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Adult Body Size (adult + body_size)
Selected AbstractsSexual dimorphism of body size and shell shape in European tortoisesJOURNAL OF ZOOLOGY, Issue 4 2003Ronald E. Willemsen Adult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca, T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni. Males grew to a larger size than females in T. marginata, and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata, vertical head bobs and carapace butting in T. graeca, and mounting and tail thrusting in T. hermanni. There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species. [source] Ecological Traits Predicting Amphibian Population Declines in Central AmericaCONSERVATION BIOLOGY, Issue 4 2003Karen R. Lips Populations of some species are extirpated, others have declined but survive, some have not obviously declined, and some are increasing. If amphibian populations at multiple sites were affected by the same factors, then surviving species should share traits that promote persistence, whereas declining species should share traits that promote susceptibility. Identifying these traits can help diagnose potential causes and thus help to direct conservation actions. Using logistic regression, we quantified the vulnerability of amphibian populations in four areas in Central America. We analyzed a species-specific database of taxonomic identity, geographic and elevational range, elevational distribution, adult and larval habitat, activity period, and maximum adult body size. We found that ( 1 ) all four sites exhibited the same pattern of decline ( there were no interactions between site and other variables ); ( 2 ) declining populations shared aquatic habitats, restricted elevational ranges, and large body sizes; and ( 3 ) there was an interaction between body size and elevational range. The most significant variable in the model was lifetime aquatic index, a factor unrelated to demographic vulnerability and one that therefore might indicate the potential causative agent( s ). Our results provide a predictive model with which to assess potential causes of population declines in other areas, and we generated a list of 52 species predicted to decline at a currently unaffected site in central Panama. Resumen: Las poblaciones de anfibios están declinando en todos los continentes donde ocurren, pero no todas las especies han sido afectadas por igual. Algunas especies han sido extirpadas, otras han declinado pero sobreviven, algunas no han declinado notablemente y otras están aumentando. Si las poblaciones de anfibios en varios sitios fueran afectadas por los mismos factores, las especies sobrevivientes deberían compartir características que promuevan la persistencia mientras que las especies en declinación deberían compartir características que promuevan la susceptibilidad. La identificación de estas características puede ayudar a diagnosticar las causas potenciales y así ayudar a dirigir medidas de conservación. Utilizando regresión logística, cuantificamos la vulnerabilidad de las poblaciones de anfibios en cuatro áreas de Centro América. Analizamos una base de datos de identidad taxonómica de especies, rango geográfico y altitudinal, distribución altitudinal, hábitat de larvas y adultos, período de actividad y máxima talla corporal de adultos. Encontramos que ( 1 ) los cuatro sitios presentaron el mismo patrón de declinación ( no hubo interacciones entre el sitio y otras variables ), ( 2 ) las poblaciones en declinación compartieron hábitats acuáticos, rangos altitudinales restringidos y tamaño corporal grande y ( 3 ) hubo interacción entre el tamaño corporal y el rango altitudinal. La variable más significativa del modelo fue el índice de vida acuática, un factor no relacionado con la vulnerabilidad demográfica y que, por lo tanto, podría indicar el agente causal potencial. Nuestros resultados proporcionan un modelo predictivo para evaluar las causas potenciales de declinación poblacional en otras áreas, y generamos una lista de 52 especies de declinación prevista en un sitio actualmente no afectado del centro de Panamá. [source] Density-dependent polyphenism and geographic variation in size among two populations of lubber grasshoppers (Romalea microptera)ECOLOGICAL ENTOMOLOGY, Issue 5 2009JASON E. JANNOT Abstract. 1. Density-dependent phase polyphenism occurs when changes in density during the juvenile stages result in a developmental shift from one phenotype to another. Density-dependent phase polyphenism is common among locusts (Orthoptera: Acrididae). 2. Previously, we demonstrated a longitudinal geographic cline in adult body size (western populations = small adults; eastern populations = large adults) in the eastern lubber grasshopper (Romalea microptera) in south Florida. As lubbers are confamilial with locusts, we hypothesised that the longitudinal size cline was partly due to density-dependent phase polyphenism. 3. We tested the effect of density, population, and density×population interaction on life-history traits (pronotum length, mass, cumulative development time, growth rate) of, and proportion surviving to, each of the five instars and the adult stage in a 2 × 3 factorial laboratory experiment with two lubber populations, each reared from hatchling to adult at three different densities. 