Summary: Kessler et al. (2012)

The evolution of social systems has been largely influenced by kin selection. Within a social group, the ability to recognize paternal kin is important for minimizing inbreeding and loss of genetic diversity. Kessler et al. (2012) investigated vocal paternal kin recognition in the grey mouse lemur (Microcebus murinus), one of the first studies to do so. They analysed ultrasonic male courtship and alarm calls, and found that advertisement calls contain patrilineal signatures, which females use to assess relatedness of males. Alarm calls did not seem to contain these signatures. Kessler et al. (2012) conclude that paternal kin recognition is not reliant on brain size or social complexity, but could be the ancestral state from which more complex, kin-based sociality has arisen.

Summary: Foster et al. (2012)

Postmenopausal life span in humans has encouraged studies investigating the evolution prolonged post-reproductive life span in other animals. Two mechanisms are proposed: 1) increased longevity - evolutionary benefits accumulate only during the reproductive phase; 2) evolved adaptation - the post-reproductive life span increases individual "genetic" survival, resulting in increased inclusive fitness. Foster et al. (2012) used a Cox proportional hazards model (6) to study the influence of a mother killer whale’s (Orcinus orca) death on offspring survival. Neither sex disperses from the maternal group, so old mothers can maximise their inclusive fitness by increasing offspring survival and reproductive success. In addition, mothers should only help sons, as mating occurs outside the matriline. Foster et al. (2012) showed that old females assist male offspring. As reproductive success increases with male age, increased survival of sons increases the inclusive fitness of mothers. Mothers can assist with foraging or will provide support during agonistic encounters. Foster et al.'s (2012) results support the premise that a long post-reproductive life span is an evolved adaptation.

Summary: Hut & Scharff (1998)

Endoscopic equipment can be used to observe the behaviour of ground-dwelling animals inside their burrows. Hut & Scharff (1998) used a 205cm manoeuvrable fibre optic industrial endoscope attached to a video system to assess tunnel-blocking behaviour in European ground squirrels Spermophilus citellus. They found that, in 82% of cases, a tunnel block was found approximately 57 cm from the tunnel entrance. They suggest that ground squirrels are actively avoiding under-ground predation by blocking the tunnels with sand, and that they do this when both entering and leaving the burrow. Hut & Scharff (1998) suggest that these squirrels likely show a high tolerance to low oxygen (hypoxia) and high carbon dioxide (hypercapnia) conditions.

Summary: Blumstein et al. (2004)

Blumstein et al. (2004) investigated social hibernation in yellow-bellied marmots (Marmota flaviventris), as the species has a harem/polygynous social system, by monitoring emergence patterns from hibernation. Females share burrows and show home-range overlap in summer. They found that, as for 14 other species of the marmots, yellow-bellied marmots are social hibernators. They indicate that, although they hibernate socially, they might not accrue benefits of social thermoregulation. Blumstein et al. (2004) suggest that emergence times are occurring earlier in the year, consistent with global climate change models that suggest an influence of climate change on hibernation patterns in sub-alpine areas.

Summary: Callander et al. (2012)

 Fighting success in most males is determined by physical strength and the value of the resource over which males fight. Callander et al. (2012) looked at the how much fiddler crabs Uca annulipes valued a territory/burrow as a resource during the breeding season. During the mating season, burrows were deemed more valuable, as males escalated fights to maintain a territory for breeding and mating. In the non-breeding season, however, males did not fight as hard, even though burrows are still considered a valuable resource for access to food. Interestingly, although males with regenerated claws are weaker competitors than males with undamaged appendages, damaged males fought extra hard to avoid evictions during the breeding season and escalated fights more to maintain the resource. Callander et al. (2012) suggest that weaker males should fight harder when the resource is required for breeding.

