Extinction Space-a Method for the Quantification and Classification of Changes in Morphospace Across Extinction Boundaries

Korn, Dieter; Hopkins, Melanie J.; Walton, Sonny A.

doi:10.1111/evo.12162

Cited by 41 publications

(100 citation statements)

References 108 publications

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“…In this study, the indices of morphological disparity did not provide enough information regarding the spatial distribution of species within morphospaces. The variance of the different axes changes among morphospaces, but their cumulative contribution can express similar total variability even if the morphospaces possess different configurations (Foote 1997, Ciampaglio et al 2001, Korn et al 2013, as also shown in our results. Although calculating the areas occupied by points helps to analyse the distribution pattern of points, the measure does not permit the establishment of the specific location and occupation of these points within the morphospace.…”

Section: Discussionsupporting

confidence: 87%

“…Among the various disparity measures described in the literature (Ciampaglio et al 2001, Wills 2001, Korn et al 2013, the following two indices of morphological disparity were used: a) Sum of variance (SOV), which is the sum of the variances along all the morphospace axes; and b) Sum of range of the middle two quartiles (QSOR), which defines the area that is Table 2. In method 1 (morphospace 1), landmark 15 is a semilandmark; in method 2 (morphospace 2), landmarks 16, 17, 18 and 24 are semilandmarks; and in method 3 (morphospace 3), landmarks 3, 10,11,13,15,18,19,20,23,24,25 and 27 are semilandmarks.…”

Section: Point Pattern Analysesmentioning

confidence: 99%

“…From then until now, this approach has been applied in many studies and has been suggested as a useful tool for better understanding the mechanisms promoting species coexistence, for inferring the ecological strategies of species (e.g. Gatz 1979, Bellwood et al 2006) and for investigating fluctuations within a community due to natural or anthropogenic perturbations (Villéger et al 2010, Korn et al 2013. Initially, changes in shape of species were assessed from linear measurements (Strauss and Bookstein 1982, Winemiller 1991, Klingenberg and Ekau 1996.…”

Section: Introductionmentioning

confidence: 99%

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Selection of landmarks and semilandmarks in fishes for geometric morphometric analyses: a comparative study based on analytical methods

Farré¹,

Tuset²,

Maynou³

et al. 2016

Sci. Mar.

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Summary: We applied and compared three different sets of landmarks and semilandmarks commonly used in studies of fish assemblages to identify a standardized method of landmark selection that includes the maximum amount of morphological information of species. The different landmark-based methods used produced differences regarding the distribution of casestudy species within the morphospace. We suggest that adding landmarks and semilandmarks that provide more specific information about anatomical structures with important roles in the biology of species, such as transformed fins or sensory organs, contributes to a clearer differentiation of species within the morphospace and a better interpretation of their occupancy. In addition, three types of method were used to establish how species are distributed within morphospace. The results demonstrated that aggregation points methods, including analyses based on quadrants or distances, are more appropriate for this purpose than indices of morphological disparity. The results also confirmed that although numerical methods are needed to test the statistical significance of outcomes, graphical methods provide a more intuitive interpretation of morphospace occupancy. The kernel density and Gabriel graph were useful to infer the morphospace zone where species are more densely grouped, improving the knowledge of space occupancy and structural complexity of fish assemblages.Keywords: morphological traits; landmarks; geometric morphometrics; diversity; point pattern; morphospace; marine fishes. Selección de puntos homólogos (landmarks) y equidistantes (semilandmarks) en peces para análisis de morfometría geométrica: un estudio comparativo basado en métodos analíticosResumen: En el presente estudio se compara la estructura de una comunidad de peces a partir del análisis morfológico de puntos homólogos (landmarks) y equidistantes (semilandmarks) en las especies de dicha comunidad. Para este propósito, se utilizaron tres metodologías distintas descritas en la literatura a la hora de definir dichos puntos con el fin de identificar cuál de ellas incluía la máxima cantidad de información morfológica posible sobre las especies. Las tres opciones proporcionaron diferentes resultados en relación a la distribución de las especies dentro del morfoespacio. Los resultados sugirieron que la incorporación de puntos que proporcionen información más específica sobre estructuras anatómicas que tienen papeles importantes en la biología de las especies, como aletas modificadas u órganos sensoriales, contribuye a una diferenciación más clara de las especies y a una mejor interpretación de la ocupación del morfoespacio. Adicionalmente, varios métodos numéri-cos y gráficos se emplearon con el fin de establecer cómo las especies se distribuyen dentro del morfoespacio. Los resultados demostraron que los métodos de agregación de puntos, incluyendo análisis basados en cuadrantes o distancias, fueron más apropiados para este propósito que los índices de disparidad morfológica. Además, los resultados tam...

