Biology subjects

Munoz, M. M.

Publications and source records attributed to Munoz, M. M..

3 recordsLinked to original sources

bioRxiv2026

The macroevolutionary impact of an innovation reversal in ray-finned fishes

The evolution of new traits can drive species diversification by facilitating the use of new resources, but environmental change may turn these same adaptations into liabilities.Trait loss is also often associated with the origin of new ecologies, but how losses modulate diversification remains unclear. The swim bladder allows ray-finned fishes to regulate their buoyancy and exploit ecosystems throughout the water column, yet this organ has been lost many times among species-rich lineages. Here, we show that timing and ecological context control the macroevolutionary effects of swim bladder loss. Many lineages of fishes lost the swim bladder over the last 66 million years as they specialized for benthic habitats where buoyancy regulation is unnecessary. Swim bladder loss enabled the descendants of these benthic fishes to diversify in the deep sea where extreme pressure makes its inflation untenable, and in the frigid, oxygen-saturated Southern Ocean, where loss of the oxygen delivery mechanisms required for swim bladder inflation carries little physiological cost. Yet, we detect a selective filter associated with swim bladder loss during extreme global warming 56 to 50 million years ago, when its absence limited the capacity of fishes to escape ecological disruptions on the ocean floor. These contrasting patterns explain how the loss of a complex trait promoted major ecological transitions without increasing overall diversification through deep time. As human activity drives rapid global warming, the evolutionary legacies of swim bladder loss may again shape the fate of marine fish diversity.

evolutionary biology↗

bioRxiv2026

A mosaic of climate vulnerability: local warming rates meet intraspecific divergence in heat tolerance

Climate warming is increasing mismatches between thermal phenotypes and habitat temperatures, driving range shifts and population extirpations. While within-species variation in heat tolerance and local warming rates can predict responses to climate warming, how these factors shape differences in vulnerability among taxa and ecosystems is uncertain. Here we combine climate and thermal trait data from 69 species across four ecosystem types to examine the effects of incorporating intraspecific variation in heat tolerance and local warming rates on projected vulnerability to climate warming. Because vulnerability to warming depends on existing phenotypic variation in thermal performance and relative rates of habitat warming, we develop a new metric that integrates localized rates of warming with spatial variation in thermal tolerances, termed the minimum trait velocity. Incorporating intraspecific variation in heat tolerance lowered estimates of warming tolerance (a measure of vulnerability) across most ecosystem types, with the strongest negative impact on marine taxa. Although intraspecific variation in heat tolerance could facilitate adaptation to climate change, our results suggest such variation is generally less than the projected near future warming. This suggests that opportunities for evolutionary rescue via gene flow between locally adapted populations are limited, adding to mounting concern as the climate warms.

ecology↗

bioRxiv2025

Universal genomic constraints in the evolvability of thermal physiology

Thermal physiological traits such as body temperature often show surprisingly slow evolutionary rates over macroevolutionary time, despite apparent lability at microevolutionary time scales. While long-term stabilizing selection may slow rates of thermal evolution, we propose an alternative hypothesis from a bottom-up, population genomic perspective: the nature of body temperature (Tb) as an organism-level trait that must accommodate diverse protein thermal performances leads to evolutionary constraints at the organismal level. We support this hypothesis using a simulation framework in which we modeled and compared the rates of evolution for Tb alongside one or more proteins. Protein performances and organismal Tb were modeled as evolving, QTL-encoded traits, and organismal fitness was determined based on Tb given the performance curves of each protein. As predicted, a greater number of proteins led to drastic decrease in the rate of Tb evolution. When a shift in environmental temperature was simulated, Tb evolved with an initial rapid pulse toward the new optimum, followed by a phase of gradual evolution as the cumulative fitness costs of mismatching Tb and protein optima constrained thermal adaptation. That is, lability and stasis are predictable features of body temperature evolution: rapid, yet bounded microevolutionary bursts followed by long phases of sluggish evolution are both expected outcomes of directional selection operating on hierarchically structured traits like Tb. We suggest that protein thermal coordination might contribute to intrinsic, universal macroevolutionary patterns of stasis in organismal physiology across endotherms and ectotherms.

evolutionary biology↗