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Other Life-history Traits (other + life-history_trait)
Selected AbstractsEgg maturation strategy and its associated trade-offs: a synthesis focusing on LepidopteraECOLOGICAL ENTOMOLOGY, Issue 4 2005Mark A. Jervis Abstract., 1.,Insects vary considerably between and within orders, and even within the same genus, in the degree to which the female's lifetime potential egg complement is mature when she emerges as an adult. 2.,The ,ovigeny index' (OI) , the number of eggs females have ready to lay divided by the lifetime potential fecundity , quantifies variation in the degree of early life concentration of egg production, and also variation in initial reproductive effort. 3.,Here, an integrated set of hypotheses is presented, based on a conceptual model of resource allocation and acquisition, concerning trade-offs at the interspecific level between initial investment in egg production (as measured by OI) and other life-history traits in holometabolous insects. 4.,The evidence supporting each of these hypotheses is reviewed, and particular attention is paid to the Lepidoptera, as relevant life-history data are rapidly accumulating for this ecologically and economically important group. 5.,There is evidence at the interspecific level supporting: (i) a link between OI and a trade-off between soma and non-soma in Trichoptera and Hymenoptera (the proportionate allocation to soma decreases with increasing OI); (ii) a negative correlation between OI and dependency on external nutrient inputs (via adult feeding) in Hymenoptera and in Lepidoptera; (iii) a negative correlation between OI and the degree of polyandry (and nuptial gift, i.e. spermatophore, use) in Lepidoptera; (iv) negative correlations between OI and resource re-allocation capabilities (egg and thoracic musculature resorption) in Hymenoptera and in Lepidoptera; (v) a negative correlation between lifespan and OI in Trichoptera, Hymenoptera, and Lepidoptera, indicating a cost of reproduction; (vi) a link between winglessness and an OI of one in Lepidoptera; (vii) a negative correlation between OI and the degree of female mobility in winged Lepidoptera; and (viii) a negative correlation between OI and larval diet breadth (as mediated by oviposition strategy) in Lepidoptera. [source] EVOLUTION OF INTRINSIC GROWTH RATE: METABOLIC COSTS DRIVE TRADE-OFFS BETWEEN GROWTH AND SWIMMING PERFORMANCE IN MENIDIA MENIDIAEVOLUTION, Issue 6 2006Stephen A. Arnott Abstract There is strong evidence that genetic capacity for growth evolves toward an optimum rather than an absolute maximum. This implies that fast growth has a cost and that trade-offs occur between growth and other life-history traits, but the fundamental mechanisms are poorly understood. Previous work on the Atlantic silverside fish Menidia menidia has demonstrated a trade-off between growth and swimming performance. We hypothesize that the trade-off derives from the competing metabolic demands associated with growth and swimming activity. We tested this by measuring standard metabolic rate (MSTD), maximum sustainable metabolic rate (MACT) and metabolic scope of laboratory-reared silversides originating from two geographically distinct populations with well-documented differences in genetic capacity for growth. The fast-growth genotype had a significantly greater MSTD than the slow-growth genotype, but a similar MACT when swum to near exhaustion. The scope for activity of the fast-growth genotype was lower than that of the slow-growth genotype. Furthermore, the fast-growth genotype eats larger meals, thereby incurring a greater postprandial oxygen demand. We conclude that a metabolic trade-off occurs between growth and other metabolic demands and that this trade-off provides a general mechanism underlying the evolution of growth rate. [source] The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plantsJOURNAL OF ECOLOGY, Issue 5 2009Richard P. Shefferson Summary 1.,I present an evolutionary ecology interpretation of vegetative dormancy in mature herbaceous perennials. This kind of vegetative dormancy has been noted for at least 40 years, but has only recently become a topic of study. 2.,Vegetative dormancy may be considered in a life-history context. Both vegetative dormancy and mortality typically decrease with increasing size. Vegetative dormancy's relationship to reproduction is more complex, because some species increase flowering and fruiting after dormancy while others do the opposite. 3.,If vegetative dormancy is adaptive, then it is most likely a bet-hedging trait. Dormancy-prone plants are often long-lived, and in such organisms, bet-hedging traits should counter the effects of environmental stochasticity on adult survival. This adaptive context may vary by life span, because in shorter-lived plants, fitness is most sensitive to changes in reproduction rather than survival. 4.,Vegetative dormancy could evolve if the costs of sprouting ever outweigh the benefits. The benefits of sprouting include: (i) photosynthesis and (ii) the opportunity to flower and reproduce. The costs include: (i) greater chance of herbivory, (ii) greater need for limiting nutrients, and (iii) greater maintenance costs. The many losses of photosynthesis among plants suggest that these benefits may not always outweigh the costs. 5.,Vegetative dormancy may be an evolutionary step towards the loss of photosynthesis. Many non-photosynthetic plants acquire carbon from their mycorrhizal fungi. Many autotrophic, dormancy-prone plants also acquire some carbon from their mycorrhizal fungi. Further, non-photosynthetic plants often become dormant to an even greater extent than autotrophic, dormancy-prone plants. 