4. The effect of density on life history and survival was independent of the effects of population on life history and survival. Higher densities led to larger adult sizes (pronotum, mass) and lower survivorship. The western population had smaller adult masses, fewer cumulative days to the adult stage, and higher survivorship than the eastern population. 5. Our data suggest that lubber grasshoppers exhibit density-dependent phase polyphenism initiated by the physical presence of conspecifics. However, the plastic response of adult size to density observed in the laboratory is not consistent with the relationship between phenotypes and adult density in the field. Genetic differences between populations observed in the laboratory could contribute to size and life-history differences among lubber populations in the field. [source] Selection for discontinuous life-history traits along a continuous thermal gradient in the butterfly Aricia agestisECOLOGICAL ENTOMOLOGY, Issue 6 2005Steve Burke Abstract., 1.,Voltinism may be conceptualised as the product of development rate and the timing of diapause , two components that together translate gradual environmental variation, through periods of growth and development, into ,generational units'. This may result in very different selection pressures on diapause induction and development time in populations with different numbers of generations per year. 2.,Developmental data from univoltine and bivoltine populations of the butterfly Aricia agestis (Lepidoptera: Lycaenidae) in North Wales were used to examine larval development time and the timing of diapause, and their contribution towards voltinism in populations that occur at the same latitude and in geographic proximity to one another along a thermal gradient. 3.,The critical photoperiod for diapause induction in univoltines and bivoltines from the same latitude differed by more than 1.5 h. 4.,Development time also differed significantly between these populations, in line with predictions that bivoltines would need to exhibit shorter development times in order to achieve two complete generations per year. Shorter development times for bivoltines result in lower pupal weights, suggesting a trade-off exists between generation number and body size that may dictate the position of the transition zone between the two life-history strategies. Analysis of development times in a third population, from southern England, with greater thermal availability than those from North Wales, further supports this hypothesised trade-off. 5.,To achieve the conversion of a continuous thermal gradient into the binary biological response from univoltism to bivoltism, bivoltines speed up development, reduce adult body size and shift their diapause induction response. [source] Oviposition habitat selection for a predator refuge and food source in a mosquitoECOLOGICAL ENTOMOLOGY, Issue 3 2005J. Guillermo Bond Abstract., 1.,The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2.,A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3.,Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0,99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4.,The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5.,Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae. [source] Body size as an estimator of production costs in a solitary beeECOLOGICAL ENTOMOLOGY, Issue 2 2002Jordi Bosch Abstract 1. Body weight is often used as an estimator of production costs in aculeate Hymenoptera; however, due to differences between sexes in metabolic rates and water content, conversion of provision weight to body weight may differ between males and females. As a result, the cost of producing female progeny may often have been overestimated. 2. Provision weight and body weight loss throughout development were measured in a solitary bee, Osmia cornuta (Latreille), to detect potential differences between sexes in food weight/body weight conversion. 3. Male O. cornuta invest a larger proportion of larval weight in cocoon spinning, and presumably have higher metabolic rates than females during the larval period; however, this is compensated by a slightly longer larval period in females. 4. Overall, body weight loss throughout the life cycle does not differ significantly between sexes. As a result, cost production ratios calculated from provision weights and from adult body weights are almost identical. 5. The validity of other weight (cocoon, faeces) and linear (head width, intertegular span, wing length, cocoon length, and cell length) measures as estimators of production costs is also discussed. 