Subhronil Mondal

Bio: Subhronil Mondal is an academic researcher from University of Calcutta. The author has contributed to research in topic(s): Predation & Naticidae. The author has an hindex of 10, co-authored 33 publication(s) receiving 251 citation(s). Previous affiliations of Subhronil Mondal include University of South Florida & Indian Institute of Science.

Record of intense predatory drilling from Upper Jurassic bivalves of Kutch, India: Implications for the history of biotic interaction

Abstract: The study of past biotic interactions is important not only to understand the paleoecological history of a community, but also to test the evolutionary role of such interactions. Drill holes in invertebrate exoskeletons provide one of the very few scenarios where biotic interaction could be studied directly and the related hypotheses could be tested with statistical rigor. Hence, the documentation and interpretation of the spatio-temporal patterns of drill hole frequencies has been the subject of extensive paleontological research. The two main gastropod groups responsible for the drilling predation in modern marine environment arose in Cretaceous as supported by their body fossil. However, the drill holes have been reported from the fossils of as far back as Precambrian age. The trend shows an overall low but variable intensity in Paleozoic and Mesozoic and a significant increase in Cenozoic. There are few reported cases of drilled bivalves from the Mesozoic, although in those instances, frequencies are fairly low. Most of the previous records of drilling predation during Paleozoic and Mesozoic come from North America and Western Europe. Here we report 148 drilled bivalve specimens of a single species from the Upper Jurassic horizon in western India. This is highest in number for any taxon ever recorded since Precambrian to Cretaceous. The frequency of drilling constitutes 30% of shells of the same species examined. This drilling frequency is highest when compared to all the reported Mesozoic drilling frequencies in Bivalves. The shapes of the drill holes are indicative of gastropod predation. The drilling gastropods responsible for these lethal attacks are also similar to their modern counterparts in terms of their highly selective prey choice and site-specificity. These results suggest that (1) Mesozoic bivalves were preyed upon by drilling gastropods, often with high intensities, and (2) the specialized characters of modern drilling predators were also present in Mesozoic. This largely unexplored record of bivalve drill holes from the Middle Mesozoic contradicts the general trend of “Mesozoic quiescence” as claimed by most researchers.

Subaerial naticid gastropod drilling predation by Natica tigrina on the intertidal molluscan community of Chandipur, Eastern Coast of India

Abstract: Chandipur intertidal flat in eastern coast of India is a killing field. The vast stretch of intertidal habitat opens up during the low tide, and is monopolized by a single naticid species which preys extensively on intertidal taxa. The predator, Natica tigrina, wades through the soft sediments and ambushes on epi- or infaunal prey. There were reports on naticid subaerial hunting, where the workers made vivid observations, but only in few instances quantified different aspects of predation. Detailed quantitative analyses of the present study revealed that N. tigrina attacks opportunistically on all infaunal and epifaunal intertidal bivalve and gastropod prey taxa. Drilling frequencies ranged from 9.70% to 67.67% with no apparent relation with relative abundances of the taxa. High drilling frequency on conspecific predation perhaps suggested elimination of the potential competitor as well as a profitable prey. Behavioral data of predation, i.e., stereotypy of site and size of drillholes on prey shells and low prey effectiveness indicated that the predator was highly efficient.

Phanerozoic trends in ecospace utilization: The bivalve perspective

Abstract: Ecologic diversity within marine invertebrates has typically been reconstructed by examining three components: mobility, feeding habit, and tiering. Based on various combinations of these three features, a wide range of hypothetical ecospaces or “cubes” (the agglomeration of which forms a “Bambachian cube”) can be delineated. Given the range of constraints on a specific clade's morphologic diversity, however, only a relatively limited proportion of these possible combinations are actualized. Previous studies investigating Phanerozoic trends have documented the general pattern of ecologic diversity – measured as the total number of filled cubes – of all metazoan groups which displays a major increase in the range of ecospace inhabited. However, detailed, clade-specific studies are limited. In this Phanerozoic-level study on the Class Bivalvia, a group with a very robust and virtually unparalleled fossil record, the clade's ecologic diversity is reconstructed based on a set of newly compiled taxonomic and ecologic databases that were initially derived from a combination of the Sepkoski Compendium and the Paleobiology Database. These data have been binned into 94 intervals, from the Fortunian up to the Piacenzian. The ecologic position of each genus was determined relative to the 140 ecologic cubes that reflect the hypothetical range of ecospace bivalves may have inhabited (i.e. fundamental cubes or ecospaces) and which are based on a substantially modified version of the earlier Bambachain cube (Bambach et al., 2007). The overall results show several features: (1) given the various morphologic constraints, bivalves have only occupied 44 of the total, hypothetically available cubes which represents the clade's realized ecospace; (2) the most significant and dramatic phase of increase in the range of ecologic types occurred during the Ordovician; following this event, new ecospace was exploited in a much more limited fashion; (3) most changes in ecospace utilization involved increased packing within a relatively limited suite of cubes; and (4) mass extinctions had a very limited impact on ecospace utilization despite their impacts on bivalve taxonomic richness; only the K-Pg extinction had significant effect on the overall ecologic diversity of bivalves, largely reflecting the demise of a novel reef-building group, the rudistids.

