Coevolutionary interactions in a host-parasite system (original) (raw)
Related papers
Coevolution of an Avian Host and Its Parasitic Cuckoo
Evolution, 2003
We use a quantitative genetic model to examine the coevolution of host and cuckoo egg characters (termed ''size'' as a proxy for general appearance), host discrimination, and host and cuckoo population dynamics. A host decides whether to discard an egg using a comparison of the sizes of the eggs in her nest, which changes as host and cuckoo eggs evolve. Specifically, we assume that the probability that she discards the largest egg in her nest depends on how much larger it is than the second largest egg. This decision rule (i.e., the acceptable difference in egg sizes) also evolves, changing both the chance of successful rejection of a cuckoo egg in parasitized nests and the chance of mistaken rejection of a host egg in both parasitized and unparasitized nests. We find a stable equilibrium for coexistence of the host and cuckoo where there is cuckoo egg mimicry, evolutionary displacement of the host egg away from the cuckoo egg phenotype, and host discrimination against unusual eggs. Both host discrimination and host egg displacement are fairly weak at the equilibrium. Cuckoo egg mimicry, although imperfect, usually evolves more extensively and quickly than the responses of the host. Our model provides evidence for both the evolutionary equilibrium and evolutionary lag hypotheses of host acceptance of parasitic eggs.
Cuckoos versus hosts in insects and birds: adaptations, counter-adaptations and outcomes
Biological Reviews
Avian parents and social insect colonies are victimized by interspecific brood parasites-cheats that procure costly care for their dependent offspring by leaving them in another species' nursery. Birds and insects defend themselves from attack by brood parasites; their defences in turn select counter-strategies in the parasite, thus setting in motion antagonistic co-evolution between the two parties. Despite their considerable taxonomic disparity, here we show striking parallels in the way that co-evolution between brood parasites and their hosts proceeds in insects and birds. First, we identify five types of co-evolutionary arms race from the empirical literature, which are common to both systems. These are: (a) directional co-evolution of weaponry and armoury; (b) furtiveness in the parasite countered by strategies in the host to expose the parasite; (c) specialist parasites mimicking hosts who escape by diversifying their genetic signatures; (d) generalist parasites mimicking...
Cuckoo hosts shift from accepting to rejecting parasitic eggs across their lifetime
Evolution; international journal of organic evolution, 2014
One of the best-known outcomes of coevolution between species is the rejection of mimetic parasite eggs by avian hosts, which has evolved to reduce costly cuckoo parasitism. How this behavioral adaptation varies along the life of individual hosts remains poorly understood. Here, we identify for the first time, lifetime patterns of egg rejection in a parasitized long-lived bird, the magpie Pica pica and show that, during the years they were studied, some females accept, others reject, and some others modify their response to model eggs, in all cases switching from acceptance to rejection. Females tested in their first breeding attempt always accepted the model egg, even those individuals whose mothers were egg rejecters. A longitudinal analysis showed that the probability of egg rejection increased with the relative age of the female, but was not related to the risk of parasitism in the population. We conclude that ontogeny plays a fundamental role in the process leading to egg rejec...
PLoS ONE, 2011
Background: Antagonistic species often interact via matching of phenotypes, and interactions between brood parasitic common cuckoos (Cuculus canorus) and their hosts constitute classic examples. The outcome of a parasitic event is often determined by the match between host and cuckoo eggs, giving rise to potentially strong associations between fitness and egg phenotype. Yet, empirical efforts aiming to document and understand the resulting evolutionary outcomes are in short supply. Methods/Principal Findings: We used avian color space models to analyze patterns of egg color variation within and between the cuckoo and two closely related hosts, the nomadic brambling (Fringilla montifringilla) and the site fidelic chaffinch (F. coelebs). We found that there is pronounced opportunity for disruptive selection on brambling egg coloration. The corresponding cuckoo host race has evolved egg colors that maximize fitness in both sympatric and allopatric brambling populations. By contrast, the chaffinch has a more bimodal egg color distribution consistent with the evolutionary direction predicted for the brambling. Whereas the brambling and its cuckoo host race show little geographical variation in their egg color distributions, the chaffinch's distribution becomes increasingly dissimilar to the brambling's distribution towards the core area of the brambling cuckoo host race. Conclusion: High rates of brambling gene flow is likely to cool down coevolutionary hot spots by cancelling out the selection imposed by a patchily distributed cuckoo host race, thereby promoting a matching equilibrium. By contrast, the site fidelic chaffinch is more likely to respond to selection from adapting cuckoos, resulting in a markedly more bimodal egg color distribution. The geographic variation in the chaffinch's egg color distribution could reflect a historical gradient in parasitism pressure. Finally, marked cuckoo egg polymorphisms are unlikely to evolve in these systems unless the hosts evolve even more exquisite egg recognition capabilities than currently possessed.
