Reconciling the convergence of supraspinous fossa shape among hominoids in light of locomotor differences

Differences in scapular morphology between modern humans and the African and lesser apes are associated with the distinct locomotor habits of these groups. However, several traits, particularly aspects of the supraspinous fossa, are convergent between Homo and Pongo—an unexpected result given their divergent locomotor habits. Many morphological assessments of the scapula rely on the limited number of static landmarks available, and traditional approaches like these tend to oversimplify scapular shape. Here, we present the results of two geometric morphometric (GM) analyses of hominoid supraspinous fossa shape—one employing five homologous landmarks and another with 83 sliding semilandmarks—alongside those of traditional methods to evaluate if three-dimensional considerations of fossa shape afford more comprehensive insights into scapular shape and functional morphology. Traditional measures aligned Pongo and Homo with narrow and transversely oriented supraspinous fossae, whereas African ape and Hylobates fossae are broader and more obliquely situated. However, our GM results highlight that much of the convergence between Homo and Pongo is reflective of their more medially positioned superior angles. These approaches offered a more complete assessment of supraspinous shape and revealed that the Homo fossa, with an intermediate superior angle position and moderate superoinferior expansion, is actually reminiscent of the African ape shape. Additionally, both Pongo and Hylobates were shown to have more compressed fossae, something that has not previously been identified through traditional analyses. Thus, the total morphological pattern of the Pongo supraspinous fossa is unique among hominoids, and possibly indicative of its distinctive locomotor habits. Am J Phys Anthropol 156:498–510, 2015. © 2015 Wiley Periodicals, Inc.     

Cleaning to corallivory: ontogenetic shifts in feeding ecology of tubelip wrasse

Cleaning and corallivory are two prevalent feeding modes among coral reef fishes. Some fishes exhibit ontogenetic shifts between cleaning behaviour and corallivory, suggesting some common physiological or morphological adaptations suited to these highly contrasting feeding habits. This study investigated ontogenetic changes in feeding behaviour for three species of coral-feeding wrasses (F: Labridae). All three species (Labrichthys unilineatus, Labropsis alleni and Diproctacanthus xanthurus) exhibited substantial changes in feeding behaviour from juvenile to adult size classes. While L. unilineatus was corallivorous throughout its entire life, the coral taxa consumed varied greatly with ontogeny. Labropsis alleni and D. xanthurus exhibited pronounced changes, with juveniles cleaning before a switch to obligate corallivory at approximately 3.5–5 cm. The ability of L. alleni and D. xanthurus to adopt a cleaning strategy may be a consequence and their close relationship to the obligate cleaner wrasses (Genus: Labroides).     

Divergent ontogenies of trophic morphology in two closely related haplochromine cichlids

Fish develop morphological specializations in their trophic and locomotor systems as a result of varying functional demands in response to environmental pressures at different life stages. These specializations should maximize particular performances in specialists, adapting them to their trophic and habitat niches at each ontogenetic stage. Because differential growth rates of the structural components comprised in the head are likely to be linked to the diet of a fish throughout its development, we investigated the ontogenetic development of two haplochromine cichlid species belonging to different trophic guilds. We employed geometric morphometric techniques to evaluate whether starting from morphologically similar fry they diverge into phenotypes that characterize trophic guilds and locomotor types. Our examination of overall body shape shows that certain specialized morphological features are already present in fry, whereas other traits diverge through ontogeny due to differences in species‐specific allometric variation. Allometric shape variation was found to be more relevant for the biter specialist than for the sucker morphotype. Our results confirm that phenotypic changes during ontogeny can be linked to dietary and habitat shifts in these fish. Furthermore, evidence for an integrated development of trophic and locomotor specializations in morphology was observed. J. Morphol. 276:860–871, 2015. © 2015 Wiley Periodicals, Inc.     

