scholarly journals On dangerous ground: the evolution of body armour in cordyline lizards

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180513 ◽  
Author(s):  
Chris Broeckhoven ◽  
Yousri El Adak ◽  
Cang Hui ◽  
Raoul Van Damme ◽  
Theodore Stankowich
Keyword(s):  
Predation Risk ◽  
Comparative Studies ◽  
Comparative Methods ◽  
Phylogenetic Comparative Methods ◽  
Arid Environments ◽  
Animal Body ◽  
Environmental Correlates ◽  
Selective Pressures ◽  
Body Armour ◽  
Differential Predation

Animal body armour is often considered an adaptation that protects prey against predatory attacks, yet comparative studies that link the diversification of these allegedly protective coverings to differential predation risk or pressure are scarce. Here, we examine the evolution of body armour, including spines and osteoderms, in Cordylinae, a radiation of southern African lizards. Using phylogenetic comparative methods, we attempt to identify the ecological and environmental correlates of body armour that may hint at the selective pressures responsible for defensive trait diversification. Our results show that species inhabiting arid environments are more likely to possess elaborated body armour, specifically osteoderms. We did not find any effect of estimated predation pressure or risk on the degree of body armour. These findings suggest that body armour might not necessarily evolve in response to direct interactions with predators, but rather as a result of increased habitat-mediated predation risk. Furthermore, we discuss the possibility that osteoderms might have been shaped by factors unrelated to predation.

scholarly journals The evolution of tail weaponization in amniotes

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172299 ◽  
Author(s):  
Victoria M. Arbour ◽  
Lindsay E. Zanno
Keyword(s):  
Life History ◽  
Evolutionary History ◽  
Phenotypic Diversity ◽  
Large Body ◽  
Phylogenetic Comparative Methods ◽  
Rare Form ◽  
Large Body Size ◽  
Selective Pressures ◽  
Body Armour ◽  
Predator Defence

Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not well understood. Here, we investigate the evolution of tail weaponry in amniotes, a rare form of weaponry that nonetheless evolved independently among a broad spectrum of life including mammals, turtles and dinosaurs. Using phylogenetic comparative methods, we test for links between morphology, ecology and behaviour in extant amniotes known to use the tail as a weapon, and in extinct taxa bearing osseous tail armaments. We find robust ecological and morphological correlates of both tail lashing behaviour and bony tail weaponry, including large body size, body armour and herbivory, suggesting these life-history parameters factor into the evolution of antipredator behaviours and tail armaments. We suggest that the evolution of tail weaponry is rare because large, armoured herbivores are uncommon in extant terrestrial faunas, as they have been throughout evolutionary history.

scholarly journals Explaining large-scale patterns of vertebrate diversity

2015 ◽  
Vol 11 (7) ◽  
pp. 20150506 ◽  
Author(s):  
John J. Wiens
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Comparative Methods ◽  
Phylogenetic Comparative Methods ◽  
Metabolic Rates ◽  
Diversification Rates ◽  
Richness Patterns ◽  
Current Species

The major clades of vertebrates differ dramatically in their current species richness, from 2 to more than 32 000 species each, but the causes of this variation remain poorly understood. For example, a previous study noted that vertebrate clades differ in their diversification rates, but did not explain why they differ. Using a time-calibrated phylogeny and phylogenetic comparative methods, I show that most variation in diversification rates among 12 major vertebrate clades has a simple ecological explanation: predominantly terrestrial clades (i.e. birds, mammals, and lizards and snakes) have higher net diversification rates than predominantly aquatic clades (i.e. amphibians, crocodilians, turtles and all fish clades). These differences in diversification rates are then strongly related to patterns of species richness. Habitat may be more important than other potential explanations for richness patterns in vertebrates (such as climate and metabolic rates) and may also help explain patterns of species richness in many other groups of organisms.

scholarly journals Особенности бурятских вариантов Гэсэриады

2021 ◽  
Vol 14 (4) ◽  
pp. 847-857
Author(s):  
Ludmila S. Dampilova ◽  
◽  
Erzhena B. Ayusheeva
Keyword(s):  
Central Asia ◽  
Comparative Studies ◽  
Traditional Culture ◽  
Comparative Methods ◽  
Authentic Texts ◽  
Detailed Review ◽  
Central Asian ◽  
Introductory Part ◽  
The Common ◽  
First Time

