Year: 2022

APHID ADAPTIVE SUICIDE. "The host suicide hypothesis, which derives from inclusive fitness theory, postulates that parasitized individuals in spatially aggregated populations consisting of close kin may actively enhance their probability of dying. The fitness cost associated with suicide becomes negligible when infection by a parasitoid causes the expected reproduction of the host to approach zero." https://lnkd.in/dnVKjrQ View in LinkedIn

VALIDATION. "But the host will benefit from suicide, if by its death (and that of its parasite) the level of subsequent parasitism in its kin is reduced relative to that in non-kin. Here we report that pea aphid (Acyrthosiphon pisum) parasitized by the braconid wasp Aphidius ervi, exhibit apparent suicidal behaviour in response to both aphid alarm pheromone and approaching coccinellid (ladybird beetle) predators. We believe this to be the first convincing evidence in support of the host suicide hypothesis." https://lnkd.in/dnVKjrQ View in LinkedIn

"ALTRUISM can evolve when relatedness is low: evidence from bacteria committing suicide upon phage infection. High relatedness among interacting individuals has generally been considered a precondition for the evolution of altruism. However, kin-selection theory also predicts the evolution of altruism when relatedness is low, as long as the cost of the altruistic act is minor compared with its benefit." https://lnkd.in/d53-z28 View in LinkedIn

E COLI SUICIDE. "We investigated Escherichia coli responding to the attack of an obligately lytic phage by committing suicide in order to prevent parasite transmission to nearby relatives. We found that bacterial suicide provides large benefits to survivors at marginal costs to committers. The cost of suicide was low, because infected cells are moribund, rapidly dying upon phage infection, such that no more opportunity for reproduction remains." https://lnkd.in/d53-z28 View in LinkedIn

E COLI ALTRUISM. "Here, we demonstrate evidence of such a low-cost altruistic act in Escherichia coli bacteria, which express an abortive infection system (Abi) that responds to lethal phage attacks by causing infected cells to die together with the infecting phage. From an evolutionary perspective, the expression of an Abi system could reflect an altruistic act that allows infected bacteria to commit suicide in order to prevent parasite transmission to nearby relatives." https://lnkd.in/d53-z28 View in LinkedIn

LOW-COST SUICIDE. "Altogether, our findings demonstrate that low-cost suicide can evolve with ease, represents an effective host-defence strategy, and seems to be widespread among microbes. Moreover, low-cost suicide might also occur in higher organisms as exemplified by infected social insect workers leaving the colony to die in isolation." https://lnkd.in/d53-z28 View in LinkedIn

CONSTRAINTS. "In real biological communities, the efficacy of innate and adaptive immune systems is constrained by ecological factors such as population size, structure and diversity. The never-stopping arms race between hosts and pathogens sets a limit on the performance of defense strategies, which is determined by the ability of the host to keep the pace with pathogen escape mutations." https://lnkd.in/d9zsv9R View in LinkedIn

LEADING THE RACE. "Studies on host-parasite local adaptation suggest that parasites are usually ahead of hosts in this coevolutionary arms race." https://lnkd.in/d9zsv9R View in LinkedIn

SINGLE ENTITY. "Important to note is that in many cases the interests of the bacterium and an already resident prophage become completely aligned upon obligately lytic phage infection (i.e. infection by phages that do not insert into the bacterial genome, but kill the bacterium instantly), such that they can be regarded as one genetic entity." https://lnkd.in/d53-z28 View in LinkedIn

NON-ALIGNED INTERESTS. "The results of the present model of suicide evolution reveal an antagonism between the ‘interests’ of hosts and pathogens in structured populations whereby, while hosts tend to evolve suicide, prevention of host death is the preferred strategy for the pathogen." https://lnkd.in/d9zsv9R View in LinkedIn