6. Valid estimators of production costs vary across species due to differences in sex weight ratio, cocoon shape, provision size in reference to cell size, and adult body size. [source] Small-scaled geographical variation in life-history traits of the blowfly Calliphora vicina between rural and urban populationsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2009C. C. Hwang Abstract The impact of the urban heat-island effect, the warming-up of an urban area caused by human activity, on the blowfly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) was examined at two British sites, 30 km apart. Waterloo in Central London is a highly urbanised built-up area, whereas Box Hill in the county of Surrey is a rural pasture and woodland location. The phenotypic plasticity of 12 C. vicina cultures, originated from single females from each of the two sites, was measured using three developmental characters: adult body size (represented as the length of the cross vein dm-cu of the right wing), development time as accumulated degree-days (ADD), and growth rate (length of dm-cu/ADD), along a constant temperature series of 16, 20, 24, and 28 °C in the laboratory. The blowflies from Box Hill had the same ADD as those from Waterloo, but showed a significantly larger adult size and growth rate at lower temperatures, suggesting the existence of local adaptations that may be caused by the differing levels of urbanisation between the two studied sites. Not surprisingly, a trade-off between adult size and development time was found. Females showed longer development times than males at all four temperatures, indicating they may need to ingest more food as larvae to furnish ovarioles and increase fecundity. However, females had larger adult size than males at 16 and 20 °C but a reverse at 28 °C, suggesting that females may be more cold-adapted than males. [source] Non-lethal effects of invertebrate predators on Daphnia: morphological and life-history consequences of water mite kairomoneFRESHWATER BIOLOGY, Issue 9 2008MAURICIO J. CARTER Summary 1. Here, we report morphological and life-historical changes in the cladoceran Daphnia ambigua in response to chemical cues released by the predatory water mite Piona chilensis. Both species are common inhabitants of southern temperate lakes. 2. We found significant differences in adult body size at first, second and third reproduction. Also, individuals exposed to kairomones had longer tail spines at first reproduction, and the resultant offspring had smaller bodies and shorter tail spines. 3. Exposure to mite cues did not exert effects on brood size at first reproduction, but decreased offspring number in subsequent broods. Similarly, only the second and third reproduction events were delayed by kairomone exposure. 4. The intrinsic population growth rate of predator-induced animals was lower than that in controls, but simulations based on a parameterized matrix model showed that the fitness costs could be overcome if the reported phenotypic responses reduced predation rate moderately. The gain in protection from predators needed to cancel out the reduction in fitness associated with predator cues was directly related to juvenile survival and fertility, and inversely related to adult survival. 5. This is the first work reporting phenotypic plasticity in Cladocera in response to kairomones released by water mites, which are conspicuous predators in many austral fresh waters. [source] Female and male plumage brightness correlate with nesting failure in azure-winged magpies Cyanopica cyanusJOURNAL OF AVIAN BIOLOGY, Issue 2 2008Jesús M. Avilés Animals may assess the quality of other individuals by using information that is contained in elaborate traits. We investigated the degree of sexual dimorphism in structural blue plumage coloration and the potential signal value of these traits in the azure-winged magpie Cyanopica cyanus. We predicted that in this species blue coloration should signal individual quality in both sexes since both females and males invest significantly in caring for offspring. Males have more saturated UV/blue coloration than females and blueness decreased from moulting to reproduction. Males and females did not mate assortatively for blue coloration although they did in relation to body size and condition. Blue colour did not correlate with adult body size or condition. However, nest predation decreased with female and male brightness. Our results suggest that blue coloration may potentially be used to assess parental qualities by potential mates in both sexes of the azure-winged magpie. [source] Maternal and paternal condition effects on offspring phenotype in Telostylinus angusticollis (Diptera: Neriidae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007R. BONDURIANSKY Abstract It is widely recognized that maternal phenotype can have important effects on offspring, but paternal phenotype is generally assumed to have no influence in animals lacking paternal care. Nonetheless, selection may favour the transfer of environmentally acquired condition to offspring from both parents. Using a split-brood, cross-generational laboratory design, we manipulated a key environmental determinant of condition , larval diet quality , of parents and their offspring in the fly Telostylinus angusticollis, in which there is no evidence of paternal provisioning. Parental diet did not affect offspring survival, but high-condition mothers produced larger eggs, and their offspring developed more rapidly when on a poor larval diet. Maternal condition had no effect on adult body size of offspring. By contrast, large, high-condition fathers produced larger offspring, and follow-up assays showed that this paternal effect can be sufficient to increase mating success of male offspring and fecundity of female offspring. Our findings suggest that both mothers and fathers transfer their condition to offspring, but with effects on different offspring traits. Moreover, our results suggest that paternal effects can be important even in species lacking conventional forms of paternal care. In such species, the transfer of paternal condition to offspring could