Recent papers by Cardini et al. (Evolutionary Biology 46:307–316, 2019) and Bookstein (Evolutionary Biology 46:271–302, 2019) show that, when there are many variables and when sample sizes are small, scatterplots made using the between-groups principal components analysis method can appear to indicate clear group differences with little or no overlap between samples even though the samples are all

A new view of the tree of life has been conceived and implemented to construct a molecular-based phylogeny for a wide range of animal species without the need for gene or protein sequences using mass map data in a so-called “phylonumerics” approach. Numerical mass map data generated following the proteolytic digestion of proteins expressed across an array of organisms are used to build phylogenetic-like

In this paper, we present the points of convergence between of adaptive memory and cultural attraction, and how these two approaches can help evolutionary ethnobiologists understand human cognition and behavior in relation to nature. In addition, we present empirical evidence of how the union of genetic, cultural and ecological factors can shape the human mind and behavior, aspects that are often dissociated

Many studies have attested to the consequences of the recent and intense artificial selection on the morphological variability of the cranium and mandible in domestic animals. However, the functional relations of the cranium with other constituents of the masticatory apparatus (the mandibles and the adductor muscles) have rarely been explored. Previous work has demonstrated strong relationships between

Although there are various indices available for calculating morphological integration, the integration coefficient of variation (ICV) is most suited for assessing magnitudes of integration within and between morphological variance/covariance (V/CV) matrices. However, it is currently not known what the effects of varying sample sizes are on the reliable estimation of distributions of ICV scores. In

The transition to asexual reproduction is frequent and widespread across the tree of life and constitutes a major life history change. Without sexual reproduction, selection on sexually selected traits is expected to be weaker or absent, allowing the decay and ultimately loss of sexual traits. In this study, we applied an experimental approach to investigate the decay of reproductive traits under asexuality

The original version of this article unfortunately contained an error. The authors would like to correct the error with this erratum.

More and more analyses of biological shapes are using the techniques of geometric morphometrics based on configurations of landmarks in two or three dimensions. A fundamental concept at the core of these analyses is Kendall’s shape space and local approximations to it by shape tangent spaces. Kendall’s shape space is complex because it is a curved surface and, for configurations with more than three

Environmental shifts are projected to lead to expansions, contractions and shifts in the geographic range of species in response to climate change. Most distribution forecasting methods assume that species respond to the environment as an undifferentiated entity along their entire distribution. However, environmental heterogeneity along a species’ range plays a key role in driving the evolutionary

Organismal performance is often key in understanding macroevolutionary patterns but characterizing performance across many species is challenging, as the disparate geographic locations of taxa often prohibit in vivo measures. In theory, however, inferences on the evolution of performance could be investigated using anatomical approximations of performance parameters, allowing for a wider range of species

Geometric morphometrics is the statistical analysis of landmark-based shape variation and its covariation with other variables. Over the past two decades, the gold standard of landmark data acquisition has been manual detection by a single observer. This approach has proven accurate and reliable in small-scale investigations. However, big data initiatives are increasingly common in biology and morphometrics

The visualization of the molecular context of an amino acid mutation in a protein structure is crucial for the assessment of its functional impact and the understanding of its evolutionary implications. Currently, searches for fast evolving amino acid positions using codon substitution models like those implemented in PAML (Yang and Nielsen in Estimating synonymous and nonsynonymous substitution rates

Theoretical and experimental studies have provided evidence for a positive role of phenotype resistance to genetic mutation in enhancing long-term adaptation to novel environments. With the aim of contributing to an understanding of the origin and evolution of phenotypic robustness to genetic mutations in organismal systems, we adopted a theoretical approach, elaborating on a classical mathematical

The inclusion of fossil phenotypes as ancestral character values at nodes in phylogenetic trees is known to increase both the power and reliability of phylogenetic comparative methods (PCMs) applications. We implemented the R function RRphylo as to integrate fossil phenotypic information as ancestral character values. We tested the new implementation, named RRphylo-noder (which is available as part

Researchers using geometric morphometric methods can be confronted with a need to combine separate landmark configurations from the same research subjects as a more holistic description of organismal morphology. Combining configurations might be valid if single configurations represent separate anatomical structures that can change position with respect to each other or have been shown to be phenotypically

The page where the original version of this article is posted unfortunately contained an error. In that page, the supplementary material is not currently included along with the article and this problem has been corrected with this erratum.

