scholarly journals Geography is more important than life history in the recent diversification of the tiger salamander complex

2020 ◽  
Author(s):  
Kathryn M. Everson ◽  
Levi N. Gray ◽  
Angela G. Jones ◽  
Nicolette M. Lawrence ◽  
Mary E. Foley ◽  
...  
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Life History Strategies ◽  
Conservation Priorities ◽  
Tiger Salamander ◽  
Life History Variation ◽  
Wide Range ◽  
History Of ◽  
Lineage Divergence ◽  
Salamander Species

AbstractThe North American tiger salamander species complex, including its flagship species the axolotl, has long been a source of biological fascination. The complex exhibits a wide range of variation in developmental life history strategies, including populations and individuals that undergo metamorphosis and those able to forego metamorphosis and retain a larval, aquatic lifestyle (i.e., paedomorphosis). Such disparate life history strategies are assumed to cause populations to become reproductively isolated, but the degree to which they have actually shaped population- and species-level boundaries is poorly understood. Using a large multi-locus dataset from hundreds of samples across North America, we identified genetic clusters with clear signs of admixture across the geographic range of the tiger salamander complex. Population clusters often contain a mixture of paedomorphic and metamorphic taxa, and we conclude that geography has played a large role in driving lineage divergence relative to obligate paedomorphosis in this system. This conclusion is bolstered by model-based analyses demonstrating gene flow between metamorphic and paedomorphic populations. Even the axolotl, a paedomorphic species with an isolated native range, apparently has a history of gene flow with its neighboring populations. This fine-scale genetic perspective on life-history variation establishes a framework for understanding how plasticity, local adaptation, and gene flow contribute to lineage divergence. The axolotl is currently used as the vertebrate model system in regenerative biology, and our findings chart a course for more informed use of these and other tiger salamander species in experimental and field research, including conservation priorities.Significance StatementPopulation structure and speciation are shaped by a variety of biotic and abiotic factors. In the tiger salamander complex, one factor that may influence diversification is life history: some taxa are obligately paedomorphic–a condition where adults maintain an aquatic, larval phenotype–while others are facultatively paedomorphic or entirely metamorphic. Using a large multi-locus dataset, we found evidence of gene flow and/or panmixia between obligately and facultatively paedomorphic taxa, suggesting that an obligately paedomorphic life history is not a strong driver of speciation in the tiger salamander complex. We also recovered a history of gene flow between the critically endangered axolotl and its neighboring populations, providing important information for its conservation and captive management.

scholarly journals Geography is more important than life history in the recent diversification of the tiger salamander complex

2021 ◽  
Vol 118 (17) ◽  
pp. e2014719118
Author(s):  
Kathryn M. Everson ◽  
Levi N. Gray ◽  
Angela G. Jones ◽  
Nicolette M. Lawrence ◽  
Mary E. Foley ◽  
...  
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Population Genetic ◽  
Tiger Salamander ◽  
Life History Variation ◽  
Mexican Axolotl ◽  
Population Genetic Differentiation ◽  
Wide Range ◽  
Lineage Divergence

The North American tiger salamander species complex, including its best-known species, the Mexican axolotl, has long been a source of biological fascination. The complex exhibits a wide range of variation in developmental life history strategies, including populations and individuals that undergo metamorphosis; those able to forego metamorphosis and retain a larval, aquatic lifestyle (i.e., paedomorphosis); and those that do both. The evolution of a paedomorphic life history state is thought to lead to increased population genetic differentiation and ultimately reproductive isolation and speciation, but the degree to which it has shaped population- and species-level divergence is poorly understood. Using a large multilocus dataset from hundreds of samples across North America, we identified genetic clusters across the geographic range of the tiger salamander complex. These clusters often contain a mixture of paedomorphic and metamorphic taxa, indicating that geographic isolation has played a larger role in lineage divergence than paedomorphosis in this system. This conclusion is bolstered by geography-informed analyses indicating no effect of life history strategy on population genetic differentiation and by model-based population genetic analyses demonstrating gene flow between adjacent metamorphic and paedomorphic populations. This fine-scale genetic perspective on life history variation establishes a framework for understanding how plasticity, local adaptation, and gene flow contribute to lineage divergence. Many members of the tiger salamander complex are endangered, and the Mexican axolotl is an important model system in regenerative and biomedical research. Our results chart a course for more informed use of these taxa in experimental, ecological, and conservation research.

scholarly journals Patterns of genomic diversification reflect differences in life history and reproductive biology between figs (Ficus) and the stone oaks (Lithocarpus)

Genome ◽  
2017 ◽  
Vol 60 (9) ◽  
pp. 756-761 ◽  
Author(s):  
Chai-Shian Kua ◽  
Charles H. Cannon
Keyword(s):  
Life History ◽  
Evolutionary Relationship ◽  
Genomic Diversity ◽  
Evolutionary Strategies ◽  
Life History Strategies ◽  
Wide Range ◽  
Genomic Divergence ◽  
History Of ◽  
Background History ◽  
Diverse Groups

