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opencc-zeroDec 2016View details →

Data from: The evolution of clutch size in hosts of avian brood parasites

Coevolution with avian brood parasites shapes a range of traits in their hosts, including morphology, behavior, and breeding systems. Here we explore whether brood parasitism is also associated with the evolution of host clutch size. Several studies have proposed that hosts of highly virulent parasites could decrease the costs of parasitism by evolving a smaller clutch size, because hosts with smaller clutches will lose fewer progeny when their clutch is parasitized. We describe a model of the evolution of clutch size, which challenges this logic and shows instead that an increase in clutch size (or no change) should evolve in hosts. We test this prediction using a broad-scale comparative analysis to ask whether there are differences in clutch size within hosts and between hosts and nonhosts. Consistent with our model, this analysis revealed that host species do not have smaller clutches and that hosts that incur larger costs from raising a parasite lay larger clutches. We suggest that brood parasitism might be an influential factor in clutch-size evolution and could potentially select for the evolution of larger clutches in host species.

opencc-zeroDec 2013View details →

Data from: Parasitism in early life: environmental conditions shape intra-brood variation in responses to infection

Parasites play key ecological and evolutionary roles through the costs they impose on their host. In wild populations, the effect of parasitism is likely to vary considerably with environmental conditions, which may affect the availability of resources to hosts for defense. However, the interaction between parasitism and prevailing conditions is rarely quantified. In addition to environmental variation acting on hosts, individuals are likely to vary in their response to parasitism, and the combined effect of both may increase heterogeneity in host responses. Offspring hierarchies, established by parents in response to uncertain rearing conditions, may be an important source of variation between individuals. Here, we use experimental antiparasite treatment across 5 years of variable conditions to test how annual population productivity (a proxy for environmental conditions) and parasitism interact to affect growth and survival of different brood members in juvenile European shags (Phalacrocorax aristotelis). In control broods, last-hatched chicks had more plastic growth rates, growing faster in more productive years. Older siblings grew at a similar rate in all years. Treatment removed the effect of environment on last-hatched chicks, such that all siblings in treated broods grew at a similar rate across environmental conditions. There were no differences in nematode burden between years or siblings, suggesting that variation in responses arose from intrinsic differences between chicks. Whole-brood growth rate was not affected by treatment, indicating that within-brood differences were driven by a change in resource allocation between siblings rather than a change in overall parental provisioning. We show that gastrointestinal parasites can be a key component of offspring's developmental environment. Our results also demonstrate the value of considering prevailing conditions for our understanding of parasite effects on host life-history traits. Establishing how environmental conditions shape responses to parasitism is important as environmental variability is predicted to increase.

opencc-zeroDec 2013View details →

Data from: A likelihood-based approach for assessment of extra-pair paternity and conspecific brood parasitism in natural populations

Genotypes are frequently used to assess alternative reproductive strategies such as extra-pair paternity and conspecific brood parasitism in wild populations. However, such analyses are vulnerable to genotyping error or molecular artefacts that can bias results. For example, when using multilocus microsatellite data, a mismatch at a single locus, suggesting the offspring was not directly related to its putative parents, can occur quite commonly even when the offspring is truly related. Some recent studies have advocated an ad-hoc rule that offspring must differ at more than one locus in order to conclude that they are not directly related. While this reduces the frequency with which true offspring are identified as not directly related young, it also introduces bias in the opposite direction, wherein not directly related young are categorized as true offspring. More importantly, it ignores the additional information on allele frequencies which would reduce overall bias. In this study, we present a novel technique for assessing extra-pair paternity and conspecific brood parasitism using a likelihood-based approach in a new version of program cervus. We test the suitability of the technique by applying it to a simulated data set and then present an example to demonstrate its influence on the estimation of alternative reproductive strategies.

opencc-zeroDec 2014View details →

Data from: Cuckoo parasitism in a cavity nesting host: near absent egg-rejection in a northern redstart population under heavy apparent (but low effective) brood parasitism

