Latent Genetic Effects of Past Selection on Blood Feeding: History Matters.

Conventional wisdom is that selection decreases genetic variation in populations, variation that should enable and be essential for population persistence in an ever-changing world. Basically, we find the opposite. Response to selection on biting in the pitcher-plant mosquito, Wyeomyia smithii, increases from 20 to 80% in 19 generations, but reverts back to the original 20% after seven generations of relaxed (not reversed) selection. At the same time, biting in the control line remains at the original 20% through 30 generations without blood feeding. Imposition of selection on biting in both lines elicits a rapid response in the previously selected line, but, importantly, not in the control line. Genetic variation for biting has increased, not decreased, as a consequence of long-term directional selection, contrary to expectations. Convergent phenotypes belie the underlying difference in future adaptive potential. Selection events over time in the background of individuals or populations will determine outcomes of applied research, be it in the fields of medicine, agriculture, or conservation. In short, history matters.

First Record of Wyeomyia mitchellii in Nuevo León, Mexico.

On October 5, 2021, mosquito collections were conducted in Nuevo León in search of an undescribed species within the genus Wyeomyia reported previously in this state. Species collected included Aedes quadrivittatus, Ae. amabilis, Ae. triseriatus group, Ae. albopictus, and Wy. mitchellii. Although the undescribed species was not found, the occurrence record for Wy. mitchellii in Nuevo León constitutes the 1st record for this species in this state. Additionally, historical records of the presence of Wy. mitchelli in Mexico, available in the literature, were reviewed and updated. Specimens collected during this study were deposited in the Culicidae Collection of the Parasitology Department, Autonomous Agrarian University Antonio Narro, Laguna unit. With the addition of Wy. mitchellii to the mosquito fauna of Nuevo León, there are currently 67 species in the state.

Conserved molecular pathways underlying biting in two divergent mosquito genera.

Mosquitoes transmit a wide variety of devastating pathogens when they bite vertebrate hosts and feed on their blood. However, three entire mosquito genera and many individual species in other genera have evolved a nonbiting life history in which blood is not required to produce eggs. Our long-term goal is to develop novel interventions that reduce or eliminate the biting behavior in vector mosquitoes. A previous study used biting and nonbiting populations of a nonvector mosquito, Wyeomyia smithii, as a model to uncover the transcriptional basis of the evolutionary transition from a biting to a nonbiting life history. Herein, we ask whether the molecular pathways that were differentially expressed due to differences in biting behavior in W. smithii are also differentially expressed between subspecies of Culex pipiens that are obligate biting (Culex pipiens pipiens) and facultatively nonbiting (Culex pipiens molestus). Results from RNAseq of adult heads show dramatic upregulation of transcripts in the ribosomal protein pathway in biting C. pipiens, recapitulating the results in W. smithii, and implicating the ancient and highly conserved ribosome as the intersection to understanding the evolutionary and physiological basis of blood feeding in mosquitoes. Biting Culex also strongly upregulate energy production pathways, including oxidative phosphorylation and the citric acid (TCA) cycle relative to nonbiters, a distinction that was not observed in W. smithii. Amino acid metabolism pathways were enriched for differentially expressed genes in biting versus nonbiting Culex. Relative to biters, nonbiting Culex upregulated sugar metabolism and transcripts contributing to reproductive allocation (vitellogenin and cathepsins). These results provide a foundation for developing strategies to determine the natural evolutionary transition between a biting and nonbiting life history in vector mosquitoes.

Bacterial communities in carnivorous pitcher plants colonize and persist in inquiline mosquitoes.

