Paedomorphosis in Ambystoma talpoideum: Maintenance of Population Variation and Alternative Life-History Pathways

Evolution ◽  
1990 ◽  
Vol 44 (6) ◽  
pp. 1604 ◽  
Author(s):  
Raymond D. Semlitsch ◽  
Reid N. Harris ◽  
Henry M. Wilbur
Keyword(s):  
Life History ◽  
Population Variation ◽  
Ambystoma Talpoideum

Life history and allozyme variation in populations of the weed species Setaria faberi

1987 ◽  
Vol 65 (7) ◽  
pp. 1396-1402 ◽  
Author(s):  
S. I. Warwick ◽  
B. K. Thompson ◽  
L. D. Black
Keyword(s):  
Life History ◽  
Significant Variation ◽  
Allozyme Variation ◽  
Growth Characteristics ◽  
Population Variation ◽  
Weed Species ◽  
Setaria Faberi ◽  
Single Genotype ◽  
Variable Population ◽  
Low Levels

Life-history features and allozyme variation were examined among and within eight populations of Setaria faberi collected at the northern limits of its distribution range from 39 to 45° N latitude. Statistically significant variation among the eight populations was evident for all 16 characters relating to morphology, phenology, and growth characteristics of the plants. Very low levels of allozyme variation were detected in the eight populations, i.e., only 3 of the 22 loci surveyed were polymorphic. Nine multilocus genotypes were present. Six of the eight populations contained a single genotype, whereas the most variable population (A) contained eight genotypes. Estimates of within-population variation of nine life-history features indicated that population A was the most variable with 7 of 9 characters showing statistically significant among-family variation.

scholarly journals Individual variability in life-history traits drives population size stability

2012 ◽  
Vol 58 (2) ◽  
pp. 358-362 ◽  
Author(s):  
Ned A. Dochtermann ◽  
C. M. Gienger
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Individual Variability ◽  
Population Variation ◽  
Sceloporus Undulatus ◽  
Natural Systems ◽  
Size Stability ◽  
Population Sizes ◽  
The Individual ◽  
Dynamics Of Populations

Abstract Understanding how population sizes vary over time is a key aspect of ecological research. Unfortunately, our understanding of population dynamics has historically been based on an assumption that individuals are identical with homogenous life-history properties. This assumption is certainly false for most natural systems, raising the question of what role individual variation plays in the dynamics of populations. While there has been an increase of interest regarding the effects of within population variation on the dynamics of single populations, there has been little study of the effects of differences in within population variation on patterns observed across populations. We found that life-history differences (clutch size) among individuals explained the majority of the variation observed in the degree to which population sizes of eastern fence lizards Sceloporus undulatus fluctuated. This finding suggests that differences across populations cannot be understood without an examination of differences at the level of a system rather than at the level of the individual [Current Zoology 58 (2): 358–362, 2012].

scholarly journals Population Variation in the Life History of a Land Fish, Alticus arnoldorum, and the Effects of Predation and Density

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0137244 ◽  
Author(s):  
Edward R. M. Platt ◽  
Terry J. Ord
Keyword(s):  
Life History ◽  
Population Variation ◽  
History Of

Genetically distinct sympatric populations of resident and anadromous Atlantic salmon, Salmo salar

1989 ◽  
Vol 67 (6) ◽  
pp. 1453-1461 ◽  
Author(s):  
E. Verspoor ◽  
L. J. Cole
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
River System ◽  
Population Variation ◽  
The Other ◽  
Gene Pools ◽  
Sympatric Populations ◽  
Polymorphic Loci ◽  
Atlantic Salmon Salmo Salar

Atlantic salmon (Salmo salar) from Little Gull Lake on the Gander River system of central Newfoundland were found to be electrophoretically polymorphic at 5 of 20 protein loci screened. Four of the polymorphic loci were structural and one was regulatory. Major heterozygote deficiencies relative to Castle–Hardy–Weinberg expectations were detected at the two most polymorphic loci, Aat-3 and Mdh-3,4, and significant nonrandom associations between genotypes at these loci and the other polymorphic loci, Sdh-1, Me-2, and Pgm1-t, were also found. The heterozygote deficiencies and the nonrandom genotype associations were attributable to the admixture of genetically distinct gene pools of resident and anadromous salmon in the lake. This is the first documented case of coexistence of reproductively separated populations of Atlantic salmon of the two life history types, and shows that the sympatric occurrence of the two forms can represent between-population variation.