Brood parasite - host systems continue to offer insights into species coevolution. A notable system is the redstart Phoenicurus phoenicurus parasitized by the "redstart-cuckoo" Cuculus canorus gens. Redstarts are the only regular cuckoo hosts that breed in cavities, which challenges adult cuckoos in egg laying and cuckoo chicks in host eviction. We investigated parasitism in this system and found high overall parasitism rates (31.1% of 360 redstart nests), but also that only 33.1% of parasitism events (49 of 148 eggs) were successful in laying eggs into redstart nest cups. The majority of cuckoo eggs were mislaid and found on the rim of the nest; outside the nest cup. All available evidence suggests these eggs were not ejected by hosts. The effective parasitism rate was therefore only 12.8% of redstart nests. Redstarts responded to natural parasitism by deserting their nests in 13.0% of cases, compared to desertion rates of 2.8% for non-parasitized nests. Our egg parasitism experiments found low rates (12.2%) of rejection of artificial non-mimetic cuckoo eggs. Artificial mimetic and real cuckoo eggs added to nests were rejected at even lower rates, and were always rejected via desertion. Under natural conditions, only 21 cuckoo chicks fledged of 150 cuckoo eggs laid. Adding to this low success, is that cuckoo chicks are sometimes unable to evict all host young, and were more likely to die as a result compared to cuckoo chicks reared alone. This low success seems to be mainly due to the cavity nesting strategy of the redstart which is a challenging obstacle for the cuckoo. The redstart-cuckoo system appears to be a fruitful model system and we suggest much more emphasis should be placed on frontline defences such as nest site selection strategies when investigating brood parasite-host coevolution.

FIGURE 7 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 7. Nipponodipogon sudai sp. nov. (A–F, holotype, ♀; G–K, paratype, ♂, Japan). A. head, frontal view; B. head, lateral view; C, G. head, dorsal view; D. mesosoma, lateral view; E. apical portion of left hind femur, outer view; F. S1, ventrolateral view; H. S6, ventrolateral view; I. subgenital plate, lateral view; J. genitalia (left half, dorsal view; right half, ventral view); K. aedeagus and parapenial lobe, dorsal view. Scale lines: 0.5 mm.

FIGURE 6 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 6. Nipponodipogon rossicus. (A–F, holotype, ♀; G–J, paratype, ♂, Russian Far East). A. head, frontal view; B. head, lateral view; C, G. head, dorsal view; D. mesosoma, lateral view; E. T1, dorsal view; F. S1 and S2, ventral view; H. S6, ventral view; I. subgenital plate, lateral view; J. genitalia (left half, dorsal view; right half, ventral view). Scale lines: 0.5 mm.

FIGURE 1 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 1. Nipponodipogon hayachinensis, ♀, type locality. A. head, frontal view; B. head, dorsal view; C. propodeum, lateral view; D. outer claw of left hind tarsus. Scale lines: 0.5 mm.

FIGURE 3 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 3. Nipponodipogon kurilensis, holotype, ♀. A. head, frontal view; B. head, dorsal view; C. mesosoma, lateral view; D. T1, dorsal view; E. S1 and S2, ventrolateral view. Scale lines: 0.5 mm.

FIGURE 2 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 2. Nipponodipogon iwatai. (A–E, holotype, ♀; F–I, ♂, Japan). A. head, frontal view; B. head, dorsal view; C. mesosoma, lateral view; D. apical portion of left hind femur, outer view; E. S1 and S2, ventral view; F. S6 and subgenital plate, ventrolateral view; G, subgenital plate, lateral view; H, genitalia, ventral view; I. genitalia, dorsal view. Scale lines: 0.5 mm.

FIGURE 9 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 9. Nipponodipogon, fore and hind wings. A. N. hayachinensis, ♀, Japan; B. N. iwatai, holotype; C, D. N. kurilensis, holotype; E. N. mandibularis, holotype; F, G. N. nagasei, holotype; H, I. N. rossicus, holotype. J. H. sudai sp. nov., paratype, ♀, Japan; K. H. sudai, paratype, ♂, Japan. Scale lines: 1.0 mm.