Encapsulated within the temporal bone and comprising the smallest elements of the vertebrate skeleton, the ear is key to multiple senses: balance, posture control, gaze stabilization, and hearing. The transformation of the primary jaw joint into the mammalian ear ossicles is one of the most iconic transitions in vertebrate evolution, but the drivers of this complex evolutionary trajectory are not fully

Many authors have hypothesized an association between rates of morphological evolution and rates of species diversification, however, this association has yet to be empirically tested in the primate cranium. In this investigation, we used phylogeny-based approaches to examine the relationship between rates of species diversification, rates of cranial size and shape evolution, and observed cranial morphological

Manual landmark data collection on large samples takes a long time. Several options exist to speed the process, though each introduces problems or raises concerns of its own. For bilaterally symmetric structures (e.g., crania), some recent papers recommend limiting landmark collection to one side and the anatomical midline, then approximating the true bilateral configuration by merging the hemi-form

Facultative traits can provide phenotypic lability in dynamic environments, but it is unclear how weaving between disparate habitats impacts non-facultative traits that are carried along the way. The life cycles of salamanders are associated with distinct ontogenies, aquatic-to-terrestrial (biphasic), completely-terrestrial (direct development), and completely-aquatic (larval form paedomorphic). Salamanders

Despite the considerable scientific interest in the variability and patterns of integration in the dog skull, how these patterns impact or are driven by function remains largely unexplored. Since the mandible is directly involved in mastication, it can be expected to be directly related to the development of the adductor and abductor muscles. Here, we explore whether variation in the architecture and

The increasing availability of 3D-imaging technology provides new opportunities for measuring morphology. Photogrammetry enables easy 3D-data acquisition compared to conventional methods and here we assess its accuracy for measuring the size of deer antlers, a complex morphological structure. Using a proprietary photogrammetry software, we generated 3D images of antlers for 92 individuals from 29 species

The neck connects the head and the trunk and is the key structure allowing all movements of the head. The neck morphology of birds is the most variable among living tetrapods, including significant differences in the number and shape of the cervical vertebrae. Despite these differences, according to the literature, three morphofunctional regions (i.e., modules) have been identified along the neck.

The identification of mechanisms that have generated biodiversity is one of the major tasks in biogeography and evolutionary biology. Here, using a set of environmental variables and historical presence records, we assessed whether closely related allopatric lineages in the Arremon brunneinucha (Aves: Passerellidae) complex are either more ecologically similar or different throughout their distribution

The natural selection of metabolism and mass can explain inter-specific body mass allometries from prokaryotes to mammals (Witting in Theor Popul Biol 117:23–42, https://doi.org/10.1016/j.tpb.2017.08.005, 2017a), with allometric exponents that depend on the selected metabolism and the packing of home ranges in predominately one (1D), two (2D), or three (3D) spatial dimensions. The predicted exponent

Between group PCA (bgPCA) has been developed to summarize group differences in high dimensional spaces like in geometric morphometrics and microarray data where the number of variables is often larger than sample size. However, it has been very recently shown that this technique inflates apparent differences as seen in scatterplots and, in extreme cases, can even create differences where there are

Many organisms studied by evolutionary biologists have different sexes, and the evolution of separate sexes and sexual dimorphisms in morphology and behaviour are central questions in evolutionary biology. Considering scientists to be embedded in a social and cultural context, we are also subjected to the risk of gender-biased assumptions and stereotypical thinking to appear when working on topics

In this article, we present the central ideas of evolutionary psychology, and discuss how their assumptions can help ethnobiologists to understand the dynamic relationship between people and their environments. In this sense, investigating this relationship from an evolutionary perspective can bring new empirical evidence about human evolution, also contributing to both evolutionary psychology and

Evolutionary relationships among and across species are almost exclusively examined through phylogenetic analysis based on trees constructed using gene sequences. Such trees are not without their limitations. Here we show that sets of numbers representing the masses of peptide segments within proteins encoded by those genes can also be used to construct trees of life employing a phylonumerics approach

Identifying the evolutionary processes that underlie morphological variation at the intraspecific level is cornerstone for understanding the drivers of phenotypic diversity at higher macro-evolutionary scales. The fire salamander, Salamandra salamandra, exhibits exceptional intraspecific variation in multiple phenotypic traits (i.e. body size, head shape, coloration, reproductive modes). Pueriparity

Evolutionary dynamics of covariation patterns in craniometric traits was studied for bats from the Myotis myotis–Myotis blythii species group (Mammalia, Chiroptera, Vespertilionidae) namely M.m.myotis, M.b.oxygnathus, M.b.omari, M.b.blythii, and M.b.altaicus. These species evolved towards increasing the size. One more species, M.dasycneme, which is phylogenetically, morphologically, and ecologically