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Section: Discussionsupporting

confidence: 87%

Section: Point Pattern Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Selection of landmarks and semilandmarks in fishes for geometric morphometric analyses: a comparative study based on analytical methods

Farré¹,

Tuset²,

Maynou³

et al. 2016

Sci. Mar.

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“…Similarly, articulate brachiopods rapidly increased their disparity in the wake of the end Permian mass extinction; a pattern consistent with rebound after the removal of highly structured guilds and the freeing up of ecospace [204]. Comparable post-extinction rebounds have been observed for crinoid and blastozoan echinoderms [27], as well as ammonoids [205] through multiple events. Similarly, rapid increases in disparity may occur when a clade is first able to colonize a fundamentally new region of ecospace.…”

Section: Extrinsic Physical and Biological (Ecological) Restrictionsmentioning

confidence: 59%

What limits the morphological disparity of clades?

et al. 2015

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The morphological disparity of species within major clades shows a variety of trajectory patterns through evolutionary time. However, there is a significant tendency for groups to reach their maximum disparity relatively early in their histories, even while their species richness or diversity is comparatively low. This pattern of early high-disparity suggests that there are internal constraints (e.g. developmental pleiotropy) or external restrictions (e.g. ecological competition) upon the variety of morphologies that can subsequently evolve. It has also been demonstrated that the rate of evolution of new character states decreases in most clades through time (character saturation), as does the rate of origination of novel bodyplans and higher taxa. Here, we tested whether there was a simple relationship between the level or rate of character state exhaustion and the shape of a clade's disparity profile: specifically, its centre of gravity (CG). In a sample of 93 extinct major clades, most showed some degree of exhaustion, but all continued to evolve new states up until their extinction. Projection of states/steps curves suggested that clades realized an average of 60% of their inferred maximum numbers of states. Despite a weak but significant correlation between overall levels of homoplasy and the CG of clade disparity profiles, there were no significant relationships between any of our indices of exhaustion curve shape and the clade disparity CG. Clades showing early high-disparity were no more likely to have early character saturation than those with maximum disparity late in their evolution.

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“…The Hangenberg Event had the biggest impact on the Ammonoidea out of all of the Devonian extinction events (Korn 1993(Korn , 2000Korn et al 2013b). As a result of the massive loss of species, especially in the Clymeniida and the Goniatitida, there was a dramatic drop in taxonomic diversity and morphological disparity.…”

Section: Hangenberg Event and Its Aftermathmentioning

confidence: 99%

Taxonomic Diversity and Morphological Disparity of Paleozoic Ammonoids

Korn

Klug

Walton

2015

Topics in Geobiology

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The Ammonoidea are well represented in terms of numbers of species over a large range of time and they have survived many extinction events. The time interval from the Early Devonian through to the Triassic has seen ammonoid groups evolve and become extinct. The evolutionary history of the Paleozoic ammonoids was punctuated by some extinction events with near extinction events and subsequent recoveries. A Principal Components Analysis (PCA) based on the conch width index (CWI), umbilical width index (UWI) and whorl expansion rate (WER) parameters from 4834 ammonoid species of Devonian to Triassic age produced an empirical morphospace this time interval. The morphospace of Paleozoic ammonoids shows some subtle changes between the periods, but generally, the occupied area is remarkably similar.

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Extinction Space-a Method for the Quantification and Classification of Changes in Morphospace Across Extinction Boundaries

Cited by 41 publications

References 108 publications

Selection of landmarks and semilandmarks in fishes for geometric morphometric analyses: a comparative study based on analytical methods

Selection of landmarks and semilandmarks in fishes for geometric morphometric analyses: a comparative study based on analytical methods

What limits the morphological disparity of clades?

Taxonomic Diversity and Morphological Disparity of Paleozoic Ammonoids

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