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FIG. 9 in Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae

FIG. 9. — Dictyla rasilis (Drake & Maa, 1955), fifth larvae habitus. Scale bar: 1 mm.

FIG. 7 in Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae

FIG. 7. — Corythucha mcelfreshi Drake, 1921, fifth larvae habitus. Scale bar: 1 mm.

FIG. 5 in Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae

FIG. 5. — Corythauma ayyari (Drake, 1933), fifth larvae habitus. Scale bar: 1 mm.

FIG. 4 in Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae

FIG. 4. — Atheas insignis Heidmann, 1909, fifth larvae habitus. Scale bar: 1 mm.

FIG. 1 in Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae

FIG. 1. — Amblystira peltogyne Drake & Hambleton, 1935, fifth larvae habitus. Scale bar: 1 mm.

opencc-by-4.0Mar 2006View details →

Fig. 4 in Morphology and distribution of the cave knifefish Eigenmannia vicentespelaea Triques, 1996 (Gymnotiformes: Sternopygidae) from Central Brazil, with an expanded diagnosis and comments on subterranean evolution

Fig. 4. Regression between OD and LEA in Eigenmannia vicentespelaea (n = 25).

opencc-by-4.0Sep 2009View details →

Figure 8 in The radiation of red colobus monkeys (Primates, Colobinae): morphological evolution in a clade of endangered African primates

Figure 8. Males. Phenogram of the species mean shapes. See Figure 7 for further explanation.

opencc-zeroSep 2021View details →

Adding the third dimension to studies of parallel evolution of morphology and function: an exploration based on parapatric lake-stream stickleback

Recent methodological advances have led to a rapid expansion of evolutionary studies employing three-dimensional landmark-based geometric morphometrics (GM). GM methods generally enable researchers to capture and compare complex shape phenotypes, and to quantify their relationship to environmental gradients. However, some recent studies have shown that the common, inexpensive, and relatively rapid two-dimensional GM methods can distort important information and produce misleading results because they cannot capture variation in the depth (Z) dimension. We use micro-CT scanned threespine stickleback (Gasterosteus aculeatus Linnaeus, 1758) from six parapatric lake-stream populations on Vancouver Island, British Columbia, to test whether the loss of the depth dimension in 2D GM studies results in misleading interpretations of parallel evolution. Using joint locations described with 2D or 3D landmarks, we compare results from separate 2D and 3D shape spaces, from a combined 2D-3D shape space, and from estimates of biomechanical function. We show that, although shape is distorted enough in 2D projections to strongly influence the interpretation of morphological parallelism, estimates of biomechanical function are relatively robust to the loss of the Z dimension.

opencc-zeroOct 2021View details →

Analyzing disparity and rates of morphological evolution with model-based phylogenetic comparative methods

Understanding variation in rates of evolution and morphological disparity is a goal of macroevolutionary research. In a phylogenetic comparative methods framework, we present three explicit models for linking the rate of evolution of a trait to the state of another evolving trait. This allows testing hypotheses about causal influences on rates of phenotypic evolution with phylogenetic comparative data. We develop a statistical framework for fitting the models with generalized least-squares regression, and use this to discuss issues and limitations in the study of rates of evolution more generally. We show that the power to detect effects on rates of evolution is low in that even strong causal effects are unlikely to explain more than a few percent of observed variance in disparity. We illustrate the models and issues by testing if rates of beak-shape evolution in birds are influenced by brain size, as may be predicted from a Baldwin effect in which presumptively more behaviorally flexible large-brained species generate more novel selection on themselves leading to higher rates of evolution. From an analysis of morphometric data for 645 species we find evidence that both macro- and microevolution of the beak are faster in birds with larger brains, but with the caveat that there are no consistent effects of relative brain size.

opencc-zeroNov 2022View details →

Phenotypic traits evolution and morphological traits associated with echolocation calls in cryptic horseshoe bats (Rhinolophidae)

