scholarly journals Palaeohistology reveals a slow pace of life for the dwarfed Sicilian elephant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Meike Köhler ◽  
Victoria Herridge ◽  
Carmen Nacarino-Meneses ◽  
Josep Fortuny ◽  
Blanca Moncunill-Solé ◽  
...  
Keyword(s):  
Life History ◽  
Body Mass ◽  
Growth Period ◽  
Extended Period ◽  
Island Rule ◽  
Rule Based ◽  
Age At First Reproduction ◽  
Slow Pace ◽  
First Reproduction ◽  
Adaptive Shifts

AbstractThe 1-m-tall dwarf elephant Palaeoloxodon falconeri from the Pleistocene of Sicily (Italy) is an extreme example of insular dwarfism and epitomizes the Island Rule. Based on scaling of life-history (LH) traits with body mass, P. falconeri is widely considered to be ‘r-selected’ by truncation of the growth period, associated with an early onset of reproduction and an abbreviated lifespan. These conjectures are, however, at odds with predictions from LH models for adaptive shifts in body size on islands. To settle the LH strategy of P. falconeri, we used bone, molar, and tusk histology to infer growth rates, age at first reproduction, and longevity. Our results from all approaches are congruent and provide evidence that the insular dwarf elephant grew at very slow rates over an extended period; attained maturity at the age of 15 years; and had a minimum lifespan of 68 years. This surpasses not only the values predicted from body mass but even those of both its giant sister taxon (P. antiquus) and its large mainland cousin (L. africana). The suite of LH traits of P. falconeri is consistent with the LH data hitherto inferred for other dwarfed insular mammals. P. falconeri, thus, not only epitomizes the Island Rule but it can also be viewed as a paradigm of evolutionary change towards a slow LH that accompanies the process of dwarfing in insular mammals.

The Evolution of Life History Parameters in Teleosts

1984 ◽  
Vol 41 (6) ◽  
pp. 989-1000 ◽  
Author(s):  
Derek A. Roff
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Life History Theory ◽  
Larval Survival ◽  
Reasonable Assumption ◽  
Natural Mortality ◽  
Age At First Reproduction ◽  
Life History Parameters ◽  
First Case ◽  
First Reproduction

Empirical studies have shown that in teleosts there is a significant correlation between the life history parameters, age at first reproduction, natural mortality, and growth rate. In this paper 1 hypothesize that these correlations are the result of evolutionary adjustments due to the trade-off between reproduction, growth, and survival. A simple and reasonable assumption is that the costs of reproduction are sufficient to cause the ltmt function to decrease. A simple expression relating the age at first reproduction is derived from this assumption. This formula accounts for a statistically significant portion (60.6%) of the variation in age at first reproduction in 30 stocks of fish. To extend the model to predict the distribution of life history parameters across all teleosts, an explicit cost function is incorporated. The model is analyzed with respect to two fitness measures, the expected lifetime fecundity and malthusian parameter, r. In the first case it is shown that the optimal age at maturity, T, depends only on the natural mortality rate (M) and the growth rate (k). In the second case, T is a function of k and the logarithm of a parameter, In C; the latter is a product of egg and larval survival, maximum body length (Lx), and the proportionality coefficient of the fecundity/length function. Difficulties of measuring egg and larval survival make the testing of the latter case difficult for particular species. However, this method provides a simple formula for the computation of r; this is shown generally to be approximately zero, thereby adding strength to the assumptions of the first analysis. The distribution patterns of T on k and M on k are predicted and compared with the observed pattern. In general, the predictions are validated: however, certain combinations of k and ln C are shown to occur very infrequently. The prediction of such "empty" regions of the parameter space remains a challenge for future development of life history theory.

scholarly journals Effects of non-toxic filamentous cyanobacteria isolated from tri an reservoir on Daphnia

2020 ◽  
Vol 42 (3) ◽  
Author(s):  
Pham Thanh Luu ◽  
Tran Thi Hoang Yen ◽  
Tran Thanh Thai ◽  
Ngo Xuan Quang ◽  
Hoang Nghia Son
Keyword(s):  
High Performance Liquid Chromatography ◽  
Life History ◽  
Liquid Chromatography ◽  
Secondary Metabolites ◽  
High Performance ◽  
Toxic Effects ◽  
Filamentous Cyanobacteria ◽  
Age At First Reproduction ◽  
Bioactive Secondary Metabolites ◽  
First Reproduction