Toothed whales (Odontoceti, Cetacea) are well-known for their ability to produce complex vocalizations, to use tools, to possess self-recognition, and for their extreme behavioural plasticity. The toothed whale intelligence is said to compete with that of primates, so does their extremely large brain to body size ratio. Common explanations for the acquisition of such large brains over the evolutionary

Using sampling experiments, we found that, when there are fewer groups than variables, between-groups PCA (bgPCA) may suggest surprisingly distinct differences among groups for data in which none exist. While apparently not noticed before, the reasons for this problem are easy to understand. A bgPCA captures the g − 1 dimensions of variation among the g group means, but only a fraction of the \(\sum

Quantifying the inner structure of bones is central to various analyses dealing with the phenotypic evolution of animals with an ossified skeleton. Computed tomography allows to assess the repartition of bone tissue within an entire skeletal element. Two parameters of importance for such analyses are the global compactness (Cg) and total cross-sectional area (Tt.Ar). However, no open-source, time-efficient

Good empirical applications of geometric morphometrics (GMM) typically involve several times more variables than specimens, a situation the statistician refers to as “high p/n,” where p is the count of variables and n the count of specimens. This note calls your attention to two predictable catastrophic failures of one particular multivariate statistical technique, between-groups principal components

Sexual size dimorphism in orb-weaving spiders is a relatively well-studied phenomenon, and numerous works have documented evolutionary variation in interspecific size and degree of dimorphism. To date, these studies have been largely limited to assessing the evolution of a single or few linear measurements correlated with body size. While the descriptive and comparative literature is rich with qualitative

The inhibitory cascade (IC) model is a widely used evolutionary developmental explanation of among-species differences in relative molar tooth size. The IC model posits that, as molars develop from front to back, the relative strength of activating and inhibiting influences establishes a “ratcheting” mechanism leading to predictable relative molar sizes. Such a constraint on molar covariation would

Morphological and functional hierarchies occurring in contemporary biological entities are amalgamated via a small number of progressive key-steps termed as Major Transition in Evolution (MTE) that encompass steps of Major Transition in Individuality (MTI). Literature views MTE/MTI in nature as a sequential increase in complexity, and has contributed insights into the emergence of genuine MTI candidates

The development of techniques for the acquisition of high-resolution 3D images, such as computed tomography and magnetic resonance imaging, has opened new avenues to the study of complex morphologies. Detailed descriptions of internal and external traits can be now obtained, allowing the intensive sampling of surface points. In this paper, we introduce a morphometric and statistical framework, grounded

It has been suggested that larger species of mammals tend to become long-faced when they diverge in size during an evolutionary radiation. However, whether this allometric pattern, reminiscent of ontogenetic changes in skull proportions, is indeed a rule has yet to be thoroughly tested. Using ~ 6000 adult specimens from 14 phylogenetically well separated and ecomorphologically distinctive lineages

Photogrammetry (PH) is relatively cheap, easy to use, flexible and portable but its power and limitations have not been fully explored for studies of small animals. Here we assessed the accuracy of PH for the reconstruction of 3D digital models of bat skulls by evaluating its potential for evolutionary morphology studies at interspecific (19 species) level. Its reliability was assessed against the

Eucaridan evolution involved a process starting from a body organization characterized by an elongate and cylindrical cephalothorax, a well-developed abdomen composed of swimming appendages, ending in a tail fan formed by flattened uropods and a telson. This process would lead, ultimately, to a body organization characterized by a shortened and depressed cephalothorax, and a reduced and ventrally folded

The Tree of Life (ToL) has been of central importance in the biological sciences, usually understood as a model or a metaphor, and portrayed in various graphical forms to summarize the history of life as a single diagram. If it is seen as a mathematical construct—a rooted graph theoretical tree or, as more recently viewed, a directed network [Network of Life (NoL)]—then its proper visualization is

Temporal variation in reproductive investment, e.g. maternal egg provisioning, has a substantial effect on offspring fitness therefore has received great attention by evolutionary biologists. Maternal allocation into egg size and egg content directly influences performance of offspring in many taxa, but spiders have rarely been investigated in this regard. In this study, we investigate the temporal

Much is known about the genetic variance in certain components of metabolism, most notably resting and maximum metabolic rate. This is in stark contrast to the lack of information on genetic variance in the metabolic rate of individuals that feed and express routine activity, and how this rate correlates with other components of the energy budget or life history traits. Here we quantify genetic variance