BACKGROUND: The leaves of carnivorous pitcher plants harbor diverse communities of inquiline species, including bacteria and larvae of the pitcher plant mosquito (Wyeomyia smithii), which aid the plant by processing captured prey. Despite the growing appreciation for this microecosystem as a tractable model in which to study food web dynamics and the moniker of W. smithii as a 'keystone predator', very little is known about microbiota acquisition and assembly in W. smithii mosquitoes or the impacts of W. smithii-microbiota interactions on mosquito and/or plant fitness. RESULTS: In this study, we used high throughput sequencing of bacterial 16S rRNA gene amplicons to characterize and compare microbiota diversity in field- and laboratory-derived W. smithii larvae. We then conducted controlled experiments in the laboratory to better understand the factors shaping microbiota acquisition and persistence across the W. smithii life cycle. Methods were also developed to produce axenic (microbiota-free) W. smithii larvae that can be selectively recolonized with one or more known bacterial species in order to study microbiota function. Our results support a dominant role for the pitcher environment in shaping microbiota diversity in W. smithii larvae, while also indicating that pitcher-associated microbiota can persist in and be dispersed by adult W. smithii mosquitoes. We also demonstrate the successful generation of axenic W. smithii larvae and report variable fitness outcomes in gnotobiotic larvae monocolonized by individual bacterial isolates derived from naturally occurring pitchers in the field. CONCLUSIONS: This study provides the first information on microbiota acquisition and assembly in W. smithii mosquitoes. This study also provides the first evidence for successful microbiota manipulation in this species. Altogether, our results highlight the value of such methods for studying host-microbiota interactions and lay the foundation for future studies to understand how W. smithii-microbiota interactions shape the structure and stability of this important model ecosystem.

Pirahy virus: Identification of a new and potential emerging arbovirus in South Brazil.

Genomic and epidemiological surveillance are paramount for the discovery of new viruses with the potential to cross species barriers. Here, we present a new member of the genus Alphavirus found in Trichoprosopon and Wyeomia mosquitoes, tentatively named Pirahy virus (PIRAV). PIRAV was isolated from mosquito pools collected in a rural area of Piraí do Sul, South Brazil. In vitro assays revealed that PIRAV replicates and causes cytopathic effects in vertebrate cell lines such as Vero E6, SH-SY5Y, BHK-21 and UMNSAH/DF-1. Genomic signature analysis supports these results showing a dinucleotide and codon usage balance compatible with several hosts. Phylogenetic analyses placed PIRAV basal to the Venezuelan equine encephalitis complex. Genome analyses, electron microscopy, and biological characterization show findings that may alert for the emergence of a new arbovirus in South America.

Arbovirus expansion: New species of culicids infected by the Chikungunya virus in an urban park of Brazil.

The Dengue, Zika and Chikungunya viruses have been spreading in tropical regions, causing epidemics with high morbidity rates and fatal cases. The aim of this study was to assess the diversity and abundance of culicid species and the presence of arboviruses in mosquitoes, at the epicenter of an epidemic outbreak that occurred in people living near an urban Atlantic Forest park. Mosquitoes were captured with a Shannon trap between 2 and 6 pm in seven months of 2019. The Chikungunya virus was investigated according to the protocol described by Lanciotti (2007). The most abundant species were Wyeomyia bourrouli (66.9%) and Aedes albopictus (23.9%). Also captured were Aedes fluviatilis (3.2%); Haemagogus leucocelaenus (2.2%); Aedes scapularis (2.2%); Aedes aegypti (1.6%); Aedes serratus and (0.3%) and Aedes taeniorhynchus (0.3%). The Chikungunya virus was identified in A. aegypti females; A. albopictus females and males; Aedes fluviatilis and Wy.bourrouli. The presence of the Chikungunya virus in the afore mentioned mosquitoes reinforces the hypothesis that arbovirus expansion is associated with the participation of other mosquito species in the transmission areas, primarily the Chikungunya virus in the study area. The data also demonstrate the need for permanent entomological surveillance and measures to preserve the area, in order to hinder its degradation, the adaptation of culicid species to new habitats and the formation of enzootic cycles of these viruses in the forest.

Dataset for mosquito collections on Big Pine Key, Florida, USA.

The Florida Keys Mosquito Control District has deployed dry ice-baited light traps to monitor mosquito (Diptera: Culicidae) populations throughout the Florida Keys starting in 1998. American Biophysics Company traps were deployed throughout the year at the same collection point. Traps were placed in the late afternoon and collected the following morning. Common mosquitoes are the black salt marsh mosquito, Aedes taeniorhynchus (Wiedemann), the crabhole mosquito, Deinocerites cancer Theobald, the Bahamian Culex, Culex bahamensis Dyar and Knab, and Anopheles atropos Dyar and Knab.

Taxonomic history of species without subgeneric placement in the genus Wyeomyia Theobald (Diptera: Culicidae) and recognition of Wy. compta Senevet amp; Abonnenc as a junior synonym of Wy. argenteorostris (Bonne-Wepster amp; Bonne).