This study is aimed to examine whether the presence of non-toxic filamentous cyanobacteria can cause toxic effects on Daphnia magna. Six strains of Oscillatoria perornata were isolated from the Tri An Reservoir and cultured in our laboratory for investigation. The results revealed that all strains were negative with the mcyA moleculer marker. The high performance liquid chromatography (HPLC) results showed that toxin was not detected in their culture products, indicating that these strains corresponded to non-toxin producing strains. However, the results of chronic assay indicated that these non-toxin producing O. perornata conferred toxic effects on the tested animals. The age at first reproduction of D. magna was delayed and the survival of D. manga decreased in proportional with the increase of the density of cells of O. perornata exposed. Significant differences in the life history responses were observed for D. mangna exposed to O. perornata. These results suggested that bioactive secondary metabolites other than microcystins produced by the filamentous cyanobacteria O. perornata may contribute to the toxic effects on Daphnia. Besides cyanotoxins, other secondary metabolites must be taken into account when investigating the toxic effects of cyanobacteria.   

scholarly journals How do invasion syndromes evolve? An experimental evolution approach using the ladybird Harmonia axyridis

2019 ◽  
Author(s):  
Julien Foucaud ◽  
Ruth A. Hufbauer ◽  
Virginie Ravigné ◽  
Laure Olazcuaga ◽  
Anne Loiseau ◽  
...  
Keyword(s):  
Body Mass ◽  
Artificial Selection ◽  
Female Body ◽  
Harmonia Axyridis ◽  
Direct Selection ◽  
Age At First Reproduction ◽  
Introduced Populations ◽  
First Reproduction ◽  
Selection Experiments ◽  
Female Body Mass

ABSTRACTExperiments comparing native to introduced populations or distinct introduced populations to each other show that phenotypic evolution is common and often involves a suit of interacting phenotypic traits. We define such sets of traits that evolve in concert and contribute to the success of invasive populations as an ‘invasion syndrome’. The invasive Harlequin ladybird Harmonia axyridis displays such an invasion syndrome with, for instance, females from invasive populations being larger and heavier than individuals from native populations, allocating more resources to reproduction, and spreading reproduction over a longer lifespan. Invasion syndromes could emerge due to selection acting jointly and directly on a multitude of traits, or due to selection on one or a few key traits that drive correlated indirect responses in other traits. Here, we investigated the degree to which the H. axyridis invasion syndrome would emerge in response to artificial selection on either female body mass or on age at first reproduction, two traits involved in their invasion syndrome. To further explore the interaction between environmental context and evolutionary change in molding the phenotypic response, we phenotyped the individuals from the selection experiments in two environments, one with abundant food resources and one with limited resources. The two artificial selection experiments show that the number of traits showing a correlated response depends upon the trait undergoing direct selection. Artificial selection on female body mass resulted in few correlated responses and hence poorly reproduced the invasion syndrome. In contrast, artificial selection on age at first reproduction resulted in more widespread phenotypic changes, which nevertheless corresponded only partly to the invasion syndrome. The artificial selection experiments also revealed a large impact of diet on the traits, with effects dependent on the trait considered and the selection regime. Overall, our results indicate that direct selection on multiple traits was likely necessary in the evolution of the H. axyridis invasion syndrome. Furthermore, they show the strength of using artificial selection to identify the traits that are correlated in different selective contexts, which represents a crucial first step in understanding the evolution of complex phenotypic patterns, including invasion syndromes.

scholarly journals Carex secalina (Cyperaceae), a species critically endangered in Europe: from propagule germination to propagule production

2011 ◽  
Vol 74 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Waldemar Żukowski ◽  
Marlena Lembicz ◽  
Paweł Olejniczak ◽  
Agnieszka Bogdanowicz ◽  
Julian Chmiel
Keyword(s):  
Life History ◽  
Small Area ◽  
Critically Endangered ◽  
Age At First Reproduction ◽  
The Third ◽  
Germination Ability ◽  
First Reproduction ◽  
History Of ◽  
Selected Traits ◽  
And Bisexual