FIGURE 5 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 5. Nipponodipogon nagasei. (A–D, holotype, ♀; E–G, ♂, Japan). A. head, frontal view; B. head, dorsal view; C. mesosoma, lateral view; D. outer claw of right hind tarsus; E. S6 and subgenital plate, ventrolateral view; F. subgenital plate, lateral view; G. genitalia (left half, ventral view; right half, dorsal view). Scale lines: 0.5 mm.

FIGURE 8 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 8. Nipponodipogon, female head, anterolateral view (A, B), female T1, dorsal view (C–E) and male subgenital plate, ventral view (F–I). A. N. mandibularis, paratype, Japan. B. N. nagasei, Japan. C. N. iwatai, Japan; D. N. nagasei, Japan; E. N. sudai sp. nov., paratype, Japan; F. N. iwatai, Japan; G. N. nagasei, Japan; H. N. rossicus, paratype, Russian Far East; I. N. sudai, paratype, Japan. Scale lines: 0.5 mm for A–E, 0.25 mm for F–I.

FIGURE 4 in Revision of the Palaearctic brood parasitic genus Nipponodipogon Ishikawa, 1965 of spider wasps (Hymenoptera: Pompilidae: Pepsinae)

FIGURE 4. Nipponodipogon mandibularis, holotype, ♀. A. head, frontal view; B. head, dorsal view; C. mesosoma, lateral view. Scale lines: 0.5 mm.

opencc-zeroApr 2024View details →

Conspecific brood parasitism and nest predation in moorhens

Conspecific brood parasitism was investigated in three species of moorhens on three different continents: common moorhens in the United Kingdom, lesser moorhens in Namibia, and American moorhens in Panama. These are nest data used to summarize population-level rates of conspecific brood parasitism and nest predation. The data reported here were collected using similar field methods, and include nest dates, clutch sizes (number of host eggs), number of parasitic eggs, and nest fates.

opencc-zeroMay 2022View details →

Data from: A tiny cuckoo: risk-dependent interspecific brood parasitism in a predatory mite

Many animal species protect their eggs against predators while others do not. When these species share the same habitat, the latter species may profit by adding their eggs to those of the protecting species. We show that one tiny predatory mite species protects its own eggs only to a limited extent, and instead adds them to those of another predatory mite species that does guard its eggs, resulting in reduced egg predation. This cuckoo behaviour comes with a cost, and therefore only occurs when egg predators are present. Furthermore, the parasites only add eggs to those of the guarding host species, not to those of another mite species that does not guard its eggs. To the best of our knowledge, this is the first study to show that facultative brood parasitism is more effective than brood care, in increasing offspring survival in the presence of egg predators.

opencc-zeroJul 2022View details →

The overlooked complexity of avian brood parasite–host relationships

The interactions between avian brood parasites and their hosts have become widely recognised as model systems for studying coevolutionary processes. These systems have traditionally been viewed as relationships between one species of brood parasite and one species of host; however, with most brood parasites being known to parasitise multiple species of host and hosts often being subject to parasitism by multiple brood parasite species, opportunities to examine the ecology and evolution of multispecies interactions have generally been overlooked. Here, we compile data on all known brood parasite–host relationships and investigate where and how multiple species of brood parasites and hosts coexist. Considering these relationships as interactions in ecological networks, we find that complex brood parasite–host systems (i.e. those that include multiple species of brood parasites and hosts) exhibiting highly connected networks are found globally, with increased prevalence at lower latitudes in tropical and sub-tropical ecosystems. We also examine patterns of past research, outline the disparity between global patterns of network complexity and past research emphases, and discuss spatial and temporal factors that may be associated with these observed patterns. Drawing on insights gained from the handful of brood parasitism studies involving more complex scenarios and other biological systems that have embraced the use of a multispecies framework, we highlight the potential benefits of considering brood parasite–host interactions as ecological networks and brood parasitism as a model system for studying multispecies interactions. Overall, our results provide new insights into the diversity of these relationships when considered in a multispecies framework, highlight the stark mismatch between past research efforts and global patterns of system complexity, and draw attention to the opportunities that the study of more complex arrangements offers for examining how species interactions shape global patterns of biodiversity.