Summary: Boyd (2012)

Boyd (2012) indicates that, although ecological models may be limited in their ability to predict various ecosystem responses, they are important for determining what drives ecosystem vulnerability in the face of disturbance. He provides a brief review of Mougi & Kondoh's (2012) network models. These models suggest that positive (mutualistic) and negative (agonistic) interactions play a role in ecosystem stability. He further suggests that ecological network models, while limiting, are important for describing ecosystem characteristics on a general level and for providing an indication of how these systems respond under stressful conditions. He further stresses that management decisions are likely to be driven by the status keystone species in ecological networks.

Summary: Etterson & Shaw (2001)

Etterson & Shaw (2001) described the genetic structure of three populations of the native North American annual legume Chamaecrista fasciculata, under experimental field conditions designed to simulate a warmer, drier climate (as predicted by global climate change models) to evaluate the evolutionary potential of the species. Although they found genetic variance in numerous traits (fecundity, leaf number, leaf thickness, rate of phenological development) under selection, they noted that among-trait correlations antagonistic to the direction of selection may function to limit adaptive evolution. They predict that the rate of evolutionary response in this species is slow than the predicted rate of climate change and could have a negative impact on the species.

Summary: McMahon et al. (2012)

Supporters of animal welfare often oppose research conducted on wild animals by wildlife scientists. However, this is of concern as the biodiversity crisis requires knowledge of many animals' biology and ecology, amongst other things (e.g. behaviour). Although some studies might result in "invasive" research, this could lead to increased conservation goals for threatened populations. Supporters of animal welfare often find this level of invasion unacceptable, regardless of the proposed outcomes. McMahon et al. (2012) suggest that a resolution between these two opposing sides can be resolved. They suggest that scientists should apply Bateson's Decision Cube to research studies to highlight and efficiently demonstrate the benefits of the research. This will also allow them to engage more successfully with the public sector (including animal welfare supporters) in debates of conservation value research.

Summary: Sheth et al. (2012)

One of the major components to human cognition is the ability to behave in the most appropriate manner to constantly changing environmental pressure. Cognitive control is regulated by the dorsal anterior cingulate cortex (dACC). This has been proposed to play a role in reward-based decision making, conflict resolution between two competing responses and assessment/prediction of the difficulty of a task. Sheth et al. (2012) used functional imaging and human single-neuron recordings to show the precise mechanisms of dACC function, indicating that individual dACC neurons encode cognitive load (recent and current). They further show that prior activity modifies current dACC activity to produce a behavioural adaptation that speeds up reactions to cues previously experienced as difficult, but can slow reactions to cues with different difficulties (known as the Gratton effect). Sheth et al.'s (2012) results show that future behavioural responses can be optimized by the continuous updating of predictions of expected cognitive demand by the dACC. They further suggest that in stable conditions, efficiency is promoted by speeding up responses, but when conditions become variable or unstable, accuracy is improved through the delay of responses.

Summary: Suzuki (2012)

Antipredator alarm calls are produced by many birds and mammals in response to perceived presence of a predator. Alarm calls often vary in their acoustic structure and are dependent of the level of perceived risk and on the type of predator perceived (e.g. a snake vs. and eagle). These alarm calls are designed to elicit an appropriate escape response by conspecifics, such as looking to the sky or running up a tree. Alarm calls may also encourage individuals to join together to mob predators, but the information contained in the calls is crucial for determining the manner in which to mob. Japanese great tits Pares major minor produce distinct mobbing calls in response to jungle crows Corvus macrorhynchos ('chicka' calls) and Japanese rat snakes Elaphe climacophora ('jar' calls). Suzuki (2012) found that, in a playback experiment, adult birds responded different to the the different mobbing calls: they looked to the sky in response to a 'chicka' call, but gazed toward the ground in response to a 'jar' call. Suzuki (2012) suggests that the mobbing calls of Japanese great tits transmit referential information about the type of predator posing the risk, and also help to elicit appropriate anti-predator (predator-searching) behaviours.