The mosquito genus Wyeomyia (Diptera: Culicidae) includes 17 subgenera and 140 species, 30 of which are without subgeneric placement. The taxonomic history of the unplaced species is summarized and the validity of Wy. compta Senevet Abonnenc is discussed based on examination of the type material. It is clear that the description of Wy. compta was based on specimens belonging to two different species. The holotype adult female is identical to Wy. argenteorostris (Bonne-Wepster Bonne) whereas the characters described from a larval exuviae mounted on the same slide with the holotype of Wy. albocaerulea Senevet Abonnenc coincide with those which characterize the subgenus Dodecamyia. Since the larval exuviae cannot be definitely associated with the holotype female and it belongs to either Wy. aphobema Dyar or another species of the subgenus Dodecamyia, it cannot be afforded type status. Therefore, Wy. compta is synonymized with Wy. argenteorostris.

The correct type localities of three species of Sabethini.

The correct type localities were noted for the following mosquito species: 1) Sabethes fabricii, municipality of Angra dos Reis, state of Rio de Janeiro, Brazil; 2) Sa. soperi 1942 , municipality of Nova Iguaçu, state of Rio de Janeiro, Brazil; and 3) Wyeomyia finlayi 1942 , Xerém, in the municipality of Duque de Caxias, state of Rio de Janeiro, Brazil.

Mosquitoes in Bromeliads at Ground Level of the Brazilian Atlantic Forest: the Relationship Between Mosquito Fauna, Water Volume, and Plant Type.

Water accumulating in the axils of bromeliads provides habitat for numerous invertebrates, frequently among them, immature mosquitoes. To evaluate mosquito richness in bromeliads and the relationship between mosquito presence and biotic and abiotic variables, we performed a study in the Parque Nacional do Itatiaia, Rio de Janeiro, Brazil. Mosquitoes of genus Culex were the most abundant and varied in species richness, among which nine belonged to subgenus Microculex, Culex (Microculex) neglectus Lutz and Culex ocellatus Theobald being the most frequent species. Sabethines of genera Wyeomyia and Runchomyia were found in low numbers. Wyeomyia (Spilonympha) airosai Lane and Cerqueira and Wyeomyia (Spilonympha) finlayi Lane and Cerqueira tend to proliferate in bromeliads of the genus Bilbergia which hold less than 50 ml of water and grow either alone or with Runchomyia frontosa (Theobald). The larger the volume of water, the greater the chance of finding Culex, Anopheles as well as Wyeomyia (Phoniomyia) species, which seems to be the more generalist as it is present in different bromeliad types with a large range of plant water holding capacities.

A NEW PHYTOTELM PLANT, CRINUM MOOREI (ASPARAGALES: AMARYLLIDACEAE), FOR THE AMERICAS AND ITS MOSQUITO INHABITANT (DIPTERA: CULICIDAE) IN ECUADOR.

A new phytotelm plant for the Americas is recorded for San Miguel de los Bancos, Pichincha Province, Ecuador. In the leaf axils of Crinum moorei Hook. f. (Amaryllidaceae) were collected larvae and pupae of a common mosquito, Wyeomyia (Dendromyia) complosa (Dyar) (Diptera: Culicidae: Sabethini). This plant is a South African native, introduced into several countries, but never reported as a habitat for immature mosquitoes. We provide notes about its botanical and ecological characteristics, and also of the mosquito associated at this locality.

Una nueva planta phytotelma para el continente Americano es registrada en San Miguel de los Bancos, Provincia de Pichincha, Ecuador. En las axilas de Crinum moorei Hook, f. (Amaryllidaceae) fueron colectadas larvas y pupas de la especie de mosquito Wyeomyia (Dendromyia) complosa (Dyar) (Diptera: Culicidae: Sabethini). Esta planta es nativa de Africa del Sur, y ha sido introducida en varios países, pero nunca había sido señalada como hábitat para las fases inmaduras de mosquitos. Se hacen comentarios botánicos acerca de la planta así como también del mosquito asociado en la localidad.

