From Climate to Cuisine: Climatic Divergence as a Predictor of Diet Divergence in Mammals

A major goal in evolutionary biology is to understand how species differentiate and adapt to their distinct environments. 

Ecological niche divergence is the process by which closely related species evolve different ecological roles by adapting to distinct resources or environmental conditions, often reducing competition.

Both biotic factors (e.g., diet and resource use) and abiotic factors (e.g., climate) are key drivers of this divergence.

Climate can influence species directly through physiological constraints and indirectly by shaping resource availability, while diet reflects how species utilize those resources.

Although both climate and diet contribute to niche divergence, the extent to which climatic differences drive dietary differences among closely related species remains unclear. 

This study investigates the relationship between climate and diet in shaping niche divergence among sister species.

To do this, divergence was quantified along both climate (temperature and precipitation) and diet axes and compared across multiple mammalian families.

Species pairs were identified using published phylogenetic hypotheses within focal carnivore families.

Pairs were defined as terminal sister taxa, representing the two most closely related extant species sharing an immediate common ancestor exclusive of other taxa.

Phylogenetic relationships were cross-validated across multiple primary literature sources to ensure consistency of sister-pair assignments.

Divergence times (mya) for each species pair were obtained from TimeTree and cross-referenced with published molecular phylogenies when available.

When multiple estimates existed, consensus or most recent calibrated values were used to standardize comparisons across families.

Divergence time estimates were used to evaluate whether ecological niche divergence increased with evolutionary age.

Diet composition data was compiled from EltonTraits and supporting literature sources 

Diet categories were standardized into broad resource groups (e.g. vertebrates, invertebrates, fruit)

Proportional diet data for each species were compared between sister species 

Bray-Curtis dissimilarity was used to quantify dietary divergence, with values ranging from 0 (identical diets) to 1 (different diets)

Geographic occurrence records were compiled for each species and matched with WorldClim bioclimatic variables

Climatic niches were summarized using principle component analysis (PCA) to reduce multiple climate variables into major environmental gradients 

Pairwise climatic divergence between sister species was quantified using Schoener’s D

Higher values indicated greater climatic differences 

Sister species exhibited a more consistent diet between one another in comparison to climate

Certain families (e.g. Mephitidae) had almost no variation in diet composition within sister species 

Other families (e.g. Canidae) showed large variation between sister species

Climatic divergence varied across families, with most pairs showing moderate to high climatic differences

Several families exhibited broad variation, indicating that closely related species differ in climate niche overlap to varying degrees.

Some families showed consistently high climatic divergence, while others contained pairs occupying more similar climatic conditions

Climate and diet divergence were weakly associated, indicating that climatic differentiation does not consistently correspond with trophic divergence across sister-species pairs.

Several species pairs exhibited high climate divergence but low diet divergence, suggesting conservation of feeding niches despite occupation of different environments.

In contrast, some pairs showed moderate to high diet divergence within similar climates, implying that resource partitioning can occur independently of broad-scale climate differences.