Summary: Murase & Sunobe (2011)

Tube blennies (Neoclinus bryope) are small fish that occupy rocky intertidal areas in Japan. Murase & Sunobe (2011) investigated territorial behaviour in this species, noting that males occupied small holes for spawning nests. These males maintained the nest area and excluded other males from entering. The area these males occupied was fairly small (approximately 30cm) and males showed aggressive behaviour to fish that intruded close to the nest holes. Males also actively removed threatening egg predators (such as carnivorous snails). Males do not leave nest holes during the courtship period, which Murase & Sunobe (2011) suggest could be related to the cost of maintaining a courtship territory. They maintain that tube blennies maintain territories around these small holes in order to guard eggs and protect food resources while remaining in the small space during the spawning season.

Summary: Lovering et al. (2007)

Lovering et al. (2007) investigated whether tail snips collected from young mice (less than 4 weeks of age) could be used for immunofluroescence assays of muscle proteins. They found that skeletal muscle fibres present in the distal end of the tail (1 cm) of neonatal mice can be used in this procedure to determine the presence of three different muscle proteins, namely desmin null, dysferlin null and dystrophin null. Lovering et al. (2007) suggest that the use of immunofluroescence assays can allow for phenotypic confirmation of genetic screening of mutant mouse strains, allowing for scientists to evaluate muscle from mice expressing genotypes of particular interest.

Summary: Hugali & Stuart-Fox (2012)

Roulin (2004) defined a colour polymorphic species as one that possesses a colour trait that can be "easily classified into a limited number of morphs within one species suggesting a strong
genetic determinism." While colour polymorphism is widespread in a taxonomic sense, it is considered rare (occurring in only 3.5% of bird species for example). Hugali & Stuart-Fox (2012) suggested that the processes that generate and maintain colour polymorphism might also promote speciation. They found that colour polymorphism in three families of non-passerine bird species is linked to faster speciation rates. They also noted that rate of loss of colour polymorphism is much higher than the rate of gain. Hugali & Stuart-Fox (2012) suggest that the rarity of colour polymorphism, and its phylogenetic dispersion, is a result of an interaction between this higher rate of speciation and a greater transition rate between morphic types (poly- to monomorphism). Their results provide support for the general proposition that increased speciation rates can result from colour polymorphism.

Summary: Nie et al. (2012)

 Animals signal in a variety of ways, one of which is scent marking. Scent marking can provide information on the sex, age and reproductive status of individuals, but is energetically costly and relies on optimizing opportunity efficiency. Animals need to consider where scent should be placed in the environment in order to maximize the detection probability by receivers, while minimizing these costs. Giant pandas Ailuropoda melanoleuca are solitary and rely on chemical cues to distribute and gain information. Nie et al. (2012) investigated the scent-marking patterns of pandas living in Foping Nature reserve and found that scent marks were not posted randomly, but were targeted at specific trees. These trees increased the range and likelihood of detection of scents, and also promoted signal persistence. Nie et al. (2012) also found that pandas used different scent-marking behaviour, depending on the characteristic of the tree (either urine marks or anogenital marks). They also suggest that marking patterns vary depending on the season and the sexual status of animals, which could be important in a reproductive and competitive context.

Summary: Bennett et al. (1984)

 Xerus inauris, commonly known as the Cape ground squirrel, is a diurnal, highly social, sciurid rodent that occurs in the arid regions of southern Africa. Squirrels are common in the southern Kalahari. The bushy tail of this species acts like a sunshade, allowing individuals to reduce environmental heat loads by raising the tail and shading the body. Bennett et al. (1984) measured the operative environmental temperature of squirrel mannequins oriented in different postures and with different tail orientations (late spring). At the same time, they observed naturally occurring thermoregulatory behaviour in a free-living colony. Bennett et al. (1984) noted a change in squirrel behaviour when environmental temperatures exceeded 40 C. Squirrels raised the tail over the body and turned their backs to the sun. By raising the tail over the body (to cover the head), the tail reduced the environmental temperature by over 5 C, allowing squirrels to increase time foraging above the surface (7h shaded vs. 3h unshaded). Squirrels also showed behavioural changes when the shaded temperature exceeded 40 C, by retreating into their cooler underground burrows.

