nucleation

THEORY-1214: Cicada hosts whose endosymbiont Hodgkinia has split into many interdependent lineages compensate by sending more Hodgkinia cells to each egg, with Sulcia numbers and the transmission route unchanged, so that every egg still receives every lineage; the raised titre is a host adaptation driven by the symbiont's fragmentation, and a cost of it

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Properties5
StatusProposed
Tagsendosymbiosis, natural-sciences
SourceLIT-1590 — Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas
ExtendsTHEORY-1106 — Campbell and colleagues report, from four cicada species with five or six eggs each, that Hodgkinia cells per egg range from about 4,900 in a species with one Hodgkinia lineage to about 30,000, some six times as many, in Magicicada septendecim, whose Hodgkinia has split into many interdependent lineages and the only species that differs significantly, while Sulcia numbers are not raised, the transmission route is the same, and every egg sampled carries every lineage tracked by marker genes; the authors take the raised titre as a host adaptation that compensates for the symbiont's fragmentation, and a cost of it
Bears onQUESTION-277 — When formerly autonomous partners come to depend on one another, which of mutual dependence, reproductive cohesion, the distribution of essential functions across genomes, the host's regulatory control and the alignment of selection does each route to dependence bring about, and which of them, alone or together, make the partnership a new evolutionary individual?

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Source

Campbell et al. (2018), LIT-1590, read in full in NOTE-1235. The paper’s title asserts it: “Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas”.

Where the evidence stands

What the paper shows, and what it does not, is THEORY-1106, Active, which this entry extends: that entry is the reading, this one the thesis. The promote_when above is THEORY-1106’s condition before the twenty-second status review promoted it, carried here unchanged, because it asks what would make the thesis true and not what the paper says.

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