scholarly journals A simple index to quantify and compare the magnitude of intraspecific geographic plumage colour variation in typical antbirds (Aves: Passeriformes: Thamnophilidae)

2020 ◽  
Vol 130 (2) ◽  
pp. 239-246
Author(s):  
Rafael S Marcondes ◽  
Robb T Brumfield

Abstract Intraspecific geographic phenotypic variation is a crucial theme in evolutionary biology. Comparing its magnitude across species can provide insights into its ecological and genetic correlates. Here, we developed an index, which we dub the V index, to quantify intraspecific plumage colour variation in typical antbirds (Thamnophilidae), a family which has long interested ornithologists due to a high prevalence of intraspecific variation. The V index is based on a bivariate colour space defined by brightness and redness. Its value for each species equals the mean area occupied by each of its subspecies in that colour space, divided by the area of the species. Lower values indicate greater intraspecific geographic variation. Based on this index, Thamnophilus caerulescens (Variable Antshrike) was exceptionally geographically variable compared to other thamnophilids, as previously suggested based on qualitative evidence. In general, we found that the most variable species had disjunct distributions and deep phylogeographic structure, suggesting an effect of historical population dynamics in producing geographic variation. The V index can be adapted for use with other taxa, traits, and taxonomic levels, and we expect it will instigate novel ways of thinking about phenotypic variation in birds and other animals.

Diabetes ◽  
1979 ◽  
Vol 28 (10) ◽  
pp. 937-942 ◽  
Author(s):  
P. J. Savage ◽  
P. H. Bennett ◽  
R. G. Senter ◽  
M. Miller

Studies of animal behavior often assume that all members of a species exhibit the same behavior. Geographic Variation in Behavior shows that, on the contrary, there is substantional variation within species across a wide range of taxa. Including work from pioneers in the field, this volume provides a balanced overview of research on behavioral characteristics that vary geographically. The authors explore the mechanisms by which behavioral differences evolve and examine related methodological issues. Taken together, the work collected here demonstrates that genetically based geographic variation may be far more widespread than previously suspected. The book also shows how variation in behavior can illuminate both behavioral evolution and general evolutionary patterns. Unique among books on behavior in its emphasis on geographic variation, this volume is a valuable new resource for students and researchers in animal behavior and evolutionary biology.


Author(s):  
Baohua Chen ◽  
Zhixiong Zhou ◽  
Yue Shi ◽  
Jie Gong ◽  
Chengyu Li ◽  
...  

Temperature is an important climatic factor that shapes the distribution of eurythermal species. Thermal adaptation of species is important to both evolutionary biology and climate-change biology because it frequently leads to latitudinal gradients of various phenotypes among populations. Spotted sea bass (Lateolabrax maculatus) has a broad latitudinal distribution range along the marginal seas of the Northwest Pacific, providing an excellent teleost model for climate adaptation studies. We generated over 8.57 million SNP loci using whole genome re-sequencing from 100 samples collected at 14 geographic loci. We built the phylogeographic structure and demographic history of L. maculatus and determined sea surface temperature as the key environmental factor and major driving force for genetic divergence and local adaptation. We also identified distinct selective signatures and functional genes underlying adaptive mechanisms and ecological tradeoffs in the southernmost and northernmost populations inhabiting distinct climatic and latitudinal zones. The results offer an opportunity to better understand the genetic basis of the phenotypic variation in eurythermal fishes inhabiting different climatic regions.


2019 ◽  
Vol 128 (3) ◽  
pp. 550-568 ◽  
Author(s):  
Marie Fan ◽  
Liliana D’alba ◽  
Matthew D Shawkey ◽  
Anne Peters ◽  
Kaspar Delhey

AbstractClosely related species often differ in coloration. Understanding the mechanistic bases of such differences can reveal whether evolutionary changes in colour are driven by single key mechanisms or changes in multiple pathways. Non-iridescent structural plumage colours in birds are a good model in which to test these questions. These colours result from light absorption by pigments, light scattering by the medullary spongy layer (a nanostructure found within barbs) and contributions from other structural elements. Fairy-wrens (Malurus spp.) are a small clade of closely related birds that display a large diversity of ornamental structural colours. Using spectrometry, electron microscopy and Fourier analysis, we show that 30 structural colours, varying from ultraviolet to blue and purple, share a similar barb morphology. Despite this similarity, we find that at the microscopic scale, variation across multiple structural elements, including the size and density of the keratin cortex, spongy layer and melanin, explains colour diversity. These independent axes of morphological variation together account for sizeable amounts of structural colour variability (R2 = 0.21–0.65). The coexistence of many independent, evolutionarily labile mechanisms that generate colour variation suggests that the diversity of structural colours in this clade could be mediated by many independent genetic and environmental factors.