One of the remarkable aspects of the tremendous biodiversity found in tropical forests is the wide range of evolutionary strategies that have produced this diversity, indicating many paths to diversification. We compare two diverse groups of trees with profoundly different biologies to discover whether these differences are reflected in their genomes. Ficus (Moraceae), with its complex co-evolutionary relationship with obligate pollinating wasps, produces copious tiny seeds that are widely dispersed. Lithocarpus (Fagaceae), with generalized insect pollination, produces large seeds that are poorly dispersed. We hypothesize that these different reproductive biologies and life history strategies should have a profound impact on the basic properties of genomic divergence within each genus. Using shallow whole genome sequencing for six species of Ficus, seven species of Lithocarpus, and three outgroups, we examined overall genomic diversity, how it is shared among the species within each genus, and the fraction of this shared diversity that agrees with the major phylogenetic pattern. A substantially larger fraction of the genome is shared among species of Lithocarpus, a considerable amount of this shared diversity was incongruent with the general background history of the genomes, and each fig species possessed a substantially larger fraction of unique diversity than Lithocarpus.

scholarly journals Prey productivity and predictability drive different axes of life-history variation in carnivorous marsupials

2018 ◽  
Vol 285 (1890) ◽  
pp. 20181291 ◽  
Author(s):  
Rachael A. Collett ◽  
Andrew M. Baker ◽  
Diana O. Fisher
Keyword(s):  
Life History ◽  
Food Availability ◽  
Reproductive Output ◽  
Life History Strategies ◽  
Annual Rainfall ◽  
Species Variation ◽  
Life History Variation ◽  
Wide Range ◽  
Iteroparous Species ◽  
Reproductive Events

Variation in life-history strategies has usually been characterized as a single fast–slow continuum of life-history variation, in which mean lifespan increases with age at maturity as reproductive output at each breeding event declines. Analyses of plants and animals suggest that strategies of reproductive timing can vary on an independent axis, with iteroparous species at one extreme and semelparous species at the other. Insectivorous marsupials in the Family Dasyuridae have an unusually wide range of life-history strategies on both purported axes. We test and confirm that reproductive output and degree of iteroparity are independent in females across species. Variation in reproductive output per episode is associated with mean annual rainfall, which predicts food availability. Position on the iteroparity-semelparity axis is not associated with annual rainfall, but species in regions of unpredictable rainfall have longer maximum lifespans, more potential reproductive events per year, and longer breeding seasons. We suggest that these two axes of life-history variation arise because reproductive output is limited by overall food availability, and selection for high offspring survival favours concentrated breeding in seasonal environments. Longer lifespans are favoured when reproductive opportunities are dispersed over longer periods in environments with less predictable food schedules.

scholarly journals Fast–slow continuum and reproductive strategies structure plant life-history variation worldwide

2015 ◽  
Vol 113 (1) ◽  
pp. 230-235 ◽  
Author(s):  
Roberto Salguero-Gómez ◽  
Owen R. Jones ◽  
Eelke Jongejans ◽  
Simon P. Blomberg ◽  
David J. Hodgson ◽  
...  
Keyword(s):  
Life History ◽  
Plant Species ◽  
Growth Form ◽  
Demographic Data ◽  
The Other ◽  
Life History Strategies ◽  
Life History Variation ◽  
Plant Life ◽  
Reproduction Strategy ◽  
Wide Range

The identification of patterns in life-history strategies across the tree of life is essential to our prediction of population persistence, extinction, and diversification. Plants exhibit a wide range of patterns of longevity, growth, and reproduction, but the general determinants of this enormous variation in life history are poorly understood. We use demographic data from 418 plant species in the wild, from annual herbs to supercentennial trees, to examine how growth form, habitat, and phylogenetic relationships structure plant life histories and to develop a framework to predict population performance. We show that 55% of the variation in plant life-history strategies is adequately characterized using two independent axes: the fast–slow continuum, including fast-growing, short-lived plant species at one end and slow-growing, long-lived species at the other, and a reproductive strategy axis, with highly reproductive, iteroparous species at one extreme and poorly reproductive, semelparous plants with frequent shrinkage at the other. Our findings remain consistent across major habitats and are minimally affected by plant growth form and phylogenetic ancestry, suggesting that the relative independence of the fast–slow and reproduction strategy axes is general in the plant kingdom. Our findings have similarities with how life-history strategies are structured in mammals, birds, and reptiles. The position of plant species populations in the 2D space produced by both axes predicts their rate of recovery from disturbances and population growth rate. This life-history framework may complement trait-based frameworks on leaf and wood economics; together these frameworks may allow prediction of responses of plants to anthropogenic disturbances and changing environments.

