Hi Vasco! I was wondering if you’ve thought about the effects of land use change on soil nematodes at finer taxonomic resolutions. I think this could be relevant for the following reasons:
Even though most soil nematodes have similar simple nervous systems, there is significant variation in their life history strategies. The equivalent of r vs K-selected life histories for nematodes is the colonizer-persister scale from 1 to 5. On the lower extreme, colonizers (roughly comparable to r-strategists) have high reproduction rates and experience large fluctuations in population density under uncertain environmental conditions. The Rhabditid family of nematodes, which includes C. elegans, is one such example. On the higher extreme, persisters (roughly comparable to K-strategists) have low reproduction rates and maintain population size in more stable conditions. The Thornematidae and Nygolaimidae families are examples of persisters. Of course, many nematode families fall somewhere in the middle. The colonizer-persister scale also probably obscures other important differences between nematode species, like variation in lifespan. I’m wondering if all this variation suggests that all soil nematodes shouldn’t be thought of as a single group in such welfare analyses because some might have much lower welfare than others.
Soil nematodes also have ecologically diverse roles: plant parasites, predators, animal parasites, and bacterial/​fungal feeders. Land use change will probably differentially impact these functional groups (as well as colonizers vs. persisters). For example, this study suggests that intensively managed land might produce disturbance regimes that select for colonizers, who probably have worse lives than persisters. And here’s another study that observed decreased predator nematodes population abundances after urbanization, which might be bad if predators have particularly good lives. If these studies are right, it seems really important to take local selective conditions into account to avoid land use changes that cause harm.
Thanks for your post, and I apologize if you’ve addressed this elsewhere!
Hi Vasco! I was wondering if you’ve thought about the effects of land use change on soil nematodes at finer taxonomic resolutions. I think this could be relevant for the following reasons:
There is some variation in neuron counts between nematode species. For example, Mermis negrescens is a grasshopper parasite that has ~1,000 neurons in its ventral nerve cord.
Even though most soil nematodes have similar simple nervous systems, there is significant variation in their life history strategies. The equivalent of r vs K-selected life histories for nematodes is the colonizer-persister scale from 1 to 5. On the lower extreme, colonizers (roughly comparable to r-strategists) have high reproduction rates and experience large fluctuations in population density under uncertain environmental conditions. The Rhabditid family of nematodes, which includes C. elegans, is one such example. On the higher extreme, persisters (roughly comparable to K-strategists) have low reproduction rates and maintain population size in more stable conditions. The Thornematidae and Nygolaimidae families are examples of persisters. Of course, many nematode families fall somewhere in the middle. The colonizer-persister scale also probably obscures other important differences between nematode species, like variation in lifespan. I’m wondering if all this variation suggests that all soil nematodes shouldn’t be thought of as a single group in such welfare analyses because some might have much lower welfare than others.
Soil nematodes also have ecologically diverse roles: plant parasites, predators, animal parasites, and bacterial/​fungal feeders. Land use change will probably differentially impact these functional groups (as well as colonizers vs. persisters). For example, this study suggests that intensively managed land might produce disturbance regimes that select for colonizers, who probably have worse lives than persisters. And here’s another study that observed decreased predator nematodes population abundances after urbanization, which might be bad if predators have particularly good lives. If these studies are right, it seems really important to take local selective conditions into account to avoid land use changes that cause harm.
Thanks for your post, and I apologize if you’ve addressed this elsewhere!