10.5061/DRYAD.19MN6VM
Budd, Graham E.
Uppsala University
Mann, Richard P.
University of Leeds
Data from: Modelling durophagous predation and mortality rates from the
fossil record of gastropods
Dryad
dataset
2019
Gastropoda
2019-01-07T23:04:41Z
en
https://doi.org/10.1017/pab.2019.2
3138 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Gastropods often show signs of unsuccessful attacks by durophagous
predators in the form of healed scars in their shells. As such, fossil
gastropods can be taken as providing a record of predation through
geological time. However, interpreting the number of such scars has proved
to be problematic - would a low number of scars mean a low rate of attack,
or a high rate of success, for example? Here we develop a model of
population dynamics amongst individuals exposed to predation, including
both lethal and non-lethal attacks. Using this model we calculate the
equilibrium distributions of ages and healed scars in the population and
amongst fossilised specimens, based on the assumption that predation is
independent of age or scar number. Based on these results we formally show
that the rates of attack and success cannot be disambiguated without
further information about population structure. Nevertheless, by making
the assumptions that the non-durophagous predatory death rate is both
constant and low, we show that it is possible to use relatively small
assemblages of gastropods to produce accurate estimates of both attack and
success rates, if the overall death rate can be estimated. We consider
likely violations of the assumptions in our model and what sort of
information would be required to solve this problem in these more general
cases. However, it is not easy to extract the relevant information easily
from the fossil record: a variety of important biases are likely to
intervene to obscure the data that gastropod assemblages may yield.
Code for simulating snail populations and performing analysesR code for
simulating scar distribution and inferring predation
parameters.budd_mann_SI.R