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Natal philopatry, or delayed dispersal of sexually mature offspring, may be due to ecological constraints on dispersal. In this study, we manipulated the population density of prairie voles (Microtus ochrogaster) living in experimental outdoor enclosures to test a prediction from the habitat saturation hypothesis that philopatry and subsequent group formation in this cooperatively breeding mammal is affected by the availability of suitable territories. We detected a significant, positive relationship between the proportion of offspring remaining philopatric and density, with females being more philopatric than males at all densities. This increase in philopatry led to a significant increase in the proportion of social units that were groups as well as a significant increase in group size. These results provide the strongest evidence of a causal effect of density on dispersal and group formation in a mammal. Our findings suggest that habitat saturation is at least a partial explanation for philopatry in prairie voles. However, we cannot eliminate the possibility that other variables, such as benefits accrued from remaining philopatric, may also be factors contributing to philopatry. Nonetheless, these results show that changes in ecological conditions can influence social structure within a population, leading to group formation and a social milieu conducive to the evolution of cooperative breeding. [ABSTRACT FROM PUBLISHER]

Most primates live in social groups in which affiliative bonds exist between individuals. Because these bonds need to be maintained through social interactions (grooming in most primates), sociality will be limited by time constraints. It has previously been shown that the time primates invest in grooming increases with group size. However, when groups become too large, individuals will not have enough time available to service all possible social relationships and group cohesion is expected to decrease. In this study, we used data from previously published studies to determine how large groups compromise on their grooming time and how ecological, phylogenetic and life history variables affect time invested in grooming (across species as well as within taxa). We used path analysis to analyse direct and indirect (via group size) effects on grooming. We showed that not only is grooming time determined by group size, but it is also affected by dispersal patterns and sex ratio. Furthermore, we found that grooming time is asymptotic when group size exceeds 40 individuals, indicating that time constraints resulting from ecological pressure force individuals to compromise on their grooming time. This was true across species, but a similar effect was also found within taxa. Cognitive constraints and predation pressure strongly affect group sizes and thereby have an indirect effect on primate grooming time. Primates that were found to live in groups larger than predicted by their neocortex size usually suffered from greater predation risk. However, most populations in our analysis were placed well within what we define as their eco-cognitive niche. [Copyright &y& Elsevier]

Social insects are popular models for studying the evolution of cooperation. Casteless taxa where individuals have the flexibility to either nest alone or cooperate are particularly valuable for understanding the causes and consequences of cooperative behavior. For example, some ‘workers’ from Polistes paper wasp nests disappear from their natal colony soon after pupal emergence and nest independently. However, little is known about dispersal behavior. In this paper, I compare predispersal behavior of wasps who leave their natal colony soon after emergence with behavior of individuals who remain on the natal colony as true workers. I found that P. dominulus females with short nest tenure behave much like gynes (reproductive-destined offspring produced at the end of the season), as wasps with short nest tenure are behaviorally selfish while on the natal colony. They spend a smaller proportion of their time foraging and a larger proportion of their time resting than workers with long nest tenure. In addition, I assessed the factors that may favor early dispersal. Nest environment strongly influenced dispersal; large colonies had a smaller proportion of females with short nest tenure. Queen turnover also increased dispersal behavior perhaps because queen turnover reduces relatedness between a colony’s current and future offspring, thereby reducing the kin-selected benefits of cooperation. Therefore, casteless social insects exhibit a surprising degree of reproductive flexibility. Individuals may use information about their internal state and nest environment to optimize their behavioral strategies. [ABSTRACT FROM AUTHOR]

