Evidence for rapid phenotypic and behavioural shifts in a recently established cavefish population

2019 ◽  
Author(s):  
Suzanne E McGaugh ◽  
Sam Weaver ◽  
Erin N Gilbertson ◽  
Brianna Garrett ◽  
Melissa L Rudeen ◽  
...  
Keyword(s):  
Extreme Environments ◽  
Time Frame ◽  
South Texas ◽  
Astyanax Mexicanus ◽  
North East ◽  
Surface Population ◽  
Cave Population ◽  
Cave Environment ◽  
Central Texas ◽  
Recent Origin

Abstract Cave colonization offers a natural laboratory to study an extreme environmental shift, and diverse cave species from around the world often have converged on robust morphological, physiological and behavioural traits. The Mexican tetra (Astyanax mexicanus) has repeatedly colonized caves in the Sierra de El Abra and Sierra de Guatemala regions of north-east Mexico ~0.20–1 Mya, indicating an ability to adapt to the cave environment. The time frame for the evolution of these traits in any cave animal, however, is poorly understood. Astyanax mexicanus from the Río Grande in South Texas were brought to Central Texas beginning in the early 1900s and colonized underground environments. Here, we investigate whether phenotypic and behavioural differences have occurred rapidly between a surface population and a geographically proximate cave population, probably of recent origin. Fish from the cave and surface populations differ significantly in morphological traits, including coloration, lateral line expansion and dorsal fin placement. Striking behavioural shifts in aggression, feeding and wall-following have also occurred. Together, our results suggest that morphological and behavioural changes accompanying cave colonization can be established rapidly, and this system offers an exciting and unique opportunity for isolating the genetic and environmental contributions to colonization of extreme environments.

scholarly journals Evidence for Late Pleistocene origin of Astyanax mexicanus cavefish

2016 ◽  
Author(s):  
Julien Fumey ◽  
Hélène Hinaux ◽  
Céline Noirot ◽  
Claude Thermes ◽  
Sylvie Rétaux ◽  
...  
Keyword(s):  
Nuclear Dna ◽  
Middle Pleistocene ◽  
Population Divergence ◽  
Demographic Parameters ◽  
Summary Statistics ◽  
Astyanax Mexicanus ◽  
Phenotypic Changes ◽  
Surface Population ◽  
Cave Population ◽  
Recent Origin

AbstractBackgroundCavefish populations belonging to the Mexican tetra species Astyanax mexicanus are outstanding models to study the tempo and mode of adaptation to a radical environmental change. They share similar phenotypic changes such as blindness and depigmentation resulting from independent and convergent evolution. As such they allow examining whether their evolution involved the fixation of preexisting standing genetic variations and/or de novo mutations. Cavefish populations are currently assigned to two main groups, the so-called "old" and "new" lineages, which would have populated several caves independently and at different times. However, we do not have yet accurate estimations of the time frames of evolution of these populations.ResultsFirst, we reanalyzed the geographic distribution of mitochondrial and nuclear DNA polymorphisms and we found that these data do not support the existence of two cavefish lineages, neither the ancient origin of the “old” lineage. Using IMa2, a program based on a method that does not assume that populations are at mutation/migration/drift equilibrium and thus allows dating population divergence in addition to demographic parameters, we found that microsatellite polymorphism strongly supports a very recent origin of cave populations (i.e. less than 20,000 years). Second, we identified a large number of single-nucleotide polymorphisms (SNPs) in transcript sequences of pools of embryos (Pool-seq) belonging to the “old” Pachón cave population and a surface population from Texas. Pachón cave population has accumulated more neutral substitutions than the surface population and we showed that it could be another signature of its recent origin. Based on summary statistics that can be computed with this SNP data set together with simulations of evolution of SNP polymorphisms in two recently isolated populations, we looked for sets of demographic parameters that allow the computation of summary statistics with simulated populations that are similar to the ones with the sampled populations. In most simulations for which we could find a good fit between the summary statistics of observed and simulated data, the best fit occurred when the divergence between simulated populations was less than 30,000 years.ConclusionsAlthough it is often assumed that some cave populations such as Pachón cavefish have a very ancient origin, within the range of the late Miocene to the middle Pleistocene, a recent origin of these populations is strongly supported by our analyses of two independent sets of nuclear DNA polymorphism using two very different methods of analysis. Moreover, the observation of two divergent haplogroups of mitochondrial and nuclear genes with different geographic distributions support a recent admixture of two divergent surface populations before the isolation of cave populations. If cave populations are indeed only several thousand years old, many phenotypic changes observed in cavefish would thus have mainly involved the fixation of genetic variants present in surface fish populations and within a very short period of time.

