What Can We Learn From All Those Pieces? Obtaining Data on Drilling Predation From Fragmented High-Spired Gastropod Shells

Johnson, Eugene H.; Anderson, Brendan M.; Allmon, Warren D.

doi:10.2110/palo.2016.088

Cited by 16 publications

(18 citation statements)

References 32 publications

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“…Shell lifespans were estimated based on δ 18 O cyclicity, with the presence of a full sinusoid indicating a full year of life. Shell lifespans varied between <1 to 1.5 years as a minimum estimate (Table S2), in agreement with previous studies of Turritella (Allmon, 2011;Anderson et al, 2017). There is not known to be any relationship between shell size and lifespan in turritellids (Allmon and Jones, 1992).…”

Section: Supplemental Materials Figure 8 (S8) -Comparison Between δ 18supporting

confidence: 90%

“…All sampled carbonate powders were analyzed for their stable isotopic composition (δ 18 O and δ 13 C). Based on resulting δ 18 O cyclicity, shell lifespans were estimated to vary between <1 to 2 years as a minimum estimate (Table S2), in agreement with previous studies of Turritella (Allmon, 2011;Anderson et al, 2017).…”

Section: Shell Samplingsupporting

confidence: 83%

“…The high-resolution sampling scheme is illustrated in the photo below ( Figure S1). When the apex tip was broken, missing shell length was estimated using the Theoretical Apex System (TAS) method (Johnson et al, 2017), as employed by Anderson et al, (2017). 28 specimens underwent highresolution drilling (3-12 samples/whorl, 40-50μg/sample), and 6 were sampled at coarser resolution (1 sample/whorl, ~10-40 μg/sample) using a handheld drill at low speed.…”

Section: Shell Samplingmentioning

confidence: 99%

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Supplemental Material: Isotope sclerochronology indicates enhanced seasonal precipitation in northern South America (Colombia) during the Mid-Miocene Climatic Optimum

Scholz¹

2020

Preprint

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Section: Supplemental Materials Figure 8 (S8) -Comparison Between δ 18supporting

confidence: 90%

Section: Shell Samplingsupporting

confidence: 83%

Section: Shell Samplingmentioning

confidence: 99%

See 1 more Smart Citation

Supplemental Material: Isotope sclerochronology indicates enhanced seasonal precipitation in northern South America (Colombia) during the Mid-Miocene Climatic Optimum

Scholz¹

2020

Preprint

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“…Specimens with intact protoconchs were almost entirely found on juveniles less than one centimeter in length. Protoconchs are often abraded away in turritellines, even during the life of the organism (Johnson, Anderson, & Allmon, ). The protoconch is composed of two parts: protoconch I, which is the embryonic shell, formed prior to hatching and is unornamented, and protoconch II which is produced prior to metamorphosis, and which may be smooth or ornamented (Jablonski & Lutz, ; Robertson, ).…”

Section: Methodsmentioning

confidence: 99%

Protoconch enlargement in Western Atlantic turritelline gastropod species following the closure of the Central American Seaway

Sang

Friend

Allmon

et al. 2019

Ecology and Evolution

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The closure of the late Neogene interoceanic seaways between the Western Atlantic (WA) and Tropical Eastern Pacific (TEP)—commonly referred to as the Central American Seaway—significantly decreased nutrient supply in the WA compared to the TEP. In marine invertebrates, an increase in parental investment is expected to be selectively favored in nutrient‐poor marine environments as prolonged feeding in the plankton becomes less reliable. Here, we examine turritelline gastropods, which were abundant and diverse across this region during the Neogene and serve as important paleoenvironmental proxies, and test whether species exhibit decreased planktotrophy in the WA postclosure as compared to preclosure fossils and extant TEP species. We also test for differences in degree of planktotrophy in extant sister species pairs. Degree of planktotrophy was inferred by measuring the size of protoconchs, the species' larval shell that represents egg size. Protoconch size was compared between extant postclosure WA and TEP species and preclosure fossil species. To compare extant sister species, we reconstructed the phylogeny of available WA and TEP species using one nuclear (H3) and three mitochondrial markers (12S, 16S, and COI). Compared to the preclosure fossils, protoconch size increased in WA species but remained the same in the TEP species. In the two extant sister species pairs recovered in the phylogenetic analysis, the WA species are inferred to be nonplanktotrophic while the TEP species are planktotrophic. This suggests that decreased nutrient availability and primary productivity in the WA may have driven this change in developmental mode, and was the primary selective force resulting in postclosure turritelline extinctions.

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“…Shells armor bivalves against both vertebrate predators (e.g., shell-crushing fishes, birds, and mammals) and invertebrate predators (e.g., drilling gastropods and cephalopods, asteroids and gastropods which attack at the shell margin, and shell-crushing arthropods), providing structural protection and permitting escape and/or avoidance behaviors 1 – 6 . The shapes of bivalve shells are often indicative of life mode: whether the organism lives above or below substrate, how it feeds, and how or if it locomotes 7 , 8 .…”

Section: Introductionmentioning

confidence: 99%

Experimental tests of bivalve shell shape reveal potential tradeoffs between mechanical and behavioral defenses

Johnson

2020

Sci Rep

Self Cite

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Bivalves protect themselves from predators using both mechanical and behavioral defenses. While their shells serve as mechanical armor, bivalve shells also enable evasive behaviors such as swimming and burrowing. Therefore, bivalve shell shape is a critical determinant of how successfully an organism can defend against attack. Shape is believed to be related to shell strength with bivalve shell shapes converging on a select few morphologies that correlate with life mode and motility. In this study, mathematical modeling and 3D printing were used to analyze the protective function of different shell shapes against vertebrate shell-crushing predators. Considering what life modes different shapes permit and analyzing the strength of these shapes in compression provides insight to evolutionary and ecological tradeoffs with respect to mechanical and behavioral defenses. These empirical tests are the first of their kind to isolate the influence of bivalve shell shape on strength and quantitatively demonstrate that shell strength is derived from multiple shape parameters. The findings of this theoretical study are consistent with examples of shell shapes that allow escape behaviors being mechanically weaker than those which do not. Additionally, shell elongation from the umbo, a metric often overlooked, is shown to have significant effects on shell strength.

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What Can We Learn From All Those Pieces? Obtaining Data on Drilling Predation From Fragmented High-Spired Gastropod Shells

Cited by 16 publications

References 32 publications

Supplemental Material: Isotope sclerochronology indicates enhanced seasonal precipitation in northern South America (Colombia) during the Mid-Miocene Climatic Optimum

Supplemental Material: Isotope sclerochronology indicates enhanced seasonal precipitation in northern South America (Colombia) during the Mid-Miocene Climatic Optimum

Protoconch enlargement in Western Atlantic turritelline gastropod species following the closure of the Central American Seaway

Experimental tests of bivalve shell shape reveal potential tradeoffs between mechanical and behavioral defenses

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