Evolution of quantitative traits in the wild: mind the ecology

Recent advances in the quantitative genetics of traits in wild animal populations have created new interest in whether natural selection, and genetic response to it, can be detected within long-term ecological studies. However, such studies have re-emphasized the fact that ecological heterogeneity can confound our ability to infer selection on genetic variation and detect a population''s response to selection by conventional quantitative genetics approaches. Here, I highlight three manifestations of this issue: counter gradient variation, environmentally induced covariance between traits and the correlated effects of a fluctuating environment. These effects are symptomatic of the oversimplifications and strong assumptions of the breeder''s equation when it is applied to natural populations. In addition, methods to assay genetic change in quantitative traits have overestimated the precision with which change can be measured. In the future, a more conservative approach to inferring quantitative genetic response to selection, or genomic approaches allowing the estimation of selection intensity and responses to selection at known quantitative trait loci, will provide a more precise view of evolution in ecological time.     

Human behavioral ecology: I

New fields of inquiry rarely spring fully grown from the forehead of a single genius, and in addition, it is often difficult to decide when a related set of inquiries has coalesced sufficiently to define a field. As measured by the solicitation and publication of review articles, human behavioral ecology has recently become a self-conscious field, for this is the third essay to review it^1,2 and a book-length survey will appear later this year.³ In this two-part article, I will try to give readers a sense of the field by outlining its theoretical and methodological principles and key issues and by summarizing representative studies and unresolved questions in three main topical areas: subsistence strategies (Part I) and reproductive strategies and social interactions (Part II).     

Human behavioral ecology: II

Human behavioral ecology is an interdisciplinary field of study applying theory from evolutionary ecology to a variety of anthropological questions. In Part I of this essay,¹ which appeared in an earlier issue, I surveyed key theoretical and methodological elements of the field, and summarized representative studies and issues in the topical area of subsistence strategies. In Part II, I turn to studies of reproductive strategies, and those analyzing patterns of cooperation and competition in an ecological and adaptive framework. I conclude with a brief look at possible future developments in the field.     

生态预报: 生态学的一个前沿领域

生态预报对于资源,环境的决策和管理将起着越来越重要的作用。计算机科学和定量分析的进步,生态学理论的发展以及新技术的应用增加了人类预测生态系统变化的能力。本文介绍了有关生态预报的内涵,相关研究进展及案例,提出生态预报是生态学的一个重要前沿领域,也将是今后生态学研究的一个重要努力方向。     

Ecological skills: mind the gap(s)

Anecdotal evidence indicated that there is a shortage of ecological skills. A three year project has been established by the profession, the Institute of Ecology and Environmental Management (IEEM), which runs from May 2008 until April 2011, to examine the issue and to make recommendations. Botany and plant sciences are used as a case study to provide an illustration of what is happening in part of the sector.     

Programming paradigms and mind metaphors: convergence and cross-fertilization in the study of cognition

This paper describes a notable convergence between biological organization and programming language abstractions. Our aim is to explore possibilities of cross-fertilization, at both conceptual and empirical levels, towards the understanding of what cognition and cognitive systems might be.     

Human collective aggression: A behavioral ecology perspective

Moller (1967/68) proposes that the presence of a large number of adolescents and young adults in a population is a precursor of violent conflicts. But acts of collective aggression are typically perpetrated by males, particularly young males between 15 and 30 years of age. This marked sex difference in the degree of participation is found in all human societies, and it has persisted since the beginning of recorded history. Sexually dimorphic behaviors are invariably found in the context of reproduction, and we discuss male coalitional aggression as a reproductive fitness-enhancing social behavior. This type of social behavior may not increase the welfare of an entire population but it is likely to promote the fitness of the coalition participants. This study argues that the age composition of the male population should be regarded as the critical ecological/demographic factor affecting a population's tendency toward peace or violent conflicts. Our analyses of interstate and intrastate episodes of collective aggression since the 1960s indicate the existence of a consistent correlation between the ratio of males 15 to 29 years of age per 100 males 30 years of age and older, and the level of coalitional aggression as measured by the number of reported conflict related deaths.     

