4,222 results match your criteria American Naturalist[Journal]

Organisms as Complex Structures Wrapped in a Complex Web of Life.

Am Nat 2022 Jun 21;199(6):804-807. Epub 2022 Apr 21.

AbstractA pressing issue is to understand how biological complexity impacts the persistence and adaptation of populations. Natural environments are under unprecedented pressure as a result of climate change and land use change, which makes biological populations and ecological communities vulnerable. Evolution by natural selection-that is, genetic change in response to selection-is one important way species can cope with such changes. Read More

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Evolution of Plant Niche Construction Traits in Biogeomorphic Landscapes.

Xiaoli Dong

Am Nat 2022 Jun 21;199(6):758-775. Epub 2022 Apr 21.

AbstractBy virtue of their niche construction traits, plants play a significant role in shaping landscapes. The resultant outcome could change the selective environment, which then influences the evolution of these same plants. To date, almost all biogeomorphic models have assumed that niche construction traits are invariant in time. Read More

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Relaxed Feeding Constraints Facilitate the Evolution of Mouthbrooding in Neotropical Cichlids.

Am Nat 2022 Jun 22;199(6):E197-E210. Epub 2022 Apr 22.

AbstractMultifunctionality is often framed as a core constraint of evolution, yet many evolutionary transitions involve traits taking on additional functions. Mouthbrooding, a form of parental care where offspring develop inside a parent's mouth, increases multifunctionality by adding a major function (reproduction) to a structure already serving other vital functions (feeding and respiration). Despite increasing multifunctionality, mouthbrooding has evolved repeatedly from other forms of parental care in at least seven fish families. Read More

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Intergenerational Effects of Early-Life Starvation on Life History, Consumption, and Transcriptome of a Holometabolous Insect.

Am Nat 2022 Jun 20;199(6):E229-E243. Epub 2022 Apr 20.

AbstractIntergenerational effects, also known as parental effects in which the offspring phenotype is influenced by the parental phenotype, can occur in response to factors that occur not only in early but also in late parental life. However, little is known about how these parental life stage-specific environments interact with each other and with the offspring environment to influence offspring phenotypes, particularly in organisms that realize distinct niches across ontogeny. We examined the effects of parental larval starvation and adult reproductive environment on offspring traits under matching or mismatching offspring larval starvation conditions using the holometabolous, haplodiploid insect (turnip sawfly). Read More

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Sequestration of Defenses against Predators Drives Specialized Host Plant Associations in Preadapted Milkweed Bugs (Heteroptera: Lygaeinae).

Am Nat 2022 Jun 29;199(6):E211-E228. Epub 2022 Apr 29.

AbstractHost plant specialization across herbivorous insects varies dramatically, but while the molecular mechanisms of host plant adaptations are increasingly known, we often lack a comprehensive understanding of the selective forces that favor specialization. The milkweed bugs (Heteroptera: Lygaeinae) are ancestrally associated with plants of the Apocynaceae from which they commonly sequester cardiac glycosides for defense, facilitated by resistant Na/K-ATPases and adaptations for transport, storage, and discharge of toxins. Here, we show that three Lygaeinae species independently colonized four novel nonapocynaceous hosts that convergently produce cardiac glycosides. Read More

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Frequency-Dependent Hybridization Contributes to Habitat Segregation in Monkeyflowers.

Am Nat 2022 Jun 21;199(6):743-757. Epub 2022 Apr 21.

AbstractSpatial segregation of closely related species is usually attributed to differences in stress tolerance and competitive ability. For both animals and plants, reproductive interactions between close relatives can impose a fitness cost that is more detrimental to the rarer species. Frequency-dependent mating interactions may thus prevent the establishment of immigrants within heterospecific populations, maintaining spatial segregation of species. Read More

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The Demographic Consequences of Adaptation: Evidence from Experimental Evolution.

Am Nat 2022 Jun 20;199(6):729-742. Epub 2022 Apr 20.

AbstractThe process of adaptation toward novel environments is directly connected to the acquisition of higher fitness relative to others. Such increased fitness is obtained by changes in life history traits that may directly impact population dynamics. From a functional perspective, increased fitness can be achieved through higher resource use or more efficient resource use, each potentially having its own impact on population dynamics. Read More

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The Ecology of Spider Sociality: A Spatial Model.