Predation on Recent Turritelline Gastropods from the Indian Subcontinent and Comparison with a Revised Global Database

Abstract: Traces of predation by drilling gastropods and peeling crabs provide important insights about predator-prey interaction in ecological as well as evolutionary times. Predation on turritelline gastropods, in this context, has been frequently discussed in literature. Here, we have estimated the intensity of predation (both drilling and peeling) on Recent turritelline gastropods from the Indian subcontinent, which has been underrepresented in previous studies. Our samples include our own collections from several Indian coasts as well as a vast collection which was locked in the archive of the Zoological Survey of India (ZSI) in Kolkata for the past 150 years. It includes samples from different parts of the Indian subcontinent as well as from many other countries. Drilling frequency (DF) of Indian turritelline species is low compared to average values of global data. We suggest that this is mainly because most of the Indian species are larger (> 4 cm) than species living elsewhere. Smaller species show higher DF and lower values of peeling frequency. Size selectivity of drill holes shows both intra- and interspecific variation. Shell thickness and ornamentation appear to be antipredatory in nature.We have compared our results with a revised global database. Distribution of intensity of predation shows latitudinal variation where both drilling and peeling frequencies increase towards the tropics.

A note on exceptionally high confamilial naticid drilling frequency on Natica gualteriana from the Indian subcontinent

Abstract: Although common, confamilial naticid predation intensity was not very high in the geological record. Here, we gathered modern confamilial predation data from the Indian coasts and showed that confamilial naticid predation on a naticid species, Natica gualteriana, is exceptionally high at Chandipur, one of our studied areas. We studied the different aspects of confamilial predation from the Indian coasts and showed that the predators in Chandipur were highly efficient as evident from high drilling frequency (DF), site stereotypy and low prey effectiveness. Unusually high DF on N. gualteriana may be attributed to its new arrival in Chandipur where it faced competitive elimination through predation by sympatric naticid predators. Reports of failed invasion are rare. Natica gualteriana is a small invader and therefore its invasion success is threatened by resident populations of large species that extensively drill on young individuals of N. gualteriana just to break the bottleneck of their own offspring from...

Shaping the Latitudinal Diversity Gradient: New Perspectives from a Synthesis of Paleobiology and Biogeography.

Abstract: An impediment to understanding the origin and dynamics of the latitudinal diversity gradient (LDG)-the most pervasive large-scale biotic pattern on Earth-has been the tendency to focus narrowly on a single causal factor when a more synthetic, integrative approach is needed. Using marine bivalves as a model system and drawing on other systems where possible, we review paleobiologic and biogeographic support for two supposedly opposing views, that the LDG is shaped primarily by (a) local environmental factors that determine the number of species and higher taxa at a given latitude (in situ hypotheses) or (b) the entry of lineages arising elsewhere into a focal region (spatial dynamics hypotheses). Support for in situ hypotheses includes the fit of present-day diversity trends in many clades to such environmental factors as temperature and the correlation of extinction intensities in Pliocene bivalve faunas with net regional temperature changes. Support for spatial dynamics hypotheses includes the age-frequency distribution of bivalve genera across latitudes, which is consistent with an out-of-the-tropics dynamic, as are the higher species diversities in temperate southeastern Australia and southeastern Japan than in the tropical Caribbean. Thus, both in situ and spatial dynamics processes must shape the bivalve LDG and are likely to operate in other groups as well. The relative strengths of the two processes may differ among groups showing similar LDGs, but dissecting their effects will require improved methods of integrating fossil data with molecular phylogenies. We highlight several potential research directions and argue that many of the most dramatic biotic patterns, past and present, are likely to have been generated by diverse, mutually reinforcing drivers.

Increase in predator-prey size ratios throughout the Phanerozoic history of marine ecosystems.

Abstract: The escalation hypothesis posits that predation by increasingly powerful and metabolically active carnivores has been a major driver of metazoan evolution. We test a key tenet of this hypothesis by analyzing predatory drill holes in fossil marine shells, which provide a ~500-million-year record of individual predator-prey interactions. We show that drill-hole size is a robust predictor of body size among modern drilling predators and that drill-hole size (and thus inferred predator size and power) rose substantially from the Ordovician to the Quaternary period, whereas the size of drilled prey remained stable. Together, these trends indicate a directional increase in predator-prey size ratios. We hypothesize that increasing predator-prey size ratios reflect increases in prey abundance, prey nutrient content, and predation among predators.