In addition to the degree of geographical isolation (sympatry, parapatry, allopatry and peripatry), ecology can be an important factor promoting diversification of lineages, both by niche divergence as well as niche conservatism. Tetraglochin is a genus of shrubs with six species distributed along the Southern and Central Andes, from Peru to southern Argentina and central Chile. Although monophyly

Evolutionary theories generally concur that sexual reproduction and genetic recombination evolved to maximize genetic variability. Thus, the existence of monozygotic (MZ) twins, which do not take advantage of genetic recombination for each offspring, poses a puzzle. Evolutionary logic of inclusive fitness suggests that parents with high-quality genes may be more likely to produce MZ twins. Analyses

Leaf-eating monkeys (colobines) are a highly diversified subfamily with 61 species in ten genera, in which patterns and constraints of morphological evolution are still poorly resolved. In the present study, we measured the skulls of 452 specimens collected from different museums worldwide. Using one of the most extensive samples ever employed, and geometric morphometric techniques, we aimed to elucidate

One outstanding phenotypic character in Homo is its brain evolution. Pagel (Morphology, shape and phylogeny, CRC Press, Boca Raton, 2002) performed a phylogenetic analysis of the evolution of cranial capacity (as a surrogate of brain size) in fossil hominins, finding evidence for gradual evolutionary change with accelerating rate. Since Pagel’s pioneering investigation, the hominin fossil record expanded

The possibility of undertaking matrix/optimization-free cladistic analysis is one of the most interesting ideas to emerge in the last few decades from within the field of systematics, particularly in the development of cladistics. The purpose of this paper is to design further opportunities and prospects made possible by eliminating the matrix as the primary source of data representation. The main

Periodic bottlenecks play a major role in shaping the adaptive dynamics of natural and laboratory populations of asexual microbes. Here we study how they affect the ‘Extent of Adaptation’ (EoA), in such populations. EoA, the average fitness gain relative to the ancestor, is the quantity of interest in a large number of microbial experimental-evolution studies which assume that for any given bottleneck

Coloration is often key in animal communication, and is frequently subjected to strong natural and sexual selection, often with opposed directions: natural selection typically favors cryptic colorations whereas sexual selection may favor conspicuous colorations. Also, different coloration traits may convey different pieces of information. Plus, coloration may vary among habitats, mirroring local selective

The selection of prey by predators should, theoretically, favour uniformity in the warning signals displayed by unpalatable prey. Nevertheless, some aposematically coloured species are polymorphic. We tested the hypothesis that colour morphs of unpalatable prey differ in the efficacy of their aposematic signal for birds, thereby affecting the selective advantages of these morphs. We used colour morphs

Principal component analysis (PCA) is the most widely used dimensionality reduction technique in the biological sciences, and is commonly employed to create 2D visualizations of geometric morphometric data. However, interesting biological information may be lost or misrepresented in these plots due to PCA’s inability to summarize nonlinear dependencies between variables. Nonlinear alternative methods

Studies of morphological integration and modularity are a hot topic in evolutionary developmental biology. Geometric morphometrics using Procrustes methods offers powerful tools to quantitatively investigate morphological variation and, within this methodological framework, a number of different methods has been put forward to test if different regions within an anatomical structure behave like modules

Characterizing the relationships between genotype and phenotype for developmental adaptive traits is essential to understand the evolutionary dynamics underlying biodiversity. In holometabolous insects, the time to reach the reproductive stage and pupation site preference are two such traits. Here we characterize aspects of the genetic architecture for Developmental Time (decomposed in Larval and Pupal

The increasing maximal hierarchical complexity of organisms is one of the best-supported macroevolutionary trends. The nature and causes of this trend, as well as several accompanying macroevolutionary phenomena are, however, still unclear. In this theoretical article, we propose that the cause of this trend could be the increasing pressure of species selection, which results from the gradual decrease

Mice from the Orkney archipelago exhibit an important diversity regarding molar shape. While on some islands mice display a usual dental pattern, teeth from other islands display additional cusplets and unusual phenotypes that may constitute case studies for evaluating the potential functional relevance of dental changes. We developed a multifaceted approach combining 2D and 3D geometric morphometrics

Understanding the relative importance of various reproductive barriers to the early stages of speciation is an essential question in evolutionary biology. The closely related killifishes Fundulus heteroclitus and F. grandis occasionally hybridize in a small region in coastal Northeastern Florida showing that while barriers to reproduction exist, they are incomplete. The objective of this study was