The ecological constraints of practice have a significant effect on the acquisition of functional information-movement couplings and learners need to converge on information-specifying perceptual variables. Consequently, the prolonged and widespread use of ball projection machines for the practice of interceptive actions may lack theoretical foundation because they afford information-specifying variables that are not present in competition. The timing and coordination of the forward defensive stroke in cricket batting were examined in experienced batters under two typical practice task constraints: batting against a representative "real" bowler and a representative bowling machine (mean delivery velocity 26.76 m·s-1 under both conditions). Significant adaptation of coordination and timing was observed under the different practice task constraints. For example, initiation of the backswing was later against a bowler and downswing was faster with a different ratio of backswing-downswing when batting against the bowling machine (47%-53%) compared with the bowler (54%-46%). Peak bat height differed under the two constraints (bowling machine: mean 1.56 m, s=19.89; bowler: 1.72 m, s=10.36 m). Mean length of front foot stride was shorter against the bowling machine (0.55 m, s=0.07 m) than the bowler (0.59 m, s=0.06 m). The correlation between initiation of backswing and front foot movement was much higher against the bowler (r = 0.88) than the bowling machine (r=0.65). [ABSTRACT FROM AUTHOR]

Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests. After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures, M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate of solitary nest productivity. [ABSTRACT FROM AUTHOR]

Xyleborini are a species-rich tribe of ambrosia beetles, which are haplodiploid and typically mate among siblings within their natal brood chamber. Several characteristics of this tribe would predict the evolution of higher levels of sociality: high genetic relatedness within galleries due to inbreeding, high costs of dispersal and the potential benefit of cooperation in brood care within the natal gallery (e.g. by fungus gardening, gallery extension, offspring feeding and cleaning). However, information on the social system of these beetles is very limited. We examined the potential for cooperative breeding in Xyleborinus saxeseni by monitoring dispersal in relation to brood size and composition. Results show that adult female offspring delay dispersal despite dispersal opportunities, and apparently some females never disperse. The females’ decision to stay seems to depend on the presence of eggs and dependent siblings. We found no indication that female offspring reproduce in their natal gallery, as colonies with many mature daughters do not contain more eggs than those with few or no daughters. There is a significant positive relationship between the number of females present and the number of dependent siblings (but not eggs), which suggests that cooperative brood care of female offspring raises colony productivity by improving survival rates of immatures. Our results suggest that cooperative breeding is likely to occur in X. saxeseni and possibly other xyleborine species. We argue that a closer look at sociality within this tribe may yield important information on the factors determining the evolution of cooperative breeding and advanced social organization. [ABSTRACT FROM AUTHOR]

The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 319–348. [ABSTRACT FROM AUTHOR]

Researchers consider group size in primates to be determined by complex relationships among numerous ecological forces. Antipredator benefits and better resource defense are the primary pressures for large groups. Conversely, intragroup limited food availability, can result in greater intragroup feeding competition and individual energy expenditure in larger groups, creating energetic advantages for individuals in small groups and placing an upper limit group size. However, the extent to which food availability constrains group size remains unclear for many species, including black howlers (Alouatta pigra), which ubiquitously live in small social groups (≤10 individuals). We studied the relationship between group size and 2 key indices of feeding competition—day journey length and activity budgets—in 3 groups of wild Alouatta pigra at a hurricane-damaged site in Belize, Central America. We controlled for differences in food availability between home ranges (food tree density) and compared both indicators of feeding competition directly with temporal variation in food availability for each group. Our results show no consistent association between resource availability, group size, and either index of competition, indicating that feeding competition does not limit group size at the site—i.e., that larger groups can form without increased costs of feeding competition. The results support the search for other explanations, possibly social ones, for small group size in the primates, and we conclude with suggestions and evidence for such alternative explanations. [ABSTRACT FROM AUTHOR]