6.Synthesis,Vegetative dormancy often occurs in clades with non-photosynthetic, myco-heterotrophic plants, with implications for the evolution of traits involved in carbon nutrition. The links between vegetative dormancy, other life-history traits, mycorrhizas and the loss of photosynthesis should provide exciting directions for further research in plant evolutionary ecology. Particularly needed is an assessment of the physiology of vegetative dormancy, including whether the mycorrhiza is a carbon source in all dormancy-prone plant species. Equally important is a better understanding of the genetic relationships among photosynthesis, myco-heterotrophy and dormancy. [source] Phylogeography and speciation of colour morphs in the colonial ascidian Pseudodistoma crucigasterMOLECULAR ECOLOGY, Issue 10 2004I. TARJUELO Abstract Variation in pigmentation is common in marine invertebrates, although few studies have shown the existence of genetic differentiation of chromatic forms in these organisms. We studied the genetic structure of a colonial ascidian with populations of different colour morphs in the northwestern Mediterranean. A fragment of the c oxidase subunit 1 (COI) mitochondrial gene was sequenced in seven populations of Pseudodistoma crucigaster belonging to three different colour morphs (orange, yellow and grey). Maximum likelihood analyses showed two well-supported clades separating the orange morph from the yellow-grey morphotypes. Genetic divergence between these clades was 2.12%, and ,ST values between populations of the two clades were high (average 0.936), pointing to genetic isolation. Nested clade and coalescence analyses suggest that a past fragmentation event may explain the phylogeographical origin of these two clades. Non-neutral mtDNA evolution is observed in our data when comparing the two clades, showing a significant excess of nonsynonymous polymorphism within the yellow,grey morphotype using the McDonald,Kreitman test, which is interpreted as further support of reproductive isolation. We conclude that the two clades might represent separate species. We compare the population genetic differentiation found with that estimated for other colonial and solitary ascidian species, and relate it to larval dispersal capabilities and other life-history traits. [source] Six costs of immunity to gastrointestinal nematode infectionsPARASITE IMMUNOLOGY, Issue 2 2008I. G COLDITZ SUMMARY The strength of the immune response and the outcome of the interaction of a host with a parasite are influenced by genetic and phenotypic characteristics of both parties, and by environmental variables. Allocation of host resources to immune defence reduces resources available for other life-history traits. This review identifies six potential costs to the host from immune activation. The costs are likely to be broadly applicable to other immune responses in vertebrate species. Five phenotypic costs arise from: (i) increased metabolic activity; (ii) reduced nutrient availability due to anorexia; (iii) altered priorities for nutrient utilization; (iv) change in size and turnover of pools of immune cells and proteins; and (v) immunopathology from inappropriate or excessive immune activation. Subsumed by these costs is the cost of altered efficiency of nutrient use. A sixth cost is the genetic cost which arises from a change in the capacity of offspring to express production and life-history traits following selection for parasite resistance. The sensitivity of immune responses to the phenotypic status of the host, and the role the immune system shares with the neuroendocrine system in controlling use of resources underpin the importance of immunocompetence to the life-history of the host. [source] Direct and correlated responses to artificial selection on flight activity in the oriental fruit moth (Lepidoptera: Tortricidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010MARCO V. G. TORRIANI The ability of a sufficient number of individuals to disperse is crucial for long-term survival of populations. However, dispersal is often energetically costly, and thus is expected to trade-off against other life-history traits. In insect pest species, the occurrence of individuals with high flight activity challenges management practices. We performed artificial selection on flight activity and measured correlated responses to selection in the oriental fruit moth, Grapholita (= Cydia) molesta, a widely distributed and expanding lepidopteran pest of fruit crops. Both sexes rapidly responded to the imposed regime of divergent selection, indicating an adaptive potential of flight activity in this species. Upward-selected moths died sooner than downward-selected ones, providing evidence for a cost of flight activity to adult survival, reputedly associated with enhanced metabolic rates. Oppositely-selected females had similar total reproductive output, disproving a trade-off between dispersal and reproduction, although females with higher flight activity laid their eggs sooner. The ratio of body weight to forewing surface (forewing loading) did not significantly differ between selected lines. The present study contributes to the understanding of dispersal evolution, and also provides new insights into life-history theory as well as important baseline data for the improvement of pest management practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 879,889. [source] A parallel geographical mosaic of morphological and behavioural aposematic traits of the newt, Cynops pyrrhogaster (Urodela: Salamandridae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009KOJI MOCHIDA Aposematic animals advertise their unprofitability to potential predators with conspicuous coloration, occasionally in combination with other life-history traits. Theory posits that selection on functionally interrelated aposematic characters promotes the unidirectional evolution of these characters, resulting in an increase or decrease in the effectiveness of the signal. To test whether this prediction applies on a microevolutionary scale, the intra- and interpopulational variations in aposematic coloration, behaviour (which enhances the effectiveness of the coloration) and body size of newts, Cynops pyrrhogaster (Urodela: Salamandridae), were investigated. A parallel geographical mosaic of variation in aposematic coloration and behaviour among populations, independent of body size, was found. Newts on islands displayed more conspicuous aposematic traits than those on the mainland, both morphologically and behaviourally. There was no significant relationship between variation in coloration and behaviour within populations. Male newts displayed more conspicuous coloration than females. Surveys of potential predators suggest that variable natural selection at a local scale, such as predation pressure, may primarily be responsible for the microevolution of variable aposematic traits in newts. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 613,622. [source] | ||||||||||