The size and reproduction ability of the three field populations of <em>Carex secalina</em> Willd. ex Wahlenb. have been assessed. In the parallel garden study selected traits from the life history of the species have been studied, such as age at first reproduction, fertility, the size of seeds, their germination ability and size of seedlings. The populations of <em>C. secalina</em> discovered in Poland in 2000 are characterised by small abundance and small area. All individuals from the three populations in the garden produced generative shoots in the third year of life. Statistically significant differences between the populations were found in the production of shoots with unisexual spikes and bisexual ones, the latter had not been reported in the hitherto literature on the species. The seeds started germinating after a 6-months rest. The first seedlings were observed in the first decade of May. The largest seedlings were noted in the population producing the smallest seeds. The results contribute to explaining the renewal of the populations of this species in the field.

scholarly journals Age at first reproduction in wolves: different patterns of density dependence for females and males

2021 ◽  
Vol 288 (1948) ◽  
Author(s):  
Camilla Wikenros ◽  
Morgane Gicquel ◽  
Barbara Zimmermann ◽  
Øystein Flagstad ◽  
Mikael Åkesson
Keyword(s):  
Life History ◽  
Population Size ◽  
Life History Trait ◽  
Parameter Estimates ◽  
Age At First Reproduction ◽  
Illegal Hunting ◽  
Reproductive Experience ◽  
First Reproduction ◽  
Pup Survival ◽  
Benefits And Costs

Age at first reproduction constitutes a key life-history trait in animals and is evolutionarily shaped by fitness benefits and costs of delayed versus early reproduction. The understanding of how intrinsic and extrinsic changes affects age at first reproduction is crucial for conservation and management of threatened species because of its demographic effects on population growth and generation time. For a period of 40 years in the Scandinavian wolf ( Canis lupus ) population, including the recolonization phase, we estimated age at first successful reproduction (pup survival to at least three weeks of age) and examined how the variation among individuals was explained by sex, population size (from 1 to 74 packs), primiparous or multiparous origin, reproductive experience of the partner and inbreeding. Median age at first reproduction was 3 years for females ( n = 60) and 2 years for males ( n = 74), and ranged between 1 and 8–10 years of age ( n = 297). Female age at first reproduction decreased with increasing population size, and increased with higher levels of inbreeding. The probability for males to reproduce later first decreased, reaching its minimum when the number of territories approached 40–60, and then increased with increasing population size. Inbreeding for males and reproductive experience of parents and partners for both sexes had overall weak effects on age at first reproduction. These results allow for more accurate parameter estimates when modelling population dynamics for management and conservation of small and vulnerable wolf populations, and show how humans through legal harvest and illegal hunting influence an important life-history trait like age at first reproduction.

scholarly journals Life-history theory, chronic childhood illness and the timing of first reproduction in a British birth cohort

2012 ◽  
Vol 279 (1740) ◽  
pp. 2998-3002 ◽  
Author(s):  
David Waynforth
Keyword(s):  
Life History ◽  
Chronic Disease ◽  
Life Expectancy ◽  
Life History Theory ◽  
Pubertal Development ◽  
Experimental Studies ◽  
Past Research ◽  
Theoretical Models ◽  
Age At First Reproduction ◽  
First Reproduction

Life-history theoretical models show that a typical evolutionarily optimal response of a juvenile organism to high mortality risk is to reach reproductive maturity earlier. Experimental studies in a range of species suggest the existence of adaptive flexibility in reproductive scheduling to maximize fitness just as life-history theory predicts. In humans, supportive evidence has come from studies comparing neighbourhoods with different mortality rates, historical and cross-cultural data. Here, the prediction is tested in a novel way in a large ( n = 9099), longitudinal sample using data comparing age at first reproduction in individuals with and without life-expectancy-reducing chronic disease diagnosed during childhood. Diseases selected for inclusion as chronic illnesses were those unlikely to be significantly affected by shifting allocation of effort away from reproduction towards survival; those which have comparatively large effects on mortality and life expectancy; and those which are not profoundly disabling. The results confirmed the prediction that chronic disease would associate with early age at first reproduction: individuals growing up with a serious chronic disease were 1.6 times more likely to have had a first child by age 30. Analysis of control variables also confirmed past research findings on links between being raised father-absent and early pubertal development and reproduction.