Summary: Brassen et al. (2012)

Brassen et al. (2012)  noted that there is a deficit in information about the neurobiological mechanisms that underlie the relationship between age-related declines in the ability to undo regrettable situations and a reduction in engagement with these situations. They used a sequential risk-tasking task combined with a multimodal psychophysiological approach to investigate responsiveness to regret in young, aged emotionally successful and aged late-life depressed participants. Brassen et al. (2012) found that aged emotionally successful participants showed a reduction in responsiveness to regret that was paralleled by a corresponding neurobiological change in emotion regulation (autonomic and frontostriatal). They suggest that the ability to disengage from regretful events is critical for resilience of emotional health into old age.

Summary: Hart (2012)

 The ability to accurately determine an animal's level of pain and stress is crucial for the correct design and implementation of various handling and experimental procedures. Hart (2012) suggests that the quantification of physiological neuroendocrine responses could allow for an objective measure of associated stress and pain than behavioural observations alone. She notes that the hypothalamic-pituitary-adrenal (HPA) axis plays a large role in the neuroendocrine response  of an animal to various types of stressors (environmental,  emotional  and  physiological). This system is integrated with the production of cortisol, a glucocortiocoid stress hormone commonly used in behavioural studies as a measure of stress. Hart (2012) suggests that using the concentration of cortisol as a measure of objective stress assessment could be misinterpreted, as aspects of HPA physiology are often overlooked. She notes that using plasma cortisol concentration as a measure of stress can be useful in some cases, but notes that investigators should take into account the unique variable nature of HPA axis activation.

Summary: Atagan & Forstmeier (2012)

 Male ornamentation is suggested to be indicative of physical quality, particularly over long periods of time. In contrast, behavioural displays, such as many courtship displays of birds, may be influenced by more by body condition over short-term periods. Male courtship rate in Zebra finches Taenipygia guttata may honestly reflect a male's physical condition. However, little support for condition changes over the short term have been found. Atagan & Forstmeier (2012) investigated whether courtship rate of male zebra finches is influenced by nutritional enrichment, which males prefer when given the choice. In contrast to expectations, male courtship rate was decreased by consumption of a high-protein diet, suggesting that males have either acquired a maladaptive strategy in captivity (preference for high-protein diet not a natural tendency) or that condition may be increased by nutritional enrichment, and courtship rate is not directly dependent on body condition. Atagan & Forstmeier (2012) suggest that the presence of improved food quality (as occurs during the summer) may cause males to shift towards parental care (which generally occurs in the warmer summer months) and away from courtship (which occurs prior to breeding).

Summary: Kasurak et al. (2012)

 Signalling between conspecifics is rarely unimodal, relying rather on multiple signals used simultaneously. This makes testing the influence of multiple sensory modalities difficult, as often one type of sensory modality may be influenced by another. Kasurak et al. (2012) tested whether female round goby Neogobius melansotomus response to reproductive male stimuli were different when exposed either separately to the signals (unimodal response) or simultaneously (multimodal response). They also investigated the effect of female reproductive status on response to stimuli. Reproductive females were more responsive than nonreproductive females, and spent significantly more time in the stimulus presentation area when presented with multiple stimuli. However, they were still attracted to unimodal signals. Kasurak et al. (2012) suggest that male signals may vary in attractiveness depending on female reproductive state and that females may have a synergistic response when exposed to multimodal signals from males in breeding condition.