Although holism has long been a central theme in anthropology, current perception is that anthropological discourse is being pulled apart along its biology-culture seams. Despite reservations among sociocultural theorists, Darwinism remains the only body of theory that purports to link sub-disciplines of anthropology. The importance of holism in anthropology is reconciled here with disciplinary fragmentation and evolutionary theory. While Darwinism appears to provide interdisciplinary theoretical ties, it cannot successfully relate sub-disciplines of anthropology because this theory itself relies on a preformationist divide between inherited and acquired characteristics. Increasingly subtle language of genetic information and constraints does not ameliorate this problem. Research potential for the ecological constraints model in biological anthropology is discussed. Developmental systems theory (DST) is advocated as a tool for working toward a holistic anthropology [Susan Oyama, Paul Griffiths, and Russell Gray, ``Introduction: What is Developmental Systems Theory?,'' in Susan Oyama, Paul Griffiths, and Russell Gray, eds., Cycles of Contingency: Developmental Systems and Evolution (Cambridge, MA: MIT Press, 2001), 1–11]. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Following an ecological approach, expertise effects on decision-making in sailing were studied. Dynamic tasks in sailing were provided through interactive computer simulations, used to reveal the utilisation of information, and the active exploration of ecological constraints by participants. Methods and design: Sailors (n=35) were divided into three skill groups, according to ranking: Expert, Skilled, and Intermediate. There was also a non-sailors group (N=23). During six successive phases of a computer-simulated regatta, a concurrent verbal protocol analysis was used to measure utilization of four sources of available information: adversary, spatial, manoeuvres and wind. Simultaneously, participants pressed keys on a keyboard, registering two categories of actions used to explore the task: technical actions and adjustment actions. The outcome variables, final classification and total time were also recorded. Results: Expertise level was significantly predicted by total time. Statistical analyses showed that non-sailors significantly differed from sailors in the use of adversary and wind information during the regatta. But, there were no significant differences among the sailors'' groups. Non-sailors performed significantly more actions than sailors, during almost all the regatta. However, polynomial trend analysis revealed that each group of sailors exhibited specific patterns of information utilization and performed actions. Conclusions: Data demonstrated that the better the sailor, the better was performance on a simulated regatta. Decision-making in sailing is characterized by non-linear accumulated effects of exploring and using informational constraints in a regatta, which are dependent on the level of individual attunement to sport-specific information. [Copyright &y& Elsevier]

1. The ecological factors that promote delayed dispersal of offspring in cooperatively breeding bird species are poorly understood. While single population studies have supported the view that natal dispersal is delayed as a consequence of lack of suitable breeding vacancies (ecological constraints hypothesis), recent theoretical models claim that habitat saturation cannot be the main factor leading to kin sociality. 2. The carrion crow ( Corvus corone ssp.) is an ideal model to investigate the ecology of delayed dispersal. The occurrence of kin sociality is highly variable among European populations, and it is known to be determined by environmental rather than genetic factors. Here we compare juvenile dispersal, territory turnover, habitat saturation (number of competitors per breeding vacancy), variability of territory quality and territoriality of two crow populations that differ in social organization (extensive kin sociality in Spain vs. social monogamy in Italy). 3. We found that philopatry occurred in the less competitive and less variable environment. A review of the information available in literature on other crow populations qualitatively supports this result. 4. In crows, juvenile philopatry seemed to be associated with breeders’ year-round residency in territories. This association is widespread among birds and it has been previously explained through an ecological constraints perspective, with residency slowing territory turnover and therefore augmenting saturation. Our data do not support this explanation. 5. We suggest that year-round residency might play a direct role in determining kin sociality in crows. In Spain, adults occupy and defend the territory year-round, providing the offspring with a place where they enjoy a preferential access to resources that may represent an incentive to stay. Conversely in Italy, where adults often abandon their territories after breeding, the natal site does not have any special value for the offspring that hence disperse. [ABSTRACT FROM AUTHOR]

We studied the Azure-winged Magpie's (Cyanopica cyanus) breeding performance and cooperative breeding system in two consecutive breeding seasons with varying climate conditions. We found a strong year effect on most breeding parameters. Helpers were more frequent in the year with more severe weather conditions, and helper presence significantly increased provisioning rates and breeding success of the breeders. Some of the helpers were adults that had failed on a previous breeding attempt, while others were offspring of the breeding pair from the previous season. We suggest that helping in this species is a "best-of-a-bad-job" strategy, in which individuals facing a breeding attempt with low prospects of success, or with high costs associated, assist others. [ABSTRACT FROM AUTHOR]

