共查询到20条相似文献,搜索用时 15 毫秒
1.
Ruth G. Shaw Charles J. Geyer 《Evolution; international journal of organic evolution》2010,64(9):2510-2520
Since 1983, study of natural selection has relied heavily on multiple regression of fitness on the values for a set of traits via ordinary least squares (OLSs), as proposed by Lande and Arnold, to obtain an estimate of the quadratic relationship between fitness and the traits, the fitness surface. However, well‐known statistical problems with this approach can affect inferences about selection. One key concern is that measures of lifetime fitness do not conform to a normal or any other standard sampling distribution, as needed to justify the usual statistical tests. Another is that OLS may yield an estimate of the sign of the fitness function's curvature that is opposite to the truth. We here show that the recently developed aster modeling approach, which explicitly models the components of fitness as the basis for inferences about lifetime fitness, eliminates these problems. We illustrate selection analysis via aster using simulated datasets involving five fitness components expressed in each of four years. We demonstrate that aster analysis yields accurate estimates of the fitness function in cases in which OLS misleads, as well as accurate confidence regions for directional selection gradients. Further, to evaluate selection when many traits are under consideration, we recommend model selection by information criteria and frequentist model averaging. 相似文献
2.
Although fitness is central to the evolutionary process, metrics vary by timescale. Different timescales may give rise to different estimates of selection, especially during demographic transitions caused by rapid environmental and socioeconomic change. In this study, we used a dataset of a human population in Finland from 1775 to 1950 to compare two fitness metrics and their estimates of selection pressures, before and during a demographic transition. Both metrics, lifetime reproductive success and an annual metric of individual performance, declined while selection on the ages at first and last reproduction remained nearly constant, favouring individuals with wider reproductive windows. The ability to partition the annual metric into contributions from reproduction and survival revealed the short‐term effects of a famine and the reversal of selection pressure via the survival component of annual fitness. Although the metrics generally agreed, the annual metric detected the effects of environmental variation and demographic change occurring within a generation. 相似文献
3.
Evolutionary biology is poised for a third major synthesis. The first presented Darwin's evidence from natural history. The second incorporated genetic mechanisms. The third will be based on energy and biophysical processes. It should include the equal fitness paradigm (EFP), which quantifies how organisms convert biomass into surviving offspring. Natural selection tends to maximise energetic fitness, E=PcohGFQ$$ E={P}_{mathrm{coh}}mathrm{GFQ} $$, wherePcoh$$ {P}_{mathrm{coh}} $$ is mass-specific rate of cohort biomass production, is generation time, is fraction of cohort production that is passed to surviving offspring, and is energy density of biomas. At steady state, parents replace themselves with offspring of equal mass-specific energy content, ≈ 22.4 kJ/g, and biomass, ≈ 1 g/g. The EFP highlights: (i) the energetic basis of survival and reproduction; (ii) how natural selection acts directly on the parameters of ; (iii) why there is no inherent intrinsic fitness advantage for higher metabolic power, ontogenetic or population growth rate, fecundity, longevity, or resource use efficiency; and (iv) the role of energy in animals with a variety of life histories. Underlying the spectacular diversity of living things is pervasive similarity in how energy is acquired from the environment and used to leave descendants offspring in future generations. 相似文献
4.
Michael G. Wolfersberger 《Archives of insect biochemistry and physiology》1989,12(4):267-277
Rapid filtration assays were used to determine the effects of barium, calcium and an insecticidal δ-endotoxin from Bacillus thuringiensis on sodium and potassium ion gradient dependent phenylalanine accumulation by brush border membrane vescles from the larval midgut of the tobacco hornworm (Manduca sexta). Neither barium nor calcium had a significant effect on sodium ion gradient dependent phenylalanine accumulation by the membrane vesicles. Both barium and calcium inhibited potassium ion gradient dependent phenylalanine accumulation by the membrane vesicles. B. thuringiensis δ-endotoxin inhibited both sodium and potassium ion gradient dependent phenylalanine accumulation by the vesicles. Inhibition of both sodium and potassium ion gradient dependent phenylalanine accumulation increased similarly with increasing δ-endotoxin inhibition of either sodium or potassium dependent phenylalanine accumulation by the vesicles. 相似文献
5.
