Animal personalities: consequences for ecology and evolution

Personality differences are a widespread phenomenon throughout the animal kingdom. Past research has focused on the characterization of such differences and a quest for their proximate and ultimate causation. However, the consequences of these differences for ecology and evolution received much less attention. Here, we strive to fill this gap by providing a comprehensive inventory of the potential implications of personality differences, ranging from population growth and persistence to species interactions and community dynamics, and covering issues such as social evolution, the speed of evolution, evolvability, and speciation. The emerging picture strongly suggests that personality differences matter for ecological and evolutionary processes (and their interaction) and, thus, should be considered a key dimension of ecologically and evolutionarily relevant intraspecific variation.     

Visual prey discrimination of queen and worker ants by a generalist lizard

Laboratory experiments were conducted to test the hypothesis that widelyforaging generalist lizard,Eumeces okadae, visually discriminates palatable queen ants from unpalatable worker ants. The workers ofCamponotus japonicus andLasius niger were rejected on sight, while the queens of both species were eaten with little prior chemical examination by tongue flicks or licks. Comparison of the lizards' responses towards the workers and wingless queens of similar size indicated that neither body size nor presence or absence of wings accounted for difference in responses toward the 2 ant castes. The lizards probably discriminated different ant castes by body proportions.     

Funding troubles for evolution and ecology

The human population passed the 7 billion mark last month. As the population grows, the environment, which in turn is necessary for our survival, suffers as a result of increased demand for natural resources and global warming. Key to addressing these challenges will be new knowledge provided by the evolutionary and ecological sciences. But, alarmingly, these areas are underfunded, as Cyrus Martin reports.     

Evolutionary ecology of movement by predators and prey

An essential key to explaining the mechanistic basis of ecological patterns lies in understanding the consequences of adaptive behavior for distributions and abundances of organisms. We developed a model that simultaneously incorporates (a) ecological dynamics across three trophic levels and (b) evolution of behaviors via the processes of mutation, selection, and drift in populations of variable, unique individuals. Using this model to study adaptive movements of predators and prey in a spatially explicit environment produced a number of unexpected results. First, even though predators and prey had limited information and sometimes moved in the “wrong” direction, evolved movement mechanisms allowed them to achieve average spatial distributions approximating optimal, ideal free distributions. Second, predators’ demographic parameters had marked, nonlinear effects on the evolution of movement mechanisms in the prey: As the predator mortality rate was increased past a critical point, prey abruptly shifted from making very frequent movements away from predators to making infrequent movements mainly in response to resources. Third, time series analyses revealed that adaptive, conditional movements coupled ecological dynamics across species and space. Our results provide general predictions, heretofore lacking, about how predators and prey should respond to one another on both ecological and evolutionary time scales.     

Hinged teeth for hard-bodied prey: a case of convergent evolution between snakes and legless lizards

Savitzky (1981) described hinged teeth in several taxa of snakes, and interpreted this type of dentition as an adaptation to feeding on hard-bodied prey (scincid lizards). We tested this hypothesis by examining the dentition of insectivorous and saurophagous members of the Australian legless lizards, Pygopodidae. Insectivorous taxa ( Delma, Pygopus ) have peg-like pleurodont dentition, but the saurophagous Lialis has slender, recurved, sharply-pointed teeth, like those of many snakes. The teeth of Lialis are 'hinged' on their supporting bones: each tooth folds when pressure is applied to its anterior surface, but locks in an erect position when forced from behind, The tooth hinge is probably collagenous, and does not contain elastin. The presence of hinged teeth in Lids , which feeds predominately on scincid lizards, offers strong support for Savitzky's hypothesis.     

