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1.  Imprinted green beards: a little less than kin and more than kind 
Biology Letters  2013;9(6):20130199.
RNA is complementary to the DNA sequence from which it is transcribed. Therefore, interactions between DNA and RNA provide a simple mechanism of genetic self-detection within nuclei. Imprinted RNAs could enable alleles of maternal and paternal origin to detect whether they are the same (homozygous) or different (heterozygous), and thereby provide strategic information about expected relatedness to siblings.
PMCID: PMC3871330  PMID: 24132086
inclusive fitness; imprinting; siRNA; green beards; relatedness
2.  Hamiltonian inclusive fitness: a fitter fitness concept 
Biology Letters  2013;9(6):20130335.
In 1963–1964 W. D. Hamilton introduced the concept of inclusive fitness, the only significant elaboration of Darwinian fitness since the nineteenth century. I discuss the origin of the modern fitness concept, providing context for Hamilton's discovery of inclusive fitness in relation to the puzzle of altruism. While fitness conceptually originates with Darwin, the term itself stems from Spencer and crystallized quantitatively in the early twentieth century. Hamiltonian inclusive fitness, with Price's reformulation, provided the solution to Darwin's ‘special difficulty’—the evolution of caste polymorphism and sterility in social insects. Hamilton further explored the roles of inclusive fitness and reciprocation to tackle Darwin's other difficulty, the evolution of human altruism. The heuristically powerful inclusive fitness concept ramified over the past 50 years: the number and diversity of ‘offspring ideas’ that it has engendered render it a fitter fitness concept, one that Darwin would have appreciated.
PMCID: PMC3871333  PMID: 24132089
Darwinian fitness; inclusive fitness; Hamilton's rule; kin selection; social evolution; altruism
3.  The veil of ignorance can favour biological cooperation 
Biology Letters  2013;9(6):20130365.
Lack of information is a constraint but ignorance can sometimes assist the evolution of cooperation by constraining selfishness. We discuss examples involving both ignorance of role or pay-off and ignorance of relatedness. Ignorance can favour cooperative traits like grouping and warning coloration and reduce conflicts from meiotic drive, imprinting, greenbeards and various forms of nepotism.
PMCID: PMC3871334  PMID: 24132090
veil of ignorance; cooperation; conflict; relatedness; meiosis; nepotism
4.  Parasites and altruism: converging roads 
Biology Letters  2013;9(6):20130367.
W.D. Hamilton was most known for his work on two topics: social evolution and parasites. Although at first glance these seem to be disparate interests, they share many attributes and have logical connections within evolutionary biology. Nevertheless, Hamilton's contributions in these areas met with very different receptions, with his place in the field of social evolution assured, but his work on the role of parasites perceived as more specialized. We take an historical approach to examine the reasons for this difference.
PMCID: PMC3871335  PMID: 24132091
Hamilton; parasites; social evolution
5.  Dissecting ant recognition systems in the age of genomics 
Biology Letters  2013;9(6):20130416.
Hamilton is probably best known for his seminal work demonstrating the role of kin selection in social evolution. His work made it clear that, for individuals to direct their altruistic behaviours towards appropriate recipients (kin), mechanisms must exist for kin recognition. In the social insects, colonies are typically comprised of kin, and colony recognition cues are used as proxies for kinship cues. Recent years have brought rapid advances in our understanding of the genetic and molecular mechanisms that are used for this process. Here, I review some of the most notable advances, particularly the contributions from recent ant genome sequences and molecular biology.
PMCID: PMC3871338  PMID: 24132093
Formicidae; genomics; chemosensory receptors; cuticular hydrocarbons
6.  Nice to kin and nasty to non-kin: revisiting Hamilton's early insights on eusociality 
Biology Letters  2013;9(6):20130444.
When helping behaviour is costly, Hamiltonian logic implies that animals need to direct helpful acts towards kin, so that indirect fitness benefits justify the costs. We revisit inferences about nepotism and aggression in Hamilton's 1964 paper to argue that he overestimated the general significance of nepotism, but that other issues that he raised continue to suggest novel research agendas today. We now know that nepotism in eusocial insects is rare, because variation in genetic recognition cues is insufficient. A lower proportion of individuals breeding and larger clutch sizes selecting for a more uniform colony odour may explain this. Irreversible worker sterility can induce both the fiercest possible aggression and the highest likelihood of helping random distant kin, but these Hamiltonian contentions still await large-scale testing in social animals.
PMCID: PMC3871339  PMID: 24132094
clutch size; recognition; Gestalt; inclusive fitness; nepotism; unmatedness
7.  Kinship and the evolution of social behaviours in the sea 
Biology Letters  2013;9(6):20130454.