contribute to indirect selection on female mate preferences. [source] Temperature dependent larval resource allocation shaping adult body size in Drosophila melanogasterJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2003Z. Bochdanovits Abstract Geographical variation in Drosophila melanogaster body size is a long-standing problem of life-history evolution. Adaptation to a cold climate invariably produces large individuals, whereas evolution in tropical regions result in small individuals. The proximate mechanism was suggested to involve thermal evolution of resource processing by the developing larvae. In this study an attempt is made to merge proximate explanations, featuring temperature sensitivity of larval resource processing, and ultimate approaches focusing on adult and pre-adult life-history traits. To address the issue of temperature dependent resource allocation to adult size vs. larval survival, feeding was stopped at several stages during the larval development. Under these conditions of food deprivation, two temperate and two tropical populations reared at high and low temperatures produced different adult body sizes coinciding with different probabilities to reach the adult stage. In all cases a phenotypic trade-off between larval survival and adult size was observed. However, the underlying pattern of larval resource allocation differed between the geographical populations. In the temperate populations larval age but not weight predicted survival. Temperate larvae did not invest accumulated resources in survival, instead they preserved larval biomass to benefit adult weight. In other words, larvae from temperate populations failed to re-allocate accumulated resources to facilitate their survival. A low percentage of the larvae survived to adulthood but produced relatively large flies. Conversely, in tropical populations larval weight but not age determined the probability to reach adulthood. Tropical larvae did not invest in adult size, but facilitated their own survival. Most larvae succeeded in pupating but then produced small adults. The underlying physiological mechanism seemed to be an evolved difference in the accessibility of glycogen reserves as a result of thermal adaptation. At low rearing temperatures and in the temperate populations, glycogen levels tended to correlate positively with adult size but negatively with pupation probability. The data presented here offer an explanation of geographical variation in body size by showing that thermal evolution of resource allocation, specifically the ability to access glycogen storage, is the proximate mechanism responsible for the life-history trade-off between larval survival and adult size. [source] Temperature and clinal variation in larval growth efficiency in Drosophila melanogasterJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2001S. J. W. Robinson Geographic clines in ectotherm species including Drosophila melanogaster have been found throughout the world, with genetically larger body size and shorter development time occurring at high latitudes. Temperature is thought to play a major role in the evolution of this clinal variation. Laboratory thermal selection has effects similar to those seen in geographical clines. Evolution at low temperatures results in more rapid development to larger adult flies. This study investigated the effects of geographical origin and experimental temperature on larval growth efficiency in D. melanogaster. Larvae from populations that had evolved at high latitudes were found to use limited food more efficiently, so that the overall adult body size achieved was larger. Larvae reared at a lower experimental temperature (18 °C) used food more efficiently than those reared at a higher temperature (25 °C). The increases in growth efficiency found in populations from high latitudes could explain their increased body size and more rapid development. [source] Sex-specific selection and sexual size dimorphism in the waterstrider Aquarius remigisJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2000Ferguson We estimated selection on adult body size for two generations in two populations of Aquarius remigis, as part of a long-term study of the adaptive significance of sexual size dimorphism (SSD). Net adult fitness was estimated from the following components: prereproductive survival, daily reproductive success (mating frequency or fecundity), and reproductive lifespan. Standardized selection gradients were estimated for total length and for thorax, abdomen, genital and mesofemur lengths. Although selection was generally weak and showed significant temporal and spatial heterogeneity, patterns were consistent with SSD. Prereproductive survival was strongly influenced by date of eclosion, but size (thorax and genital lengths in females; total and abdomen lengths in males) played a significant secondary role. Sexual selection favoured smaller males with longer external genitalia in one population. Net adult fitness was not significantly related to body size in females, but was negatively related to size (thorax and total length) in males. [source] Environmental influence and cohort effects in a sexual ornament in the house sparrow, Passer domesticusOIKOS, Issue 2 2006Henrik Jensen Presence of phenotypic variation is necessary for selection to occur, yet processes affecting