We report the discovery of intraspecific variation in both colony composition and patterns of paternity in two populations of the social common mole-rat Cryptomys hottentotus hottentotus. These two populations represent the mesic and arid habitat extremes of the species’ broad ecological range in South Africa. Until recently colonies of the common mole-rat were thought to consist of familial groups whereby all colony members were the offspring of a monogamous reproductive pair. The remaining colony members were thought to forego reproduction until both social and ecological conditions favoured dispersal and opportunities for independent outbreeding. Results from genetic assignment tests using microsatellite markers indicate that while colony composition is dominated by familial groups, colonies within both populations included both adult and subadult foreign conspecifics. Analysis of parentage reveals that the social organization of C. h. hottentotus is not that of strict monogamy; paternity of offspring was not assigned consistently to the largest, most dominant male within the colony. Moreover, a number of significantly smaller males were found to sire offspring, suggesting a sneak-mating strategy by subordinate within-colony males. Extra-colony extra-pair paternity (ECP) was also found to characterize C. h. hottentotus colonies, occurring with similar frequencies in both habitats. Both dominant established breeding males and subordinate males were identified as siring young in nonsource colonies. Furthermore, established breeding males were found to sire extra-colony young in the same season as siring young within their source colonies. We discuss the significance of these results within the context of the divergent ecological regimes characterizing the two sites and observe that our results revisit the accuracy of using behavioural and morphological characters, which have structured the basis of our understanding of the behavioural ecology of this species, as indicators of breeding status in mark–recapture studies. [ABSTRACT FROM AUTHOR]

The costs and benefits of philopatry (remaining at the natal nest) have been discussed in numerous papers. Nevertheless, there is still debate about the relative importance of factors that favor philopatry, which can result in the formation of social groups. The decision to remain at the natal nest can be examined by using models such as the delayed-dispersal threshold model, which takes into account risks of dispersal, probability of becoming established on a suitable territory, and probability of finding a mate. These factors, in turn, are influenced by ecological variables such as distribution of critical resources and population density. The often-cited conclusion from this and similar models is that ecological or social constraints promote philopatry whereas relaxation of the constraints result in dispersal. More recent theoretical approaches have included not only some of these ecological factors but also life-history traits (e.g., survival and age of maturation). Some of the latter models suggest that external constraints alone are inadequate to explain interspecific variation in group living. I review existing data to evaluate the relative importance of variables proposed to influence philopatry in rodents and argue that future studies may benefit from a broad approach that encompasses life-history and ecological factors, such as adult survival and territory quality. [ABSTRACT FROM AUTHOR]

Both theoretical and empirical work has shown that group size increases with increasing ecological constraints on solitary breeding. Ecological constraints refer to extrinsic factors such as availability of breeding sites, food or mates. Common eider (Somateria mollissima) females pool their broods and share brood-rearing duties, or rear broods alone. Females are often in poor condition at hatching, as incubation is accomplished without feeding, and variation in body condition is largely environmentally induced and thus unpredictable. We found that the intensity of and duration of parental care that females provide is positively correlated with their body condition at hatching. This suggests that body condition is an ecological constraint on successful solitary breeding. We further observed that group productivity in common eider broods is a decelerating function of the number of tending females. As predicted, females in poorer condition (i.e., facing stronger ecological constraints) were found in larger groups. This result is straightforward if solitary tenders can enter any group at no cost. However, if entry is group-controlled, stable groups of non-relatives are predicted not to occur when per capita reproduction declines with group size. The N-person staying incentive model permits groups to form under these conditions, because reproduction is unevenly divided between dominants and subordinates in the group. We discuss the plausibility of these alternative models of group size for understanding the grouping behavior of brood-caring female common eiders. [ABSTRACT FROM AUTHOR]

