
In a new study, researchers set out to test this idea of dietary conservatism in a group of bats known as leaf-nosed bats, which are found throughout the tropical Americas. These bats are famous for their incredible variety of diets; while some eat only fruit, others sip nectar, hunt insects, eat other vertebrates, or even drink blood. The scientists wanted to know if these dietary habits are deeply rooted in the family tree of these bats. Do close relatives tend to eat the same things? Do entire branches of the family tree stick to specific diets, or do they constantly switch things up? To find out, the team looked at the dietary habits of 163 species of these bats, analyzing their eating patterns at three different levels of the family tree: the entire family, the smaller subgroups within the family, and finally, between individual pairs of closely related species. They examined two specific aspects of the diet: the "position," which is essentially what the animal prefers to eat, and the "breadth," which is how varied its diet is.
The researchers found that the answer depends entirely on which part of the family tree you look at and which aspect of the diet you measure. When they looked at the entire family of leaf-nosed bats as a whole, they discovered that the variety of food a bat eats—its dietary breadth—has remained surprisingly stable over time. Most of these bats tend to stick to a narrow diet, focusing on just one or two types of food, and this tendency to specialize appears to be a trait that has been conserved across the whole group. However, the specific type of food they prefer, or their dietary position, did not show this same pattern of stability for the whole family. Instead, the data suggested that the entire group has been free to explore different dietary options without being locked into a single ancestral preference.
When the scientists zoomed in to look at the smaller subgroups within the family, the pattern flipped. Here, they found strong evidence that the specific type of food a bat eats is indeed conserved. For example, the subgroup known for eating fruit tends to stay fruit-eaters, while the group known for drinking nectar stays with nectar. These subgroups have distinct dietary identities that have been preserved over millions of years. Interestingly, within these specific subgroups, the variety of their diet was not as strictly conserved as the specific food type was. This suggests that while a group of bats might be locked into a general category of food, the individual species within that group can still vary in how specialized or broad their eating habits are.
At the most detailed level, comparing individual pairs of sister species—bats that are each other's closest relatives—the researchers found that these close relatives have much more similar diets than bats that are not related. This confirms that dietary habits are indeed passed down through the family tree, at least among the most recent branches. The study also identified specific moments in evolutionary history where major shifts occurred, such as when a lineage of bats switched from eating fruit to drinking blood, or when a group of nectar-eaters evolved to also eat fruit. These shifts happened at specific points in the family tree, often corresponding to the origins of the different subgroups.
The overall picture that emerges is that dietary evolution in these bats is not a simple, uniform process. It is a complex story where different rules apply at different scales. The entire family has maintained a general tendency to be specialized eaters, but the specific types of food they eat have been free to change and diversify at the highest level. Once those diversifications happened and distinct subgroups formed, those specific dietary preferences became locked in and conserved. This research highlights that to truly understand how animals evolve their habits, scientists cannot just look at the whole group or just at the individuals; they must look at the family tree at multiple levels to see the full story. By doing so, they found that the way these bats eat is a mix of deep-rooted traditions and specific, stable family identities, shaped by millions of years of evolution.
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