scholarly journals The preeminent role of directional selection in generating extreme morphological change in Glyptodonts (Cingulata; Xenarthra)

2021 ◽  
Author(s):  
Fabio Andrade Machado ◽  
Gabriel Marroig ◽  
Alex Hubbe
Keyword(s):  
Morphological Evolution ◽  
Morphological Diversity ◽  
Directional Selection ◽  
Stabilizing Selection ◽  
Specialist Herbivore ◽  
Rates Of Evolution ◽  
Morphological Modification ◽  
Empirical Tests ◽  
Adaptive Zone

The prevalence of stasis on paleontological and comparative data has been classically taken as evidence of the strong role of stabilizing selection in shaping morphological evolution. When confronted against biologically informed predictions, empirical rates of evolution tend to fall below what is expected under genetic drift, suggesting that the signal for directional selection is erased at longer time scales. However, empirical tests of these claims are few and tend to focus on univariate traits, ignoring the potential roles of trait covariances in constraining evolution. Here we investigated the multivariate rates of morphological evolution in a fossil lineage that underwent extreme morphological modification, the glyptodonts. Contrary to what was expected, biologically informed models of evolution suggest a preeminent role of directional selection on the divergence of glyptodonts from living armadillos. Furthermore, the reconstruction of selection patterns shows that traits selected to generate a glytodont morphology are markedly different from those necessary to explain the extant armadillos' morphological diversity. Changes in both direction and magnitude of selection are probably tied to the invasion of a specialist-herbivore adaptive zone by glyptodonts. These results suggest that directional selection might have played a more important role in the evolution of extreme morphologies than previously imagined.

scholarly journals Biomechanical trade-offs bias rates of evolution in the feeding apparatus of fishes

2011 ◽  
Vol 279 (1732) ◽  
pp. 1287-1292 ◽  
Author(s):  
Roi Holzman ◽  
David C. Collar ◽  
Samantha A. Price ◽  
C. Darrin Hulsey ◽  
Robert C. Thomson ◽  
...  
Keyword(s):  
Genetic Factors ◽  
Morphological Evolution ◽  
The Body ◽  
Body Parts ◽  
Phenotypic Evolution ◽  
Genetic Constraints ◽  
Functional Systems ◽  
Rates Of Evolution ◽  
Trade Offs

Morphological diversification does not proceed evenly across the organism. Some body parts tend to evolve at higher rates than others, and these rate biases are often attributed to sexual and natural selection or to genetic constraints. We hypothesized that variation in the rates of morphological evolution among body parts could also be related to the performance consequences of the functional systems that make up the body. Specifically, we tested the widely held expectation that the rate of evolution for a trait is negatively correlated with the strength of biomechanical trade-offs to which it is exposed. We quantified the magnitude of trade-offs acting on the morphological components of three feeding-related functional systems in four radiations of teleost fishes. After accounting for differences in the rates of morphological evolution between radiations, we found that traits that contribute more to performance trade-offs tend to evolve more rapidly, contrary to the prediction. While ecological and genetic factors are known to have strong effects on rates of phenotypic evolution, this study highlights the role of the biomechanical architecture of functional systems in biasing the rates and direction of trait evolution.

scholarly journals The Cardamine hirsuta genome offers insight into the evolution of morphological diversity

Nature Plants ◽  
2016 ◽  
Vol 2 (11) ◽  
Author(s):  
Xiangchao Gan ◽  
Angela Hay ◽  
Michiel Kwantes ◽  
Georg Haberer ◽  
Asis Hallab ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
Human Genetics ◽  
Morphological Evolution ◽  
Morphological Diversity ◽  
Close Relative ◽  
Gene Duplications ◽  
Tandem Gene Duplication ◽  
Genome Wide ◽  
Differential Gene

Abstract Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine hirsuta, a close relative of the model plant Arabidopsis thaliana. We combined comparative genome and transcriptome analyses with the experimental tools available in C. hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5/7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change.

scholarly journals Dynamic evolutionary change in post-Paleozoic echinoids and the importance of scale when interpreting changes in rates of evolution