This study investigated in a sample of infants and mothers that represented the full SES spectrum in Israel (n=704) the hypothesis that low quality non-maternal care imposes ecological constraints on infant–mother attachment formation by moderating the relations between maternal sensitivity and infant attachment security. Infant attachment to mother was assessed with the Strange Situation Procedure (SSP) [Patterns of Attachment: A Psychological Study of the Strange Situation, Erlbaum, Hillsdale, NJ, 1978] and maternal sensitivity was assessed with the Emotional Availability Scales [The Emotional Availability Scales, Unpublished manuscript, University of Colorado, Health Science Center, Denver, 1993]. Results show that the expected links between maternal sensitivity and infant attachment security were found only for infants in individual care but not for infants in daycare centers, which were of low quality. The findings suggest that extensive exposure to difficult environments of non-maternal care constrains infants’ relations with their mothers by moderating the associations between maternal sensitive caregiving and infants’ attachment security. [Copyright &y& Elsevier]

Annual cycles in day length are an important consideration in any analysis of seasonal behaviour patterns, since they determine the period within which obligate diurnal or nocturnal animals must conduct all of their essential activities. As a consequence, seasonal variation in day length may represent an ecological constraint on behaviour, since short winter days restrict the length of the time available for foraging in diurnal species (with long summer days, and thus short nights, a potential constraint for nocturnal species). This paper examines monthly variation in activity patterns over a 4-year study of chacma baboons (Papio cynocephalus ursinus) at De Hoop Nature Reserve, South Africa. Time spent feeding, moving, grooming and resting are all significant positive functions of day length, even before chance events such as disease epidemics and climatically mediated home range shifts have been accounted for. These results provide strong support for the idea that day length acts as an ecological constraint by limiting the number of daylight hours and thus restricting the active period at certain times of year. Day length variation also has important implications across populations. Interpopulation variation in resting time, and non-foraging activity in general, is a positive function of latitude, with long summer days at temperate latitudes apparently producing an excess of time that cannot profitably be devoted to additional foraging or social activity. However, it is the short winter days that are probably of greatest importance, since diurnal animals must still fulfil their foraging requirements despite the restricted number of daylight hours and elevated thermoregulatory requirements at this time of year. Ultimately this serves to restrict the maximum ecologically tolerable group sizes of baboon populations with increasing distance from the equator. Seasonal variation in day length is thus an important ecological constraint on animal behaviour that has important implications both within and between populations, and future studies at non-equatorial latitudes must clearly be mindful of its importance. [ABSTRACT FROM AUTHOR]

The extraordinary success of unicolonial insect invaders has renewed interest in the origins and maintenance of unicoloniality, a social system characterized by the absence of aggressive behavior between individuals of neighboring conspecific nests. In this study, I explore how traits associated with unicoloniality, particularly nest budding and the local exchange of workers between nests, vary across environments. Comparisons of nest characteristics in three introduced populations of Argentine ants, Linepithema humile, reveal considerable variation in nest density and social structure across populations. The population with the highest nest density has smaller, less productive nests and fewer queens per nest than the two populations with low nest densities. Nestmate relatedness is low in all populations, but multi-locus genotype analyses reveal that levels of connectivity vary among populations. In particular, high nest density is associated with higher levels of genotypic similarity between nests. Assignment distances in the two populations with low nest density are similar to a native population, suggesting that the amount of mixing between neighboring nests is shared among some native and introduced populations. Because the study populations are similar in age and genetic diversity, these results suggest that the social structure of L. humile populations depend on the ecological context. Understanding the patterns of expression of unicolonial traits in different environments helps to shed light on the origins of unicoloniality and to explain the success of Argentine ants as invaders. [ABSTRACT FROM AUTHOR]

Subsocial behavior or postovipositional parental care in insects has evolved in response to a variety of environmental stresses and ranges from briefly guarding eggs after oviposition to elaborate nidification and provisioning behaviors. Investment in parental care bears various costs, and should not continue beyond the point at which the costs to future reproductive success exceed the benefits to current reproductive effort. Progressive provisioning is a rare form of subsociality in insects. Females of the subsocial shield bug Parastrachia japonensis progressively provision their nymph-containing nests with drupes of the single resource, Schoepfia jasminodora, and this provisioning drastically enhances offspring survival. A female rears only one brood throughout her lifetime and continues provisioning the brood until about the third larval stadium, when the female dies. Thus, the female's entire reproductive effort is expressed in the success of that one brood, which suggests a reproductive strategy with enormous costs and risks. Why has such an extreme life history evolved in this species? Here, to answer that question and to contribute to our understanding of the evolutionary implications of subsocial behavior, in particular, progressive provisioning, we review what we have discovered about the ecological parameters of subsociality in this species during a long-term field study. We also discuss these parameters in P. japonensis in reference to other subsocial insects and related species and conclude with a suggestion that semelparity and progressive provisioning in this species are extreme adaptations to evolving complete dependency on an unreliable resource. [ABSTRACT FROM AUTHOR]