Patterns of intraspecific variation through ontogeny: a case study of the Cretaceous nautilid Eutrephoceras dekayi and modern Nautilus pompilius

The magnitude and ontogenetic patterns of intraspecific variation can provide important insights into the evolution and development of organisms. Understanding the intraspecific variation of organisms is also a key to correctly pursuing studies in major fields of palaeontology. However, intraspecific variation has been largely overlooked in ectocochleate cephalopods, particularly nautilids. Furthermore, little is known regarding the evolutionary pattern. Here, we present morphological data for the Cretaceous nautilid Eutrephoceras dekayi (Morton) and the modern nautilid Nautilus pompilius Linnaeus through ontogeny. The data are used to describe conch morphology and to elucidate the evolutionary patterns of intraspecific variation. We discovered a similar overall pattern of growth trajectories and the presence of morphological changes at hatching and maturity in both taxa. We also found that intraspecific variation is higher in earlier ontogeny than in later ontogeny in both taxa. The high variation in earlier ontogeny may imply increased flexibility in changing the timing of developmental events, which probably played an important role in nautilid evolution. We assume that the decrease in variation in later ontogeny reflects developmental constraints. Lastly, we compared the similarity/dissimilarity of ontogenetic patterns of variation between taxa. Results reveal that the similarity/dissimilarity of the ontogenetic pattern differs between E. dekayi and N. pompilius. We conclude that this shift in the ontogenetic pattern of variation may be rooted in changes in the developmental programme of nautilids through time. We propose that studying ontogenetic patterns of intraspecific variation can provide new insights into the evolution and development of organisms.     

Differential habitat use byCebus apella andSaimiri sciureus in central surinam

Cebus apella, the black-capped or tufted capuchin, andSaimiri sciureus, the squirrel monkey, are frequently found in mixed species feeding and foraging groups throughout tropical South America and have been reported previously to show marked differences in techniques of insect foraging. Individuals of these taxa observed in central Surinam show numerous additional species-specific differences in other aspects of habitat utilization including gross dietary preferences, utilization of forest strata, locomotor behavior and arboreal support preferences.Cebus apella is more frugivorous, frequents the middle and lower levels of the main canopy, is predominantly quadrupedal and moves on medium-sized arboreal supports. By contrast, the smallerSaimiri sciureus is more insectivorous, frequents the lower strata of the forest, is more saltatory and moves on the smallest arboreal supports. Many of these differences in habitat use are interrelated and accord with patterns of habitat use seen in other primate taxa. The differences betweenCebus apella andSaimiri sciureus also accord with the types of behavioral differences frequently associated with differences in body size.     

Postnatal temporal bone ontogeny in Pan,Gorilla, and Homo,and the implications for temporal bone ontogeny in Australopithecus afarensis

Assessments of temporal bone morphology have played an important role in taxonomic and phylogenetic evaluations of fossil taxa, and recent three‐dimensional analyses of this region have supported the utility of the temporal bone for testing taxonomic and phylogenetic hypotheses. But while clinical analyses have examined aspects of temporal bone ontogeny in humans, the ontogeny of the temporal bone in non‐human taxa is less well documented. This study examines ontogenetic allometry of the temporal bone in order to address several research questions related to the pattern and trajectory of temporal bone shape change during ontogeny in the African apes and humans. We further apply these data to a preliminary analysis of temporal bone ontogeny in Australopithecus afarensis. Three‐dimensional landmarks were digitized on an ontogenetic series of specimens of Homo sapiens, Pan troglodytes, Pan paniscus, and Gorilla gorilla. Data were analyzed using geometric morphometric methods, and shape changes throughout ontogeny in relation to size were compared. Results of these analyses indicate that, despite broadly similar patterns, African apes and humans show marked differences in development of the mandibular fossa and tympanic portions of the temporal bone. These findings indicate divergent, rather than parallel, postnatal ontogenetic allometric trajectories for temporal bone shape in these taxa. The pattern of temporal bone shape change with size exhibited by A. afarensis showed some affinities to that of humans, but was most similar to extant African apes, particularly Gorilla. Am J Phys Anthropol 151:630–642, 2013. © 2013 Wiley Periodicals, Inc.     

A multivariate approach reveals diversity of ontogenetic niche shifts across taxonomic and functional groups

1. Shifts in the fundamental and realised niche of individuals during their ontogeny are ubiquitous in nature, but we know little about what aspects of the niche change and how these changes vary across species within communities. However, this knowledge is essential to predict the dynamics of populations and communities and how they respond to environmental change.
2. Here I introduce a range of metrics to describe different aspects of shifts in the realised trophic niche of individuals based on stable isotopes. Applying this multi-variate approach to 2,272 individuals from 13 taxonomic and functional distinct species (Amphibia, Hemiptera, Coleoptera, Odonata) sampled in natural pond communities allowed me to: (1) describe and quantify the diversity of trophic niche shift patterns over ontogeny in multi-dimensional space, and (2) identify what aspects of ontogenetic shifts vary across taxa, and functional groups.
3. Results revealed that species can differ substantially in which aspects of the trophic niche change and how they change over ontogeny. Interestingly, patterns of ontogenetic niche shifts grouped in distinct taxonomic clusters in multi-variate space, including two distinct groups of predators (Hemiptera versus Odonata). Given the differences in traits (especially feeding mode) across groups, this suggests that differences in ontogenetic niche shifts across species could at least partially be explained by variation in traits and functional roles of species.
4. These results emphasise the importance of a multivariate approach to capture the large diversity of trophic niche shifts patterns possible in natural communities and suggest that differences in ontogenetic niche shifts follow general patterns.