《Evolutionary Applications》2017,10(3):215-225
Central to evolutionary theory is the idea that living organisms face phenotypic and/or genetic trade‐offs when allocating resources to competing life‐history demands, such as growth, survival, and reproduction. These trade‐offs are increasingly considered to be crucial to further our understanding of cancer. First, evidences suggest that neoplastic cells, as any living entities subject to natural selection, are governed by trade‐offs such as between survival and proliferation. Second, selection might also have shaped trade‐offs at the organismal level, especially regarding protective mechanisms against cancer. Cancer can also emerge as a consequence of additional trade‐offs in organisms (e.g., eco‐immunological trade‐offs). Here, we review the wide range of trade‐offs that occur at different scales and their relevance for understanding cancer dynamics. We also discuss how acknowledging these phenomena, in light of human evolutionary history, may suggest new guidelines for preventive and therapeutic strategies. 相似文献
6.
Vandock KP Smith SL Fioravanti CF 《Archives of insect biochemistry and physiology》2008,69(3):118-126
Midgut mitochondria from fifth larval instar Manduca sexta exhibited a transhydrogenase that catalyzes the following reversible reaction: NADPH + NAD(+) <--> NADP(+) + NADH. The NADPH-forming transhydrogenation occurred as a nonenergy- and energy-linked activity. Energy for the latter was derived from the electron transport-dependent utilization of NADH or succinate, or from Mg++-dependent ATP hydrolysis by ATPase. The NADH-forming and all of the NADPH-forming reactions appeared optimal at pH 7.5, were stable to prolonged dialysis, and displayed thermal lability. N,N'-dicyclohexylcarbodiimide (DCCD) inhibited the NADPH --> NAD(+) and energy-linked NADH --> NADP(+) transhydrogenations, but not the nonenergy-linked NADH --> NADP(+) reaction. Oligomycin only inhibited the ATP-dependent energy-linked activity. The NADH-forming, nonenergy-linked NADPH-forming, and the energy-linked NADPH-forming activities were membrane-associated in M. sexta mitochondria. This is the first demonstration of the reversibility of the M. sexta mitochondrial transhydrogenase and, more importantly, the occurrence of nonenergy-linked and energy-linked NADH --> NADP(+) transhydrogenations. The potential relationship of the transhydrogenase to the mitochondrial, NADPH-utilizing ecdysone-20 monooxygenase of M. sexta is considered. 相似文献
7.
Zahida Sultanova Roberto García‐Roa Pau Carazo 《Journal of evolutionary biology》2020,33(8):1086-1096
Disentangling the relationship between age and reproduction is central to understand life‐history evolution, and recent evidence shows that considering condition‐dependent mortality is a crucial piece of this puzzle. For example, nonrandom mortality of ‘low‐condition’ individuals can lead to an increase in average lifespan. However, selective disappearance of such low‐condition individuals may also affect reproductive senescence at the population level due to trade‐offs between physiological functions related to survival/lifespan and the maintenance of reproductive functions. Here, we address the idea that condition‐dependent extrinsic mortality (i.e. simulated predation) may increase the age‐related decline in male reproductive success and with it the potential for sexual conflict, by comparing reproductive ageing in Drosophila melanogaster male/female cohorts exposed (or not) to condition‐dependent simulated predation across time. Although female reproductive senescence was not affected by predation, male reproductive senescence was considerably higher under predation, due mainly to an accelerated decline in offspring viability of ‘surviving’ males with age. This sex‐specific effect suggests that condition‐dependent extrinsic mortality can exacerbate survival‐reproduction trade‐offs in males, which are typically under stronger condition‐dependent selection than females. Interestingly, condition‐dependent extrinsic mortality did not affect mating success, hinting that accelerated reproductive senescence is due to a decrease in male post‐copulatory fitness components. Our results support the recent proposal that male ageing can be an important source of sexual conflict, further suggesting this effect could be exacerbated under more natural conditions. 相似文献
8.
Eva Serrano‐Davies Yimen G. Araya‐Ajoy Niels J. Dingemanse Juan José Sanz 《Ethology : formerly Zeitschrift fur Tierpsychologie》2017,123(11):861-869
Habitat‐specific selection pressures have been widely recognized, but whether selection favours different personality types in different habitats has rarely been evaluated. This study aimed to test whether personality‐related differences in annual reproductive success differed between two populations of blue tits (Cyanistes caeruleus) occupying different Mediterranean habitats (oakwood and pinewood). We measured exploration and parental provisioning behaviours and used a path analysis to ask how the interplay between these two behavioural traits affected reproductive success in each of these two habitats. We found that blue tits breeding in the pinewood were slow‐exploring compared to blue tits breeding in the oakwood, suggesting the occurrence of personality‐related differences in settlement, or behavioural plasticity in response to habitat. Exploration behaviour and feeding rates were positively associated, suggesting that they affect each other or that there is an environmental factor affecting both traits simultaneously. Finally, fast explorers were favoured in the pinewood, while there was no selection acting on exploration behaviour in the oak habitat. These findings emphasize the importance of integrating habitat selection, plasticity and personality in the study of behavioural evolution. 相似文献
9.