The biodiversity and ecology of Antarctic lakes: models for evolution

Antarctic lakes are characterised by simplified, truncated food webs. The lakes range from freshwater to hypersaline with a continuum of physical and chemical conditions that offer a natural laboratory in which to study evolution. Molecular studies on Antarctic lake communities are still in their infancy, but there is clear evidence from some taxonomic groups, for example the Cyanobacteria, that there is endemicity. Moreover, many of the bacteria have considerable potential as sources of novel biochemicals such as low temperature enzymes and anti-freeze proteins. Among the eukaryotic organisms survival strategies have evolved, among which dependence on mixotrophy in phytoflagellates and some ciliates is common. There is also some evidence of evolution of new species of flagellate in the marine derived saline lakes of the Vestfold Hills. Recent work on viruses in polar lakes demonstrates high abundance and high rates of infection, implying that they may play an important role in genetic exchange in these extreme environments.     

Inference in ecology and evolution

Most ecologists and evolutionary biologists continue to rely heavily on null hypothesis significance testing, rather than on recently advocated alternatives, for inference. Here, we briefly review null hypothesis significance testing and its major alternatives. We identify major objectives of statistical analysis and suggest which analytical approaches are appropriate for each. Any well designed study can improve our understanding of biological systems, regardless of the inferential approach used. Nevertheless, an awareness of available techniques and their pitfalls could guide better approaches to data collection and broaden the range of questions that can be addressed. Although we should reduce our reliance on significance testing, it retains an important role in statistical education and is likely to remain fundamental to the falsification of scientific hypotheses.     

EvolMarkers: a database for mining exon and intron markers for evolution, ecology and conservation studies

Recent innovations in next-generation sequencing have lowered the cost of genome projects. Nevertheless, sequencing entire genomes for all representatives in a study remains expensive and unnecessary for most studies in ecology, evolution and conservation. It is still more cost-effective and efficient to target and sequence single-copy nuclear gene markers for such studies. Many tools have been developed for identifying nuclear markers, but most of these have focused on particular taxonomic groups. We have built a searchable database, EvolMarkers, for developing single-copy coding sequence (CDS) and exon-primed-intron-crossing (EPIC) markers that is designed to work across a broad range of phylogenetic divergences. The database is made up of single-copy CDS derived from BLAST searches of a variety of metazoan genomes. Users can search the database for different types of markers (CDS or EPIC) that are common to different sets of input species with different divergence characteristics. EvolMarkers can be applied to any taxonomic group for which genome data are available for two or more species. We included 82 genomes in the first version of EvolMarkers and have found the methods to be effective across Placozoa, Cnidaria, Arthropod, Nematoda, Annelida, Mollusca, Echinodermata, Hemichordata, Chordata and plants. We demonstrate the effectiveness of searching for CDS markers within annelids and show how to find potentially useful intronic markers within the lizard Anolis.     

Below-threshold mortality: implications for studies in evolution,ecology and demography

Evolutionary biologists, ecologists and experimental gerontologists have increasingly used estimates of age-specific mortality as a critical component in studies of a range of important biological processes. However, the analysis of age-specific mortality rates is plagued by specific statistical challenges caused by sampling error. Here we discuss the nature of this ‘demographic sampling error’, and the way in which it can bias our estimates of (1) rates of ageing, (2) age at onset of senescence, (3) costs of reproduction and (4) demographic tests of evolutionary models of ageing. We conducted simulations which suggest that using standard statistical techniques, we would need sample sizes on the order of tens of thousands in most experiments to effectively remove any bias due to sampling error. We argue that biologists should use much larger sample sizes than have previously been used. However, we also present simple maximum likelihood models that effectively remove biases due to demographic sampling error even at relatively small sample sizes.     

Chloroplast microsatellites: new tools for studies in plant ecology and evolution

The nonrecombinant, uniparentally inherited nature of organelle genomes makes them useful tools for evolutionary studies. However, in plants, detecting useful polymorphism at the population level is often difficult because of the low level of substitutions in the chloroplast genome, and because of the slow substitution rates and intramolecular recombination of mtDNA. Chloroplast microsatellites represent potentially useful markers to circumvent this problem and, to date, studies have demonstrated high levels of intraspecific variability. Here, we discuss the use of these markers in ecological and evolutionary studies of plants, as well as highlighting some of the potential problems associated with such use.