Introduction. The article aims to analyze Buryat versions of the epic Geser to identify their local features. It includes a detailed review not only of published texts, but also of manuscripts stored in the archives of Buryatia. For the first time, the regional versions of Geser are systematically examined as a necessary stage for further comparative studies of the genesis and transformation of epic traditions in Central Asia. Methods. The work uses comparative-historical and comparative methods of analysis. Of these, the latter was of key importance in comparing the versions of the epic that differ in terms of the place of their origin and temporal parameters. Results and discussion. The analysis began with a detailed discussion of published authentic texts of Geser represented by the Ekhirit-Bulagat and Ungin versions. Then, the features of archival versions of the epic are systematized and defined. The previous work on the plot composition and characters of each individual text is thoroughly compared to finally identify the features of the Buryat versions of the epic. Conclusion. The authors argue that the Ungin versions are quite close to the Mongolian ones, while the Ekhirit-Bulagat version, in their opinion, stands apart both in terms of their composition and themes. The introductory part of the uliger, a mythological prologue with a shamanic pantheon of deities, is characteristic only of the Buryat versions of Geser. Also, as far as the Western Buryat version is concerned, it may be pointed out that the influence of Buddhist teachings, which were not widespread in the heyday of the epic, was minimum. Of relevance are also the contaminations of the common Mongolian storytelling traditions with the characteristic motifs of the Central Asian epic. The identification of specific features of the local versions of Geser may expand our understanding of the specifics of the national epic as one of the main manifestations of traditional culture.

Vegetation height and egg coloration differentially affect predation rate and overheating risk: an experimental test mimicking a ground-nesting bird

2012 ◽  
Vol 90 (6) ◽  
pp. 694-703 ◽  
Author(s):  
H. Gillis ◽  
B. Gauffre ◽  
R. Huot ◽  
V. Bretagnolle
Keyword(s):  
Predation Risk ◽  
Breeding Season ◽  
Nest Site Selection ◽  
Artificial Nests ◽  
Vegetation Height ◽  
Selective Pressures ◽  
Wide Range ◽  
Nest Microclimate ◽  
Egg Coloration ◽  
Ground Nesting

Avian eggs need to be laid in protected environments to develop and survive. Nest predation is known as the main cause of breeding failure for many birds, but nest microclimate conditions are also important for embryo development. These two selective pressures are particularly marked in ground-nesting birds. Vegetation height has been shown to be a critical factor for nest-site selection in ground-nesting birds because it can counteract predation and overheating simultaneously. It is therefore difficult to disentangle the respective influences of these risks on selection of a particular nest vegetation height. To develop a conceptual framework for understanding and predicting the relative effects of vegetation on predation and nest microclimate during a breeding season, we used vegetation height to manipulate differentially these two risks. We therefore exposed artificial nests to a wide range of vegetation heights, replicated the experimental tests during spring, and manipulated egg color to estimate predation risk. We confirmed that tall vegetation is relevant to protect unattended eggs against both risks. Whereas predation risk is stable for a given vegetation height, overheating risk presents inter- and intra-seasonal variations. Therefore, over a breeding season, for a given vegetation height, the respective strengths of the two risks are unbalanced and depends on egg coloration. The breeding strategy of ground-nesting birds thus should have been shaped by both selective pressures, but the ultimate choice may depend on the species-specific laying dates and alternative behavioral strategies for protecting the clutch. This study provides new perspectives to investigate avian parental behaviour.

scholarly journals Phylogenetic Comparative Methods and the Evolution of Multivariate Phenotypes

2019 ◽  
Vol 50 (1) ◽  
pp. 405-425 ◽  
Author(s):  
Dean C. Adams ◽  
Michael L. Collyer
Keyword(s):  
Phylogenetic Analysis ◽  
Evolutionary Biology ◽  
Generalized Least Squares ◽  
Comparative Methods ◽  
High Dimensional ◽  
Phenotypic Integration ◽  
Phylogenetic Comparative Methods ◽  
Evolutionary Trends ◽  
Phenotype Space ◽  
Multivariate Phenotypes

Evolutionary biology is multivariate, and advances in phylogenetic comparative methods for multivariate phenotypes have surged to accommodate this fact. Evolutionary trends in multivariate phenotypes are derived from distances and directions between species in a multivariate phenotype space. For these patterns to be interpretable, phenotypes should be characterized by traits in commensurate units and scale. Visualizing such trends, as is achieved with phylomorphospaces, should continue to play a prominent role in macroevolutionary analyses. Evaluating phylogenetic generalized least squares (PGLS) models (e.g., phylogenetic analysis of variance and regression) is valuable, but using parametric procedures is limited to only a few phenotypic variables. In contrast, nonparametric, permutation-based PGLS methods provide a flexible alternative and are thus preferred for high-dimensional multivariate phenotypes. Permutation-based methods for evaluating covariation within multivariate phenotypes are also well established and can test evolutionary trends in phenotypic integration. However, comparing evolutionary rates and modes in multivariate phenotypes remains an important area of future development.

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