     

Morphological evolution in Ceratophryinae frogs (Anura,Neobatrachia): the effects of heterochronic changes during larval development and metamorphosis

Heterochrony produces morphological change with effects in shape, size, and/or timing of developmental events of a trait related to an ancestral ontogeny. This paper analyzes heterochrony during the ontogeny of Ceratophryinae (Ceratophrys, Chacophrys, and Lepidobatrachus), a monophyletic group of South American frogs with larval development, and uses different approaches to explore their morphological evolution: (1) inferences of ancestral ontogenies and heterochronic variation from a cladistic analysis based on 102 morphological larval and adult characters recorded in ten anuran taxa; (2) comparisons of size, morphological variation, and timing (age) of developmental events based on a study of ontogenetic series of ceratophryines, Telmatobius atacamensis, and Pseudis platensis. We found Chacophrys as the basal taxon. Ceratophrys and Lepidobatrachus share most derived larval features resulting from heterochrony. Ceratophryines share high rates of larval development, but differ in rates of postmetamorphic growth. The ontogeny of Lepidobatrachus exhibits peramorphic traits produced by the early onset of metamorphic transformations that are integrated in an unusual larval morphology. This study represents an integrative examination of shape, size, and age variation, and discusses evolutionary patterns of metamorphosis. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 752–780.     

Ontogeny of the Massospondylus labyrinth: implications for locomotory shifts in a basal sauropodomorph dinosaur

Ontogeny is a vital aspect of life history sometimes overlooked in palaeontological studies. However, the changing geometry of anatomical structures during growth can be informative regarding ecological and functional reconstructions. The inner ear, or labyrinth, is an ideal ontogenetic study system because it has a strong functional signal in its morphology that is linked to locomotor mode. Yet almost nothing is known about labyrinth development in dinosaurs. We quantified labyrinth scale and geometry through ontogeny in the Early Jurassic dinosaur Massospondylus carinatus, which has an exceptional fossil record and is hypothesized to have undergone a gait change, from quadrupedal juvenile to bipedal adult. To test whether this putative locomotor shift is reflected in labyrinth morphology, computed microtomography (μCT) and propagation phase‐contrast synchrotron radiation microtomography (PPC‐SRμCT) were used to obtain labyrinths from eight specimens, ranging from near‐hatchling to adult. Labyrinths grow substantially but scale with slight negative allometry compared to skull length throughout ontogeny, the first time this has been documented in dinosaurs. Geometric morphometric analysis of the labyrinth using a sliding semilandmark approach shows some morphological change through ontogeny, but little evidence supporting a locomotor shift. These results have implications for our understanding of sauropodomorph development and provide a better understanding of dinosaur locomotory evolution.     

Are diminutive turtles miniaturized? The ontogeny of plastron shape in emydine turtles

Miniaturization, or the evolution of a dramatically reduced body size compared to related lineages, is an extraordinarily widespread phenomenon among metazoans. Evolutionary biologists have been fascinated by miniaturization because this transition has occurred numerous times, often among close relatives, providing a model system for studying convergent evolution and its underlying mechanisms. Much of the developmental work describing the ontogeny of miniature species suggests that paedomorphosis is the predominant avenue of miniaturization. Nevertheless, specific alterations to ontogeny appear highly variable, so that even related lineages with similar miniaturized traits produce those similarities via distinct ontogenetic paths. One major vertebrate group that has been overlooked in research on miniaturization is turtles. In the present study, we examined patterns of shape change in the plastron (the ventral part of the shell) over the course of ontogeny in a small clade of turtles (Emydinae) aiming to investigate whether two independently evolved diminutive members of the clade (Glyptemys muhlenbergii and Clemmys guttata) should be considered as miniaturized. We employ geometric morphometric methods to quantify the patterns of shape change these potentially miniaturized species and their relatives undergo during ontogeny, and use molecular phylogenetic trees to reconstruct ancestral conditions and provide information on the polarity of shape changes. We find that differing changes in ontogenetic parameters relative to ancestral conditions accompany the evolution of small size in emydines: G. muhlenbergii changes the duration of ontogeny and rate of shape change, whereas C. guttata changes growth rate. The observed ontogenetic repatterning of these species is reminiscent of changes in ontogeny and life history often found in miniaturized taxa. However, we conclude that C. guttata and G. muhlenbergii are not truly miniaturized because they still produce typical adult shell morphologies, and larger emydines display comparable ontogenetic flexibility. Because no emydines carry juvenile shell features forward into adulthood, we speculate that few, if any turtles, will show paedomorphic shell traits without corresponding changes in defensive strategy because such shells may offer insufficient protection. © 2013 The Linnean Society of London     