Summary: Bowen et al. (2012)

Individuals of a species, such as rats, may show defensive responses (hiding, fleeing, reduction in foraging) when exposed to predators or to predator-related cues. While individuals are also known to aggregate together, it is not yet known whether individuals with show these same responses in the presence of conspecifics. Bowen et al. (2012) investigated the defensive responses of rat dyads (two familiar individuals) and quads (four familiar individuals) to two stressors (bright ambient light and cat odour). They found that quads of rats responded to negative stimuli by huddling together (increased social proximity), but dyads did not show an increase in social proximity. Exposure to cat odour caused rats in both dyads and quads to decrease locomotor activity and increase defecation (signs of stress). Bowen et al. (2012) suggested that huddling is a defensive strategy for rats when they occur in larger groups, but not necessarily when they occur in pairs.

Summary: Zilles & Amunts (2012)

Zilles & Amunts (2012) review Chen et al. (2012) and Wedeen et al. (2012) to understand how the human brain is constructed and organized beyond the functional and cellular details. They note that these two separate papers rely on analysis of fibre pathway spatial course and the cortex's genetic topography. They highlight that the two studies "find unifying hierarchical and geometric rules behind the organizational details". Zilles & Amunts (2012) note that the brain appears to be highly regionally differentiated, but is also hierarchically and geometrically organized in its spatial organisation (referred to as "canonical brain organization"). They also note that this type of organization is altered by the prevailing environmental conditions (e.g. pathology and genetic diversity). They suggest the use of mathematical models to help understand the factors driving phenotypic variation.

Summary: Dzieweczynski et al (2012)

Communication between individuals is more likely to occur when they interact in groups, than when encountering individuals alone. However, other social factors might also influence communication between individuals. Dzieweczynski et al (2012) used Siamese fighting fish Betta splendens to investigate whether prior experience with an opponent influences the audience effect on male-male interactions. They found that males were more aggressive (opponent-directed gill flaring) when they were unfamiliar with each other and there were other males in the nearby vicinity. In contrast, they found that, when females were in the nearby vicinity, males made more opponent-directed tail beats, a behaviour more commonly associated with courtship than opponent-directed gill flaring. Dzieweczynski et al (2012) suggest that prior history with an opponent, in conjunction with the type of audience, can interact to influence aggressive interactions in Siamese fighting fish.

Summary: Durup & Thinus-Blanc (1987)

Durup & Thinus-Blanc (1987) investigated whether exploratory experience influences an individual golden hamster's (Mesocricetus auratus) ability to learn a shortcut. They allowed hamsters to explore two baited tables that could be accessed by a runway. Then, the animals were allowed to explore a shorter pathway that connected the two tables together. Finally, animals were given a choice between the longer pathway and two new shorter ones. Durup & Thinus-Blanc (1987) found that hamsters preferred the shortcut that did not cross over the previously experience linking path, or either of the two far portions that animals had linkage experience with. They suggest that prior experience of a linking element is important for establishing spatial relationships between objects and could be important for situational representation.

Summary: Leese (2012)

Prior to mating, pair bonding often occurs in monogamous animals. Leese (2012) tested the hypothesis that this behaviour allows for continuous partner (and potential other mates) quality assessment using the convict cichlid Amatitlania nigrofasciata. He allowed males and females to choose between their partners and novel individuals (opposite sex) at various times after pair bond formation. Leese (2012) found that females were more likely to remain with their partners, while males generally spent more time away from their partner with a novel female. However, this pattern differed with time spent in the pair bond. Males were initially very aggressive to novel females, while females initially ignored novel males. Even when individuals were given a "better option" (i.e. a larger mate), both males and females showed no preference. Leese (2012) suggests that pair bonding allows for continuous mate assessment by females, but not for males.

Summary: Anstee (1996)

The western pebble-mound mouse Pseudomys chapmani is a small conilurine rodent found throughout the Pilbara region of Western Australia. They construct mounds out of pebbles gathered from the surrounding areas. At any given time, not all mounds in a region might be occupied. Therefore, Anstee (1996) devised a scoring system, using the external features of the mound, to assess the likelihood that mounds are inhabited by mice. He found that mounds containing mice had a significantly higher index score than mounds without mouse and suggests that this scoring system is an effective predictor of P. chapmani presence within mounds.