《Ethology, Ecology and Evolution》2012,24(4):387-397
A variety of methods for measuring natural selection have been introduced recently, spurring a large number of empirical studies. Each method has its own strengths and weaknesses, and the use of different techniques in different ways has hampered comparisons among studies. I outline a method for integrating selection gradients, multiplicative fitness components and path analysis in a standardized way, to utilize the strengths of each technique and facilitate comparisons among studies. First, selection gradients are calculated using total lifetime fitness; these estimates can be used in equations to predict evolutionary change. Second, path analysis and multiplicative fitness components are used to understand the causes of selection. Examples of the method applied to studies of selection in an animal and a plant are given; use of this method allows comparisons to be made between the two studies of disparate taxa. 相似文献
10.
Ellie O. Osir Michael A. Wells John H. Law 《Archives of insect biochemistry and physiology》1986,3(3):217-233
In the tobacco hornworm moth, Manduca sexta, vitellogenin (Vg) is a very high-density (1.29 g/ml) phosphoglycolipoprotein containing 13% lipids, 3% carbohydrates, and 0.6% protein-bound phosphorus. Vitellogenin (Mr~500,000) has two apoproteins designated apoVg-l (Mr 177,000 ± 3,600) and apoVg-ll (Mr45,000 ± 5,000). ApoVg-l and apoVg-II can be dissociated with 6 M guanidine HCI and separated from each other by gel permeation chromatography. Immunoblotting experiments using antibodies against the apoproteins showed that apoVg-l and apoVg-II antigens were immunologically distinct polypeptides. Antibodies against Vg reacted only with apoVg-l. Antibodies against Vg and apoVg-l reacted with Vg in double immunodiffusion experiments, whereas antibodies against apoVg-II did not. These results suggest that in the native Vg molecule, apoVg-II is positioned inside the molecule away from the aqueous environment. Only apoVg-I contained covalently bound carbohydrate as shown by fluorescein isothiocyanateconjugated concanavalin A, periodate-Schiff reagent, and in vivo labeling with 3H-Man. In vivo labeling with 32P-inorganic phosphate and chemical determination showed that apoproteins of both Vg and vitellin contain covalently bound phosphate groups. 相似文献
11.
As the environment changes, so too must plant communities and populations if they are to persist. Life‐history transitions and their timing are often the traits that are most responsive to changing environmental conditions. To compare the contributions of plasticity and natural selective response to variation in germination and flowering phenology, we performed a quantitative genetic study of phenotypic selection on Chamaecrista fasciculata (Fabaceae) across two consecutive years in a restored tallgrass prairie. The earliest dates of germination and flowering were recorded for two parental cohorts and one progeny cohort in an experimental garden. Environmental differences between years were the largest contributors to phenological variation in this population. In addition, there was substantial heritability for flowering time and statistically significant selection for advancement of flowering. Comparison between a progeny cohort and its preselection parental cohort indicated a change in mean flowering time consistent with the direction of selection. Selection on germination time was weaker than that on flowering time, while environmental effects on germination time were stronger. The response to selection on flowering time was detectable when accounting for the effect of the environment on phenotypic differences, highlighting the importance of controlling for year‐to‐year environmental variation in quantitative genetic studies. 相似文献
12.
R. Douglas Watson Mary E. Haire Walter E. Bollenbacher 《Archives of insect biochemistry and physiology》1988,9(2):157-165
The hemolymph of last instar Manduca sexta larvae contains a protein factor that enhances ecdysone synthesis by prothoracic glands in vitro. The titer of the factor fluctuates during development in a pattern that suggests that it is regulated by juvenile hormone (JH). In untreated control larvae, the titer drops from 2.17 U ml?1 on day 1 to 0.27 U ml?1 on day 3. When larvae were treated with (7S)-hydroprene (a JH analog), the titer remained elevated (2.09 U ml?1 on day 3). JH I, however, was ineffective in preventing the precommitment drop in the titer of the factor. After pupal commitment, the titer of the factor increases in untreated larvae from 0.84 U ml?1 on day 5 to 1.62 U ml?1 on day 7. This increase was blocked when the sources of JH (the corpora allata) were removed on day 5 by head ligation. When head-ligated day 5 larvae were treated with either (7S)-hydroprene or JH I, the titer of the factor was driven to a level (1.88 U ml?1 and 2.05 U ml?1, respectively) that was not significantly different from that found in untreated day 7 larvae (1.62 U ml?1). The combined results indicate the titer of the hemolymph factor is regulated by JH. 相似文献
13.
