| 11. |
- Gillingham, Mark, et al.
(författare)
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Cryptic preference for MHC-dissimilar females in male red junglefowl, Gallus gallus
- 2009
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society. - 0962-8452 .- 1471-2954. ; 276:1659, s. 1083-1092
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Tidskriftsartikel (refereegranskat)abstract
- An increasing number of studies test the idea that females increase offspring fitness by biasing fertilization in favour of genetically compatible partners; however, few have investigated or controlled for corresponding preferences in males. Here, we experimentally test whether male red junglefowl, Gallus gallus, prefer genetically compatible females, measured by similarity at the major histocompatibility complex (MHC), a key gene complex in vertebrate immune function. Theory predicts that because some degree of MHC heterozygosity favours viability, individuals should prefer partners that carry MHC alleles different from their own. While male fowl showed no preference when simultaneously presented with an MHC-similar and an MHC-dissimilar female, they showed a 'cryptic' preference, by allocating more sperm to the most MHC-dissimilar of two sequentially presented females. These results provide the first experimental evidence that males might respond to the MHC similarity of a female through differential ejaculate expenditure. By revealing that cryptic male behaviours may bias fertilization success in favour of genetically compatible partners, this study demonstrates the need to experimentally disentangle male and female effects when studying preferences for genetically compatible partners.
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| 12. |
- Hayward, A., et al.
(författare)
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Evolutionary associations between host traits and parasite load : insights from Lake Tanganyika cichlids
- 2017
-
Ingår i: Journal of Evolutionary Biology. - : WILEY. - 1010-061X .- 1420-9101. ; 30:6, s. 1056-1067
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Tidskriftsartikel (refereegranskat)abstract
- Parasite diversity and abundance (parasite load) vary greatly among host species. However, the influence of host traits on variation in parasitism remains poorly understood. Comparative studies of parasite load have largely examined measures of parasite species richness and are predominantly based on records obtained from published data. Consequently, little is known about the relationships between host traits and other aspects of parasite load, such as parasite abundance, prevalence and aggregation. Meanwhile, understanding of parasite species richness may be clouded by limitations associated with data collation from multiple independent sources. We conducted a field study of Lake Tanganyika cichlid fishes and their helminth parasites. Using a Bayesian phylogenetic comparative framework, we tested evolutionary associations between five key host traits (body size, gut length, diet breadth, habitat complexity and number of sympatric hosts) predicted to influence parasitism, together with multiple measures of parasite load. We find that the number of host species that a particular host may encounter due to its habitat preferences emerges as a factor of general importance for parasite diversity, abundance and prevalence, but not parasite aggregation. In contrast, body size and gut size are positively related to aspects of parasite load within, but not between species. The influence of host phylogeny varies considerably among measures of parasite load, with the greatest influence exerted on parasite diversity. These results reveal that both host morphology and biotic interactions are key determinants of host-parasite associations and that consideration of multiple aspects of parasite load is required to fully understand patterns in parasitism.
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| 13. |
- Lisney, Thomas J., et al.
(författare)
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Behavioural assessment of flicker fusion frequency in chicken Gallus gallus domesticus
- 2011
-
Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 51:12, s. 1324-1332
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Tidskriftsartikel (refereegranskat)abstract
- To interact with its visual environment, an organism needs to perceive objects in both space and time. High temporal resolution is hence important to the fitness of diurnally active animals, not least highly active aerial species such as birds. However, temporal resolution, as assessed by flicker fusion frequency (FFF; the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous) or critical flicker fusion frequency (CFF; the highest flicker fusion frequency at any light intensity) has rarely been assessed in birds. In order to further our understanding of temporal resolution as a function of light intensity in birds we used behavioural experiments with domestic chickens (Gallus gallus domesticus) from an old game breed 'Gammalsvensk dvarghona' (which is morphologically and behaviourally similar to the wildtype ancestor, the red jungle fowl, G. gallus), to generate an 'Intensity/FFF curve' (I/FFF curve) across full spectrum light intensities ranging from 0.2 to 2812 cd m(-2). The I/FFF curve is double-branched, resembling that of other chordates with a duplex retina of both rods and cones. Assuming that the branches represent rod and cone mediated responses respectively, the break point between them places the transition between scotopic and photopic vision at between 0.8 and 1.9 cd m(-2). Average FFF ranged from 19.8 Hz at the lowest light intensity to a CFF 87.0 Hz at 1375 cd m(-2). FFF dropped slightly at the highest light intensity. There was some individual variation with certain birds displaying CFFs of 90-100 Hz. The FFF values demonstrated by this non-selected breed appear to be considerably higher than other behaviourally derived FFF values for similar stimuli reported for white and brown commercial laying hens, indicating that the domestication process might have influenced temporal resolution in chicken.
