Evolutionary and ecological patterns in body size, shape, and ornamentation in the Jurassic bivalve Chlamys (Chlamys) textoria (Schlotheim, 1820)

Nürnberg, Sabine; Aberhan, Martin; Krause, Richard A.

doi:10.1002/mmng.201200002

Cited by 5 publications

(6 citation statements)

References 63 publications

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“…A similar case was noted for the pectinid Chlamys textoria with a size increase persisting through until Pliensbachian stage (Nürnberg et al . ). During the same interval that Plagiostoma giganteum increases in size ( planorbis to bucklandi zones) there is a marked increase in the size of ammonites.…”

Section: Discussionmentioning

confidence: 97%

Body size changes in bivalves of the family Limidae in the aftermath of the end‐Triassic mass extinction: the Brobdingnag effect

et al. 2019

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Reduction in body size of organisms following mass extinctions is well-known and often ascribed to the Lilliput effect. This phenomenon is expressed as a temporary body size reduction within surviving species. Despite its wide usage the term is often loosely applied to any small postextinction taxa. Here we assess the size of bivalves of the family Limidae (Rafineque) prior to, and in the aftermath of, the end-Triassic mass extinction event. Of the species studied only one occurs prior to the extinction event, though is too scarce to test for the Lilliput effect. Instead, newly evolved species originate at small body sizes and undergo a within-species size increase, most dramatically demonstrated by Plagiostoma giganteum (Sowerby) which, over two million years, increases in size by 179%. This trend is seen in both field and museum collections. We term this within-species size increase of newly originated species in the aftermath of mass extinction, the Brobdingnag effect, after the giants that were contemporary with the Lilliputians in Swift's Gulliver's Travels. The size increase results from greater longevity and faster growth rates. The cause of the effect is unclear, although it probably relates to improved environmental conditions. Oxygen-poor conditions in the Early Jurassic are associated with populations of smaller body size caused by elevated juvenile mortality but these are local/regional effects that do not alter the long-term, size increase. Although temperature-size relationships exist for many organisms (Temperature-Size Rule and Bergmann's Rule), the importance of this is unclear here because of a poorly known Early Jurassic temperature record.

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Section: Discussionmentioning

confidence: 97%

Body size changes in bivalves of the family Limidae in the aftermath of the end‐Triassic mass extinction: the Brobdingnag effect

et al. 2019

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“…Depending on the physiological mechanisms involved and the possible causes, a body size decrease could be recognized at different biological scales of organization (Daufresne et al, 2009;Ohlberger, 2013). Therefore, a body size decrease at the community level can reflect changes in the taxonomic composition of the assemblages at the population level (i.e.…”

Section: A Belemnite Size Decrease During the Toarcian?mentioning

confidence: 99%

“…However, the evolutionary and ecological importance of the Lilliput effect remains poorly understood. Furthermore, because of physiological differences, not all organisms necessarily exhibit a body size reduction in the face of warming or other environmental stresses (Gardner et al, 2011;Ohlberger, 2013). Some authors even consider that, in some cases, the body size reduction might reflect a preservation or collection artefact (McGowan et al, 2009;Brayard et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Rostrum size differences between Toarcian belemnite battlefields

Rita¹,

Baets²,

Schlott³

2018

Foss. Rec.

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Abstract. Body size changes have been reported across crisis intervals. Belemnites – now considered extinct stem-decabrachians – have rarely been investigated for this purpose, and the few studies have resulted in ambiguous outcomes. Here we investigate two Toarcian belemnite accumulations in southern Germany from a morphometric point of view with the support of computed tomography data. The aim of this study is to test whether a difference in size can be observed between the rostra of the two studied samples, from individual lineage to community, and which proxy is more reliable. A significant decrease in median size from the Early Toarcian (Dactylioceras tenuicostatum Zone) to the Middle Toarcian (Haugia variabilis Zone) is recognized. This is observed at the community level of organization, considering the whole assemblage, but also within Passaloteuthis–Acrocoelites lineage, at the genus level. It is also demonstrated that diameter-based measurements or maximum preserved length are not reliable proxies for size, and therefore apical length or three-dimensional approximations, such as the geometric mean or the post-phragmocone volume, are more advisable. This is especially important when comparing specimens with markedly different rostrum shapes. Further studies are, however, still necessary to disentangle the mechanisms behind the reduction in rostrum size within the Toarcian and their putative environmental causes.

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“…Further, recognition of shape can contribute to detectability independently of an object's colour (Ings et al, 2012, Brown et al, 1992, Carlile et al, 2006, Schluessel et al, 2012, Lehrer and Campan, 2004, with shape properties relied on for recognition when colour polymorphism occurs (Tanaka and Presnell, 1999). Therefore, an animal's shape influences its ability to conceal itself and may have evolved characteristics to minimise its detection (Nuernberg et al, 2012, Smith, 2003.…”

Section: Animal Shape and Concealmentmentioning

confidence: 99%

“…in visual environments with low complexity (Merilaita, 2003)), shape might provide additional concealment. There is some limited evidence that shape has evolved as an adaptation for concealment (Nuernberg et al, 2012, Smith, 2003.…”

Section: Animal Shape and Concealmentmentioning

confidence: 99%

Animal Camouflage: Disentangling Disruptive Coloration from Background Matching

Webster¹

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Camouflage is ubiquitous in the natural world and provides adaptive benefits to both predators and their prey. In this study I test concepts of animal camouflage using the experimental paradigm of humans foraging for real and artificial moth targets on a computer screen and assessed camouflage efficacy by measuring detection rates. Chapter 1 outlines the questions and objectives of this doctoral thesis. In Chapter 2 I introduce the phenomenon of disruptive coloration, followed by a brief-review of the visual mechanisms contributing to visual search. Chapter 3 tested if non-random orientation behaviour of moths in the field could be explained by behaviourally-mediated camouflage. I showed that the preferred fieldorientations of moths were associated with lower detection rates in the lab, and that the relative orientation of the moth to the tree was the key driver. Chapter 4 tested the fundamental assumption that disruptive coloration functions by impairing shape perception.It was predicted that if edge-intersecting patches are disruptive, then altering the shape of a target would interact with edge coloration. Artificial moth-like targets did show an interaction between edge coloration and target shape, which explained detectability. These findings suggest that effectiveness of camouflage due to edge markings is dependent on target shape, which further supports the hypothesis that edge markings function as disruptive coloration. Chapter 5 took a similar approach to chapter 4 but tested if there was an interaction between edge coloration and target boundary visibility, which could explain detectability of moth-like targets. Results from Chapters 4 and 5 suggest that shape and boundary properties play a role in disruptive function of edge markings. Chapter 6 tested how this might occur. It is thought that edge-intersecting patches impair object recognition. It was predicted that moth-like targets with more edge-intersecting patches would be harder to recognise. Recognition was characterised by human foveal vision, monitored by eyetracking. Indeed, targets with a larger number of edge-intersecting patches were associated with being difficult to recognise, and reduced detectability even at the expense of background matching.

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Evolutionary and ecological patterns in body size, shape, and ornamentation in the Jurassic bivalve Chlamys (Chlamys) textoria (Schlotheim, 1820)

Cited by 5 publications

References 63 publications

Body size changes in bivalves of the family Limidae in the aftermath of the end‐Triassic mass extinction: the Brobdingnag effect

Body size changes in bivalves of the family Limidae in the aftermath of the end‐Triassic mass extinction: the Brobdingnag effect

Rostrum size differences between Toarcian belemnite battlefields

Animal Camouflage: Disentangling Disruptive Coloration from Background Matching

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