Am Nat 2022 Jun 20;199(6):776-788. Epub 2022 Apr 20.

AbstractThe emergence of animal societies offers unsolved problems for both evolutionary and ecological studies. Social spiders are especially well suited to address this problem given their multiple independent origins and distinct geographic distribution. On the basis of long-term research on the spider genus , we developed a spatial model that re-creates observed macroecological patterns in the distribution of social and subsocial spiders. Read More

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Niche Packing and Local Coexistence in a Megadiverse Guild of Frugivorous Birds Are Mediated by Fruit Dependence and Shifts in Interaction Frequencies.

Am Nat 2022 Jun 21;199(6):855-868. Epub 2022 Apr 21.

AbstractNiche packing is one of the prevailing mechanisms underlying the increase in the number of co-occurring species and the extraordinary diversity of tropical ecosystems. However, it is not yet understood whether niche packing is facilitated by higher specialization and reduced niche overlap or, rather, by diffuse competition and increased niche overlap. We combined highly resolved bird-plant interaction networks, bird phylogenies, and plant functional traits to compare dietary niche overlap and foraging frequencies among frugivorous birds at seven sites in the tropical Andes. Read More

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Quantitative Prediction of Interactions in Bipartite Networks Based on Traits, Abundances, and Phylogeny.

Am Nat 2022 Jun 13;199(6):841-854. Epub 2022 Apr 13.

AbstractEcological interactions link species in networks. Loss of species from or introduction of new species into an existing network may have substantial effects for interaction patterns. Predicting changes in interaction frequency while allowing for rewiring of existing interactions-and hence estimating the consequences of community compositional changes-is thus a central challenge for network ecology. Read More

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Selection of Floral Traits by Pollinators and Seed Predators during Sequential Life History Stages.

Am Nat 2022 Jun 18;199(6):808-823. Epub 2022 Apr 18.

AbstractOrganismal traits often influence fitness via interactions with multiple species. That selection is not necessarily predictable from pairwise interactions, such as when interactions occur during different life cycle stages. Theoretically, directional selection during two sequential episodes (e. Read More

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Uncovering Cryptic Coevolution.

Am Nat 2022 Jun 19;199(6):869-880. Epub 2022 Apr 19.

AbstractStudies of coevolution in the wild have largely focused on reciprocally specialized species pairs with striking and exaggerated phenotypes. Textbook examples include interactions between toxic newts and their garter snake predators, long-tongued flies and the flowers they pollinate, and weevils with elongated rostra used to bore through the defensive pericarp of their host plants. Although these studies have laid a foundation for understanding coevolution in the wild, they have also contributed to the widespread impression that coevolution is a rare and quirky sideshow to the day-to-day grind of ecology and evolution. Read More

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Using Metabolic Theory to Describe Temperature and Thermal Acclimation Effects on Parasitic Infection.

Am Nat 2022 Jun 18;199(6):789-803. Epub 2022 Apr 18.

AbstractPredicting temperature effects on species interactions can be challenging, especially for parasitism, where it is difficult to experimentally separate host and parasite thermal performance curves. Prior authors proposed a possible solution based on the metabolic theory of ecology (MTE), using MTE-based equations to describe the thermal mismatch between host and parasite performance curves and account for thermal acclimation responses. Here, we use published infection data, supplemented with experiments measuring metabolic responses to temperature in each species, to show that this modeling framework can successfully describe thermal acclimation effects on two different stages of infection in a tadpole-trematode system. Read More

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Emission Rates of Species-Specific Volatiles Vary across Communities of Species: Evidence for Multimodal Character Displacement.

Am Nat 2022 Jun 20;199(6):824-840. Epub 2022 Apr 20.

AbstractA current frontier of character displacement research is to determine whether displacement occurs via multiple phenotypic pathways and varies across communities with different species compositions. Here, we conducted the first test for context-dependent character displacement in multimodal floral signals by analyzing variation in floral scent in a system that exhibits character displacement in flower size and that has multiple types of sympatric communities. In a greenhouse common garden experiment, we measured quantitative variation in volatile emission rates of the progeny of two species of from replicated parental communities that contain one, two, or four species. Read More

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Distributing Defenses: How Resource Defendability Shapes the Optimal Response to Risk.