Transactional models of social evolution emphasize that dominant breeders may donate parcels of reproduction to subordinates in return for peaceful cooperation. We develop a general transactional model of reproductive partitioning and group size for N-person groups when (1) expected group output is a concave (decelerating) functiong[N] of the number N of group members, and (2) the subordinates may receive fractions of total group reproduction (“staying incentives”) just sufficient to induce them to stay and help the dominant instead of breeding solitarily. We focus especially on “saturated” groups, that is, groups that have grown in size just up to the point where subsequent joining by subordinates is no longer beneficial either to them (in parent-offspring groups) or to the dominant (in symmetric-relatedness groups). Decreased expected output for solitary breeding increases the saturated group size and decreases the staying incentives. Increased relatedness decreases both the saturated group size and the staying incentives. However, in saturated groups with symmetric relatedness, an individual subordinate's staying incentive converges to 1 — g[N* — 1]/g[N*]) regardless of relatedness, where N* is the size of a saturated group, provided that the g[N] function near the saturated group size N* is approximately linear. Thus, staying incentives can be insensitive to relatedness in saturated groups, although the dominant's total fraction of reproduction (total skew) will be more sensitive. The predicted ordering for saturated group size is: Parent-full sibling offspring = non-relatives > symmetrically related relatives. Strikingly, stable groups of non-relatives can form for concaveg[N] functions in our model but not in previous models of group size lacking skew manipulation by the dominant. Finally, symmetrical relatedness groups should tend to break up by threatened ejections of subordinates by dominants, whereas parent-offspring groups should tend to breakup via unforced departures by subordinates. [ABSTRACT FROM PUBLISHER]

In polygynous social insects more than one queen reproduces in a colony. In such populations ecological factors affecting survival and reproduction of queens are likely to be of prime importance for social organization. In particular, habitat saturation leading to severe limitations in the availability of nest sites has been suggested to promote high queen number. In this study we examine the social and genetic structure of colonies in the polygynous ant Myrmica sulcinodis . We investigated a single breeding population in two adjacent habitats which differed markedly in the availability of nest sites. In the main habitat M. sulcinodis occupied almost all suitable nest sites, whereas in the other (marginal) habitat most sites were unoccupied by ants, due to a recent fire. In support of the habitat saturation hypothesis, the number of queens per colony which could explain the estimated relatedness among workers was almost five times higher for the main habitat than for the marginal habitat. This is the first demonstration that the kin structure of a social insect population is plastic and responds adaptively to short-term changes in ecological constraints such as nest site availability. Based on combined genetic and demographic data we discuss queen reproductive strategies and suggest that a special class of queen ‘floaters’ only stays ephemerally in the colonies, thus causing a substantial turnover of reproducing queens across years. [ABSTRACT FROM AUTHOR]