Summary: Kemble et al. (1991)

Kemble et al. (1991) investigated how eltoprazine hydrochloride (DU 28853) influences exploratory behaviour and social attraction of conspecifics in mice. They found that exploratory behaviour was enhanced with drug treatment, but this also decreased conspecific social attraction. Kemble et al. (1991) suggest that eltroprazine, in contrast to another anxiogenic drug (fluprazine), ameliorates the neophobic response in mice. Similar to fluprazine, eltoprazine increases the aversive response to conspecifics. They suggest that this effect is mediated by alteration in olfactory function.

Summary: Sulikowski & Burke (2012)

 In foraging behaviour terminology, win-shifting consists of avoidance of locations that have yielded food recently while win-staying consists of active return to these locations. Numerous nectarivorous bird species have shown to be biased towards win-shifting, suggesting that this might be a candidate for a cognitive adaptive specialisation (since food resources that have been exploited recently will not necessarily be available). Sulikowksi & Burke (2012) demonstrated that noisy miners Manorina melanocephala and rainbow lorikeets Trichoglossus haematodus with prior reinforcement of win-shifting or win-staying maintained these preferences, although poorer performance was not necessarily a consequence of an inability to learn the win-stay event. Their results suggest that birds are sensitive to both strategies, implying that the adapted mechanisms (cognitive adaptation) may result from an inhibition of the win-stay response, rather than a lack of sensitivity to win-stay strategies.

Summary: Kasanetz et al. (2010)

 Numerous studies have shown that brain physiology is modified in a numerous ways through chronic exposure to illegal substances (i.e. drugs of abuse). Since some individuals are more likely to become addicts than others, this raises the question of which neurobiological adaptations are associated with a shift from no-addict to addict. Kasanetz et al. (2010) noted that long-term depression (LTD) can be suppressed through self-administration of cocaine and this is related to synaptic plasticity in the region of the nucleus accumbens. They found that rats that are likely to become addicts have permanently impaired LTD, while rats that are unlikely to become addicts show progressive recovering in LTD. Kasanetz et al. (2010) suggest that the transition to addiction could be mediated by a persistently impaired LTD when drug seeking behaviour is made consistently resistant to modulation by possible environmental changes.

Summary: Gonçalves et al. (2012)

The white seabream Diplodus sargus is an economically important fish that shows high levels of aggression in captivity, making aquaculture difficult. In this study, Gonçalves et al. (2012) assessed growth rate and dominance hierarchies in seabream to test whether stable dominance orders can be established in captivity and whether dominance status affects rate of growth and body condition. They established 8 groups consisting of 6 individuals and measured the linearity of hierarchies every week, and the stability of these hierarchies on a week-to-week basis, for 6 weeks. They found that the dominance structures followed a linear pattern and were stable between weeks. However, there was no significant correlation between the dominance index and both growth rate and final body condition. They conclude that aggressive competition is not the primary cause in growth differences, although longer term effects induced by stress may be contributing factors.

Summary: Kelley & Endler (2012)

Visual illusions are created when object or scene geometry is changed to trick the perception of the viewer when observing that scene/object from a specific direction. While many studies on sexual selection aim to compare signal strength, the components of the signal, and the processing of the information by the receiver's senses may interact to form visual illusions that are misleading (or are designed to capture attention). Kelley & Endler (2012) found that male great bowerbirds Ptilonorhynchus nuchalis create forced-perspective illlusions to female perceiver's in the bower avenue by actively maintaining size-distance gradients of the objects they use to create the bower court. They found that mating success and the female's perception of the gradient are significantly related and suggest that the use of illusions in mating and courtship might be more widespread than originally thought, based on orientation and distance characteristics used by males of multiple species.