Effects of body size, population density, and maternal characteristics on age at first reproduction in bighorn ewes

1993 ◽  
Vol 71 (12) ◽  
pp. 2509-2517 ◽  
Author(s):  
Jon T. Jorgenson ◽  
Marco Festa-Bianchet ◽  
Mauro Lucherini ◽  
William D. Wishart
Keyword(s):  
Population Density ◽  
Body Mass ◽  
Age Distribution ◽  
Ovis Canadensis ◽  
The Body ◽  
The Other ◽  
Significant Interaction Effect ◽  
Age At First Reproduction ◽  
Maternal Characteristics ◽  
First Reproduction

The factors affecting variation in age at first reproduction of bighorn ewes (Ovis canadensis) were investigated in two marked populations in Alberta. One population was studied for 20 years, the other for 11 years. As yearlings, females that lactated at 2 years of age were on average heavier and larger, and had longer horns than females that did not lactate at 2 years. However, there was wide overlap in body mass between early and late producers, and increases in body mass over the threshold for reproduction had little effect on the probability of early lambing. The body mass of females at 4 months of age explained less than half of the variance in female body mass at 1 year or at 15 months. In one population, the proportion of 2-year-old ewes lactating was not correlated with density and declined after a pneumonia epizootic. In the other population, the proportion of 2-year-old ewes lactating was higher during an experimental reduction of density, and dropped to near zero as density increased. There was a significant interaction effect of body mass and population density upon the probability that a ewe would lactate at 2 years of age. Independently of body mass, yearlings were less likely to lactate at 2 years of age at high population density than at low density. The number and age distribution of rams did not affect the proportion of 2-year-old ewes lactating. The mothers of lactating 2-year-olds were not older or heavier than the mothers of ewes that did not lactate at 2 years. Although some of the variation in age at first reproduction was due to differences in mass and population density, much of it remained unexplained and could be due to genetic factors.

scholarly journals Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits

2019 ◽  
Author(s):  
Jessica A. Haines ◽  
Sarah E. Nason ◽  
Alyshia M. M. Skurdal ◽  
Tenal Bourchier ◽  
Stan Boutin ◽  
...  
Keyword(s):  
Life History ◽  
Personality Traits ◽  
Life History Traits ◽  
Positive Association ◽  
Activity Levels ◽  
Life History Variation ◽  
Red Squirrels ◽  
Age At First Reproduction ◽  
Pace Of Life ◽  
First Reproduction

The pace of life syndrome hypothesis posits that personality traits (i.e., consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e., active and aggressive) with an earlier age at first reproduction, a shorter lifespan, and a higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels (Tamiasciurus hudsonicus). Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females regardless of mast experience, there was no association between activity and lifetime pup production but there was a positive association between aggression and lifetime pup production. In males that experienced a mast there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production but a negative association between aggression and lifetime pup production. Lifetime recruit production in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels.

Life history variability in response to temperature and Chaoborus exposure in three Daphnia pulex clones

1998 ◽  
Vol 55 (8) ◽  
pp. 1961-1970 ◽  
Author(s):  
Mari Walls ◽  
Anne-Mari Ventelä
Keyword(s):  
Life History ◽  
Daphnia Pulex ◽  
Age At First Reproduction ◽  
First Reproduction ◽  
Clonal Origin ◽  
Temperature Exposure ◽  
Response To Temperature ◽  
Clonal Composition ◽  
Control Water

In a 21-day life table experiment, we studied the role of temperature, exposure to Chaoborus obscuripes, and their interaction on life history parameters and neck spine development in Daphnia pulex. We used three D. pulex clones collected from different ponds in southwestern Finland. In these ponds, temperature, predation pressure, and the clonal composition of Daphnia populations may vary substantially. Each clone was exposed to Chaoborus-conditioned water or control water at 16 and 20°C. Predator exposure and temperature affected significantly age and size at first reproduction and the total number of offspring in Daphnia. Interaction between predator exposure and temperature approached significance for the age at first reproduction, and the interaction between predator exposure and clone was significant for the same trait. Temperature interacted with clonal origin for all reproductive parameters studied. All three clones showed no or only weak morphological responses to Chaoborus. This indicates that the life history changes observed are independent of neck spine formation and may be adaptive in the presence of invertebrate predation.

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