Jonathan J. Neal 《Archives of insect biochemistry and physiology》1996,32(1):55-64
Fundamental differences in midgut structure, physiology, brush border proteins, and transporters among Leptinotarsa decemlineata, lepidopteran caterpillars, other insect taxa, and vertebrates are reviewed. The effects of dietary protein concentration on Manduca sexta midgut amino acid transport and brush border membrane proteins are reported. M. sexta fed diet with reduced protein had elevated levels of leucine aminopeptidase in the brush border membrane. No changes in amino acid transport or alkaline phosphatase activity due to dietary differences were detected. Changes in brush border proteins could affect the toxicity and pathogenicity of microbial agents. © 1996 Wiley-Liss, Inc. 相似文献
14.
Robert O. Ryan Kenneth D. Cole John K. Kawooya Michael A. Wells John H. Law 《Archives of insect biochemistry and physiology》1988,9(2):81-90
The identification, purification and characterization of a new postlarval specific hemolymph protein from Manduca sexta is described. Incorporation of [35S]methionine into Manduca sexta hemolymph proteins in vivo was investigated as a function of development. A major protein band of Mr ≈ 50,000 was highly labeled during the prepupal and adult stage but not in feeding larvae. This postlarval protein (PLP) was isolated from adult male hemolymph and its chemical and immunological properties determined. PLP is a basic protein (pI ~8.6). Electrophoresis under denaturing conditions reveals a subunit Mr ≈ 50,000 while the native protein has an apparent Mr ~ 85,000 by gel permeation chromatography. Anti-PLP serum recognized PLP but not other hemolymph proteins on immunoblots. In vitro translation of fat body mRNA followed by immunoprecipitation revealed that fat body is the site of PLP synthesis. Quantitation of PLP levels in hemolymph throughout development was performed and suggests PLP may play a role in adult development of M. sexta. 相似文献
15.
Beetz S Holthusen TK Koolman J Trenczek T 《Archives of insect biochemistry and physiology》2008,67(2):63-75
We determined the changes in hemocyte titer and in the abundance of hemocyte types of the tobacco hornworm Manduca sexta during the fourth and fifth larval stadium and the beginning of the pupal stadium. As we analyzed the samples of individual insects at daily intervals, we were able to correlate phenotypical features, body weight, as well as total protein content and lysozyme activity in the hemolymph with the observations on hemocytes. In the course of the fifth larval stadium, the hemocyte titer decreased slightly and declined further after pupation. Using calculated values for total hemocyte numbers, females had about five times and males three times more hemocytes in the circulating population at the beginning of the wandering stage (in the middle of the fifth larval stadium) than immediately after the last larval--larval molt (from the fourth to the fifth larval stadium). This sexual difference was mainly due to an increase in the number of plasmatocytes, which was more prominent in females than in males. Granular cells were dominant in early fifth larval stadium while plasmatocytes were the most abundant cells in pupae. Oenocytoids and spherule cells disappeared during the wandering stage. Lysozyme activity in the hemolymph rose to a maximum during the wandering stage, with females having lysozyme values twice as high as those for males. These changes in lysozyme activity, however, did not correlate with the increase of total hemolymph protein titer which occurred already at the beginning of the wandering stage. We postulate that changes in hemocyte titers are under direct hormonal control, which has to be proven in future experiments. 相似文献
16.
Induced resistance to biotic attackers is thought to be mediated by responses elicited by jasmonic acid (JA), a subset of which are lipoxygenase 3 (LOX3) dependent. To understand the importance of LOX3-mediated insect resistance, we analysed the performance of Manduca sexta larvae on wild-type (WT) and on isogenic Nicotiana attenuata plants silenced in NaLOX3 expression and JA signalling, and we used Waldbauer nutritional indices to measure the pre- and post-ingestive effects. LOX3-mediated defenses reduced larval growth, consumption and frass production. These defenses reduced how efficiently late-instar larvae converted digested food to body mass (ECD). In contrast, LOX3-mediated defenses decreased approximate digestibility (AD) in early instar larvae without affecting the ECD and total food consumption. Larvae of all instars feeding on defended WT plants behaviourally compensate for their reduced body mass by consuming more food per unit of body mass gain. We suggest that larvae feeding on plants silenced in NaLOX3 expression (as-lox) initially increase their AD, which in turn enables them to consume more food in the later stages and consequently, to increase their ECD and efficiency of conversion of ingested food (ECI). We conclude that N. attenuata's oxylipin-mediated defenses are important for resisting attack from M. sexta larvae, and that Waldbauer nutritional assays reveal behavioural and physiological counter responses of insects to these plant defenses. 相似文献
17.
