Differential vulnerability to predation in two sympatric whelks is mediated by juvenile traits

Differential vulnerability to predation in two sympatric whelks is mediated by juvenile traits

In many taxa, initial differences in offspring size play an important role in mediating
subsequent performance; however, the consequences of interspecific variation in size
for the performance of co-occurring taxa have been rarely examined. We used the whelks
Cominella virgata and C. maculosa, which co-occur on rocky shores throughout their life
cycles, to examine the vulnerability of early life-stages to native predators under controlled
laboratory conditions. Among all the predators evaluated (the cushion sea star Patiriella
spp., the olive rockfish Acanthoclinus fuscus, the oyster borer snail Haustrum scobina, the
smooth shore crab Cyclograpsus lavauxi, and the pebble crab Heterozius rotundifrons),
hatchlings of both species (C. virgata: ~3 mm shell length [SL] and C. maculosa: ~1.5 mm
SL) were especially vulnerable to the smooth shore crab Cy. lavauxi, the only potential
predator in which mortality was greater than in the control treatment. Small shore crabs
(~8 mm carapace width [CW]) were unable to eat hatchlings of either whelk species,
whereas medium and large shore crabs (~12 and ~18 mm CW, respectively) consumed
hatchlings of both prey species. Hatchlings of C. virgata were less vulnerable to predation
by medium crabs than large ones, and those of C. maculosa were equally vulnerable to both
sizes of crabs. In hatchlings of both prey species, shell length and shell thickness increased
over time. Two months after hatching, only individuals of C. virgata had reached a size
refuge from predation. Our results show that interspecific vulnerability to predators can be
mitigated by larger sizes and thicker shells at hatching; nonetheless, our results also suggest
that other species-specific factors, such as juvenile growth rate, may also play key roles in
determining the vulnerability of hatchling and juvenile snails to shell-crushing predators.

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Descargar DocumentoSergio A. Carrascoa and Nicole E. Phillips (2012) Differential vulnerability to predation in two sympatric whelks is mediated by juvenile traits. Invertebrate Biology 131(3): 187–196. © 2012, The American Microscopical Society, Inc.