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| 14. |
- Løvlie, Hanne, et al.
(författare)
-
A cry for help : female distress calling during copulation is context dependent
- 2014
-
Ingår i: Animal Behaviour. - : Elsevier. - 0003-3472 .- 1095-8282. ; 92, s. 151-157
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Tidskriftsartikel (refereegranskat)abstract
- Owing to selection for increased mating propensity, males often expose females to sexual harassment.Consequently, females may evolve counterstrategies to retain control of mating. Females can do thisdirectly by resisting copulations, or indirectly by manipulating other males to intervene and prevent thecopulation. Uttering copulation calls may be one indirect method for females to trigger male intervention.Copulation calls are commonly observed in mammals, primarily in primates, and also in some birds.Female fowl, Gallus gallus, sometimes utter calls during copulation, particularly in forced copulationswith low-ranking males. These loud calls, called distress calls, attract other males and can result indisruption of the copulation, and subsequent mating with the intervening male if he is high ranking.Consequently, uttering such calls can act both to abort a coerced copulation and to generate novel opportunitiesfor females to copulate with higher-ranking males. Nevertheless, uttering loud calls can carrycosts, such as attracting predators. Females are therefore predicted to utter copulation calls primarilywhen doing so offers benefits, which for female fowl requires the presence of another high-ranking male.We tested this prediction by altering the social environment of female domestic fowl, G. g. domesticus.We found that females uttered copulation calls more frequently during copulations in the presence ofdominant ‘observer’ males than in their absence. Thus, we provide evidence of context-dependent utteranceof female calls during copulations in a bird. This type of female vocalization is rarely investigatedin nonprimate vertebrates, but increased research in this field offers potential to improve understandingof female mate choice strategies and the dynamics of sexual selection.
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| 15. |
- Løvlie, Hanne
(författare)
-
Cryptic Female Choice
- 2016
-
Ingår i: Oxfords Bibliographies in Evolutionary Biology. - : Oxford Bibliographies.
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Forskningsöversikt (refereegranskat)abstract
- Sexual selection (see the Oxford Bibliographies article “Sexual Selection”) is a powerful evolutionary force, selecting fortraits that increase the reproductive success of individuals. Before copulation, sexual selection can occur throughintrasexual selection, typically observed as competition among individuals of the same sex for access to mating partnersof the other sex (see Oxford Bibliographies article on Evolutionary Biology “Male-Male Competition”), and intersexualselection, observed as (typically female) mate choice (see Oxford Bibliographies article on Evolutionary Biology “MateChoice”). When females are sexually promiscuous and mate with multiple males (which is more the rule than theexception in the animal kingdom), these two processes have the potential to continue also after copulation: intrasexualselection as sperm competition (Oxford Bibliographies article on Evolutionary Biology “Sperm Competition”), andintersexual selection as cryptic female choice. The term cryptic is applied because this form of female choice can be hardto observe (e.g., when it occurs inside the female reproductive tract) and hard to quantify with classical measures ofreproductive success (e.g., mating success). In addition, this form of female choice is hard to disentangle from otherepisodes of sexual selection (see below). The framework used to understand female choice occurring after (or sometimesduring) copulation is currently somewhat divergent, since some authors adopt a very broad definition of cryptic femalechoice, while others apply a more conservative definition (see discussion of this under Definition and History). Crypticfemale choice is a relatively young research topic (it first started properly after the publication of Eberhard’s seminal bookFemale Control: Sexual Selection by Cryptic Female Choice [Eberhard 1996, cited under General Overviews] in 1996). Itwas realized early on in the history of the field that a broad range of mechanisms across a variety of species exist throughwhich females can potentially bias the outcome of a copulation (e.g., ejaculate ejection, differential sperm storage, spermchoice—see section Mechanisms and Processes Used as Cryptic Female Choice). As a consequence, measures ofprecopulatory processes or sperm competition can be misleading in species with cryptic female choice, due to femalepostcopulatory influences on fertilization. Yet, although there is no doubt that females have great potential