Phylogeny of Berosini (Coleoptera: Hydrophilidae,Hydrophilinae) based on larval and adult characters,and evolutionary scenarios related to habitat shift in larvae

Abstract A phylogenetic analysis of Berosini including 15 taxa, 11 of them belonging to Berosini (ingroup), was performed. Of the 58 characters used, 32 derive from the larval stages, and 26 from the adult stage. Two well‐supported clades are recognized, one comprising Hemiosus and Berosus, and the other comprising Derallus, Regimbartia and Allocotocerus. Several larval evolutionary trends are discussed: shifts to benthic and cryptic habits, morphological modifications and adaptations related to these habits, and morphological changes of the clypeolabrum and head appendages. A comparative table for the larval stages of the five genera is included.     

Application of the biogenetic law to behavioral ontogeny: a test using nest architecture in paper wasps

General principles derived from studies of morphological ontogeny are useful in ethology. Behavioral ontogeny may be interpreted from an holistic view in which a series of behaviors is treated as an ontogeny toward a larger, complex, behavioral product. If the component behaviors are defined broadly, many taxa may be compared to find general principles that are not evident when behaviors are dissected to their smallest recognizable units. Flow charts can illustrate such general ontogenetic sequences in a manner that shows what sorts of modifications have evolved from the general pattern. Certain changes may illustrate forms of ontogenetic evolution that are well known for morphological development, such as addition or embellishment of terminal ontogenetic steps, or compression of ontogeny by acceleration or deletion of early steps. The major modifications in nest construction behavior of 28 genera of paper wasps are presented to test the predictions of the biogenetic rule with respect to character polarity. Cladistic analyses of separate morphological and behavioral data sets show that polarity is accurately inferred with respect to the five major patterns of nest construction in paper wasps.     

Ontogenetic shifts of heart position in snakes

Heart position relative to total body length (TL) varies among snakes, with anterior hearts in arboreal species and more centrally located hearts in aquatic or ground‐dwelling species. Anterior hearts decrease the cardiac work associated with cranial blood flow and minimize drops in cranial pressure and flow during head‐up climbing. Here, we investigate whether heart position shifts intraspecifically during ontogenetic increases in TL. Insular Florida cottonmouth snakes, Agkistrodon conanti , are entirely ground‐dwelling and have a mean heart position that is 33.32% TL from the head. In contrast, arboreal rat snakes, Pantherophis obsoleta , of similar lengths have a mean heart position that is 17.35% TL from the head. In both species, relative heart position shifts craniad during ontogeny, with negative slopes = −.035 and −.021% TL/cm TL in Agkistrodon and Pantherophis , respectively. Using a large morphometric data set available for Agkistrodon (N = 192 individuals, 23–140 cm TL), we demonstrate there is an anterior ontogenetic shift of the heart position within the trunk (= 4.56% trunk length from base of head to cloacal vent), independent of head and tail allometry which are both negative. However, in longer snakes > 100 cm, the heart position reverses and shifts caudally in longer Agkistrodon but continues toward the head in longer individuals of Pantherophis . Examination of data sets for two independent lineages of fully marine snakes (Acrochordus granulatus and Hydrophis platurus ), which do not naturally experience postural gravity stress, demonstrate both ontogenetic patterns for heart position that are seen in the terrestrial snakes. The anterior migration of the heart is greater in the terrestrial species, even if TL is standardized to that of the longer P. obsoleta , and compensates for about 5 mmHg gravitational pressure head if they are fully upright.     