Wyeomyia exallos, a new species of sylvatic mosquito (Diptera: Culicidae) from Brazil

Wyeomyia exallos, a new mosquito species from Atlantic Forest of southeastern Brazil, is described based on morphological characters of the adult female, male, male genitalia, pupa and fourth-instar larva. The morphological characters of Wy. exallos sp. nov. are compared with those of different subgenera of Wyeomyia as well as of species without subgeneric position. It is proposed that the new species should be placed in genus Wyeomyia Theobald without subgeneric assignment.

Registros de mayor altitud para mosquitos (Diptera: Culicidae) en Venezuela

Highest mosquito records (Diptera: Culicidae) in Venezuela. Mosquitoes (Diptera: Culicidae) are holometabolous insects with aquatic immature stages, which use a broad variety of larval habitats, from ground water bodies to Phytothelmata (water deposits in plants) and artificial deposits. The availability of breeding sites often determines the upper limits of mosquito ranges. We built a database with 9 607 records with 432 localities, 19 genera and 254 species. The Andean mountains have 77% of the highest mosquito records including Aedes euris with record at 3 133 m, followed by three species of Anopheles -subgenera Kerteszia- with the upper limit of 2 680 m. Wyeomyia bicornis and Culex daumastocampa at 2 550 m were the highest records in the Central- Coastal cordillera, while the highest record in Pantepui was Wyeomyia zinzala at 2 252 m. The species associated with phytothelmata (Bromeliaceae and Sarraceniaceae) represent 60% of the records. The upper limits of Culex quinquefasciatus and Anopheles (Kerteszia) species could represent the theoretical limit for transmission of filariasis or arboviruses, by Culex, and malaria by Anopheles (Kerteszia) in Venezuela. Similarly, a vector of Dengue, Aedes aegypti, has not been not recorded above 2 000 m. Rev. Biol. Trop. 58 (1): 245-254. Epub 2010 March 01.

Los mosquitos (Diptera: Culicidae) son insectos holometábolos con estadios inmaduros acuáticos que utilizan una amplia variedad de hábitats larvales, desde cuerpos de agua en el suelo hasta Fitotelmata (depósitos de agua en las plantas) y depósitos artificiales. La disponibilidad de sitios de reproducción a menudo determina el límite superior del ámbito de los mosquitos. Nosotros construimos una base de datos de 9 607 registros, 432 localidades, 19 géneros y 254 especies. La coordillera Andina posee el 77% de los registros con mayor altitud incluyendo Aedes euris con un registro a 3 300 m, seguido por tres especies de Anopheles -subgénero Kerteszia- con una altitud máxima de 2 680 m. Wyeomyia bicornis y Culex daumastocampa a 2 550 m fueron los registros de mayor altitud en la cordillera Costera- Central, mientras que el record más alto en Pantepui fue Wyeomyia zinzala a 2 252 m. El 60% de los registros de máxima altitud están representados por especies asociadas con fitotelmata (Bromeliaceae y Sarraceniaceae). Los límites superiores de Culex quinquefasciatus y Anopheles (Kerteszia) podría representar el límite teórico para la transmisión de filariasis o arbovirus, por Culex y malaria por Anopheles (Kerteszia) en Venezuela. Del mismo modo, un vector del dengue, Aedes aegypti, no ha sido registrado por encima de 2 000 m.

Mosquitoes (Diptera, Culicidae) inhabiting foliar tanks of Guzmania brasiliensis Ule (Bromeliaceae) in central Amazonia, Brazil / Mosquitos (Diptera, Culicidae) habitando tanques foliares de Guzmania brasiliensis Ule (Bromeliaceae) na Amazônia Central, Brasil

Mosquitoes in the family Culicidae develop their immature forms in different environments depending on various circumstances. This study represents the first contribution to the ecological knowledge of culicids living in the bromeliad G. brasiliensis. The objectives of the study were to compare the Culicidae fauna of bromeliads in two seasonal periods, analyzing their abundance, richness and the influence of pH, conductivity and water volume, on the populations. Sampling was done at Reserva Adolpho Ducke, Manaus, Amazonas, Brazil between 2003 and 2005. Six samplings were done in the rainy season and six in the dry season. On each sampling day, six terrestrial and six epiphytic bromeliads, totaling 144 sampling units, were retrieved. A total of 444 immature mosquitoes were collected, distributed in the following species: Culex (Microculex) stonei Lane & Whitman, Culex (Microculex) chryselatus Dyar & Knab, Culex (Microculex) sp., Wyeomyia (Hystatomyia) autocratica Dyar & Knab and Wyeomyia (Hystatomyia) splendida Bonne-Wepster & Bonne. The relationship between abundance of Culicidae and sampling period was not significant, although abundance was higher in the dry period. There were significant correlations between water volume and the abundance (p = 0.003) and richness (p = 0.001) of culicids. The pH was positively related to the occurrence of the species Wy. autocratica (p= 0.010) and Wy. splendida (p= 0.006), demonstrating the influence of this factor in the structuring of bromeliad-inhabiting communities.