scholarly journals Evidence for rapid phenotypic and behavioral change in a recently established cavefish population

2019 ◽  
Author(s):  
Suzanne E. McGaugh ◽  
Sam Weaver ◽  
Erin N. Gilbertson ◽  
Brianna Garrett ◽  
Melissa L. Rudeen ◽  
...  
Keyword(s):  
Behavioral Change ◽  
Extreme Environments ◽  
Behavioral Differences ◽  
Astyanax Mexicanus ◽  
Eye Size ◽  
Exciting Opportunity ◽  
Surface Population ◽  
Cave Population ◽  
Future Work ◽  
Rapid Environmental Change

AbstractSubstantial morphological and behavioral shifts often accompany rapid environmental change, yet, little is known about the early stages of cave colonization. Relative to surface streams, caves are extreme environments with perpetual darkness and low nutrient availability. The Mexican tetra (Astyanax mexicanus), has repeatedly colonized caves throughout Mexico, suggesting an ability to adapt to these conditions. Here, we survey for phenotypic and behavioral differences between a surface population and a cave population of A. mexicanus that has recently colonized Honey Creek Cave, Comal County, Texas, likely within the last century. We found that fish from Honey Creek Cave and fish from Honey Creek surface populations differ significantly in morphological traits including length, coloration, body condition, eye size, and dorsal fin placement. Cavefish also exhibit an increased number of superficial neuromasts relative to surface fish. Behaviorally, cavefish consume fewer worms when trials are performed in both lighted and darkened conditions. Cavefish are more aggressive than surface fish and exhibit fewer behaviors associated with stress. Further in contrast to surface fish, cavefish prefer the edges to the center of an arena and are qualitatively more likely to investigate a novel object placed in the tank. While cavefish and surface fish were wild-caught and developmental environment likely play a role in shaping these differences, our work demonstrates morphological and behavioral shifts for Texas cavefish and offers an exciting opportunity for future work to explore the genetic and environmental contributions to early cave colonization.

Peanut Response to Ethalfluralin, Pendimethalin, and Trifluralin Preplant Incorporated1

2003 ◽  
Vol 30 (1) ◽  
pp. 34-37 ◽  
Author(s):  
P. A. Dotray ◽  
J. W. Keeling ◽  
W. J. Grichar ◽  
E. P. Prostko ◽  
R. G. Lemon ◽  
...  
Keyword(s):  
Field Experiments ◽  
South Texas ◽  
Stand Establishment ◽  
West Texas ◽  
Central Texas ◽  
Incorporation Method ◽  
Dinitroaniline Herbicides