I studied and compared life histories and dispersal patterns of two populations of green (red-billed) woodhoopoes Phoeniculus purpureus, occupying different habitats (with widely different vegetation, topography and climate), over a period of eight years (258 'flock years') in the eastern Cape Province, South Africa. The birds are obligate cavity-roosters, and I performed an experiment in which several woodhoopoe territories were established after the introduction of artificial roost sites in an area which previously supported no woodhoopoes. The evidence supports the hypothesis that roost cavities are critical in determining the limits to woodhoopoe distribution. Group size, dispersal frequency and dispersal distance differed significantly between the two study sites. I suggest that where cavities are in short supply and unevenly distributed, long-distance scouting forays are undertaken at a high probability of not finding a safe roost site to sleep in. This may result in an increased probability of predation, or physiological conditions with which an individual in poor body condition cannot cope. I propose that among woodhoopoes a stay-and-foray dispersal strategy is preferred to a depart-and-search strategy for a number of reasons. First, there is no within-group competition for limiting resources, since roost cavities do not provide a situation in which within-group conflict could arise. Second, I show that competition for breeding vacancies is more severe at the inland than at the coastal site, further borne out by the fact that, compared to coastal birds, inland ones are proportionally more likely to attain breeding status in the natal group than elsewhere. Finally, I propose that such environmentally-induced differential dispersal patterns between the two study sites have indirectly affected the frequency with which apparent inbreeding occurs, and I suggest that since incestuous pairings are relatively common, the either have no deleterious consequences for breeder fitness, or the potential costs of inbreeding are counterbalanced by the risks associated with dispersal. [ABSTRACT FROM AUTHOR]

Motivation seems to enhance athletes' mental efforts, but this has not been tested yet in padel. The objective was to test the effects of motivation on mental fatigue during padel trainings. Thirty-six elite youth players participated (twenty-two males, Mage = 17.40, SDage = 2.16, and fourteen females, Mage = 17.90, SDage = 3.21). We designed four padel training matches, introducing a constraint in two of them in a counterbalanced order. The constraint was: Couples that win more sets in these two matches obtain a free lesson with a professional padel player. Motivation was quantified by a questionnaire before the matches. Moreover, subjective feelings of mental load and fatigue were measured with questionnaires, and objective measures of fatigue were quantified through heart-rate variability and reaction time. Results suggest that the constraint significantly increases motivation (p < 0.001). Furthermore, in these matches, players reported significantly higher feelings and objective measures of fatigue (p < 0.001 for HRV and VAS; p = 0.04 for reaction time). An increase in the resources used by the neural facilitation system, mediated by higher values of motivation, seems a relevant candidate to explain this phenomenon. [ABSTRACT FROM AUTHOR]

Urban expansion is the spreading process of urban construction land overcoming ecological resistance. In this paper, we introduced relative resistance factors on different source levels in the minimum cumulative resistance model (MCR), and considered the inherent constraints and epitaxial ecological resistance on town expansion. Then, we constructed an improved minimal cumulative resistance (IMCR) for urban expansion simulation. The ecological resistance surface of Yuzhong county was formed to simulate the spatial distribution and boundary of town expansion to 2030. The results show: (1) the spatial difference of comprehensive ecological resistance in Yuzhong County is significant, which is decreasing from south to north. The urban expansion is affected by the ecological environment. In addition, the ecological constraints of urban expansion are higher in the areas with better ecological quality. (2) When the ecological constraints are high, the simulated area of urban expansion is smaller than the planned area. On the contrary, when the ecological constraints are low, the simulated area of urban expansion is larger than the planned area. The urban expansion boundary under the planning scenario is relatively straight, simple and rigid, and the town boundary under the ecological constraint scenario is a curve, complex and irregular. (3) The simulation results based on the IMCR model are more in line with reality and reflect the requirements of ecological protection. From the perspective of urban expansion scale and intensity control, the simulation results are more in line with actual needs and reflect the direction of policy regulation. [ABSTRACT FROM AUTHOR]

The paradox of cooperative breeding, whereby individuals assist others instead of reproducing independently, is generally explained through ecological constraints, but experimental evidence is scant. Here we performed the crucial test of the role of habitat saturation through the experimental creation of vacancies and found that, despite abundant presence of potential mates, subordinates are reluctant to disperse into suitable vacant habitat where conspecifics are absent. We argue that sudden disappearance of multiple group members might indicate a heightened risk of predation. Thereby the results of this study are consistent with the 'perceptual trap' hypothesis: the avoidance of habitats because cues do not accurately reflect their quality. Interestingly, this hypothesis can also explain previous findings, which were widely interpreted as evidence for ecological constraints as a driver of cooperative breeding. Our results can have considerable implications for conservation as they mean that opportunities for colonization might go unexploited.