2015 ◽  
Vol 112 (12) ◽  
pp. 3758-3763 ◽  
Author(s):  
Melanie J. Hopkins ◽  
Andrew B. Smith
Keyword(s):  
Initial Phase ◽  
Evolutionary History ◽  
Morphological Evolution ◽  
Morphological Diversity ◽  
Feeding Strategies ◽  
Geological Time ◽  
Internal Constraints ◽  
Rates Of Evolution ◽  
History Of ◽  
Morphological Innovation

How ecological and morphological diversity accrues over geological time has been much debated by paleobiologists. Evidence from the fossil record suggests that many clades reach maximal diversity early in their evolutionary history, followed by a decline in evolutionary rates as ecological space fills or due to internal constraints. Here, we apply recently developed methods for estimating rates of morphological evolution during the post-Paleozoic history of a major invertebrate clade, the Echinoidea. Contrary to expectation, rates of evolution were lowest during the initial phase of diversification following the Permo-Triassic mass extinction and increased over time. Furthermore, although several subclades show high initial rates and net decreases in rates of evolution, consistent with “early bursts” of morphological diversification, at more inclusive taxonomic levels, these bursts appear as episodic peaks. Peak rates coincided with major shifts in ecological morphology, primarily associated with innovations in feeding strategies. Despite having similar numbers of species in today’s oceans, regular echinoids have accrued far less morphological diversity than irregular echinoids due to lower intrinsic rates of morphological evolution and less morphological innovation, the latter indicative of constrained or bounded evolution. These results indicate that rates of evolution are extremely heterogenous through time and their interpretation depends on the temporal and taxonomic scale of analysis.

Public and Private Net Savings in Developing Countries: Some Empirical Tests for the Period 1972-88 (Distinguishedl Lecture)

1992 ◽  
Vol 31 (4I) ◽  
pp. 431-447
Author(s):  
Peter A. Cornelisse ◽  
Elma Van De Mortel
Keyword(s):  
Public Debt ◽  
World Economy ◽  
Socioeconomic Development ◽  
Critical Size ◽  
Public And Private ◽  
Critical Dimensions ◽  
The Public ◽  
Empirical Tests ◽  
Financial Issues

The severe shocks that rocked the world economy in the 1970s and the ensuing efforts to adjust and to renew economic growth have had a profound effect on the economic literature. Especially the external and public debt problems which reached critical dimensions in many countries attracted much attention. Thus, in the field of macroeconomics financial issues have gained more prominence over the last two decades. Studies relating to the fiscal deficit have been particularly numerous. The critical size of national public debts, the contribution of the public debt to external debt, the reduced confidence in the state as the guide in socioeconomic development and the role of fiscal policy in adjustment processes are among the main reasons for this increased interest.

scholarly journals Variation in pleiotropic hub gene expression is associated with interspecific differences in head shape and eye size in Drosophila

2021 ◽  
Author(s):  
Elisa Buchberger ◽  
Anıl Bilen ◽  
Sanem Ayaz ◽  
David Salamanca ◽  
Cristina Matas de las Heras ◽  
...  
Keyword(s):  
Natural Variation ◽  
Compound Eye ◽  
Genetic Manipulation ◽  
Morphological Evolution ◽  
Morphological Diversity ◽  
Network Evolution ◽  
Head Shape ◽  
Eye Size ◽  
Recurrent Mutations ◽  
Repeated Evolution

Abstract Revealing the mechanisms underlying the breath-taking morphological diversity observed in nature is a major challenge in Biology. It has been established that recurrent mutations in hotspot genes cause the repeated evolution of morphological traits, such as body pigmentation or the gain and loss of structures. To date, however, it remains elusive whether hotspot genes contribute to natural variation in the size and shape of organs. Since natural variation in head morphology is pervasive in Drosophila, we studied the molecular and developmental basis of differences in compound eye size and head shape in two closely related Drosophila species. We show differences in the progression of retinal differentiation between species and we applied comparative transcriptomics and chromatin accessibility data to identify the GATA transcription factor Pannier (Pnr) as central factor associated with these differences. Although the genetic manipulation of Pnr affected multiple aspects of dorsal head development, the effect of natural variation is restricted to a subset of the phenotypic space. We present data suggesting that this developmental constraint is caused by the co-evolution of expression of pnr and its co-factor u-shaped (ush). We propose that natural variation in expression or function of highly connected developmental regulators with pleiotropic functions is a major driver for morphological evolution and we discuss implications on gene regulatory network evolution. In comparison to previous findings, our data strongly suggests that evolutionary hotspots are not the only contributors to the repeated evolution of eye size and head shape in Drosophila.