Abstract Field experiments were conducted at Yoakum (south Texas) in 1996 and 1997, Comanche (central Texas) in 1998, and Lamesa (west Texas) in 1998 and 1999 to evaluate peanut tolerance to dinitroaniline herbicides. At Lamesa, ethalfluralin at 0.63 or 0.84 kg/ha, pendimethalin at 0.56 or 0.84 kg/ha, and trifluralin at 0.56 or 0.71 kg/ha were applied preplant incorporated (PPI), and at Yoakum and Comanche, ethalfluralin and pendimethalin were applied PPI at 0.67, 0.84, 1.12, and 1.68 kg/ha. There were no differences in stand establishment or yield for any treatment at Lamesa, Comanche, or Yoakum. Similarly, canopy stature was not affected at Lamesa nor was grade affected at Comanche or Yoakum. At Lamesa, yields by herbicide averaged across rates, incorporation methods, and years ranged from 4530 to 4920 kg/ha; by rate averaged across herbicides, incorporation methods, and years was 4600 to 4750 kg/ha; and by incorporation method averaged across herbicides, rates, and years was 4580 to 4770 kg/ha. At Yoakum and Comanche, yields by herbicide were 2640 and 2950 kg/ha, respectively, when averaged across rates; and by rate they ranged from 2630 to 2990 kg/ha when averaged across herbicides. These data indicate peanut has tolerance (safety) to ethalfluralin, pendimethalin, and trifluralin applied PPI in Texas.

scholarly journals Comparative Canopy Damage among Provenances of Baldcypress Associated with the Presence of Cercosporidium sequoiae (Ellis and Everth.) W.A. Baker and Partridge

HortScience ◽  
2008 ◽  
Vol 43 (6) ◽  
pp. 1703-1705 ◽  
Author(s):  
Garry Vernon McDonald ◽  
Geoffrey C. Denny ◽  
Michael A. Arnold ◽  
Donita L. Bryan ◽  
Larry Barnes
Keyword(s):  
Selection Criteria ◽  
Taxodium Distichum ◽  
Leaf Blight ◽  
South Texas ◽  
East Texas ◽  
Rainfall Events ◽  
Geographical Regions ◽  
Central Texas ◽  
Selection Of ◽  
Canopy Damage

Seeds of Taxodium distichum (L.) Rich. were collected, germinated, and grown from native stands ranging from Mexico, Texas, Louisiana, Mississippi, and Alabama. Twenty-two provenance selections were planted in Summer 2004 in College Station, TX, in 36 replicated single-plant replications per block for a total of 792 trees. Below-average midsummer temperatures and above-average number of rainfall events were conducive to the development of a leaf blight associated with the presence of Cercosporidium sequoiae (Ellis and Everh.) W.A. Baker and Partridge. A survey conducted in Oct. 2007 rated differential defoliation responses among provenances. Selections of Taxodium distichum var. mexicanum (Gordon) from Mexico and south Texas showed defoliation rates from 89% to 96%, whereas T. distichum var. distichum from central Texas had defoliation ratings from 79% to 99%. With the exception of one family collected from the Sabinal River in Texas, the central Texas selections had similar defoliation compared with those from south Texas. Selections of T. distichum var. distichum and one selection of T. distichum var. imbricarium (Nutt.) Croom from southeastern regions (Alabama, Louisiana, Mississippi, and east Texas) showed greater tolerance to the presence of the leaf blight with 52% to 80% mean defoliation. A few individuals within these families exhibited little or no symptoms of the leaf blight. In general, those selections from high-rainfall, high-humidity areas had less defoliation associated with the presence of the leaf blight fungus, although defoliation was variable among provenances within all geographical regions. These results suggest that tolerance to defoliation from C. sequoiae could be included in selection criteria when choosing possible germplasm releases from Taxodium distichum.

scholarly journals Genetic Diversity Analysis, Population Structure and Gene-flow Estimates among Citrus Macroptera Mont. Collections from Garo Hills, Meghalaya using SPAR Approach

2021 ◽  
Vol 4 (1) ◽  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Gene Diversity ◽  
Time Frame ◽  
Conservation Strategies ◽  
North East India ◽  
Information Index ◽  
North East ◽  
Garo Hills ◽  
Single Primer

