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Lauer DA, Lawing AM, Short RA, Manthi FK, Müller J, Head JJ, McGuire JL. Disruption of trait-environment relationships in African megafauna occurred in the middle Pleistocene. Nat Commun 2023; 14:4016. [PMID: 37463920 DOI: 10.1038/s41467-023-39480-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 06/15/2023] [Indexed: 07/20/2023] Open
Abstract
Mammalian megafauna have been critical to the functioning of Earth's biosphere for millions of years. However, since the Plio-Pleistocene, their biodiversity has declined concurrently with dramatic environmental change and hominin evolution. While these biodiversity declines are well-documented, their implications for the ecological function of megafaunal communities remain uncertain. Here, we adapt ecometric methods to evaluate whether the functional link between communities of herbivorous, eastern African megafauna and their environments (i.e., functional trait-environment relationships) was disrupted as biodiversity losses occurred over the past 7.4 Ma. Herbivore taxonomic and functional diversity began to decline during the Pliocene as open grassland habitats emerged, persisted, and expanded. In the mid-Pleistocene, grassland expansion intensified, and climates became more variable and arid. It was then that phylogenetic diversity declined, and the trait-environment relationships of herbivore communities shifted significantly. Our results divulge the varying implications of different losses in megafaunal biodiversity. Only the losses that occurred since the mid-Pleistocene were coincident with a disturbance to community ecological function. Prior diversity losses, conversely, occurred as the megafaunal species and trait pool narrowed towards those adapted to grassland environments.
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Affiliation(s)
- Daniel A Lauer
- Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
| | - A Michelle Lawing
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Rachel A Short
- Department of Natural Resource Management, South Dakota State University, Rapid City, SD, 57703, USA
| | - Fredrick K Manthi
- Department of Earth Sciences, National Museums of Kenya, Nairobi, Kenya
| | - Johannes Müller
- Leibniz Institute for Evolution and Biodiversity Science, Museum für Naturkunde Berlin, 10115, Berlin, Germany
| | - Jason J Head
- Department of Zoology and University Museum of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK
| | - Jenny L McGuire
- Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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Trophically integrated ecometric models as tools for demonstrating spatial and temporal functional changes in mammal communities. Proc Natl Acad Sci U S A 2023; 120:e2201947120. [PMID: 36745789 PMCID: PMC9963252 DOI: 10.1073/pnas.2201947120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We are in a modern biodiversity crisis that will restructure community compositions and ecological functions globally. Large mammals, important contributors to ecosystem function, have been affected directly by purposeful extermination and indirectly by climate and land-use changes, yet functional turnover is rarely assessed on a global scale using metrics based on functional traits. Using ecometrics, the study of functional trait distributions and functional turnover, we examine the relationship between vegetation cover and locomotor traits for artiodactyl and carnivoran communities. We show that the ability to detect a functional relationship is strengthened when locomotor traits of both primary consumers (artiodactyls, n = 157 species) and secondary consumers (carnivorans, n = 138 species) are combined into one trophically integrated ecometric model. Overall, locomotor traits of 81% of communities accurately estimate vegetation cover, establishing the advantage of trophically integrated ecometric models over single-group models (58 to 65% correct). We develop an innovative approach within the ecometrics framework, using ecometric anomalies to evaluate mismatches in model estimates and observed values and provide more nuance for understanding relationships between functional traits and vegetation cover. We apply our integrated model to five paleontological sites to illustrate mismatches in the past and today and to demonstrate the utility of the model for paleovegetation interpretations. Observed changes in community traits and their associated vegetations across space and over time demonstrate the strong, rapid effect of environmental filtering on community traits. Ultimately, our trophically integrated ecometric model captures the cascading interactions between taxa, traits, and changing environments.
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Mechenich MF, Žliobaitė I. Eco-ISEA3H, a machine learning ready spatial database for ecometric and species distribution modeling. Sci Data 2023; 10:77. [PMID: 36750720 PMCID: PMC9905527 DOI: 10.1038/s41597-023-01966-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 01/12/2023] [Indexed: 02/09/2023] Open
Abstract
We present the Eco-ISEA3H database, a compilation of global spatial data characterizing climate, geology, land cover, physical and human geography, and the geographic ranges of nearly 900 large mammalian species. The data are tailored for machine learning (ML)-based ecological modeling, and are intended primarily for continental- to global-scale ecometric and species distribution modeling. Such models are trained on present-day data and applied to the geologic past, or to future scenarios of climatic and environmental change. Model training requires integrated global datasets, describing species' occurrence and environment via consistent observational units. The Eco-ISEA3H database incorporates data from 17 sources, and includes 3,033 variables. The database is built on the Icosahedral Snyder Equal Area (ISEA) aperture 3 hexagonal (3H) discrete global grid system (DGGS), which partitions the Earth's surface into equal-area hexagonal cells. Source data were incorporated at six nested ISEA3H resolutions, using scripts developed and made available here. We demonstrate the utility of the database in a case study analyzing the bioclimatic envelopes of ten large, widely distributed mammalian species.
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Affiliation(s)
- Michael F Mechenich
- Department of Computer Science, University of Helsinki, 00014, Helsinki, Finland.
| | - Indrė Žliobaitė
- Department of Computer Science, University of Helsinki, 00014, Helsinki, Finland.,Department of Geosciences and Geography, University of Helsinki, 00014, Helsinki, Finland
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Short RA, Lawing AM. Geography of artiodactyl locomotor morphology as an environmental predictor. DIVERS DISTRIB 2021. [DOI: 10.1111/ddi.13371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Rachel A. Short
- Department of Ecology and Conservation Biology Texas A&M University College Station TX USA
- School of Biological Sciences Georgia Institute of Technology Atlanta GA USA
| | - A. Michelle Lawing
- Department of Ecology and Conservation Biology Texas A&M University College Station TX USA
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