Principle and application of morphospace in paleontology
Biological information is quintessentially encapsulated by the intricate relationship between genotype—the genetic makeup of an organism—and phenotype,which encompasses the tangible attributes and morphology of the organism.In the realm of paleontology,the genetic information is often difficult to obtain,so the phenotypic traits,specifically the morphology or anatomical shape of organisms,serve as the cornerstones for explicating taxonomic classifications,evolutionary relationships,and functional adaptations of extinct animals.Initial attempts at morphological quantification in paleontology were predominantly qualitative,hinging on non-numeric descriptors of form and structure.When quantitative approaches were applied,they were rudimentary at best,commonly relying on simplistic measurements such as linear distances,angles,or area calculations to provide a semblance of the organism's morphology.These simplistic metrics often fell short of capturing the full complexity of biological shapes,potentially glossing over the subtle variations and nuances that are critically informative about an organism's ecology and evolutionary history.In recent decades,the field of paleontology has witnessed a transformative shiftin the way researchers study and quantify organismal form with the advent of the morphometrics revolution.Beginning in earnest in the 1980s,this innovation in analytical techniques infused the discipline with new methodologies for more precise and nuanced morphological quantification.The inception of geometric morphometrics marked a significant milestone in this trajectory.The appearance of these quantitative indicators,such as(semi)landmarks for continuous variables,and character states for discrete variables,alongside the evolution of multivariate analytical techniques—like principal component analysis(PCA),principal coordinate analysis(PCoA),and nonmetric multidimensional scaling(NMDS)has led to the development of geometric morphometrics,which provides more comprehensive and systematic study of morphology.This method quantifies the morphology of an individual organism and projects it in two-or three-dimensional space to conduct morphospace in order to understand the morphological characteristics and differences between individuals,as well as the similarity and disparity between individuals or communities.Such analyses provide important information on the evolutionary history of organisms during the geological period,such as ammonoids,conodonts and dinosaurs.More importantly,it can explore the impact of mass extinction events on organisms,investigating whether these events exhibit selectivity toward specific morphologies or traits.Given the lengthy history of the morphospace concept and its extensive application in paleontology in recent years to understand the evolutionary trajectories of animal groups,this paper provides a detailed history of relevant studies.It also outlines the principles and basic applications of morphospace,including the processes of quantification and ordination.Moreover,it introduces the fundamental concepts of disparity analysis,which quantifies the similarity among different organisms and groups,as well as discusses various phylogenetic comparative methods employed to investigate the evolution of biological traits,phylogenetic signals,evolutionary patterns and rates,speciation,and interspecies interactions.Additionally,by using lingulid brachiopods as an exemplar—a group of special marine invertebrates that have persisted throughout the entire Phanerozoic yet exhibit limited extant generic and phenotypic diversity,branding them as"living fossils"since Darwin's"On the Origin of Species"in 1859—the results of morphospace quantification,disparity,and phylogenetic comparative analysis suggest that the restricted morphological and ecological variety of modem lingulids likely reflects a disproportionate winnowing of morphospace occupation and ecological disparity due to extinction.Last but not least,this paper critically examines the applications and existing challenges of morphospace,providing insights into its future prospects and potential developments in paleontology.
万方数据
维普