Until recently, little attention has been paid to the existence of kin structure in the sea, despite the fact that many marine organisms are sessile or sedentary. This lack of attention to kin structure, and its impacts on social evolution, historically stems from the pervasive assumption that the dispersal of gametes and larvae is almost always sufficient to prevent any persistent associations of closely related offspring or adults. However, growing evidence, both theoretical and empirical, casts doubt on the generality of this assumption, not only in species with limited dispersal, but also in species with long dispersive phases. Moreover, many marine organisms either internally brood their progeny or package them in nurseries, both of which provide ample opportunities for kinship to influence the nature and outcomes of social interactions among family members. As the evidence for kin structure within marine populations mounts, it follows that kin selection may play a far greater role in the evolution of both behaviours and life histories of marine organisms than is presently appreciated.
PMCID: PMC3871340  PMID: 24132095
kin structure; social behaviour; cooperation; marine organisms; relatedness
8.  Kin selection, species richness and community 
Biology Letters  2013;9(6):20130491.
Can evolutionary and ecological dynamics operating at one level of the biological hierarchy affect the dynamics and structure at other levels? In social insects, strong hostility towards unrelated individuals can evolve as a kin-selected counter-adaptation to intraspecific social parasitism. This aggression in turn might cause intraspecific competition to predominate over interspecific competition, permitting coexistence with other social insect species. In other words, kin selection—a form of intra-population dynamics—might enhance the species richness of the community, a higher-level structure. The converse effect, from higher to lower levels, might also operate, whereby strong interspecific competition may limit the evolution of selfish individual traits. If the latter effect were to prove more important, it would challenge the common view that intra-population dynamics (via individual or gene selection) is the main driver of evolution.
PMCID: PMC3871341  PMID: 24132096
intra-population dynamics; evolution; competition; biological hierarchy
10.  Reassessing the association between facial structure and baseball performance: a comment on Tsujimura & Banissy (2013) 
Biology Letters  2013;9(5):20130538.
PMCID: PMC3971694  PMID: 24026348
facial features; body mass index; sports achievement
11.  Possible role of soil alkalinity in plant breeding for salt-tolerance 
Biology Letters  2013;9(5):20130566.
PMCID: PMC3971701  PMID: 23925836
12.  On validity and controls in animal personality research: a comment on Galhardo et al. (2012) 
Biology Letters  2013;9(4):20121080.
PMCID: PMC3730612  PMID: 23676652
14.  How the bat got its buzz 
Biology Letters  2013;9(2):20121031.
Since the discovery of echolocation in bats, the final phase of an attack on a flying insect, the ‘terminal buzz’, has proved enigmatic. During the buzz, bats increase information update rates by producing vocalizations up to 220 times s−1. The buzz's ubiquity in hawking and trawling bats implies its importance for hunting success. Superfast muscles, previously unknown in mammals, are responsible for the extreme vocalization rate. Some bats produce a second phase—buzz II—defined by a large drop in the fundamental frequency (F0) of their calls. By doing so, bats broaden their acoustic field of view and should thereby reduce the likelihood of insect escape. We make the case that the buzz was a critical adaptation for capturing night-flying insects, and suggest that the drop in F0 during buzz II requires novel, unidentified laryngeal mechanisms in order to counteract increasing muscle tension. Furthermore, we propose that buzz II represents a countermeasure against the evasive flight of eared prey in the evolutionary arms-race that saw the independent evolution of bat-detecting ears in various groups of night-flying insects.
PMCID: PMC3639754  PMID: 23302868
bats; echolocation; terminal buzz; superfast muscles; acoustic field of view
16.  Leaf morphology shift is not linked to climate change 
Biology Letters  2013;9(1):20120659.
PMCID: PMC3565485  PMID: 23118433
17.  Chronometry for the chorusing herd: Hamilton's legacy on context-dependent acoustic signalling—a comment on Herbers (2013) 
Biology Letters  2014;10(1):20131018.
PMCID: PMC3917344  PMID: 24429686
synchronization; chorusing; rhythm; selfish herd; origins of music; agent-based model
19.  Pro-sociality without empathy 
Biology Letters  2012;8(6):910-912.
Empathy, the capacity to recognize and share feelings experienced by another individual, is an important trait in humans, but is not the same as pro-sociality, the tendency to behave so as to benefit another individual. Given the importance of understanding empathy's evolutionary emergence, it is unsurprising that many studies attempt to find evidence for it in other species. To address the question of what should constitute evidence for empathy, we offer a critical comparison of two recent studies of rescuing behaviour that report similar phenomena but are interpreted very differently by their authors. In one of the studies, rescue behaviour in rats was interpreted as providing evidence for empathy, whereas in the other, rescue behaviour in ants was interpreted without reference to sharing of emotions. Evidence for empathy requires showing that actor individuals possess a representation of the receiver's emotional state and are driven by the psychological goal of improving its wellbeing. Proving psychological goal-directedness by current standards involves goal-devaluation and causal sensitivity protocols, which, in our view, have not been implemented in available publications. Empathy has profound significance not only for cognitive and behavioural sciences but also for philosophy and ethics and, in our view, remains unproven outside humans.
PMCID: PMC3497120  PMID: 22859561
empathy; pro-social behaviour; intentionality; goal-directedness
20.  The ontogenetic origins of mirror neurons: evidence from ‘tool-use’ and ‘audiovisual’ mirror neurons 
Biology Letters  2012;8(5):856-859.