Cooperative breeding animals frequently inhabit harsh environments. It is widely accepted that harsh environments hinder independent reproduction, and this constraint maintains individuals in family groups. Yet the assumption that harsh ecological conditions reduce the success of members of cooperative breeding groups when breeding independently has not been experimentally tested. We addressed this shortcoming using the socially polymorphic Alpine silver ant, Formica selysi . This species has single-queen (independent breeders) and multiple-queen (cooperative breeders) colonies coexisting within populations. We placed newly mated queens emerging from each type of colony to breed alone in either a harsh or mild winter condition and recorded their brood production and survival. Queens emerging from single-queen colonies were unaffected by the winter condition and were more successful at founding a nest independently than queens from multiple-queen colonies. By contrast, queens from multiple-queen colonies had higher mortality after a harsh than after a mild winter. These results support the long-held assumption that harsh environments constrain independent reproduction of members of cooperative breeding groups.

Town expansion changes land-use type, and results in ecological and environmental issues. To minimize the influence of these problems and relieve the conflict between town development and ecological protection, future town expansion should be simulated based on the ecological priority principle. This study systematically designed and analyzed a simulated town expansion under the ecological constraints (EC) scenario in Zhangbei County (2013–2030). The performance of this scenario was assessed by comparing the influence on ecosystem service value with the urban–rural master plan (URMP) for Zhangbei County (2013–2030). The results indicate that town expansion under EC scenario has significant advantages over expansion under the URMP scenario; there are large differences in the town expansion areas. In the EC scenario, towns located in higher ecological quality areas had tighter constraints on expansion and only expanded slightly. In addition, most town boundaries in the EC scenario were curvilinear, complex, and soft, which could provide more ecological benefits than the straight, simple, and hard boundaries in the URMP scenario. The spatial evolution trend of the boundaries in the latter scenario tended to lower the comprehensive ecological constraints surface. In addition, in the EC scenario, the influence of town expansion on ecosystem service value was dramatically lower than in the URMP scenario. Town expansion was simulated under the minimum EC scenario, which could provide a new mechanism for allocating construction land based on ecological supply. The results provide reliable information for effectively relieving the conflict between town development and ecological protection and identifying boundary locations for conditional construction areas during regional planning. • A comprehensive ecological constraints (EC) surface was produced using the Improved Minimal Cumulative Resistance model. • Town expansion was simulated by GIS method under a minimum EC scenario based on the comprehensive EC surface. • Comparative evaluation of town expansion for simulation results was performed based on ecosystem services values. • Town expansion under EC scenario effectively relieved the conflict between town development and ecological protection. [ABSTRACT FROM AUTHOR]

Cooperatively breeding animals occur in virtually every ecosystem on earth. Comparative and biogeographic studies suggest that both benign and harsh-as well as stable and fluctuating-environments can favor the evolution of cooperative breeding behavior. The fact that cooperative societies occur in environments of such contrasting quality creates a paradox of environmental quality and sociality. The dual benefits framework-which leads to the prediction that the ecological consequences of sociality (e.g., range size) vary depending on the benefits that individuals of each species receive by forming social groups-offers a potential resolution to this paradox. Here we use a case study of two avian lineages, starlings (Sturnidae) and hornbills (Bucerotidae), in which environmental unpredictability appears to have opposite effects on the evolution of cooperation to test the dual benefits framework. Consistent with previous work, harsh and unpredictable environments promote cooperative breeding behavior in starlings, which in turn leads to larger geographic ranges. However, cooperatively breeding hornbills occur in benign and stable environments, but sociality does not influence range size. Our study suggests that the paradox of environmental quality and sociality arises largely because cooperative breeding is an umbrella term encompassing social species that form groups for different reasons. We demonstrate that differentiating among the functional causes of social group formation is critical for developing a predictive framework for understanding the evolution of cooperative breeding behavior.