Biology subjects

Blomberg, S. P.

Publications and source records attributed to Blomberg, S. P..

6 recordsLinked to original sources

bioRxiv2024

Multivariate Trait Evolution: Models for the Evolution of the Quantitative Genetic G-Matrix on Phylogenies.

Genetic covariance matrices (G-matrices) are a key focus for research and predictions from quantitative genetic evolutionary models of multiple traits. There is a consensus among quantitative geneticists that the G-matrix can evolve through deep time. Yet, quantitative genetic models for the evolution of the G-matrix are conspicuously lacking. In contrast, the field of macroevolution has several stochastic models for univariate traits evolving on phylogenies. However, despite much research into multivariate phylogenetic comparative methods, analytical models of how multivariate trait matrices might evolve on phylogenies have not been considered. Here we show how three analytical models for the evolution of matrices and multivariate traits on phylogenies, based on Lie group theory, Riemannian geometry and stochastic differential (diffusion) equations, can be combined to unify quantitative genetics and macroevolutionary theory in a coherent mathematical framework. The models provide a basis for understanding how G-matrices might evolve on phylogenies, and we show how to fit models to data via simulation using Approximate Bayesian Computation. Such models can be used to generate and test hypotheses about the evolution of genetic variances and covariances, together with the evolution of the traits themselves, and how these might vary across a phylogeny. This unification of macroevolutionary theory and quantitative genetics is an important advance in the study of phenotypes, allowing for the construction of a synthetic quantitative theory of the evolution of species and multivariate traits over deep time. Lay SummaryWe unite Quantitative Genetics, the major mathematical theory of multivariate quantitative trait microevolution, with the mathematical theory of multivariate macroevolution. To do this, we allow the key component of quantitative genetic theory, the matrix of additive genetic variances and covariances (the G-matrix) to evolve along evolutionary trees. This is an advance because the G-matrix is assumed to be constant in quantitative genetics (for convenience), but it has been recognised that it evolves on macroevolutionary timescales (in deep time). Uniting Quantitative Genetics with macroevolutionary theory allows for a more complete mathematical description of Darwins theory of evolution, and allows for further testing of evolutionary hypotheses.

evolutionary biology↗

bioRxiv2024

Diseases and invasive species have synergistic effects with other anthropogenic threats on the functional and phylogenetic diversity in Testudines and Crocodilia

Understanding how multiple threats interact is crucial for the prioritization of conservation measures. Here, we investigate how interactions between six common threats (climate change, habitat disturbance, global trade, overconsumption, pollution, and emerging diseases/invasive species) affect the functional and phylogenetic diversity of 230 species of Testudines and 21 of Crocodilia. We classify two-way threat interactions into additive, synergistic, and antagonistic according to their effects on functional and phylogenetic diversity. Most threat interactions are antagonistic, the effect of threats jointly is lower than the sum of the effects of threats separately. However, we find that the interaction between emerging diseases or invasive species with other threats has synergistic and additive effects, meaning that the combined effects are greater or equal to the effects of threats separately. Our work can help target conservation strategies and detect key places to address multiple threats when they appear together.

ecology↗

bioRxiv2022

The extinction of threatened species by anthropogenic threats endangers the functional diversity of turtles and crocodiles

The Anthropocene is tightly associated with a drastic loss of species worldwide and the disappearance of their key ecosystem functions. The on-going reduction in ecosystem functionality is driven by global and local threats. The orders Testudines (turtles and tortoises) and Crocodilia (crocodiles, alligators, and gharials) contain numerous threatened, long-lived species for which their functional diversity and potential erosion by anthropogenic impacts remains unknown. Here, we examine 259 (69%) of the existing 375 species of Testudines and Crocodilia, quantifying their life history strategies (i.e., schedules of survival, development, and reproduction) from open-access data on their demography, ancestry, and threats. We find that the loss of functional diversity in simulated extinction scenarios of threatened species is greater than expected by chance. Moreover, the effects of unsustainable local consumption, diseases, and pollution are associated with specific functional strategies. In contrast, climate change, habitat disturbance, and global trade affect all species independent of their life history strategy. Importantly, the loss of functional diversity for threatened species by habitat disturbance is twice that for all other threats. Our findings highlight the importance of conservation programmes focused on preserving the functional diversity of life history strategies jointly with the phylogenetic representativity of these highly threatened groups.