Testing for correlations between behaviours in a cuckoo host: why do host defences not covary?
Animal Behaviour, 2014
Fitness costs associated with brood parasitism have led host species to evolve several lines of defence. The first two lines of defence, aggression against adult parasites and egg rejection, are present at varying levels in almost all hosts. However, it remains unclear how these two fundamental defences covary at host individual level, with previous studies suggesting both positive and negative correlations. A theoretically critical yet empirically untested scenario is that variation in host antiparasite behaviour may relate to individual variation in host behavioural types or personalities. Here we examined whether host aggression against adult brood parasites and egg rejection behaviour were correlated with host behaviours displayed outside the context of brood parasitism. We selected the great reed warbler, Acrocephalus arundinaceus, a favourite cuckoo, Cuculus canorus, host as a suitable model. Only females reject foreign eggs and show high individual repeatability of both aggression towards cuckoos and nest guarding. We found that female behaviours in different situations (nest guarding, nest defence, handling in the net) were strongly correlated with each other. This is the first empirical evidence on correlation between individually consistent antiparasite adaptation (female nest defence) and behaviours that are not directly related to brood parasitism. In contrast, egg rejection/acceptance responses and latency to these responses did not correlate with any of the female defence/guarding behaviours and behaviour during handling. Proximately, this may be because nest defence and egg recognition represent cognitively and behaviourally completely different tasks. These patterns were not affected by female mating status in this polygynous cuckoo host. We hypothesize that differences in host behavioural types, rather than host egg discrimination ability, may predict host nest defence behaviour against adult brood parasites in general. Ó
An experimental test of host's life history traits modulation in response to cuckoo parasitism risk
PloS one, 2017
Hosts can counteract parasites through defences based on resistance and/or tolerance. The mechanistic basis of tolerance, which involve defensive mechanisms minimizing parasite damage after a successful parasitic attack, remains poorly explored in the study of cuckoo-host interactions. Here, we experimentally explore the possibility that the risk of great spotted cuckoo Clamator glandarius parasitism may induce tolerance defences in magpie Pica pica hosts through plasticity in life-history traits. We predict that magpies exposed to auditory cues indicating high parasitism risk will more likely exhibit resistance and/or modify their life-history traits to minimize parasitism costs (i.e. tolerance) compared to magpies under low parasitism risk. We found that manipulating the perceived parasitism risk did not affect host resistance (i.e. rejection of parasitic eggs) nor host life-history traits. Unexpectedly, host's egg volume increased over the season in nests exposed to auditory ...
Social Transmission of a Host Defense Against Cuckoo Parasitism
Science
Coevolutionary arms races between brood parasites and hosts involve genetic adaptations and counter-adaptations. However, hosts sometimes acquire defenses too rapidly to reflect genetic change. Our field experiments show that observation of cuckoo (Cuculus canorus) mobbing by neighbors on adjacent territories induced reed warblers (Acrocephalus scirpaceus) to increase the mobbing of cuckoos but not of parrots (a harmless control) on their own territory. In contrast, observation of neighbors mobbing parrots had no effect on reed warblers’ responses to either cuckoos or parrots. These results indicate that social learning provides a mechanism by which hosts rapidly increase their nest defense against brood parasites. Such enemy-specific social transmission enables hosts to track fine-scale spatiotemporal variation in parasitism and may influence the coevolutionary trajectories and population dynamics of brood parasites and hosts.
The evolution of egg rejection by cuckoo hosts in Australia and Europe
Behavioral Ecology, 2005
Exploitation of hosts by brood parasitic cuckoos is expected to stimulate a coevolutionary arms race of adaptations and counteradaptations. However, some hosts have not evolved defenses against parasitism. One hypothesis to explain a lack of host defenses is that the life-history strategies of some hosts reduce the cost of parasitism to the extent that accepting parasitic eggs in the nest is evolutionarily stable. Under this hypothesis, it pays hosts to accept cuckoo eggs if (1) the energetic cost of raising the cuckoo is low, (2) there is time to renest, and clutch size is small. We parasitized the nests of host and nonhost species with nonmimetic model eggs to test whether the evolution of egg recognition by cuckoo hosts could be explained by life-history variables of the host. The most significant factor explaining rates of rejection of model eggs was whether or not a species was a cuckoo host, with hosts rejecting model eggs at a higher rate than nonhosts. Egg-rejection rates were also explained by visibility within the nest and by cuckoo mass. We found little support for the life-history model of egg rejection. Our results suggest that parasitism is always sufficiently costly to select for host defenses and that the evolution of defenses may be limited by proximate constraints such as visibility within the nest.