variation in sexually selected characters in natural populations are poorly understood. Here we examine whether variation in a sexual ornament (badge size) of male house sparrows (Passer domesticus) is dependent on individual variation in the conditions during early ontogenetic stages, and whether this variation and the population-wide effects of external variables such as weather or population size jointly will generate consistent differences among cohorts later in life. Variation in badge size was independent of adult body size, whereas heavier fledglings and fledglings in good body condition developed smaller visible badges as adults. Furthermore, strong cohort-effects were present, caused by a combined effect of density-dependence and weather during the early development in the moulting period and autumn after hatching. Thus, badge size is an environmentally-dependent trait in house sparrows, and likely to be under the influence of both natural and sexual selection. [source] Growth rates and life histories in twenty-two small-scale societies,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2006Robert Walker This study investigates variation in body growth (cross-sectional height and weight velocity) among a sample of 22 small-scale societies. Considerable variation in growth exists among hunter-gatherers that overlaps heavily with growth trajectories present in groups focusing more on horticulture. Intergroup variation tends to track environmental conditions, with societies under more favorable conditions displaying faster growth and earlier puberty. In addition, faster/earlier development in females is correlated with higher mortality. For example, African "Pygmies," Philippine "Negritos," and the Hiwi of Venezuela are characterized by relatively fast child-juvenile growth for their adult body size (used as a proxy for energetic availability). In these societies, subadult survival is low, and puberty, menarche, and first reproduction are relatively early (given their adult body size), suggesting selective pressure for accelerated development in the face of higher mortality. In sum, the origin and maintenance of different human ontogenies may require explanations invoking both environmental constraints and selective pressures. Am. J. Hum. Biol. 18:295,311, 2006. © 2006 Wiley-Liss, Inc. [source] Fetal programming: Adaptive life-history tactics or making the best of a bad start?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2005James Holland Jones Fetal programming is an ontogenetic phenomenon of increasing interest to human biologists. Because the downstream consequences of fetal programming have clear impacts on specific life-history traits (e.g., age at first reproduction and the general age-pattern of reproductive investments), a number of authors have raised the question of the adaptive significance of fetal programming. In this paper, I review in some detail several classical models in life-history theory and discuss their relative merits and weaknesses for human biology. I suggest that an adequate model of human life-history evolution must account for the highly structured nature of the human life cycle, with its late age at first reproduction, large degree of iteroparity, highly overlapping generations, and extensive, post-weaning parental investment. I further suggest that an understanding of stochastic demography is essential for answering the question of the adaptive significance of fetal programming, and specifically the finding of low birth weight on smaller adult body size and earlier age at first reproduction. Using a stage-structured stochastic population model, I show that the downstream consequences of early deprivation may be "making the best of a bad start" rather than an adaptation per se. When a high-investment strategy entails survival costs, the alternate strategy of early reproduction with relatively low investment may have higher fitness than trying to play the high-investment strategy and failing. Am. J. Hum. Biol. 17:22,33, 2005. © 2004 Wiley-Liss, Inc. [source] Maternal work and childhood nutritional status among the Purari, Papua New GuineaAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2003Stanley J. Ulijaszek In traditional economies, body size, physical work capacity, subsistence productivity, and nutrition of adults may be interrelated, and one cross-generational effect of these relationships may operate through the household, influencing nutritional status of children. In this analysis, the relationships among adult body size, work productivity in terms of time spent making sago starch, dietary diversity, nutrient availability, and childhood nutritional status are examined in the Purari population of Papua New Guinea, a group largely dependent on the starchy staple palm sago, which is devoid of all nutrients apart from energy. Observations of work scheduling, household food and nutrient availability, and nutritional status were carried out for 16 women, their households, and their children. A multiple regression model of hours spent in sago making on a particular day with days spent in other subsistence activities showed a negative relationship with the number of days spent in sago-making and a positive relationship with the number of days spent fishing. The number of hours spent in sago-making on a particular day was also positively