to bias paternityat the postcopulatory stage, cryptic female choice is the least studied of the processes through which sexual selection canoccur (e.g., compared to sperm competition, or male-male competition). This is probably because demonstration of crypticfemale choice is notoriously difficult. It can be challenging to separate pre- from postcopulatory processes, the interactionof male adaptations to sperm competition and female influences on fertilization, and variation in differential embryomortality from female-induced biases in paternity (see Potential Pitfalls in the Study of Cryptic Female Choice). Thestudies that have convincingly been able to separate these processes and demonstrate cryptic female choice are currentlyprimarily from insect, bird, and externally fertilizing species (see Mechanisms and Processes Used as Cryptic FemaleChoice). I here present when we may expect to observe cryptic female choice, how females may benefit from crypticfemale choice, some techniques that can
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| 16. |
- Løvlie, Hanne, 1977-
(författare)
-
Cryptic female choice
- 2016
-
Ingår i: Encyclopedia of Evolutionary Psychological Science. - Cham : Springer. - 9783319169996 ; , s. 1-4
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Bokkapitel (refereegranskat)
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| 17. |
- Løvlie, Hanne, et al.
(författare)
-
Cryptic female choice favours sperm from major histocompatibility complex-dissimilar males
- 2013
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 280:1769
-
Tidskriftsartikel (refereegranskat)abstract
- Cryptic female choice may enable polyandrous females to avoid inbreeding or bias offspring variability at key loci after mating. However, the role of these genetic benefits in cryptic female choice remains poorly understood. Female red junglefowl, Gallus gallus, bias sperm use in favour of unrelated males. Here, we experimentally investigate whether this bias is driven by relatedness per se, or by similarity at the major histocompatibility complex (MHC), genes central to vertebrate acquired immunity, where polymorphism is critical to an individual's ability to combat pathogens. Through experimentally controlled natural matings, we confirm that selection against related males' sperm occurs within the female reproductive tract but demonstrate that this is more accurately predicted by MHC similarity: controlling for relatedness per se, more sperm reached the eggs when partners were MHC-dissimilar. Importantly, this effect appeared largely owing to similarity at a single MHC locus (class I minor). Further, the effect of MHC similarity was lost following artificial insemination, suggesting that male phenotypic cues might be required for females to select sperm differentially. These results indicate that postmating mechanisms that reduce inbreeding may do so as a consequence of more specific strategies of cryptic female choice promoting MHC diversity in offspring.
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| 18. |
- Løvlie, Hanne, 1977-
(författare)
-
Introduction to animal personality
- 2017. - 3
-
Ingår i: The ethology of domestic animals. - UK : CABI Publishing. - 9781786391650 ; , s. 104-118
-
Bokkapitel (refereegranskat)
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| 19. |
- Løvlie, Hanne, et al.
(författare)
-
Male mounting alone reduces female promiscuity in the fowl
- 2005
-
Ingår i: Current Biology. - : Cell Press. - 0960-9822 .- 1879-0445. ; 15:13, s. 1222-1227
-
Tidskriftsartikel (refereegranskat)abstract
- The fertilization success of an insemination is at risk when a female has the possibility to copulate with multiple males, generating sperm competition and sexual conflict over remating. Female propensity to remate is often reduced after copulation, and a staggering diversity of highly derived male traits that discourage female promiscuity have been investigated. However, it is difficult to separate the effect of such specialized traits and insemination products from the more basic effect that the act of mounting per se may have on female remating. Here, we use a novel approach that separates the influence of mounting from that of insemination on female remating in the promiscuous feral fowl. Mounting alone caused a transient but drastic reduction in female propensity to remate, and-crucially-the number of sperm that a female obtained from a new male. Therefore, like other taxa, female fowl show a reduction in promiscuity after copulation, but this is entirely due to mounting alone. This effect of mounting, independent of insemination and fertilization, indicates that even copulations that deliver little or no semen, a puzzling behavior common in many species including the fowl, may play a crucial role in sperm competition.
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| 20. |
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