DNA指纹图谱技术在动物行为学研究上的应用

ＤＮＡ指纹图谱技术于８０年代末在国外已被广泛应用于行为学尤其是动物繁殖行为学研究中,国内在此方面的应用尚少。综述了ＤＮＡ指纹图谱技术在动物行为学研究中的作用,介绍了ＤＮＡ指纹图谱的产生、实验操作方法、应用实例及其优缺点。     

The mind through chick eyes: memory,cognition and anticipation

To understand the animal mind, we have to reconstruct how animals recognize the external world through their own eyes. For the reconstruction to be realistic, explanations must be made both in their proximate causes (brain mechanisms) as well as ultimate causes (evolutionary backgrounds). Here, we review recent advances in the behavioral, psychological, and system-neuroscience studies accomplished using the domestic chick as subjects. Diverse behavioral paradigms are compared (such as filial imprinting, sexual imprinting, one-trial passive avoidance learning, and reinforcement operant conditioning) in their behavioral characterizations (development, sensory and motor aspects of functions, fitness gains) and relevant brain mechanisms. We will stress that common brain regions are shared by these distinct paradigms, particularly those in the ventral telencephalic structures such as AIv (in the archistriatum) and LPO (in the medial striatum). Neuronal ensembles in these regions could code the chick's anticipation for forthcoming events, particularly the quality/quantity and the temporal proximity of rewards. Without the internal representation of the anticipated proximity in LPO, behavioral tolerance will be lost, and the chick makes impulsive choice for a less optimized option. Functional roles of these regions proved compatible with their anatomical counterparts in the mammalian brain, thus suggesting that the neural systems linking between the memorized past and the anticipated future have remained highly conservative through the evolution of the amniotic vertebrates during the last 300 million years. With the conservative nature in mind, research efforts should be oriented toward a unifying theory, which could explain behavioral deviations from optimized foraging, such as "na?ve curiosity," "contra-freeloading," "Concorde fallacy," and "altruism."     

Cooperative breeding in birds: the role of ecology

Theory predicts that cooperative breeding should only occurin species in which certain individuals are constrained frombreeding independently by some peculiarity of the species' ecology.Here, we use comparative methods to examine the role of variationin ecology in explaining differences between taxa in the frequencyof cooperative breeding. We address three questions. First,does the frequency of cooperative breeding vary at just one phylogeneticlevel, or across several levels? Second, are differences inthe frequency of cooperative breeding among closely-relatedspecies correlated with ecology? Last, are ecological differencesbetween ancient lineages important in predisposing certain lineagesto cooperative breeding? We find that variation in the frequencyof cooperative breeding occurs across all phylogenetic levels,with 40% among families and 60% within families. Also, variationin the frequency of cooperative breeding between closely related speciesis associated with ecological differences. However, differencesin the frequency of cooperative breeding among more ancientlineages are not correlated with differences in ecology. Together,our results suggest that cooperative breeding is not due toany single factor, but is a two step-process: life-history predispositionand ecological facilitation. Low annual mortality predisposescertain lineages to cooperative breeding. Subsequently, changesin ecology facilitate the evolution of cooperative breedingwithin these predisposed lineages. The key ecological changesappear to be sedentariness and living in a relatively invariableand warm climate. Thus, although ecological variation is notthe most important factor in predisposing lineages to cooperativebreeding, it is important in determining exactly which speciesor populations in a predisposed lineage will adopt cooperativebreeding.     

The behavioral ecology of sympatric African apes: implications for understanding fossil hominoid ecology

The behavioral ecology of the great apes is key evidence used in the reconstruction of the behavior of extinct ape and hominid taxa. Chimpanzees and gorillas have been studied in detail in the wild, and some studies of their behavioral ecology in sympatry have also been been carried out. Although the two ape species have divergent behavior and ecology in important respects, recent studies have shown that the interspecific differences are not as stark as previously thought and subsequently urge new consideration of how they share forest resources when sympatric. These new data require re-examination of assumptions about key aspects of chimpanzee-gorilla ecological divergence, such as diet, ranging and nesting patterns, and the mating system. Diet is a key component of the species adaptive complexes that facilitates avoidance of direct competition from the other. While the nutritional basis for chimpanzee food choice remains unclear and no doubt varies from site to site, this species is a ripe fruit specialist and ranges farther during periods of ripe fruit scarcity. Gorillas in the same habitat also feed on ripe fruit when widely available, but fall back onto fibrous plant foods during lean periods. The inclusion of animal protein in the diet of the chimpanzees and its absence in that of the gorillas also distinguish the species ecologically. It may also offer clues to aspects of ecological divergence among early members of the hominid phylogeny. The paper concludes by suggesting likely characteristics of sympatric associations of Pliocene hominids, based on field data from extant sympatric apes.     

The behavioral ecology of mountain baboons

Chacma baboons (Papio ursinus)were studied in a mountain habitat where the effects of high altitude and latitude combine to produce conditions as harsh as those experienced by the desert or hamadryas baboon (P. hamadryas).The population density was as low as that of hamadryas baboons. A survey of populations at altitudes between 1400 and 3000 m showed a strong negative correlation between altitude and group size, with the highest-living groups averaging just 13 individuals and, like hamadryas baboons, seasonally retreating from marginal habitat on the fringes of the range. Foraging activities in these groups relied heavily on the underground storage organs of plants and other items that were time-consuming to find, harvest, and process, placing severe constraints on the time budget. High-altitude and low-altitude groups were nevertheless able to maintain similar activity budgets. This is explicable through an interaction between the patterns of foraging and range usage and observed altitude differences in group size, population density, and home-range size. The behavior of mountain baboons provides insights into ecological effects on behavior both through local altitudinal variation and through similarities to other populations inhabiting marginal environments, notably P. hamadryas.Mountain baboons may represent a significant southern highland population which does not fit into the neat socioecological dichotomy of desert versus savannah baboons.     