Previous studies have shown no significant effect of experimentaltail length manipulation in female barn swallows (Hirundo rustica)at the beginning of a breeding season on reproductive successor behavior during that breeding season. In the present study,we investigate if tail length manipulation had any effect onreproductive performance the following year, the so-called long-termeffect, in contrast to the short-term effects already studied.We found that females with experimentally elongated externaltail feathers at the beginning of a breeding season producedless offspring during the breeding season the following yearthan did females with shortened or unmanipulated tails. Theseresults suggest that tail elongation caused flight deficienciesthat deteriorated the condition of females and eventually reducedreproductive success. The finding of long-term effects but nosignificant short-term effects for female tail elongation suggeststhat female barn swallows have the ability to adjust immediateparental investment. Detrimental effects of long tails in femalesin terms of decreased reproductive success might explain whyfemale tails are not as long as those of males. Finally, femalesmated to long-tailed (sexually attractive) males decreased theirreproductive success the following year more than did femalesmated to short-tailed males, possibly owing to differentialparental effort causing a deterioration of their condition. 相似文献
18.
Abstract We studied the evolutionary response to novel environments by applying artificial selection for total progeny biomass in populations of Drosophila melanogaster maintained at three different larval population densities. We found the relative amount of genetic variability for characters related with biomass to be lower and the correlation between them more negative at the intermediate density, and that selection resulted in changes in phenotypic plasticity and in patterns of resource allocation between traits. We found some evidence for tradeoffs between densities, which suggests that populations living at heterogeneous densities might be subject to disruptive selection. Our results show that adaptation to new environments may be a complex process, involving not only changes in trait means, but also in correlations between traits and between environments. 相似文献
19.
Increased dispersal propensity often evolves on expanding range edges due to the Olympic Village effect, which involves the fastest and fittest finding themselves together in the same place at the same time, mating, and giving rise to like individuals. But what happens after the range's leading edge has passed and the games are over? Although empirical studies indicate that dispersal propensity attenuates following range expansion, hypotheses about the mechanisms driving this attenuation have not been clearly articulated or tested. Here, we used a simple model of the spatiotemporal dynamics of two phenotypes, one fast and the other slow, to propose that dispersal attenuation beyond preexpansion levels is only possible in the presence of trade‐offs between dispersal and life‐history traits. The Olympic Village effect ensures that fast dispersers preempt locations far from the range's previous limits. When trade‐offs are absent, this preemptive spatial advantage has a lasting impact, with highly dispersive individuals attaining equilibrium frequencies that are strictly higher than their introduction frequencies. When trade‐offs are present, dispersal propensity decays rapidly at all locations. Our model's results about the postcolonization trajectory of dispersal evolution are clear and, in principle, should be observable in field studies. We conclude that empirical observations of postcolonization dispersal attenuation offer a novel way to detect the existence of otherwise elusive trade‐offs between dispersal and life‐history traits. 相似文献
20.
Katia C. Gondim James E. Pennington José Roberto Meyer‐Fernandes Michele Alves‐Bezerra Michael A. Wells 《Archives of insect biochemistry and physiology》2013,84(3):145-156
Lipophorin (Lp) is a major insect lipoprotein and is responsible for lipid transport between organs. In this study, the effect of starvation on Lp properties was analyzed in larval Manduca sexta during the fifth instar. Lp hemolymph concentrations in larvae at days 1 and 2 were around 2–3 mg/ml and at day 3 it increased to 8 mg/ml. When larvae were starved for 24 h, they did not grow, but their body mass and hemolymph volume did not decrease significantly. Differences in Lp densities were observed. In fed larvae, from days 1 to 4, two major Lp populations were found with densities of 1.124 ± 0.002 (high density Lp‐larval1, HDLp‐L1) and 1.141 ± 0.002 g/ml (HDLp‐L2). When larvae were starved for 24 h, only one Lp population was present, with density 1.114 ± 0.001 g/ml (HDLp‐Ls). When larvae were abdominally ligated at day 1 or 2 of fifth instar, only HDLp‐Ls was found after 24 h, indicating that the formation of this HDLp population was not dependent on any factor released by head. On the other hand, larvae that were ligated at day 3 showed the same Lp populations as the fed ones. In 24‐h starved larvae, lipid load in Lp was higher as compared to the fed controls. In 24‐h ligated larvae Lp lipid content increased when ligation was performed on day 1 or 2, but not on day 3. So, different responses to starvation can be observed depending on the developmental phase of the same larval instar. 相似文献