2014 ◽  
Vol 2 (22) ◽  
pp. 1
Author(s):  
Samad Khaghaninia ◽  
Yaser Gharajedaghi ◽  
Stepan Kubik

The phenotypic variation of Thaumatomyia notate (Meigen, 1830) (Chloropidae) collected from six different regions was studied in the East Azerbaijan province in northwestern Iran during 2009-2012. Eight populations of Thaumatomyia notata with different phenotypes were recognized. Environmental parameters such as temperature, elevation and habitat were examined. The results of this study show that colour variation in T. notata is caused mostly by seasonal temperature, dark coloration in April to light in July. In addition, variation in some morphological characters such as antenna, ocellar triangle, microchaetotaxy and size as well as diagnostic characters and photos of each variation are provided.


2017 ◽  
Vol 284 (1860) ◽  
pp. 20171018 ◽  
Author(s):  
Yinan Hu ◽  
R. Craig Albertson

Understanding the developmental processes that underlie the production of adaptive variation (i.e. the ‘arrival of the fittest’) is a major goal of evolutionary biology. While most evo-devo studies focus on the genetic underpinnings of adaptive phenotypic variation, factors beyond changes in nucleotide sequence can also play a major role in shaping developmental outcomes. Here, we document a vigorous but enigmatic gaping behaviour during the early development of Lake Malawi cichlid larvae. The onset of the behaviour precedes the formation of bone, and we predicted that it might influence craniofacial shape by affecting the mechanical environment in which bone develops. Consistent with this, we found that both natural variation and experimental manipulation of this behaviour induced differential skeletal development that foreshadows adaptive variation in adult trophic morphology. In fact, the magnitude of difference in skeletal morphology induced by these simple shifts in behaviour was similar to those predicted to be caused by genetic factors. Finally, we demonstrate that this mechanical-load-induced shift in skeletal development is associated with differences in ptch1 expression, a gene previously implicated in mediating between-species differences in skeletal shape. Our results underscore the complexity of development, and the importance of epigenetic ( sensu Waddington) mechanisms in determining adaptive phenotypic variation.


2014 ◽  
Vol 114 (2) ◽  
pp. 459-473 ◽  
Author(s):  
Josselin Cornuault ◽  
Boris Delahaie ◽  
Joris A. M. Bertrand ◽  
Yann X. C. Bourgeois ◽  
Borja Milá ◽  
...  

2013 ◽  
Vol 100 (10) ◽  
pp. 983-991 ◽  
Author(s):  
Miklós Laczi ◽  
Gergely Hegyi ◽  
Márton Herényi ◽  
Dorottya Kiss ◽  
Gábor Markó ◽  
...  

2020 ◽  
Vol 60 (6) ◽  
pp. 1558-1566 ◽  
Author(s):  
Arild Husby

Synopsis There is increasing interest in understanding the potential for epigenetic factors to contribute to phenotypic diversity in evolutionary biology. One well studied epigenetic mechanism is DNA methylation, the addition of a methyl group to cytosines, which have the potential to alter gene expression depending on the genomic region in which it takes place. Obtaining information about DNA methylation at genome-wide scale has become straightforward with the use of bisulfite treatment in combination with reduced representation or whole-genome sequencing. While it is well recognized that methylation is tissue specific, a frequent limitation for many studies is that sampling-specific tissues may require sacrificing individuals, something which is generally undesirable and sometimes impossible. Instead, information about DNA methylation patterns in the blood is frequently used as a proxy tissue. This can obviously be problematic if methylation patterns in the blood do not reflect that in the relevant tissue. Understanding how, or if, DNA methylation in blood reflect DNA methylation patterns in other tissues is therefore of utmost importance if we are to make inferences about how observed differences in methylation or temporal changes in methylation can contribute to phenotypic variation. The aim of this review is to examine what we know about the potential for using blood samples in ecological epigenetic studies. I briefly outline some methods by which we can measure DNA methylation before I examine studies that have compared DNA methylation patterns across different tissues and, finally, examine how useful blood samples may be for ecological studies of DNA methylation. Ecological epigenetic studies are in their infancy, but it is paramount for the field to move forward to have detailed information about tissue and time dependence relationships in methylation to gain insights into if blood DNA methylation patterns can be a reliable bioindicator for changes in methylation that generate phenotypic variation in ecologically important traits.


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