Linking behavioural syndromes and cognition: a behavioural ecology perspective

With the exception of a few model species, individual differences in cognition remain relatively unstudied in non-human animals. One intriguing possibility is that variation in cognition is functionally related to variation in personality. Here, we review some examples and present hypotheses on relationships between personality (or behavioural syndromes) and individual differences in cognitive style. Our hypotheses are based largely on a connection between fast-slow behavioural types (BTs; e.g. boldness, aggressiveness, exploration tendency) and cognitive speed-accuracy trade-offs. We also discuss connections between BTs, cognition and ecologically important aspects of decision-making, including sampling, impulsivity, risk sensitivity and choosiness. Finally, we introduce the notion of cognition syndromes, and apply ideas from theories on adaptive behavioural syndromes to generate predictions on cognition syndromes.     

Olfactory evolution and behavioral ecology in primates

Primates are usually thought of as "visual" mammals, and several comparative studies have emphasized the role of vision in primate neural and sociocognitive specialization. Here I explore the role of olfactory systems, using phylogenetic analysis of comparative volumetric data. The relative sizes of the main olfactory bulb (MOB) and accessory olfactory bulb (AOB) tend to show different evolutionary patterns in accordance with their different functions. Although there is some evidence of correlated evolution of the two systems, this is apparent in only one clade (the strepsirhines). As predicted, the MOBs correlate predominantly with ecological factors (activity period and diet), while the AOBs correlate with social and mating systems. Related olfactory structures (i.e., the piriform cortex and amygdala) exhibit correlated evolution with the AOBs but not with the MOBs, and the corticobasolateral part of the amygdala exhibits a correlation with social group size in platyrrhines similar to that observed for the AOB. These social system correlations support the idea that there is an olfactory dimension to the concept of the social brain.     

Animal learning and memory: an integration of cognition and ecology

A wonderfully lucid framework for the ways to understand animal behaviour is that represented by the four ‘whys’ proposed by Tinbergen (1963). For much of the past three decades, however, these four avenues have been pursued more or less in parallel. Functional questions, for example, have been addressed by behavioural ecologists, mechanistic questions by psychologists and ethologists, ontogenetic questions by developmental biologists and neuroscientists and phylogenetic questions by evolutionary biologists. More recently, the value of integration between these differing views has become apparent. In this brief review, we concentrate especially on current attempts to integrate mechanistic and functional approaches.

Most of our understanding of learning and memory in animals comes from the psychological literature, which tends to use only rats or pigeons, and more occasionally primates, as subjects. The underlying psychological assumption is of general processes that are similar across species and contexts rather than a range of specific abilities. However, this does not seem to be entirely true as several learned behaviours have been described that are specific to particular species or contexts. The first conspicuous exception to the generalist assumption was the demonstration of long delay taste aversion learning in rats (Garcia et al., 1955), in which it was shown that a stimulus need not be temporally contiguous with a response for the animal to make an association between food and illness. Subsequently, a number of other examples, such as imprinting and song learning in birds (e.g., Bolhuis and Honey, 1998; Catchpole and Slater, 1995; Horn, 1998), have been thoroughly researched. Even in these cases, however, it has been typical for only a few species to be studied (domestic chicks provide the ‘model’ imprinting species and canaries and zebra finches the song learning ‘models’). As a result, a great deal is understood about the neural underpinnings and development of the behaviour, but substantially less is understood about interspecific variation and whether variation in behaviour is correlated with variation in neural processing (see review by Tramontin and Brenowitz, 2000 but see ten Cate and Vos, 1999).     

Explanations for variation in cognitive ability: Behavioural ecology meets comparative cognition

Sara Shettleworth has played a defining role in the development of animal cognition and its integration into other parts of biology, especially behavioural ecology. Here we chart some of that progress in understanding the causes and importance of variation in cognitive ability and highlight how Tinbergen's levels of explanation provide a useful framework for this field. We also review how experimental design is crucial in investigating cognition and stress the need for naturalistic experiments and field studies. We focus particularly on the example of the relationship among food hoarding, spatial cognition and hippocampal structure, and review the conflicting evidence for sex differences in spatial cognition. We finish with speculation that a combination of Tinbergen and Shettleworth-style approaches would be the way to grapple with the as-yet unanswered questions of why birds mimic heterospecifics.