Bats provide an excellent case study for studying evolution due to their remarkable flight and echolocation capabilities. In this study, we sought to understand the phenotypic evolution of key traits in Rhinolophidae (horseshoe bats) using phylogenetic comparative methods. We aim to test the phylogenetic signals of traits and evaluated the best-fit evolutionary models given the data for each trait considering different traits may evolve under different models (i.e., Brownian Motion (BM), Ornstein-Uhlenbeck (OU) and Early Burst (EB)) and reconstruct ancestral character states. We examined how phenotypic characters are associated with echolocation calls and minimum detectable prey size. We measured 34 traits of 10 Asian rhinolophids species (187 individuals). We found that the majority of traits showed a high phylogenetic signal based on Blomberg's K and Pagel's λ, but each trait may evolve under different evolutionary models. Sella traits were shown to evolve under stabilizing selection based on OU models, indicating sella traits have the tendency to move forward along the branches toward some medial value in equilibrium. Our findings highlight the importance of sella characters in association with echolocation call emissions in Rhinolophidae, as calls are important for spatial cognition and also influence dietary preferences. Minimum detectable prey size in Rhinolophidae was associated with call frequency, bandwidth, call duration, wingspan and wing surface area. Ultimately, understanding trait evolution requires sensitivity due to the differential selective pressures which may apply to different characteristics.

opencc-zeroDec 2022View details →

Testing the predictability of morphological evolution in contrasting thermal environments

Gaining the ability to predict population responses to climate change is a pressing concern. Using a 'natural experiment', we show that testing for divergent evolution in wild populations from contrasting thermal environments provides a powerful approach, and likely an enhanced predictive power for responses to climate change. Specifically, we used a unique study system in Iceland, where freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) are found in waters warmed by geothermal activity, adjacent to populations in ambient-temperature water. We focused on morphological traits across six pairs from warm and cold habitats. We found that fish from warm habitats tended to have a deeper mid-body, a sub-terminally orientated jaw, steeper craniofacial profile, and deeper caudal region relative to fish from cold habitats. Our common garden experiment showed that most of these differences were heritable. Population age did not appear to influence the magnitude or type of thermal divergence, but similar types of divergence between thermal habitats were more prevalent across allopatric than sympatric population pairs. These findings suggest that morphological divergence in response to thermal habitat, despite being relatively complex and multivariate, are predictable to a degree<a name="_Hlk345127"></a>. Our data also suggests that the potential for migration of individuals between different thermal habitats may enhance non-parallel evolution and reduce our ability to predict responses to climate change.

opencc-zeroDec 2022View details →

Songbirds of the Americas show uniform morphological evolution despite heterogeneous diversification

Studying the relationship between diversification and functional trait evolution among broadly co-occurring clades can shed light on interactions between ecology and evolutionary history. However, evidence from many studies is compromised because of their focus at overly broad geographic or narrow phylogenetic scales. We addressed these limitations by studying 46 independent, biogeographically-delimited clades of songbirds that dispersed from the Eastern Hemisphere into the Americas and assessed 1) whether diversification has varied through time and/or among clades within this assemblage, 2) the extent of heterogeneity in clade-specific morphological trait disparity, and 3) whether morphological disparity among these clades is consistent with a uniform diversification model. We found equivalent support for constant rates of birth-death and density-dependent speciation processes, with notable outliers having significantly fewer or more species than expected given their age. We also found substantial variation in morphological disparity among these clades, but that variation was broadly consistent with uniform evolutionary rates, despite the existence of diversification outliers. These findings indicate relatively continuous, ongoing morphological diversification within all clades, arguing against conceptual models of adaptive radiation. Additionally, they suggest surprisingly consistent diversification among the majority of these clades, despite tremendous variance in colonization history, habitat valences, and trophic specializations that exist among continental clades of organisms.

opencc-by-4.0May 2022View details →

Data from: Experimental evolution in the cyanobacterium Trichormus variabilis: increases in size and morphological diversity.

Data deposited in this repository was collected during the investigation entitled; Experimental evolution in the cyanobacterium Trichormus variabilis: increases in size and morphological diversity. Using experimental evolution, we selected the filamentous cyanobacteria T. viariabilis larger size by means of settling selection. The experimental design consisted of 20 replicate populations, ten propagated without selection, and ten populations were transferred by means of settling selection. Settling selection consisted of centrifugation of a 1.5 mL sample of a 72h grown population at 100 g for 30 seconds and transferring the bottom 100 µL of the 1.5 mL microcentrifuge tube to fresh media. The other ten were propagated in batch culture transferring 100 µL of a mixed population to fresh media after 72h growth. The selection experiment was carried out for 45 transfer cycles.  Data present the morphology, size, growth, and settling rate of the populations over time, and at the end of the experiment, transfer cycle 45. The population's growth cycle was assessed at transfer 45 over two transfer cycles. Populations were assessed by image analysis of populations' microphotographs.  Morphological classification of the evolved morphologies was assessed by a double-blind volunteer panel and by objective analyses of the population's microphotographs. Canonical evolved Cluster and Tangle morphologies were compared using Principal Component Analysis.  Lyticase and 2% β-glucuronidase/arylsulfatase treatment of the populations enables the assessment of heritability of the evolved morphologies starting with single cells.