Since their discovery, mirror neurons—units in the macaque brain that discharge both during action observation and execution—have attracted considerable interest. Whether mirror neurons are an innate endowment or acquire their sensorimotor matching properties ontogenetically has been the subject of intense debate. It is widely believed that these units are an innate trait; that we are born with a set of mature mirror neurons because their matching properties conveyed upon our ancestors an evolutionary advantage. However, an alternative view is that mirror neurons acquire their matching properties during ontogeny, through correlated experience of observing and performing actions. The present article re-examines frequently overlooked neurophysiological reports of ‘tool-use’ and ‘audiovisual’ mirror neurons within the context of this debate. It is argued that these findings represent compelling evidence that mirror neurons are a product of sensorimotor experience, and not an innate endowment.
PMCID: PMC3440963  PMID: 22573832
mirror neurons; associative learning; audiovisual mirror neurons; tool-use mirror neurons
21.  Is more better? Polyploidy and parasite resistance 
Biology Letters  2012;8(4):598-600.
Ploidy-level variation is common and can drastically affect organismal fitness. We focus on the potential consequences of this variation for parasite resistance. First, we elucidate connections between ploidy variation and key factors determining resistance, including allelic diversity, gene expression and physiological condition. We then argue that systems featuring both natural and artificially manipulated ploidy variation should be used to evaluate whether ploidy level influences host–parasite interactions.
PMCID: PMC3391438  PMID: 22258448
polyploidy; host–parasite interactions; allelic diversity; gene expression; host condition
22.  Plasticity of preferred body temperatures as means of coping with climate change? 
Biology Letters  2011;8(2):262-265.
Thermoregulatory behaviour represents an important component of ectotherm non-genetic adaptive capacity that mitigates the impact of ongoing climate change. The buffering role of behavioural thermoregulation has been attributed solely to the ability to maintain near optimal body temperature for sufficiently extended periods under altered thermal conditions. The widespread occurrence of plastic modification of target temperatures that an ectotherm aims to achieve (preferred body temperatures) has been largely overlooked. I argue that plasticity of target temperatures may significantly contribute to an ectotherm's adaptive capacity. Its contribution to population persistence depends on both the effectiveness of acute thermoregulatory adjustments (reactivity) in buffering selection pressures in a changing thermal environment, and the total costs of thermoregulation (i.e. reactivity and plasticity) in a given environment. The direction and magnitude of plastic shifts in preferred body temperatures can be incorporated into mechanistic models, to improve predictions of the impact of global climate change on ectotherm populations.
PMCID: PMC3297409  PMID: 22072284
acclimation; climate change; ectotherms; thermoregulatory behaviour
23.  On the inference of function from structure using biomechanical modelling and simulation of extinct organisms 
Biology Letters  2011;8(1):115-118.
Biomechanical modelling and simulation techniques offer some hope for unravelling the complex inter-relationships of structure and function perhaps even for extinct organisms, but have their limitations owing to this complexity and the many unknown parameters for fossil taxa. Validation and sensitivity analysis are two indispensable approaches for quantifying the accuracy and reliability of such models or simulations. But there are other subtleties in biomechanical modelling that include investigator judgements about the level of simplicity versus complexity in model design or how uncertainty and subjectivity are dealt with. Furthermore, investigator attitudes toward models encompass a broad spectrum between extreme credulity and nihilism, influencing how modelling is conducted and perceived. Fundamentally, more data and more testing of methodology are required for the field to mature and build confidence in its inferences.
PMCID: PMC3259946  PMID: 21666064
musculoskeletal system; dinosaur; computer modelling; simulation; palaeontology; biomechanics
24.  Models in palaeontological functional analysis 
Biology Letters  2011;8(1):119-122.
Models are a principal tool of modern science. By definition, and in practice, models are not literal representations of reality but provide simplifications or substitutes of the events, scenarios or behaviours that are being studied or predicted. All models make assumptions, and palaeontological models in particular require additional assumptions to study unobservable events in deep time. In the case of functional analysis, the degree of missing data associated with reconstructing musculoskeletal anatomy and neuronal control in extinct organisms has, in the eyes of some scientists, rendered detailed functional analysis of fossils intractable. Such a prognosis may indeed be realized if palaeontologists attempt to recreate elaborate biomechanical models based on missing data and loosely justified assumptions. Yet multiple enabling methodologies and techniques now exist: tools for bracketing boundaries of reality; more rigorous consideration of soft tissues and missing data and methods drawing on physical principles that all organisms must adhere to. As with many aspects of science, the utility of such biomechanical models depends on the questions they seek to address, and the accuracy and validity of the models themselves.
PMCID: PMC3259975  PMID: 21865242
palaeobiology; biomechanics; function; feeding; locomotion
25.  On the flexibility of lizards' cognition: a comment on Leal & Powell (2011) 
Biology Letters  2011;8(1):42-43.
PMCID: PMC3259984  PMID: 22158735

Results 1-25 (106)