Am Nat 2022 May 25;199(5):636-652. Epub 2022 Mar 25.

AbstractMany organisms divide limited defenses among heterogeneous assets. Plants allocate defensive chemicals among tissues differing in value, cost of defense, and risk of herbivory. Some ant colonies allocate specialized defenders among multiple nests differing in volume, entrance size, and risk of attack. Read More

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The Contributions of Maternal Age Heterogeneity to Variance in Lifetime Reproductive Output.

Am Nat 2022 May 28;199(5):603-616. Epub 2022 Mar 28.

AbstractVariance among individuals in fitness components reflects both genuine heterogeneity between individuals and stochasticity in events experienced along the life cycle. Maternal age represents a form of heterogeneity that affects both the mean and the variance of lifetime reproductive output (LRO). Here, we quantify the relative contribution of maternal age heterogeneity to the variance in LRO using individual-level laboratory data on the rotifer to parameterize a multistate age × maternal age matrix model. Read More

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Host Sex Modulates the Energetics of Pathogen Proliferation and Its Dependence on Environmental Resources.

Am Nat 2022 May 4;199(5):E186-E196. Epub 2022 Apr 4.

AbstractSex differences in immunity are predicted to underlie much of the frequently observed sex differences in the prevalence or severity of infection. We propose the additional hypothesis that differences in the ability of males and females to acquire and use resources will also affect how readily a pathogen can convert host energy into transmission stages, thereby contributing to sex differences in infection dynamics. To test this we manipulated the resource environment of male and female by altering the availability of food and then exposed hosts to a bacterial pathogen. Read More

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Dispersal Decreases Survival but Increases Reproductive Opportunities for Subordinates in a Cooperative Breeder.

Am Nat 2022 May 23;199(5):679-690. Epub 2022 Mar 23.

AbstractIn most socially structured populations, the formation of new groups depends on the survival and reproduction of dispersing individuals. Quantifying vital rates in dispersers, however, is difficult because of the logistic challenges of following wide-ranging animals. Here, using data from free-ranging meerkats (), we estimate survival and reproduction of dispersing females and compare these estimates to data for established residents. Read More

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The Contribution of Genetic and Environmental Effects to Bergmann's Rule and Allen's Rule in House Mice.

Am Nat 2022 May 24;199(5):691-704. Epub 2022 Mar 24.

AbstractDistinguishing between genetic, environmental, and genotype × environment effects is central to understanding geographic variation in phenotypic clines. Two of the best-documented phenotypic clines are Bergmann's rule and Allen's rule, which describe larger body sizes and shortened extremities in colder climates, respectively. Although numerous studies have found inter- and intraspecific evidence for both ecogeographic patterns, we still have a poor understanding of the extent to which these patterns are driven by genetics, environment, or both. Read More

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Thermal Costs and Benefits of Replicated Color Evolution in the White Sands Desert Lizard Community.

Am Nat 2022 May 30;199(5):666-678. Epub 2022 Mar 30.

AbstractTraits often contribute to multiple functions, complicating our understanding of the selective pressures that influence trait evolution. In the Chihuahuan Desert, predation is thought to be the primary driver of cryptic light coloration in three White Sands lizard species relative to the darker coloration of populations on adjacent dark soils. However, coloration also influences radiation absorption and thus animal body temperatures. Read More

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Sex-Specific Variance in Fitness and the Efficacy of Selection.

Am Nat 2022 May 8;199(5):587-602. Epub 2022 Apr 8.

AbstractVariance in fitness is thought to be greater in males than in females in many species. If this is so, there are two potentially contradictory consequences on the efficacy of selection (): greater variance in fitness may allow stronger selection (i.e. Read More

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Reduced Mitochondrial Respiration in Hybrid Asexual Lizards.

Am Nat 2022 May 3;199(5):719-728. Epub 2022 Mar 3.

AbstractThe scarcity of asexual reproduction in vertebrates alludes to an inherent cost. Several groups of asexual vertebrates exhibit lower endurance capacity (a trait predominantly sourced by mitochondrial respiration) compared with congeneric sexual species. Here we measure endurance capacity in five species of lizards and examine mitochondrial respiration between sexual and asexual species using mitochondrial respirometry. Read More

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Metabolic Rate Diversity Shapes Group Performance in Honeybees.