Serotiny and life history of Pinus contorta var. latifolia

1985 ◽  
Vol 63 (5) ◽  
pp. 938-945 ◽  
Author(s):  
Patricia S. Muir ◽  
James E. Lotan
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Pinus Contorta ◽  
Reproductive Effort ◽  
Basal Area ◽  
Western Montana ◽  
Tree Age ◽  
Selective Pressures ◽  
Area Growth ◽  
History Of

Mature serotinous and nonserotinous trees of Pinus contorta Dougl. var. latifolia Engelm. in the Bitterroot Watershed of western Montana do not differ in most life-history characteristics (reproductive or vegetative). No differences between trees of the two cone types were found in height, basal area, basal area growth rates over the lives of the trees, or crown ratio. Cone number, weights of individual cones and seeds, and estimates of reproductive effort were similar in serotinous and non-serotinous trees. Reproductive characteristics were either independent of tree age, or related similarly in trees of the two cone types. Nonserotinous trees may, however, have more seeds per cone than serotinous trees. This difference in seed numbers may be adaptive if serotinous trees invest relatively heavily in cone materials to protect seeds (which are retained in cones for many years), while nonserotinous trees (which shed seeds each year) invest relatively heavily in seeds. Trees of the two cone types differ mainly in the particular types of disturbance favoring their regeneration, but they often grow in the same stands where there are similar selective pressures on most aspects of their biology. Gene flow between them probably homogenizes all but those differences maintained by strong selective pressures.

Gene flow from domesticated escapes alters the life history of wild Atlantic salmon

2017 ◽  
Vol 1 (5) ◽  
Author(s):  
Geir H. Bolstad ◽  
Kjetil Hindar ◽  
Grethe Robertsen ◽  
Bror Jonsson ◽  
Harald Sægrov ◽  
...  
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Atlantic Salmon ◽  
History Of

Life History Strategies

2018 ◽  
pp. 95-126
Author(s):  
Marco Del Giudice
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Life History Theory ◽  
Human Life ◽  
Life History Strategy ◽  
Current Theory ◽  
Life History Strategies ◽  
Extended Model ◽  
Life History Variation ◽  
Basic Model

The chapter introduces the basics of life history theory, the concept of life history strategy, and the fast–slow continuum of variation. After reviewing applications to animal behavior and physiology, the chapter reviews current theory and evidence on individual differences in humans as manifestations of alternative life history strategies. The chapter first presents a “basic model” of human life history–related traits, then advances an “extended model” that identifies multiple cognitive-behavioral profiles within fast and slow strategies. Specifically, it is proposed that slow strategies comprise prosocial/caregiving and skilled/provisioning profiles, whereas fast strategies comprise antisocial/exploitative and seductive/creative profiles. The chapter also reviews potential neurobiological markers of life history variation and considers key methodological issues in this area.

scholarly journals Contrasting effects of climate change on seasonal survival of a hibernating mammal

2020 ◽  
Vol 117 (30) ◽  
pp. 18119-18126 ◽  
Author(s):  
Line S. Cordes ◽  
Daniel T. Blumstein ◽  
Kenneth B. Armitage ◽  
Paul J. CaraDonna ◽  
Dylan Z. Childs ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Dynamics ◽  
Life History ◽  
Environmental Conditions ◽  
Temporal Trends ◽  
Life History Strategies ◽  
Environmental Drivers ◽  
Age Classes ◽  
History Of ◽  
Colorado Rocky Mountains

Seasonal environmental conditions shape the behavior and life history of virtually all organisms. Climate change is modifying these seasonal environmental conditions, which threatens to disrupt population dynamics. It is conceivable that climatic changes may be beneficial in one season but result in detrimental conditions in another because life-history strategies vary between these time periods. We analyzed the temporal trends in seasonal survival of yellow-bellied marmots (Marmota flaviventer) and explored the environmental drivers using a 40-y dataset from the Colorado Rocky Mountains (USA). Trends in survival revealed divergent seasonal patterns, which were similar across age-classes. Marmot survival declined during winter but generally increased during summer. Interestingly, different environmental factors appeared to drive survival trends across age-classes. Winter survival was largely driven by conditions during the preceding summer and the effect of continued climate change was likely to be mainly negative, whereas the likely outcome of continued climate change on summer survival was generally positive. This study illustrates that seasonal demographic responses need disentangling to accurately forecast the impacts of climate change on animal population dynamics.

scholarly journals Evolutionary heritage influences Amazon tree ecology

2016 ◽  
Vol 283 (1844) ◽  
pp. 20161587 ◽  
Author(s):  
Fernanda Coelho de Souza ◽  
Kyle G. Dexter ◽  
Oliver L. Phillips ◽  
Roel J. W. Brienen ◽  
Jerome Chave ◽  
...  
Keyword(s):  
Life History ◽  
Evolutionary History ◽  
Large Scale ◽  
Phylogenetic Signal ◽  
Life History Strategies ◽  
Relative Importance ◽  
Life History Variation ◽  
Trait Variation ◽  
Closed Canopy ◽  
Repeated Evolution

Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high diversity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary diversity, ecosystem function and the response of tropical forests to global change.

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