related to daily per capita availability of protein at the household level. This is not a function of maternal nutritional status, however, since there is no association between body size of adult females and the number of hours spent making sago on a particular day. Nor does the greater per capita protein availability at the household level in households where women spend longer on a particular day in sago-making result in improved childhood nutritional status. Since relationships among adult body size, work productivity, dietary diversity, nutrient availability, and childhood nutritional status are only partially demonstrated in this population, it may be that these linkages may only be important if physically arduous work is needed more consistently than is the case in the Purari delta. Am. J. Hum. Biol. 15:472,478, 2003. © 2003 Wiley-Liss, Inc. [source] Synchrony between growth and reproductive patterns in human females: Early investment in growth among Pumé foragersAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Karen L. Kramer Abstract Life history is an important framework for understanding many aspects of ontogeny and reproduction relative to fitness outcomes. Because growth is a key influence on the timing of reproductive maturity and age at first birth is a critical demographic variable predicting lifetime fertility, it raises questions about the synchrony of growth and reproductive strategies. Among the Pumé, a group of South American foragers, young women give birth to their first child on average at age 15.5. Previous research showed that this early age at first birth maximizes surviving fertility under conditions of high infant mortality. In this study we evaluate Pumé growth data to test the expectation that if early reproduction is advantageous, then girls should have a developmental trajectory that best prepares them for young childbearing. Analyses show that comparatively Pumé girls invest in skeletal growth early, enter puberty having achieved a greater proportion of adult body size and grow at low velocities during adolescence. For early reproducers growing up in a food-limited environment, a precocious investment in growth is advantageous because juveniles have no chance of pregnancy and it occurs before the onset of the competing metabolic demands of final reproductive maturation and childbearing. Documenting growth patterns under preindustrial energetic and demographic conditions expands the range of developmental variation not otherwise captured by normative growth standards and contributes to research on human phenotypic plasticity in diverse environments. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Body size variation in insects: a macroecological perspectiveBIOLOGICAL REVIEWS, Issue 1 2010Steven L. Chown Body size is a key feature of organisms and varies continuously because of the effects of natural selection on the size-dependency of resource acquisition and mortality rates. This review provides a critical and synthetic overview of body size variation in insects from a predominantly macroecological (large-scale temporal and spatial) perspective. Because of the importance of understanding the proximate determinants of adult size, it commences with a brief summary of the physiological mechanisms underlying adult body size and its variation, based mostly on findings for the model species Drosophila melanogaster and Manduca sexta. Variation in nutrition and temperature have variable effects on critical weight, the interval to cessation of growth (or terminal growth period) and growth rates, so influencing final adult size. Ontogenetic and phylogenetic variation in size, compensatory growth, scaling at the intra- and interspecific levels, sexual size dimorphism, and body size optimisation are then reviewed in light of their influences on individual and species body size frequency distributions. Explicit attention is given to evolutionary trends, including gigantism, Cope's rule and the rates at which size change has taken place, and to temporal ecological trends such as variation in size with succession and size-selectivity during the invasion process. Large-scale spatial variation in size at the intraspecific, interspecific and assemblage levels is considered, with special attention being given to the mechanisms proposed to underlie clinal variation in adult body size. Finally, areas particularly in need of additional research are identified. [source] Male Body Size and Mating Success and Their Relation to Larval Host Plant History in the Moth Rothschildia lebeau in Costa Rican Dry ForestBIOTROPICA, Issue 2 2010Salvatore J. Agosta ABSTRACT The moth Rothschildia lebeau uses three tree species as its primary larval hosts in the tropical dry forest of northwestern Costa Rica. These hosts were shown previously to have different relative effects on caterpillar performance, resulting in an apparent host-related life history trade-off between large adult body size on the one hand but low offspring survival on the other. To further assess the potential ecological and evolutionary importance of this trade-off, an observational field study of the relationship between male body size and mating success was conducted. Across mating trials, larger males had a higher probability of being observed mating. Independent of the effect of size, the amount of wing damage an individual had sustained (a measure of relative age) was negatively correlated with the probability a male was observed mating. Within mating trials, the mated male tended to be larger than the average unmated male, but there was no difference in wing damage. Overall, results of this study were consistent with a positive effect of male body size on mating success, consistent with the idea that larval host plant history and its effects on adult body size matters in terms of adult male fitness. However, all sized males were observed mating over the course of the study, and the size advantage did not appear to be particularly strong. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source] Philopatry and Homing Behavior of Sea Snakes (Laticauda colubrina) from Two Adjacent Islands in FijiCONSERVATION BIOLOGY, Issue 5 2002Sohan Shetty Even in highly vagile species, local populations may comprise ecologically separate entities if most animals display strong and consistent site attachment. We conducted a mark-recapture study on yellow-lipped sea kraits ( Laticauda colubrina) on two small Fijian islands separated by 5.3 km. These snakes forage over many kilometers in the ocean, but return to land to reproduce, slough, and digest their food. Recovery of marked snakes showed that the populations on these two islands were essentially separate. Relocated snakes returned "home" almost immediately after they were released. Growth rates and mean adult body sizes of male sea snakes also differed between the two islands. This high site fidelity means that activities such as resort development or commercial harvesting for the skin trade are likely to have intense localized effects rather than diffuse broad-scale effects on sea snake populations. Our results also call into question the feasibility of plans to reintroduce snake populations to areas where a species has been eliminated by overexploitation. Resumen: La escala espacial a la que las perturbaciones antropogénicas afectan a una población de animales depende del grado de filopatría y de la búsqueda del hogar de individuos dentro de esta población. Aún en especies altamente móviles, las poblaciones locales pueden contener entidades ecológicamente separadas si la mayoría de los animales presentan un apego fuerte y consistente por un sitio. Llevamos a cabo un estudio de marcado-recaptura en las serpientes marinas de labios amarillos ( Laticauda colubrina) de dos islas pequeñas de Fiji, separadas por 5.3 km. Estas serpientes forrajean a lo largo de muchos kilómetros en el océano, pero regresan a tierra a reproducirse, mudar de piel y digerir su comida. La recuperación de serpientes mostró que las poblaciones en estas dos islas estaban substancialmente separadas. Las serpientes reubicadas regresaron a "casa" casi inmediatamente después de haber sido liberadas. Las tasas de crecimiento y el tamaño promedio de machos también difirieron entre las dos islas. Esta alta fidelidad al sitio significa que las actividades tales como el desarrollo de un centro turístico o de la cosecha comercial para el comercio de la piel son probablemente factores que tendrán efectos localizados en lugar de efectos difusos de amplia escala sobre las poblaciones de serpientes marinas. Nuestros resultados también cuestionan la viabilidad de planes para reintroducir poblaciones de serpientes en áreas donde una especie ha sido eliminada por sobreexplotación. [source] Cascading effects of variation in plant vigour on the relative performance of insect herbivores and their parasitoidsECOLOGICAL ENTOMOLOGY, Issue 1 2002Tiit Teder Abstract 1. Consequences of variation in food plant quality were estimated for a system consisting of two monophagous noctuid herbivores and three ichneumonid parasitoids. 2. In a natural population, pupal weights of the herbivores in this system, Nonagria typhae and Archanara sparganii, were found to be highly variable. Pupal weights increased strongly and consistently with the increase in the vigour of the host plant, Typha latifolia, providing support for the plant vigour hypothesis. Correspondingly, as the moths do not feed as adults, a strong, positive correlation between host vigour and fecundity of the herbivores would be expected. 3. There were strong and positive relationships between adult body sizes of the parasitoids and the sizes of their lepidopteran hosts. Moreover, a direct, positive link between plant quality and parasitoid size was documented. 4. For all three parasitoids, cascading effects of plant quality on body size were weaker than for the herbivores. Differences in the importance of adult feeding and oviposition behaviour suggest that dependence of fitness on body size is also weaker in the parasitoids than in the moths. It is therefore concluded that the numerical response of the herbivore population to a change in plant quality should exceed the corresponding response in the parasitoids. 5. The results of this work imply that variation in plant variables may affect performance of different trophic levels to a different extent. It is suggested that the importance of adult feeding for the reproductive success (capital vs. income breeding strategies) in both herbivores and parasitoids is an essential aspect to consider when predicting responses of such a system to changes in plant quality. [source] | ||||||||||||||||||||||