scholarly journals PAEDOMORPHOSIS INAMBYSTOMA TALPOIDEUM: MAINTENANCE OF POPULATION VARIATION AND ALTERNATIVE LIFE-HISTORY PATHWAYS

Evolution ◽  
1990 ◽  
Vol 44 (6) ◽  
pp. 1604-1613 ◽  
Author(s):  
Raymond D. Semlitsch ◽  
Reid N. Harris ◽  
Henry M. Wilbur
Keyword(s):  
Life History ◽  
Population Variation

scholarly journals Latitudinal Variation in Life History Reveals a Reproductive Disadvantage in the Texas Horned Lizard (Phrynosoma cornutum)

2018 ◽  
Author(s):  
Daniel F. Hughes ◽  
Walter E. Meshaka ◽  
Carl S. Lieb ◽  
Joseph H. K. Pechmann
Keyword(s):  
Life History ◽  
Body Size ◽  
Clutch Size ◽  
Life History Strategy ◽  
Life History Evolution ◽  
Population Variation ◽  
Latitudinal Variation ◽  
Widespread Species ◽  
Phrynosoma Cornutum ◽  
History Evolution

Geographically widespread species that occupy many thermal environments provide testable models for understanding the evolution of life-history responses to latitude, yet studies that draw range-wide conclusions using descriptive data from populations in the core of a species’ distribution can overlook meaningful inter-population variation. The phrynosomatid lizard Phrynosoma cornutum spans an extensive latitudinal distribution in North America and has been well-studied in connection with life-history evolution, yet populations occupying the most northern and coldest areas within its range were absent from previous examinations. We tested genus-wide models and challenged species-specific findings on the evolution of the life-history strategy for P. cornutum using populations at the northern edge of its geographic range and comparative material from farther south. Multivariate analyses revealed that egg dimensions decreased with clutch size, suggestive of a previously unrecognized tradeoff between egg size and egg number in this species. Interestingly, reproductive traits of females with shelled eggs did not covary with latitude, yet we found that populations at the highest latitudes typified several traits of the genus and for the species, including a model for Phrynosoma of large clutches and delayed reproduction. A significant deviation from earlier findings is that we detected latitudinal variation in clutch size. This finding, although novel, is unsurprising given the smaller body sizes from northern populations and the positive relationship between clutch size and body size. Intriguing, however, was that the significant reduction in clutch size persisted when female body size was held constant, indicating a reproductive disadvantage to living at higher latitudes. We discuss the possible selective pressures that may have resulted in the diminishing returns on reproductive output at higher latitudes. Our findings highlight the type of insights in the study of life-history evolution that can be gained across Phrynosomatidae from the inclusion of populations representing latitudinal endpoints.

Genetic variation and conservation of stream fishes: influence of ecology, life history, and water quality

1997 ◽  
Vol 54 (8) ◽  
pp. 1822-1836 ◽  
Author(s):  
M R Heithaus ◽  
R H Laushman
Keyword(s):  
Water Quality ◽  
Genetic Variation ◽  
Life History ◽  
Genetic Erosion ◽  
Population Variation ◽  
Pollution Tolerance ◽  
Niche Variation ◽  
Niche Variation Hypothesis ◽  
Etheostoma Blennioides ◽  
Etheostoma Caeruleum