Mosquitos da família Culicidae desenvolvem suas formas imaturas em vários ambientes na dependência de circunstâncias diversas. Este trabalho representa a primeira contribuição ao conhecimento ecológico de culicídeos em G. brasiliensis e tem como objetivo inventariar os imaturos em bromélias em dois períodos sazonais, analisando a abundância, riqueza e a influência das variáveis abióticas pH, condutividade e volume de água sobre as populações de Culicidae. Foram realizadas coletas na Reserva Adolpho Ducke, Manaus, Amazonas, Brasil entre 2003 e 2005. Seis coletas foram realizadas no período chuvoso e seis na estação seca. Em cada amostragem, seis bromélias terrestres e seis epífitas foram coletadas, totalizando 144 unidades amostrais. Um total de 444 imaturos foi coletado, distribuídos nas seguintes espécies: Culex (Microculex) stonei Lane & Whitman, Culex (Microculex) chryselatus Dyar & Knab, Culex (Microculex) sp., Wyeomyia (Hystatomyia) autocratica Dyar & Knab e Wyeomyia (Hystatomyia) splendida Bonne-Wepster & Bonne. A relação entre abundância de Culicidae e períodos não foi significativa, entretanto, o período seco apresentou maior representatividade de imaturos. Houve significância na relação do volume de água e abundância (p= 0,003) e riqueza (p= 0,001) de culicídeos. O pH foi o único parâmetro relacionado positivamente com a ocorrência das espécies Wy. autocratica (p= 0,010) e Wy. splendida (p= 0,006) ressaltando a influência deste fator na estruturação das comunidades bromelícolas.

New records of mosquito species (Diptera: Culicidae) for Santa Catarina and Paraná (Brazil) / Novos registros de espécies de mosquitos (Diptera: Culicidae) em Santa Catarina e Paraná (Brasil)

We provide eight new mosquito species records for Santa Catarina (Limatus flavisetosus Oliveira Castro 1935, Mansonia flaveola (Coquillett 1906), Ma. titillans (Walker 1848), Psorophora forceps Cerqueira 1939, Sabethes xyphydes Harbach 1994, Toxorhynchites bambusicolus (Lutz & Neiva 1913), Tx. theobaldi (Dyar & Knab 1906) and Wyeomyia lassalli Bonne-Wepster & Bonne 1921) and three for Paraná (Ochlerotatus argyrothorax Bonne-Wepster & Bonne 1920, Uranotaenia pallidoventer Theobald 1903 and Wyeomyia pilicauda Root 1928). Additionally, we list all species in these eight genera recorded previously in the two states. The known distribution and possible epidemiological implications of the new species records are discussed.

Relatamos o primeiro encontro de oito espécies de mosquitos para Santa Catarina (Limatus flavisetosus Oliveira Castro 1935, Mansonia flaveola (Coquillett 1906), Ma. titillans (Walker 1848), Psorophora fórceps Cerqueira 1939, Sabethes xyphydes Harbach 1994, Toxorhynchites bambusicolus (Lutz & Neiva 1913), Tx. theobaldi (Dyar & Knab 1906) e Wyeomyia lassalli Bonne-Wepster & Bonne 1921) e três para o Paraná (Ochlerotatus argyrothorax Bonne-Wepster & Bonne 1920, Uranotaenia pallidoventer Theobald 1903 e Wyeomyia pilicauda Root 1928). Adicionalmente, apresentamos lista de todas as espécies destes oito gêneros com registro nos dois estados. A distribuição conhecida das espécies e sua possível importância epidemiológica são discutidas.

EFFECTS OF POSTGLACIAL RANGE EXPANSION ON ALLOZYME AND QUANTITATIVE GENETIC VARIATION OF THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII.