Diet and morphology through ontogeny of the nonindigenous Mayan cichlid ‘<Emphasis Type="Italic">Cichlasoma</Emphasis> (<Emphasis Type="Italic">Nandopsis</Emphasis>)’ <Emphasis Type="Italic">urophthalmus</Emphasis> (Günther 1862) in southern Florida

We evaluated diet and morphology through ontogeny for a freshwater population of the Mayan cichlid Cichlasoma (Nandopsis) urophthalmus (Günther 1862) in Floridas Big Cypress National Preserve. This species is a generalist predator throughout ontogeny. Fish remained the primary prey item throughout ontogeny, but there was a shift from detritus and ostracods among juveniles to algae, gastropods (snails), decapods, Hymenoptera, and adult Diptera among adults. All morphological variables grew isometrically except total molariform tooth area and pharyngeal jaw mass, which exhibited positive allometry. Despite a moderately robust adult pharyngeal jaw apparatus, this species does not specialize on hard prey at this south Florida site. Compared to its native range in Mexico, fish in Florida have undergone a pronounced niche shift with the diet being dominated by fish and snails, probably due to greater availability. The invasive success of C. urophthalmus does not appear to be related to ontogenetic morphological shifts or dietary specialization. Rather, its successful and rapid colonization of southern Florida might in part be related to its generalized and opportunistic feeding habits and morphology.     

Ontogeny of the eodiscoid trilobite Tsunyidiscus acutus from the Lower Cambrian of South China

Abstract: The morphology and ontogeny of the eodiscid trilobite Tsunyidiscus acutus Sun is described on the basis of numerous calcified specimens collected from the Lower Cambrian Shuijingtuo Formation in Yichang and Changyang, Hubei Province, South China. An ontogenetic series is established based on the articulated material including the previously unknown protaspides and meraspides (degrees 0 and 1). The material, revealing some prominent morphological changes such as the number of pygidial axial rings, genal spines retained throughout ontogeny and pygidial pleurae from furrowed to unfurrowed, enables a discussion on the trunk segmentation schedule, indicating that somitogenesis and tagmosis occurred independently during the ontogenetic development of T. acutus.     

Musculoskeletal scapular correlates of plantigrade and acrobatic positional activities in Papio cynocephalus anubis and Macaca fascicularis

This study investigates several musculoskeletal scapular correlates of quadrupedal behavior in predominantly plantigrade, Papio cynocephalus anubis and acrobatic, less plantigrade, Macaca fascicularis. Positional behaviors differ in these two primates reflecting the amount of time spent emphasizing one or the other of these captive behavioral regimes. Stresses associated with particular patterns of behavior result in different scapular morphologies. Papio exhibits a significantly broader scapula with a more dorsoventrally curved blade accompanying an enlarged teres major muscle. The supraspinous fossa is wider in Papio, while the infraspinous/teres major attachment is wider in Macaca. Angular measurements reflect the breadth dimension of the various fossae. These results utilize two species of primates to extend a methodology developed in previous studies and to suggest that a predictable interdependence occurs between scapular dimensions and certain behavioral activities.     

The ontogeny of personality traits in the desert funnel‐web spider,Agelenopsis lisa (Araneae: Agelenidae)

Trait consistency over time is one of the cornerstones of animal personality. Behavioral syndromes are the result of correlations between behaviors. While repeatability in behavior is not a requirement for behavioral syndromes, the two concepts studied together provide a more comprehensive understanding of how behavior can change over ontogeny. The roles of ontogenetic processes in the emergence of personality and behavioral syndromes have received much individual attention. However, the characterization of both individual trait consistency and behavioral syndromes across both sexes, as in our study, has been relatively rare. Ontogeny refers to changes that occur from conception to maturation, and juveniles might be expected to undergo different selection pressures than sexually mature individuals and also will experience profound changes in hormones, morphology, and environment during this period. In this study, we test for behavioral trait consistency and behavioral syndromes across six time points during ontogenetic development in the desert funnel‐web spider (Agelenopsis lisa). Our results indicate behavioral traits generally lack consistency (repeatability) within life stages and across ontogeny. However, penultimate males and mature females do exhibit noticeable mean‐level changes, with greater aggressive responses toward prey, shorter latencies to explore their environment and in the exhibition of risk‐averse responses to predatory cues. These traits also show high repeatability. Some trait correlations do exist as well. In particular, a strong correlation between aggressiveness toward prey and exploration factors is observed in mature males. However, because correlations among these factors are unstable across ontogeny and vary in strength over time, we conclude that behavioral syndromes do not exist in this species. Nevertheless, our results indicate that increased consistency, increasing average trait values, and varying correlations between traits may coincide with developmentally important changes associated with sexual maturation, albeit at different time points in males and females. This period of the life cycle merits systematic examination across taxa.     

