Body mass evolution and diversification within horses (family Equidae).
Abstract: Horses (family Equidae) are a classic example of adaptive radiation, exhibiting a nearly 60-fold increase in maximum body mass and a peak taxonomic diversity of nearly 100 species across four continents. Such patterns are commonly attributed to niche competition, in which increased taxonomic diversity drives increased size disparity. However, neutral processes, such as macroevolutionary 'diffusion', can produce similar increases in disparity without increased diversity. Using a comprehensive database of Equidae species size estimates and a common mathematical framework, we measure the contributions of diversity-driven and diffusion-driven mechanisms for increased disparity during the Equidae radiation. We find that more than 90% of changes in size disparity are attributable to diffusion alone. These results clarify the role of species competition in body size evolution, indicate that morphological disparity and species diversity may be only weakly coupled in general, and demonstrate that large species may evolve from neutral macroevolutionary diffusion processes alone.
© 2013 John Wiley & Sons Ltd/CNRS.
Publication Date: 2013-12-05 PubMed ID: 24304872DOI: 10.1111/ele.12221Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research article discusses the evolution and diversification of body mass within the Equidae family, aka horses. The study finds that more than 90% of changes in size disparity among horse species are due to macroevolutionary ‘diffusion’, rather than species competition.
Understanding Evolution and Diversification within the Equidae Family
- The research paper begins by setting the context for the study, acknowledging that horses (family Equidae) are a prime example of adaptive radiation. This means that they’ve evolved from a common ancestor and diversified into various species, with a significant difference being their size, which has seen an approximately 60-fold increase.
- The study notes that horses have reached a peak taxonomic diversity, with nearly 100 species spread across four continents.
Exploring the Role of Niche Competition and Diffusion in Size Disparity
- Common belief attributes such evolutionary patterns to niche competition. This idea suggests that an increase in taxonomic diversity, meaning different types of species, leads to increased size disparity among the creatures within the species.
- On the other hand, the neutral processes like macroevolutionary ‘diffusion’ might result in similar increases in size disparity but without an increase in diversity.
- The researchers used a comprehensive database of size estimates for Equidae species and a common mathematical framework to measure the influence of both diversity-driven and diffusion-driven mechanisms on increased disparity during the Equidae radiation.
Results and Implications
- The findings of the study clearly show that over 90% of the changes in body size disparity among horses are attributable to diffusion alone.
- This challenges the general belief about the role of species competition in body size evolution and suggests that morphological disparity (differences in shape, size) and species diversity might not be strongly coupled.
- The study also highlights the fact that large species may evolve from neutral macroevolutionary diffusion processes alone, without any significant increase in diversity.
Cite This Article
APA
Shoemaker L, Clauset A.
(2013).
Body mass evolution and diversification within horses (family Equidae).
Ecol Lett, 17(2), 211-220.
https://doi.org/10.1111/ele.12221 Publication
Researcher Affiliations
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado, Boulder, CO, 80309, USA.
MeSH Terms
- Animals
- Biological Evolution
- Body Weight / genetics
- Horses / genetics
- Models, Genetic
Citations
This article has been cited 9 times.- Meili CH, Jones AL, Arreola AX, Habel J, Pratt CJ, Hanafy RA, Wang Y, Yassin AS, TagElDein MA, Moon CD, Janssen PH, Shrestha M, Rajbhandari P, Nagler M, Vinzelj JM, Podmirseg SM, Stajich JE, Goetsch AL, Hayes J, Young D, Fliegerova K, Grilli DJ, Vodička R, Moniello G, Mattiello S, Kashef MT, Nagy YI, Edwards JA, Dagar SS, Foote AP, Youssef NH, Elshahed MS. Patterns and determinants of the global herbivorous mycobiome. Nat Commun 2023 Jun 26;14(1):3798.
- Clauss M, Heck L, Veitschegger K, Geiger M. Teeth out of proportion: Smaller horse and cattle breeds have comparatively larger teeth. J Exp Zool B Mol Dev Evol 2022 Dec;338(8):561-574.
- Silvestro D, Tejedor MF, Serrano-Serrano ML, Loiseau O, Rossier V, Rolland J, Zizka A, Höhna S, Antonelli A, Salamin N. Early Arrival and Climatically-Linked Geographic Expansion of New World Monkeys from Tiny African Ancestors. Syst Biol 2019 Jan 1;68(1):78-92.
- Witting L. The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals. Ecol Evol 2017 Nov;7(21):9098-9118.
- Gaudry MJ, Jastroch M, Treberg JR, Hofreiter M, Paijmans JLA, Starrett J, Wales N, Signore AV, Springer MS, Campbell KL. Inactivation of thermogenic UCP1 as a historical contingency in multiple placental mammal clades. Sci Adv 2017 Jul;3(7):e1602878.
- Klopfstein S, Vilhelmsen L, Ronquist F. A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology. Syst Biol 2015 Nov;64(6):1089-103.
- Jafari H, Abebe BK, Cong L, Ahmed Z, Zhaofei W, Sun M, Muhatai G, Chuzhao L, Dang R. Review: Genomic insights into the adaptive traits and stress resistance in modern horses. Stress Biol 2026 Jan 12;6(1):5.
- van Holstein LA, Foley RA. Diversity-dependent speciation and extinction in hominins. Nat Ecol Evol 2024 Jun;8(6):1180-1190.
- Pratt CJ, Meili CH, Jones AL, Jackson DK, England EE, Wang Y, Hartson S, Rogers J, Elshahed MS, Youssef NH. Anaerobic fungi in the tortoise alimentary tract illuminate early stages of host-fungal symbiosis and Neocallimastigomycota evolution. Nat Commun 2024 Mar 28;15(1):2714.
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