CONSTRAINTS ON EPHEMERAL RESOURCE QUALITY

Shifts in abiotic factors such as temperature and moisture can change the availability of resources, especially under climate change. Both abiotic and biotic drivers can have profound, rapid effects on species distribution, survival, and reproduction. Little is known about how abiotic factors affect the availability of ephemeral resources.

Burying beetles (Nicrophorus spp.) are specialist users of ephemeral resources, as their reproduction requires locating, defending, and burying a small carcass. Abiotic factors like temperature and moisture could change how quickly carcasses dry out, affecting the length of the window of usability for burying beetles. Using male-female pairs of Nicrophorus guttula in experimental chambers in the field at the Bodega Marine Reserve, I have tested:

(1) The effects of carcass moisture and interspecific competition with a generalist scavenger on carcass burial and reproductive success

(2) The effects of carcass moisture and leaf litter presence on survival, carcass burial, and reproductive success

(3) The effects of environmental moisture addition on survival, carcass burial, and reproductive timing and success

Data for (2) and (3) are still being analyzed, but for (1) I found that pairs that were given fresh mouse carcasses were more likely to carry out reproductive behaviors and produce viable offspring than pairs that were given a partially dehydrated mouse. For those pairs that reproduced, competition limited the number of offspring. These results indicate that shifts in abiotic factors under climate change, along with biotic factors like competition, can reduce the availability of ephemeral resource patches for consumers.

SCAVENGING NETWORKS AND SPECIES INTERACTIONS

I am interested in the interactions between organisms that rely on resource patches that are rare in space and time. These ephemeral resource patches often act as ecological epicenters, or what Charles Elton referred to as “centers of action,” where species interactions, niche partitioning, and behavioral and morphological adaptations are intensified.

To the right is an example network: Burying beetles (top) are the focal species in this case, with a carcass resource (bottom), and multiple interacting species (left, a phoretic mite and blowfly; right, a confamilial competitor, Heterosilpha ramosa). Straight green arrows represent consumption; double-sided, dark orange dotted errors represent potential competition or negative interactions; and double-sided light blue dotted arrows represent potential mutualism or facilitative interactions. Note that species are not to scale.

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