The accelerating anuran: evolution of locomotor performance in cane toads (Rhinella marina,Bufonidae) at an invasion front

As is common in biological invasions, the rate at which cane toads (Rhinella marina) have spread across tropical Australia has accelerated through time. Individuals at the invasion front travel further than range-core conspecifics and exhibit distinctive morphologies that may facilitate rapid dispersal. However, the links between these morphological changes and locomotor performance have not been clearly documented. We used raceway trials and high-speed videography to document locomotor traits (e.g. hop distances, heights, velocities, and angles of take-off and landing) of toads from range-core and invasion-front populations. Locomotor performance varied geographically, and this variation in performance was linked to morphological features that have evolved during the toads'' Australian invasion. Geographical variation in morphology and locomotor ability was evident not only in wild-caught animals, but also in individuals that had been raised under standardized conditions in captivity. Our data thus support the hypothesis that the cane toad''s invasion across Australia has generated rapid evolutionary shifts in dispersal-relevant performance traits, and that these differences in performance are linked to concurrent shifts in morphological traits.     

What's Your Angle? Size Correction and Bar–Glenoid Orientation in “Lucy” (A.L. 288-1)

There has been much debate as to the locomotor repertoire of Lucy (A.L. 288-1) and other specimens of Australopithecus afarensis, ranging from fully committed bipeds to species that spent a significant time in the trees as well as on the ground. We examined the bar–glenoid angle, a character purported to indicate arboreal propensities, and its implications for this specific debate and the more general challenge of extracting behavioral information from fossils. We examined the bar–glenoid angle in ontogenetic samples of Pan paniscus, Pan troglodytes, Gorilla gorilla gorilla, Gorilla gorilla beringei, Pongo pygmaeus, Homo sapiens, and A.L. 288-1 (Lucy). We found that there is no allometry in the bar–glenoid angle for the great apes, but a weak correlation for humans. Moreover, the data scatters for the African apes and humans converge at the smaller size ranges, and Lucy's value for bar–glenoid angle falls precisely in this area of overlap. Therefore, we conclude that the bar–glenoid angle is not tightly correlated with function and, as such, cannot be used as a morphological signal of arboreal behavior, especially in the smaller size ranges, at which arboreal and nonarboreal species overlap. Our work does not resolve issues concerning Lucy's precise locomotor repertoire but adds new information to consider. The total morphological pattern, plus an appreciation of the underlying variance in morphological and behavioral characters in extant species, is key for making functional inferences from the morphology of fossils.     

Are ontogenetic shifts in foliar structure and resource acquisition spatially conditioned in tank‐bromeliads?

The phenotypic plasticity of plants has been explored as a function of either ontogeny (apparent plasticity) or environment (adaptive plasticity), although few studies have analyzed these factors together. In the present study, we take advantage of the dispersal of Aechmea mertensii bromeliads by Camponotus femoratus or Pachycondyla goeldii ants in shaded and sunny environments, respectively, to quantify ontogenetic changes in morphological, foliar, and functional traits, and to analyze ontogenetic and ant species effects on 14 traits. Most of the morphological (plant height, number of leaves), foliar (leaf thickness, leaf mass area, total water content, trichome density), and functional (leaf δ¹³C) traits differed as a function of ontogeny. Conversely, only leaf δ¹⁵N showed an adaptive phenotypic plasticity. On the other hand, plant width, tank width, longest leaf length, stomatal density, and leaf C concentration showed an adaptation to local environment with ontogeny. The exception was leaf N concentration, which showed no trend at all. Aechmea mertensii did not show an abrupt morphological modification such as in heteroblastic bromeliads, although it was characterized by strong, size‐related functional modifications for CO₂ acquisition. The adaptive phenotypic variation found between the two ant species indicates the spatially conditioned plasticity of A. mertensii in the context of insect‐assisted dispersal. However, ant‐mediated effects on phenotypic plasticity in A. mertensii are not obvious because ant species and light environment are confounding variables. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 299–312.