Ecomorphology orecological morphology is the study of the relationship between theecological role of an individual and itsmorphological adaptations.[1] The term "morphological" here is in theanatomical context. Both the morphology andecology exhibited by an organism are directly or indirectly influenced by their environment, and ecomorphology aims to identify the differences.[2] Current research places emphasis on linking morphology andecological niche by measuring the performance of traits (i.e. sprint speed, bite force, etc.) associated behaviours, andfitness outcomes of the relationships.
Current ecomorphological research focuses on a functional approach and application to the science. A broadening of this field welcomes further research in the debate regarding differences between both the ecological and morphological makeup of anorganism.
The roots of ecomorphology date back to the late 19th century.[3] Then, description and comparison of morphological form, primarily for use inavianclassification, was focal point of morphological research. However, during the 1930s and 40s morphology as a field shrank. This was likely due to the emergence of new areas of biological inquiry enabled by new techniques. The 1950s brought about not only a change in the approach of morphological studies, resulting in the development of evolutionary morphology in the form of theoretical questions, and a resurgence of interest in the field.[4]High-speed cinematography and x-ray cinematography began to allow for observations of movements of parts whileelectromyography allowed for observation of the integration of muscle activities. Together, these methodologies allowed morphologists to better delve into the intricacies of their study. It was then, in the 1950s and 60s, that ecologists began to use morphological measures to study evolutionary and ecological questions. This culminated in Karr and James coining the term "ecomorphology" in 1975.[5] The following year the links betweenvertebrate morphology andecology were finally established creating the foundations of modern ecomorphology.[6][7]
Functional morphology differs from ecomorphology in that it deals with the features arising from form at varying levels oforganisation.[8] Ecomorphology, on the other hand, refers to those features which can be shown to derive from the ecology surrounding the species. In other words, functional morphology focuses heavily on the relationship between form and function whereas ecomorphology is interested in the form and the influences from which it arises. Functional morphology studies often investigate relationships between the form ofSkeletal muscle and physical properties such as force generation and joint mobility.[9] This means that functional morphology experiments may be done under laboratory conditions whereas ecomorphological experiments may not. Moreover, studies of functional morphology themselves provide insufficient data upon which to make conclusions regarding environmental adaptations of a species. The data provided from these studies can, however, support and enrich the understanding of a species' ecomorphological adaptations.[3] For instance, the relationship between the organization of the jaw lever-arm system, mouth size, and jaw muscle force generation and the feeding behaviour of sunfish has been investigated.[10] Work of this variety lends scientific support to seemingly intuitive concepts. For instance, increases in mouth size correspond to an increase in prey size. However, less obvious trends also exist. The prey-size of fish does not seem to correlate so much to body size as to the characteristics of the feeding apparatus.
The work above is just one example of an ecomorphology based behavioural study. Studies of this variety are becoming increasingly important in the field. Behavioural studies interrelate functional and eco-morphology. Features such aslocomotory ability in foraging birds have been shown to affect dietary preferences by studies of this type.[11] Behavioural studies are particularly common infisheries and in studying birds.[12] Other studies attempt to relate ecomorphological findings with the dietary habits of species. Griffen and Mosblack (2011) investigated differences in diet and consumption rate as a function ofgut ecomorphology.[13] Indeed, gut volume was found to correlate positively to increasing metabolic rate. Ecomorphological studies can often be used to determine to presence of parasites in a given temporospatial context asparasite presence can alter hosthabitat use.[14]
Other current work within ecomorphology focuses on broadening the knowledge base to allow for ecomorphological studies to incorporate a wider range ofhabitats,taxa, and systems. Much current work also focuses on the integration of ecomorphology with other comparative fields such asphylogenetics andontogenetics to better understand evolutionary morphology.[15]
An understanding of ecomorphology is necessary when investigating both the origins of and reasons forbiodiversity within aspecies. Ecomorphology is fundamental for understanding changes in themorphology of aspecies in which subsets occupy differentecological niches, demonstrate different reproductive techniques, and have various sensory modalities.[15][16] Studies conducted onspecies with highbiodiversity frequently investigate the extent to which species morphology is influenced by their ecology.Bony fishes are often used to study ecomorphology due to their long evolutionary history, highbiodiversity, and multi-stage life cycle.[15] Studies on the morphological diversity of Africancichlids conducted by Fryer and Iles were some of the first to demonstrate ecomorphology, . This is largely due to cichlids having greatbiodiversity, wide distribution, the ability to occupy various ecological niches, and obvious morphological differences.[17] Ecomorphology is also often used to study thepaleohabitat of a species and/or its evolutionary morphology.
The history of how a species has undergone morphological adaptations to better suit its ecological role can be used to draw conclusions about itspaleohabitat. The morphologies of paleo-species found at a location help to make inferences about the previous appearance and properties of that habitat. Research using this approach has been widely conducted usingbovidfossils due to their large skeletons and extensivespecies radiation.[18] Plummer and Bishop conducted a study using extant African bovids to investigate the animal’s paleoenvironment based on their habitat preference.[19] The strong correlation found between bovidphylogeny and habitat preference suggests that linking morphology and habitat istaxon dependent. Evidence also suggests that further study of the ecomorphology of previously existing habitats may be useful in determining the phylogenetic risk associated with species living in a specific habitat.[18]
The study of evolutionary morphology concerns changes in species morphology over time in order to become better suited to their environment.[3][16] These studies are conducted by comparing the features of species groups to provide a historical narrative of the changes in morphology observed with changes in habitat. A background history of a species features andhomology must first be known before a history of evolutionary morphology can be observed. This area of biology serves only to provide a nominal explanation of evolutionary biology, as a more in depth explanation of species history is required to provide a thorough explanation of evolution within a species.
Suggestions have been made that the correlations between species biodiversity and particular environments may not necessarily be due to ecomorphology, but rather a conscious decision made by species to relocate to an ecosystem to which their morphologies are better suited. However, there are currently no studies that provide concrete evidence to support this theory. Studies have been conducted to predict fish habitat preference based on body morphology, but no definitive distinction could be made between correlation and causation of fish habitat preference.[20]
Betz, O. (2006), Ecomorphology: Integration of form, function, and ecology in the analysis of morphological structures, Mitteilungen der Deutschen Gesellschaft für Allgemeine und Angewandte Entomologie 15, 409-416.