scholarly journals Distance from Africa, not climate, explains within-population phenotypic diversity in humans

2008 ◽  
Vol 276 (1658) ◽  
pp. 809-814 ◽  
Author(s):  
Lia Betti ◽  
François Balloux ◽  
William Amos ◽  
Tsunehiko Hanihara ◽  
Andrea Manica
Keyword(s):  
Climatic Factors ◽  
Phenotypic Diversity ◽  
Morphological Diversity ◽  
Sub Saharan Africa ◽  
Relative Role ◽  
Morphometric Traits ◽  
Perfect Agreement ◽  
Skull Measurements ◽  
Sub Saharan

The relative importance of ancient demography and climate in determining worldwide patterns of human within-population phenotypic diversity is still open to debate. Several morphometric traits have been argued to be under selection by climatic factors, but it is unclear whether climate affects the global decline in morphological diversity with increasing geographical distance from sub-Saharan Africa. Using a large database of male and female skull measurements, we apply an explicit framework to quantify the relative role of climate and distance from Africa. We show that distance from sub-Saharan Africa is the sole determinant of human within-population phenotypic diversity, while climate plays no role. By selecting the most informative set of traits, it was possible to explain over half of the worldwide variation in phenotypic diversity. These results mirror those previously obtained for genetic markers and show that ‘bones and molecules’ are in perfect agreement for humans.

scholarly journals A sink host allows a specialist herbivore to persist in a seasonal source

2021 ◽  
Vol 288 (1958) ◽  
pp. 20211604
Author(s):  
Alicja Laska ◽  
Sara Magalhães ◽  
Mariusz Lewandowski ◽  
Ewa Puchalska ◽  
Kamila Karpicka-Ignatowska ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Laboratory Experiments ◽  
Field Observations ◽  
Stepping Stones ◽  
Specialist Herbivore ◽  
Negative Growth Rate ◽  
Evolutionary Rescue ◽  
Main Host ◽  
Negative Growth

In seasonal environments, sinks that are more persistent than sources may serve as temporal stepping stones for specialists. However, this possibility has to our knowledge, not been demonstrated to date, as such environments are thought to select for generalists, and the role of sinks, both in the field and in the laboratory, is difficult to document. Here, we used laboratory experiments to show that herbivorous arthropods associated with seasonally absent main (source) habitats can endure on a suboptimal (sink) host for several generations, albeit with a negative growth rate. Additionally, they dispersed towards this host less often than towards the main host and accepted it less often than the main host. Finally, repeated experimental evolution attempts revealed no adaptation to the suboptimal host. Nevertheless, field observations showed that arthropods are found in suboptimal habitats when the main habitat is unavailable. Together, these results show that evolutionary rescue in the suboptimal habitat is not possible. Instead, the sink habitat functions as a temporal stepping stone, allowing for the persistence of a specialist when the source habitat is gone.

scholarly journals Do ESG metrics reflect crisis resilience of equities during the COVID-19 pandemic?

2021 ◽  
Vol 8 (4) ◽  
pp. 371-388
Author(s):  
Fanni Dudás ◽  
Helena Naffa
Keyword(s):  
Linear Regression ◽  
Important Variable ◽  
Crisis Period ◽  
Shapley Decomposition ◽  
Empirical Tests

We examine the role of ESG metrics in explaining crisis resilience during the COVID-19 pandemic. ESG refers to Environmental, Social, and Governance aspects of companies, collectively known as ESG factors, and has gained popularity in investments. Our empirical tests cover a database of 971 company members of the MSCI World Index and examine the COVID Crisis period from February 2020 – May 2020. We performed linear regression and Owen-Shapley decomposition in our study, like the literature. Our results show that ESG is not an “equity vaccine” but is a statistically significant and economically important variable in explaining returns during the pandemic. Our findings highlight the increasing importance of sustainability aspects in finance and in investing.

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