opencc-zeroJan 2023View details →

Phenotypic and ecological data from: Widespread convergent morphological evolution within the largest family of songbirds

Although convergence is a common evolutionary phenomenon, few studies have quantified its prevalence across a large, densely sampled clade. Large-scale phylogenies and the advent of novel computational methods facilitate more robust identification of convergent events and their statistical significance. The tanagers (Aves: Thraupidae), the largest family of songbirds, offer an excellent opportunity to study the extent of phenotypic convergence in response to similar ecological pressures on a continental scale. To investigate convergence in the group, we used the largest phylogenetic and multivariate morphological dataset to date for the clade. First, we used phylogenetic comparative analyses to show a correlation between diet and aspects of bill shape. We then investigated our dataset for the presence and magnitude of convergent events and assessed significance through simulations and modeling analyses. Overall, we found that around half (45.3%) of species and clades we tested have converged in morphological space more than would be expected by chance alone. Our study shows that across Thraupidae, various bill shapes have evolved convergently to fill multiple distinct sections of ecological niche space, reflecting a signal of ecological opportunity and structural constraints.

opencc-zeroFeb 2023View details →

Perianth evolution and implications for generic delimitation in the Eucalypts (Myrtaceae): DNA sequences, morphological data

Eucalyptus was traditionally defined by the operculate perianth—hence the generic name (Latin, meaning "well-covered"). But after previous phylogenetic analysis placed Angophora, which has free sepals and petals, as sister to the bloodwood eucalypts, the latter were segregated into a new genus, Corymbia. We made a targeted capture of 101 low-copy nuclear exons from 392 samples representing 329 species-level taxa. The phylogeny was estimated using maximum likelihood (IQtree and RAxML) and the multi-species coalescent (Astral). We tested alternative relationships between four genera within Eucalypteae (Arillastrum, Angophora, Eucalyptus, Corymbia) at each of two nodes critical to generic delimitation using Shimodaira's Approximately Unbiased (AU) test. Monophyly of Arillastrum + (Corymbia + Angophora) relative to Eucalyptus sensu stricto was supported whereas monophyly of Corymbia relative to Angophora was decisively rejected. These results indicate that either Eucalyptus should be expanded to include all four genera or Corymbia should be split into two. All of the alternative relationships among the four currently recognised genera imply homoplasy in perianth evolution, specifically with respect to origins of the bud cap (operculum or calyptra), which has been traditionally used to define Eucalyptus. Inferred evolutionary transitions in perianth traits are generally congruent with divergences between major clades with a single exception: expression of separate sepals and petals in Angophora, which is nested within the operculate genus Corymbia, appears prima facie to be a reversal to the plesiomorphic perianth structure. Strictly, this is not a reversal because the petals of Angophora and Corymbia have a novel compound keel-and-limb structure that is absent in the outgroups. This structure is evident in early development, irrespective of whether the petals remain free or later become part of an operculum. Many of the currently recognised infrageneric taxa down to sectional level (and below in some cases) are well-supported by the sequence data and definable by morphological traits. Inclusion of Angophora within Eucalyptus was formally proposed two decades ago but did not gain acceptance. Here instead, we formally raise Corymbia subg. Blakella to genus rank and make the relevant new combinations.

opencc-zeroApr 2023View details →

Three-dimensional morphology of the biramous appendages in Isoxys from the early Cambrian of South China, and its implications for early euarthropod evolution