ecology↗

bioRxiv2021

Using 3D geometric morphometrics to aid taxonomic and ecological understanding of a recent speciation event within a small Australian marsupial (genus Antechinus)

Taxonomic distinction of species forms the foundation of biodiversity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species diversification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add eco-morphological characterisation of a young cryptic divergence within the marsupial carnivorous genus Antechinus. Specifically, we used 168 museum specimens to characterise the recently proposed clades A. stuartii "south", A. stuartii "north" and A. subtropicus. Beyond slight differences attributable to overall size (and therefore not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian diversity.

zoology↗

bioRxiv2021

Testing hypotheses of marsupial brain size variation using phylogenetic multiple imputations and a Bayesian comparative framework

Considerable controversy exists about which hypotheses and variables best explain mammalian brain size variation. We use a new, high-coverage dataset of marsupial brain and body sizes, and the first phylogenetically imputed full datasets of 16 predictor variables, to model the prevalent hypotheses explaining brain size evolution using phylogenetically corrected Bayesian generalised linear mixed-effects modelling. Despite this comprehensive analysis, litter size emerges as the only significant predictor. Marsupials differ from the more frequently studied placentals in displaying much lower diversity of reproductive traits, which are known to interact extensively with many behavioural and ecological predictors of brain size. Our results therefore suggest that studies of relative brain size evolution in placental mammals may require targeted co-analysis or adjustment of reproductive parameters like litter size, weaning age, or gestation length. This supports suggestions that significant associations between behavioural or ecological variables with relative brain size may be due to a confounding influence of the extensive reproductive diversity of placental mammals.

evolutionary biology↗

bioRxiv2019

Aquatic and terrestrial organisms display contrasting life history strategies as a result of environmental adaptations

AimsAquatic and terrestrial realms display stark differences in key environmental factors and phylogenetic composition. Despite such differences, their consequences for the evolution of species life history strategies remain poorly understood. Here, we examine whether and how life history strategies vary between terrestrial and aquatic species.\n\nLocationGlobal.\n\nTime periodVariable, the earliest year being in 1906 and the most recent in 2015.\n\nMajor taxa studiesMacroscopic animals and plants species.\n\nMethodsWe use demographic information for 638 terrestrial and 117 aquatic animal and plant species, to derive key life history traits capturing their population turnover, and investments in survival, development, and reproduction. We use phylogenetically corrected least squares regression to explore the differences in the trade-offs between life history traits in both realms. We then quantify the life history strategies of aquatic and terrestrial species using a phylogenetically corrected principal component analysis.\n\nResultsWe find that the same trade-offs structure terrestrial and aquatic life histories, resulting in two dominant axes of variation describing species pace- of-life and reproductive spread through time. Life history strategies differ between aquatic and terrestrial environments, with phylogenetic relationships playing a minor role. We show that adaptations of plants and animals to terrestrial environments have resulted in different life history strategies, particularly with their reproductive mode and longevity. Terrestrial plants display a great diversity of life history strategies, including the species with the longest lifespans. Aquatic animals, on the contrary, exhibit higher reproductive frequency than terrestrial animals, likely due to reproductive adaptations (i.e. internal fecundation) of the later to land.\n\nMain conclusionsOur findings show that aquatic and terrestrial species are ruled by the same life history principles, but have evolved different strategies due to distinct selection pressures. Such contrasting life history strategies have important consequences for the conservation and management of aquatic and terrestrial species.

ecology↗