Biology subjects

Rominger, A. J.

Publications and source records attributed to Rominger, A. J..

5 recordsLinked to original sources

bioRxiv2026

A maximum entropy perspective reveals deviations from steady state during active diversification

Ecosystems are rarely at steady state, yet most theory predicting universal biodiversity patterns assumes they are. Here, we test whether and how eco-evolutionary dynamics drive departures from steady state by combining arthropod community data from the geologic chronosequence of the Hawaiian Archipelago with the Maximum Entropy Theory of Ecology (METE), a minimalist steady-state framework that simultaneously predicts species abundance distributions (SADs) and individual metabolic rate distributions (IPDs). The chronosequence of the Hawaiian Archipelago has yielded insights into eco-evolutionary processes because ecosystems growing on different aged substrates offer snapshots of community assembly with different histories. We find that deviations from METE peak at geologically middle-aged sites (150 Kya-1.4 Mya), consistent with active adaptive radiation pushing communities away from statistical steady state. Within-site {beta}-diversity, which also peaks at middle-aged sites, robustly predicts deviations from METE across all sites, while the proportion of non-native species predicts deviations only after excluding the geologically youngest site. Partitioning {beta}-diversity between native and non-native species resolves this discrepancy: at the youngest site, non-native species are distributed homogeneously and do not elevate {beta}-diversity despite their high proportional representation. Together, these results are consistent with a trajectory from young, dispersal-assembled communities near statistical steady state, through an eco-evolutionary non-steady-state transition driven by diversification, to a new stable steady state at the oldest sites. Our findings suggest that periods of active diversification create windows of ecological instability that may facilitate biological invasion, with implications for understanding invasion dynamics in biodiversity hotspots.

ecology↗

bioRxiv2026

Intermediate abundance promotes speciation when dispersal is limited

Why do some lineages diversify while others do not? This remains a central question in evolutionary ecology. A long-standing assumption, dating to Darwin and embedded in the Unified Neutral Theory of Biodiversity, holds that abundant species should speciate at higher rates. Conversely, theoretical and empirical work highlights the possibility that rare and dispersal-limited clades might be more prone to speciation. Using a birth-death-immigration model with protracted speciation in a multi-population landscape connected by limited dispersal, we show that abundance has a hump-shaped effect on probability of speciation. Our model reveals that intermediate abundance maximizes speciation probability because larger populations disperse more, swamping regional differentiation and inhibiting speciation completion, while smaller populations lack the persistence and incipient speciation needed to diversify. We find empirical support for this prediction with an analysis of data from arthropods endemic to Hawaii, where genus-level species richness shows a significant hump-shaped relationship with mean genus abundance. These findings provide a mechanistic explanation for a nuanced relationship between abundance and diversification.

evolutionary biology↗

bioRxiv2022

Global determinants of the distribution of insect genetic diversity

Understanding global patterns of genetic diversity (GD) is essential for describing, monitoring, and preserving life on Earth. To date, efforts to map macrogenetic patterns have been restricted to vertebrates, which comprise only a small fraction of Earths biodiversity. Here, we construct the first global map of predicted insect mitochondrial (COI) GD, derived from publicly available data. We calculate the mitochondrial GD mean (GDM) and evenness (GDE) of insect assemblages across the globe, identify their environmental correlates, and make predictions of mitochondrial GD levels in unsampled areas based on environmental data. Using the largest single-locus genetic dataset yet assembled, we find that mitochondrial GDE follows a quadratic latitudinal gradient peaking in the subtropics. Both mitochondrial GDM and GDE positively correlate with seasonally hot temperatures, as well as climate stability since the last glacial maximum. Our models explain 27.9% and 24.0% of the observed variation in mitochondrial GDM and GDE in insects, respectively, making an important step towards understanding global biodiversity patterns in the most diverse animal taxon.

evolutionary biology↗

bioRxiv2021

On the inference of positive and negative species associations and their relation to abundance

The prevalence of rare species in ecosystems begs the question of how they persist. In a recent paper, Calatayuda et al. (CEA) provided a new hypothesis that rare species, in contrast to common species, share unique microhabitats and/or preferentially engage in mutualistic interactions. CEA support this hypotheses by reconstructing association networks from spatially replicated abundance data finding that rare species are over-representing in positive association networks while common species are over-representing in negative association networks. However, the use of abundance and co-occurrence data to infer true species associations is difficult and often inaccurate. Here, I show that the finding of rare species being more represented in positive association networks can be explained by statistical artifacts in the inference of species associations from abundance data. I caution against the inference of ecological association networks from abundance data alone.

ecology↗

bioRxiv2019

Environmental Niche Adaptation Revealed Through Fine Scale Phenological Niche Modeling

AimPhenology, the temporal response of a population to its climate, is a crucial behavioral trait shared across life on earth. How species adapt their phenologies to climate change is poorly understood but critical in understanding how species will respond to future change. We use a group of flies (Rhaphiomidas) endemic to the North American deserts to understand how species adapt to changing climatic conditions. Here we explore a novel approach for taxa with constrained phenologies aimed to accurately model their environmental niche and relate this to phenological and morphological adaptations in a phylogenetic context. TaxonInsecta, Diptera, Mydidae, Rhaphiomidas LocationNorth America, Mojave, Sonoran and Chihuahuan Deserts. MethodsWe gathered geographical and phenological occurrence data for the entire genus Rhaphiomidas, and, estimated a time calibrated phylogeny. We compared Daymet derived temperature values for a species adult occurrence period (phenology) with those derived from WorldClim data that is partitioned by month or quarter to examine what effect using more precise data has on capturing a species environmental niche. We then examined to what extent phylogenetic signal in phenological traits, climate tolerance and morphology can inform us about how species adapt to different environmental regimes. ResultsWe found that the Bioclim temperature data, which are averages across monthly intervals, poorly represent the climate windows to which adult flies are actually adapted. Using temporally-relevant climate data, we show that many species use a combination of morphological and phenological changes to adapt to different climate regimes. There are also instances where species changed only phenology to track a climate type or only morphology to adapt to different environments. Main ConclusionsWithout using a fine-scale phenological data approach, identifying environmental adaptations could be misleading because the data do not represent the conditions the animals are actually experiencing. We find that fine-scale phenological niche models are needed when assessing taxa that have a discrete phenological window that is key to their survival, accurately linking environment to morphology and phenology. Using this approach, we show that Rhaphiomidas use a combination of niche tracking and adaptation to persist in new niches. Modeling the effect of phenology on such species niches will be critical for better predictions of how these species might respond to future climate change.

evolutionary biology↗