Early euarthropod evolution involved a major transition from lobopodian-like taxa to organisms featuring a segmented, well-sclerotized trunk (arthrodization) and limbs (arthropodization). However, the precise origin of a completely arthrodized trunk and arthropodized ventral biramous appendages remain controversial, as well as the early onset of anterior-posterior limb differentiation in stem-group euarthropods. New fossil material and micro-computed tomography inform the detailed morphology of the arthropodized biramous appendages in the carapace-bearing euarthropod Isoxys curvirostratus from the early Cambrian Chengjiang biota. In addition to well-developed grasping frontal appendages. I. curvirostratus possesses two batches of morphologically and functionally distinct biramous limbs. The first batch consists of four pairs of short cephalic appendages with robust endites with a feeding function, whereas the second batch has more elongate trunk appendages for locomotion. Critically, our new material shows that the trunk of I. curvirostratus was not arthrodized. The results of our phylogenetic analyses recover isoxyids as some of the earliest branching sclerotized euarthropods, and strenghens the hypothesis that arthropodized biramous appendage evolved before full body arthrodization.

opencc-zeroJun 2023View details →

Data from: Experimentally simulating the evolution-to-ecology connection: Divergent predator morphologies alter natural food webs

The idea that changing environmental conditions drive adaptive evolution is a pillar of evolutionary ecology. But, the opposite—that adaptive evolution alters ecological processes—has received far less attention yet is critical for eco-evolutionary dynamics. We assessed the ecological impact of divergent values in a key adaptive trait using 16 populations of the brown anole lizard (Anolis sagrei). Mirroring natural variation, we established islands with short- or long-limbed lizards at both low and high densities. We then monitored changes in lower trophic levels, finding that on islands with short-limbed lizards at high-density, web spiders decreased and plants grew more via an indirect positive effect, likely through an herbivore-mediated trophic cascade. Our experiment provides strong support for evolution-to-ecology connections in nature, likely closing an otherwise well-characterized eco-evolutionary feedback loop.

opencc-zeroJun 2023View details →

Astyanax cavefish body shape coordinates from: Phylogeographic relationships and morphological evolution between cave and surface Astyanax mexicanus populations (De Fillipi 1853) (Actinopterygii, Characidae)

The Astyanax mexicanus complex includes two different morphs, a surface and a cave-adapted ecotype, found at three mountain ranges in Northeastern Mexico: Sierra de El Abra, Sierra de Guatemala, and Sierra de la Colmena (Micos). Since their discovery, multiple studies have attempted to characterize the timing and the number of events that gave rise to the evolution of these cave-adapted ecotypes. Here, using RAD-seq and genome-wide sequencing, we assessed the phylogenetic relationships, genetic structure, and gene flow events between the cave and surface Astyanax mexicanus populations, to estimate the time and mode of evolution of the cave-adapted ecotypes. We also evaluated the body shape evolution across different cave lineages using geometric morphometrics to examine the role of phylogenetic signal vs. environmental pressures. We found strong evidence of parallel evolution of cave-adapted ecotypes derived from two separate lineages of surface fish and hypothesize that there may be up to four independent invasions of caves from surface fish. Moreover, a strong congruence between the genetic structure and geographic distribution was observed across the cave populations, with the Sierra de Guatemala the region exhibiting most genetic drift among the cave populations analyzed. Interestingly, we found no evidence of phylogenetic signal in body shape evolution, but we found support for parallel evolution in body shape across independent cave lineages, with cavefish from the Sierra de El Abra reflecting the most divergent morphology relative to surface and other cavefish populations.

opencc-zeroAug 2023View details →

Data from: Downclimbing and the evolution of ape forelimb morphologies

Hominoids (non-human apes and hominins) are distinct from cercopithecoid monkeys in possessing more flexible forelimb joints, including high excursion angles at the shoulder and elbow. Both vertical climbing and forelimb suspension have been hypothesized to explain these skeletal differences, but field kinematic studies have found few differences in forelimb excursion during vertical climbs between chimpanzees and monkeys. Previous studies have focused largely on ascent (upclimbing) mechanics, while kinematic strategies employed during descents (downclimbs) are usually ignored. Here, we test the role that vertical climbing directionality plays in patterns of forelimb joint kinematics in wild populations of chimpanzees (Pan troglodytes) and sooty mangabeys (Cercocebus atys). We found that vertical descent produces greater degrees of elbow extension and shoulder flexion in chimpanzees compared to their vertical ascents, a pattern not shared with mangabeys. Chimpanzees used their forelimbs in kinematically similar ways to mangabeys during ascents; however, descent involved greater elbow extension and greater shoulder flexion in chimpanzees. Our results support functional hypotheses emphasizing the role vertical climbing–and specifically descent– plays in the evolution of increased forelimb mobility in apes.