Three stream-dwelling fish species were used to investigate effects of ecology, life history, and water quality on genetic variation. We sampled Etheostoma caeruleum, E. blennioides, and Campostoma anomalum from six streams of varying water quality. Allozyme electrophoresis revealed that the most ecologically specialized species, E. caeruleum, was the least variable (P = 68.4%, Hobs = 1.2%). Etheostoma blennioides was intermediate in specialization and variation (P = 77.8%, Hobs = 7.8%), and the least specialized species, C. anomalum, had the most variation (P = 90.0%, Hobs = 12.1%). This pattern conforms to Willis' niche-variation hypothesis and Selander and Kaufman's adaptation model. Differences in ecology, life history, and amount of genetic variation are responsible for differences in how variation is apportioned within and among populations and within and among rivers. Populations in the river with the worst water quality (Huron River) had the lowest within-population variation for each species; therefore, genetic variation may be a useful indicator of water quality. Lower genetic variation may result from selection associated with specific loci, e.g., PGM-2, in stoneroller minnows. However, indirect effects on population size probably contributed to the erosion of genetic variation. Ecology, life history, and pollution tolerance data combine as predictors of species' risk of genetic erosion.

Aging, Life History, and Human Evolution

2020 ◽  
Vol 49 (1) ◽  
pp. 101-121 ◽  
Author(s):  
Richard G. Bribiescas
Keyword(s):  
Life History ◽  
Comparative Research ◽  
Reproductive Effort ◽  
Great Apes ◽  
Population Variation ◽  
Trade Offs ◽  
Evolution Of Aging ◽  
Physical Degradation ◽  
Shed Light ◽  
Over Time

Aging occurs in all sexually reproducing organisms. That is, physical degradation over time occurs from conception until death. While the life span of a species is often viewed as a benchmark of aging, the pace and intensity of physical degradation over time varies owing to environmental influences, genetics, allocation of energetic investment, and phylogenetic history. Significant variation in aging within mammals, primates, and great apes, including humans, is therefore common across species. The evolution of aging in the hominin lineage is poorly known; however, clues can be derived from the fossil record. Ongoing advances continue to shed light on the interactions between life-history variables such as reproductive effort and aging. This review presents our current understanding of the evolution of aging in humans, drawing on population variation, comparative research, trade-offs, and sex differences, as well as tissue-specific patterns of physical degradation. Implications for contemporary health challenges and the future of human evolutionary anthropology research are also discussed.

scholarly journals Phenotypic integration and life history strategies among populations of Pinus halepensis: an insight through structural equation modelling

2019 ◽  
Vol 124 (7) ◽  
pp. 1161-1171 ◽  
Author(s):  
Filippo Santini ◽  
José M Climent ◽  
Jordi Voltas
Keyword(s):  
Life History ◽  
Water Uptake ◽  
Latent Variables ◽  
Structural Equation ◽  
Photosynthetic Capacity ◽  
Pinus Halepensis ◽  
Population Variation ◽  
Life History Strategies ◽  
Phenotypic Integration ◽  
Phenotypic Traits

Abstract Background and Aims Understanding inter-population variation in the allocation of resources to specific anatomical compartments and physiological processes is crucial to disentangle adaptive patterns in forest species. This work aims to evaluate phenotypic integration and trade-offs among functional traits as determinants of life history strategies in populations of a circum-Mediterranean pine that dwells in environments where water and other resources are in limited supply. Methods Adult individuals of 51 populations of Pinus halepensis grown in a common garden were characterized for 11 phenotypic traits, including direct and indirect measures of water uptake at different depths, leaf area, stomatal conductance, chlorophyll content, non-structural carbohydrates, stem diameter and tree height, age at first reproduction and cone production. The population differentiation in these traits was tested through analysis of variance (ANOVA). The resulting populations’ means were carried forward to a structural equation model evaluating phenotypic integration between six latent variables (summer water uptake depth, summer transpiration, spring photosynthetic capacity, growth, reserve accumulation and reproduction). Key Results Water uptake depth and transpiration covaried negatively among populations, as the likely result of a common selective pressure for drought resistance, while spring photosynthetic capacity was lower in populations originating from dry areas. Transpiration positively influenced growth, while growth was negatively related to reproduction and reserves among populations. Water uptake depth negatively influenced reproduction. Conclusions The observed patterns indicate a differentiation in life cycle features between fast-growing and slow-growing populations, with the latter investing significantly more in reproduction and reserves. We speculate that such contrasting strategies result from different arrays of life history traits underlying the very different ecological conditions that the Aleppo pine must face across its distribution range. These comprise, principally, drought as the main stressor and fire as the main ecological disturbance of the Mediterranean basin.

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