North East India is extremely rich in natural resources and is a biodiversity hotspot. Many plant species, including Citrus are known to have originated from this region. Citus macroptera Mont. is a wild, endangered species which have been found to exist naturally in various parts of this region, including Meghalaya. To access the genetic variability among genotypes and their phylogeny, 30 genotypes of wild C. macroptera Mont. were collected from Garo Hills of Meghalaya. Single primer based DNA markers viz. RAPD, ISSR, DAMD were utilized to ascertain genetic diversity. The percentage polymorphic bands for RAPD, ISSR, DAMD were found to be 97.71%, 94.67% and 100% respectively. ISSR showed the highest values for both RP (7.67) and MI (5.03) highlighting its efficacy in determining genetic variations. A concatenated approach, Single Primer Amplification Reaction (SPAR) was also followed to assess their genetic diversity. Dendogram generated from SPAR data showed that the South-West Garo Hills population is the most recently evolved amongst all others while West Garo Hills collections retain an ancestral position in the evolutionary time-frame. Population genetics parametres such as Gene flow (Nm) and the diversity among populations (GST) were found to be 1.9894 and 0.2009 respectively. Gene flow estimates (Nm>1) suggests appreciable gene flow in the populations. AMOVA data further supported this with high percentage of variations (92%) within populations whereas variations among populations were about 8% only. Shannon’s information index (I) values and Nei’s gene diversity (h) varied between 0.303-0.423and 0.201-0.285 respectively. The use of SPAR method yields a clear and concise picture of the underlying genetic variabilities, and a detailed and comprehensive data analysis will help conceive efficient and sustainable conservation strategies for this important plant.

scholarly journals Cavefish cope with environmental hypoxia by developing more erythrocytes and overexpression of hypoxia inducible genes

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Corine M van der Weele ◽  
William R Jeffery
Keyword(s):  
Normal Development ◽  
Hypoxia Inducible Factor ◽  
Hypoxia Tolerance ◽  
Astyanax Mexicanus ◽  
Hypoxia Inducible Factor 1 ◽  
Primitive Hematopoiesis ◽  
Cave Environment ◽  
Surface Dwelling ◽  
Inducible Genes ◽  
Lateral Mesoderm

Dark caves lacking primary productivity can expose subterranean animals to hypoxia. We used the surface-dwelling (surface fish) and cave-dwelling (cavefish) morphs of Astyanax mexicanus as a model for understanding the mechanisms of hypoxia tolerance in the cave environment. Primitive hematopoiesis, which is restricted to the posterior lateral mesoderm in other teleosts, also occurs in the anterior lateral mesoderm in Astyanax, potentially pre-adapting surface fish for hypoxic cave colonization. Cavefish have enlarged both hematopoietic domains and develop more erythrocytes than surface fish, which are required for normal development in both morphs. Laboratory induced hypoxia suppresses growth in surface fish but not in cavefish. Both morphs respond to hypoxia by overexpressing hypoxia-inducible factor 1 (hif1) pathway genes, and some hif1 genes are constitutively upregulated in normoxic cavefish to similar levels as in hypoxic surface fish. We conclude that cavefish cope with hypoxia by increasing erythrocyte development and constitutive hif1 gene overexpression.

US gas pipeline shortage may drive energy diversity

2015 ◽  
Keyword(s):  
Natural Gas ◽  
Gulf Coast ◽  
Gas Production ◽  
Gas Pipeline ◽  
South Texas ◽  
Content Type ◽  
North West ◽  
Natural Gas Pipeline ◽  
North East ◽  
The North

Subject The effects of natural gas pipeline supply constraints in the US North-east. Significance The shale 'revolution' has caused a sharp rise in US natural gas production, but it has been located in areas without gas infrastructure. Production has been concentrated along the Gulf Coast, and the pipeline network is oriented from that region to the North-east and Pacific North-west. Newer areas of energy production, such as Bakken in North Dakota, Eagle Ford in South Texas, and Marcellus in Appalachia, have poor connections to major markets, and constraints have led to pricing spikes in the North-east. Impacts The majority of proposed pipelines for the next several years target areas in the upper Midwest, Mid-Atlantic, and South-east markets. Manufacturers in the North-east will face competitive disadvantage from paying the highest energy costs in North America. Pipeline constraints will not dampen enthusiasm for liquefied natural gas (LNG) exports, especially out of West Coast ports.