opencc-zeroDec 2017View details →

Data from: Thick eggshells of brood parasitic cowbirds protect their eggs and damage host eggs during laying

Brood parasites lay thick-shelled eggs and numerous hypotheses have been proposed to explain the significance of this trait. We examined whether thick eggshells protect the parasite egg during laying events. We used eggs of the parasitic shiny cowbird (Molothrus bonariensis) and its hosts, the house wren (Troglodytes aedon) and chalk-browed mockingbird (Mimus saturninus) in South America and the eggs of the parasitic brown-headed cowbird (M. ater) and its hosts the house wren and red-winged blackbird (Agelaius phoeniceus) in North America. We experimentally dropped parasite eggs onto host eggs to simulate laying by the parasite, parasite eggs onto parasite eggs to simulate multiple parasitism, host eggs onto parasite eggs to simulate hosts laying from the height cowbirds lay, and stirred eggs to simulate jostling that may occur when cowbirds and hosts interact during laying events. We found that cowbird eggs were significantly less likely to be damaged than host eggs when they were laid onto a host egg and when host and cowbird eggs were laid onto them. There was minimal damage to eggs during jostling experiments, thereby failing to support the hypothesis that thick eggshells provide protection when eggs are jostled. These findings support the hypotheses that thick eggshells resist damage when laid from an elevated position, when additional cowbird eggs are laid onto them in multiply parasitized nests, and these eggs also damage host eggs when laid.

opennotspecifiedDec 2003View details →

FIGS 1–3 in A review of deviant phenotypes in bees in relation to brood parasitism, and a gynandromorph of Megalopta genalis (Hymenoptera: Halictidae)

FIGS 1–3. (1) Wild-type female Megalopta genalis. (a) Head, width~4.16 mm; (b) labrum. (2) Wild-type male M. genalis. (a) Head, width~3.16 mm; (b) labrum. (3) Gynandromorph M. genalis. (a) Head, width~3.32 mm; (b) labrum.

opencc-zeroSep 2021View details →

Choice of nest attributes as a frontline defense against brood parasitism

Breeding- and nest-site choice is a behavioral strategy often used to counter negative interactions. Site choices prior to breeding prevents costs of predation and competition but has been neglected in the context of brood parasitism. For hosts of brood parasites, the earlier brood parasitism is prevented in the breeding cycle the lower the future costs. Suitable nest-sites for cavity-nesting common redstarts (Phoenicurus phoenicurus), a host of the common cuckoo (Cuculus canorus), are a limited resource, but their cavity-nesting strategy could potentially deter predators and brood parasites. We altered the entrance size of breeding cavities and investigated redstart nest site choice and its consequences to nest predation and brood parasitism risk, while accounting for potential interspecific competition for nest sites. We set-up paired nest-boxes and let redstarts choose between 7 cm and 5 cm entrance sizes. Additionally, we monitored occupancy rates in nest-boxes with 3 cm, 5 cm and 7 cm entrance sizes and recorded brood parasitism and predation events. We found that redstarts preferred to breed in 5 cm entrance size cavities, where brood parasitism was eliminated but nest predation rates were comparable to 7 cm entrance size cavities. Only in 3 cm cavities were both brood parasitism and predation rates reduced. In contrast to the other cavity-nesting species, redstart settlement was lowest in 3 cm entrance size cavities, potentially suggesting interspecific competition for small entrance size cavities. Nest site choice based on entrance size could be a front-line defense strategy that redstarts use to reduce brood parasitism.