Summary: Maciá et al. (2004)

In this short note, Maciá et al. (2004) report new observations of flying behaviour in the Caribbean reef squid Sepioteuthis sepioidea. They distinguish between flying and gliding this type of airborne jet propulsion appears more active than simply gliding. S. sepioidea have previously been considered incapable of flight, due to their large body size. Maciá et al. (2004) also review previous accounts of flying behaviour in other squid species. They note several instances of flying behaviour in squid and indicate that S. sepioidea can indeed fly up to 50 times their own body length (20-25 cm). They note that this behaviour appears to be more widespread that initially suspected.

Summary: Fleming et al. (2012)

Extensive cytological and molecular changes occur at conception, particularly at the time of ovulation, fertilization and embryonic development. While this progression is generally programmed by intrinsic processes, environmental factors impart important information on the metabolic process, influencing the developmental programme. Fleming et al. (2012) review a variety of mammalian models and suggest that maternal nutrition modifies this developmental process throughout the gestatory period through its mediation of the peri-conceptual environment and that this can affect the physiological and metabolic health of the offspring when they reach adulthood. They indicate that the origin of adult disease risk might be a function of the quality of the mother's nutrition prior to parturition and suggest that more research on the mechanisms are required if preventative strategies for managing disease risk are to be implemented.

Summary: Ackerman et al. (2010)

The first sense to develop is touch, and it is a critical means of manipulating the environment and acquiring information. Physically touching objects allows for the development of both intra- and interpersonal conceptual and metaphorical knowledge and provide the platform for knowledge application. Impressions and decisions formed about strangers and novel situations were nonconsciously influenced when an individual experienced objects of varying weights and textures. Ackerman et al. (2010) found that job candidates appeared more important if they held heavy objects, while social interactions were more challenging when rough objects were held. Furthermore, holding hard objects increased negotiation rigiditiy. They suggest that higher social cognitive processing is influenced by basic tactile sensations in both metaphor- and dimension-specific ways.

Summary: Mateos (2005)

In vertebrates, the relationship between glucocorticoids, testosterone, social and sexual behaviours is often complicated and incompletely understood. The subordination stress paradigm predicts that subordinate individuals should show higher levels of glucocorticoids, dominants should have higher levels of testosterone and there should be an inverse relationship between glucocorticoid concentration and testosterone. Mateos (2005) studied male ring-necked  pheasants, Phasianus colchicus, and found that dominants and  high-displaying males had higher levels of testosterone, but, in contrast to expectations, also had higher levels of corticosterone. This indicates a positive correlation between testosterone and glucocorticoids. She suggests that the results support a stress-mediated version of the immunocompetence handicap hypothesis.

Summary: Mateos (2005)

The relationship between testosterone, glucocorticoids, social and sexual behaviour is complicated and poorly understood in vertebrates. It is thought that subordinates should have higher glucocorticoid levels (known as the subordination stress paradigm) and that dominant, more active, males should have higher concentrations of testosterone during the breeding season. It has thus been suggested that glucocorticoid and testosterone concentration should be inversely related. Mateos (2005) investigated the relationship between behaviour and hormone concentration in male ring-necked pheasants, Phasianus colchicus. She found that dominant and high-displaying males had higher levels of testosterone and corticosterone (a glucocorticoid) throughout the mating period, indicating that these two hormones are positively correlated. Mateos (2005) indicates that the results do not support the subordination stress paradigm, but she indicates that they may support the immunocompetence handicap hypothesis (through stress-mediation).

Summary: Garcia-Fernandez et al. (2010)

Eggs constitute most of the maternal investment in precocial birds as parents do not feed young post-hatching. The embryo and chick development are influenced by maternal testosterone in the yolk. Testosterone is deposited in eggs by females in response to the environment experienced during the laying period, which includes the quality of the mate. Garcia-Fernandez et al. (2010) assessed the relevance of female mate choice on egg characteristics in the grey partridge Perdix perdix. Females were allowed to choose between males in choice trials and were then mated with either preferred or non-preferred males. They found that eggs from both groups did not differ significantly in mass, but females mated to preferred males produced eggs with higher testosterone levels. They suggest that partner attractiveness is important in the transfer of maternally derived egg components.