scholarly journals Contrasted gene decay in subterranean vertebrates: insights from cavefishes and fossorial mammals

2020 ◽  
Author(s):  
Maxime Policarpo ◽  
Julien Fumey ◽  
Philippe Lafargeas ◽  
Delphine Naquin ◽  
Claude Thermes ◽  
...  
Keyword(s):  
Evolutionary Process ◽  
Sharp Contrast ◽  
Functional Constraints ◽  
Loss Of Function ◽  
Astyanax Mexicanus ◽  
Gene Sets ◽  
Cave Population ◽  
Cave Ecosystems ◽  
Genome Ploidy ◽  
Gene Decay

AbstractEvolution sometimes proceeds by loss, especially when structures and genes become dispensable after an environmental shift relaxing functional constraints. Gene decay can serve as a read-out of this evolutionary process. Animals living in the dark are outstanding models, in particular cavefishes as hundreds of species evolved independently during very different periods of time in absence of light. Here, we sought to understand some general principals on the extent and tempo of decay of several gene sets in cavefishes. The analysis of the genomes of two Cuban species belonging to the genus Lucifuga provides evidence for the most massive loss of eye genes reported so far in cavefishes. Comparisons with a recently-evolved cave population of Astyanax mexicanus and three species belonging to the tetraploid Chinese genus Sinocyclocheilus revealed the combined effects of the level of eye regression, time and genome ploidy on the number of eye pseudogenes. In sharp contrast, most circadian clock and pigmentation genes appeared under strong selection. In cavefishes for which complete genomes are available, the limited extent of eye gene decay and the very small number of loss of function (LoF) mutations per pseudogene suggest that eye degeneration is never very ancient, ranging from early to late Pleistocene. This is in sharp contrast with the identification of several eye pseudogenes carrying many LoF mutations in ancient fossorial mammals. Our analyses support the hypothesis that blind fishes cannot thrive more than a few millions of years in cave ecosystems.

scholarly journals Untargeted Metabolomics of the Cavefish Astyanax mexicanus Reveals the Basis of Metabolic Strategies in Adaptation to Extreme Conditions

2020 ◽  
Author(s):  
J Kyle Medley ◽  
Jenna Persons ◽  
Robert Peuß ◽  
Luke Olsen ◽  
Shaolei Xiong ◽  
...  
Keyword(s):  
Behavioral Changes ◽  
Protein Glycation ◽  
Untargeted Metabolomics ◽  
Short Term ◽  
Astyanax Mexicanus ◽  
Surface Population ◽  
Shiny App ◽  
Metabolomics Study ◽  
Metabolic Strategies

The Mexican tetra, Astyanax mexicanus, has undergone remarkable physiological and behavioral changes in order to colonize a number of subterranean caves in the Sierra de El Abra region of Mexico. A hallmark of cave-adapted populations is enhanced survival under low-nutrient conditions coupled with hyperglycemia, increased body fat, and insulin resistance, but cavefish appear to avoid the progression of the respective pathologies associated with these conditions and do not exhibit reduced longevity. The metabolic strategies underlying these adaptations are not fully understood. Here, we provide an untargeted metabolomics study of longand short-term fasting in two A. mexicanus cave populations and one surface population. We find that, although cavefish share many similarities with metabolic syndrome normally associated with the human state of obesity, important differences emerge, including cholesterol esters, urate, intermediates of protein glycation, metabolites associated with hypoxia and longevity, and unexpectedly elevated levels of ascorbate (vitamin C). This work highlights the fact that certain metabolic features associated with human pathologies are not intrinsically harmful in all organisms, and suggests promising avenues for future investigation into the role of certain metabolites in evolutionary adaptation and health. We provide a transparent pipeline for reproducing our analysis and a Shiny app for other researchers to explore and visualize our dataset.

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