Am Nat 2022 May 8;199(5):E156-E169. Epub 2022 Apr 8.

AbstractThe metabolic theory of ecology posits that the functional properties at any level of biological organization are a function of the metabolic rate (MR) of its constituent units, although we know little about how heterogeneity among them shapes group-level performance. Using honeybees as a model system, we leveraged the differences in MR associated with "slow" and "fast" malate dehydrogenase alleles to breed genetic lines with low MR and high MR, respectively, and created four experimental groups with different phenotypic compositions. We then measured MR, energetic intake, thermoregulation, and survival of these groups in low- and high-resource conditions. Read More

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The Genomic Consistency of the Loss of Anadromy in an Arctic Fish ().

Am Nat 2022 May 31;199(5):617-635. Epub 2022 Mar 31.

AbstractThe potentially significant genetic consequences associated with the loss of migratory capacity of diadromous fishes that have become landlocked in freshwater are poorly understood. Consistent selective pressures associated with freshwater residency may drive repeated differentiation both between allopatric landlocked and anadromous populations and within landlocked populations (resulting in sympatric morphs). Alternatively, the strong genetic drift anticipated in isolated landlocked populations could hinder consistent adaptation, limiting genetic parallelism. Read More

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Dynamic Changes in Begging Signal Short-Term Information on Hunger and Need.

Am Nat 2022 May 29;199(5):705-718. Epub 2022 Mar 29.

AbstractDynamic signals can convey distinct information to a receiver on different timescales, making assessment of how quickly signal strength changes important for understanding signal function. Here, we combine repeated measures of offspring begging behavior of western bluebirds with assessments of fitness as well as quantitative genetic analyses of cross-fostered offspring to investigate whether variation in begging behavior conveys information about hunger, need, or quality or has no signaling function. Begging intensity increased with food deprivation, supporting the signal-of-hunger hypothesis. Read More

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Density-by-Diet Interactions during Larval Development Shape Adult Life History Trait Expression and Fitness in a Polyphagous Fly.

Am Nat 2022 May 25;199(5):E170-E185. Epub 2022 Mar 25.

AbstractHabitat quality early in life determines individual fitness, with possible long-term evolutionary effects on groups and populations. In holometabolous insects, larval ecology plays a major role in determining the expression of traits in adulthood, but how ecological conditions during the larval stage interact to shape adult life history and fitness, particularly in nonmodel organisms, remains subject to scrutiny. Consequently, our knowledge of the interactive effects of ecological factors on insect development is limited. Read More

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Eavesdropping Micropredators as Dynamic Limiters of Sexual Signal Elaboration and Intrasexual Competition.

Am Nat 2022 May 25;199(5):653-665. Epub 2022 Mar 25.

AbstractTo thoroughly understand the drivers of dynamic signal elaboration requires assessing the direct and indirect effects of naturally interacting factors. Here, we use structural equation modeling to test multivariate data from in situ observations of sexual signal production against a model of causal processes hypothesized to drive signal elaboration. We assess direct and indirect effects, and relative impacts, of male-male competition and attacks by eavesdropping frog-biting midges (Diptera: Corethrellidae) on call elaboration of male túngara frogs (). Read More

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Am Nat 2022 Apr 15;199(4):584-585. Epub 2022 Mar 15.

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Evolutionary Impact of Size-Selective Harvesting on Shoaling Behavior: Individual-Level Mechanisms and Possible Consequences for Natural and Fishing Mortality.

Am Nat 2022 04 4;199(4):480-495. Epub 2022 Mar 4.

AbstractIntensive and size-selective harvesting is an evolutionary driver of life history as well as individual behavioral traits. Yet whether and to what degree harvesting modifies the collective behavior of exploited species are largely unknown. We present a multigeneration harvest selection experiment with zebrafish, , as a model species to understand the effects of size-selective harvesting on shoaling behavior. Read More

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Disentangling Niche Theory and Beta Diversity Change.

Am Nat 2022 04 18;199(4):510-522. Epub 2022 Feb 18.

AbstractBeta diversity describes the differences in species composition among communities. Changes in beta diversity over time are thought to be due to selection based on species' niche characteristics. For example, theory predicts that selection that favors habitat specialists will increase beta diversity. Read More

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