We determined allozyme variability of 34 populations of the pitcher-plant mosquito, Wyeomyia smithii, from Florida (30°N) to northern Manitoba (54°N) and compared allozyme variability with the additive genetic variance for preadult development time and photoperiodic response determined previously for six populations over a similar range (30-50°N). Phylogenetic analysis of allozymes shows a well-defined split between Gulf Coast and lowland North Carolina populations, similar to previously observed phylogeographic patterns in a wide variety of taxa. A deeper split in the phylogeny of W. smithii coincides with the location of the maximum extent of the Laurentide Ice Sheet. Furthermore, both average heterozygosity and patterns of isolation-by-distance decline in populations north of the former glacial border. It is likely that northern populations are the result of a range expansion that occurred subsequent to the late-Wisconsin retreat of the Laurentide Ice Sheet and that these populations have not yet reached a drift-migration equilibrium. The northern decline in allozyme heterozygosity contrasts sharply with the northern increase in additive genetic variance of development time and photoperiodic response found in previous studies. These previous studies also showed that the genetic divergence of populations has involved stochastic variation in the contribution of dominance and epistasis to the genetic architecture underlying demographic traits, including preadult development time, and photoperiodic response. When taken together, the present and prior studies identify the genetic processes underlying the lack of concordance between geographic patterns of allozyme and quantitative genetic variation in natural populations of W. smithii. In the presence of nonadditive genetic variation, isolation and drift can result in opposite patterns of genetic variation for structural genes and quantitative traits.

EVOLUTION OF THE GENETIC ARCHITECTURE UNDERLYING FITNESS IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII.

We examined the genetic basis for evolutionary divergence among geographic populations of the pitcher-plant mosquito, Wyeomyia smithii, using protein electrophoresis and line-cross analysis. Line-cross experiments were performed under both low density, near-optimal conditions, and at high, limiting larval densities sufficient to reduce fitness (rc ) in parental populations by approximately 50%. We found high levels of electrophoretic divergence between ancestral and derived populations, but low levels of divergence between two ancestral populations and between two derived populations. Assessed under near-optimal conditions, the genetic divergence of fitness (rc ) between ancestral and derived populations, but not between two derived populations or between two ancestral populations, has involved both allelic (dominance) and genic (epistatic) interactions. The role of dominance and epistasis in the divergence of rc among populations affects its component traits in a pattern that is unique to each cross. Patterns of genetic differentiation among populations of W. smithii provide evidence for a topographically complex "adaptive landscape" as envisioned by Wright in his "shifting balance" theory of evolution. Although we cannot definitively rule out the role of deterministic evolution in the divergence of populations on this landscape, ecological inference and genetic data are more consistent with a stochastic than a deterministic process. At high, limiting larval density, hybrid vigor is enhanced and the influence of epistasis disappears. Thus, under stressful conditions, the advantages to fitness due to hybrid heterozygosity can outweigh the deleterious effects of fragmented gene complexes. These results have important implications for the management of inbred populations. Outbreeding depression assessed in experimental crosses under benign lab, zoo, or farm conditions may not accurately reveal the increased advantages of heterozygosity in suboptimal or marginal conditions likely to be found in nature.

Variance in composition of inquiline communities in leaves of Sarracenia purpurea L. on multiple spatial scales.

A survey of the abundances of species that inhabit the water-bearing leaves of the pitcher plant Sarracenia purpurea was conducted at several different spatial scales in northern Florida. Individual leaves are hosts to communities of inquiline species, including mosquitoes, midges, mites, copepods, cladocerans, and a diverse bacterial assemblage. Inquiline communities were quantified from four pitchers per plant, three plants per subpopulation, two subpopulations per population, and three populations. Species varied in abundance at different spatial scales. Variation in the abundances of mosquitoes and copepods was not significantly associated with any spatial scale. Midges varied in abundance at the level of populations; one population contained significantly more midges than the other two. Cladocerans varied at the level of the subpopulation, whereas mites varied at the level of the individual plants. Bacterial communities were described by means of Biolog plates, which quantify the types of carbon media used by the bacteria in each pitcher. Bacterial communities were found to vary significantly in composition among individual plants but not among populations or subpopulations. These results suggest that independent factors determining the abundances of individual species are important in determining community patterns in pitcher-plant inquilines.

GENETIC CONSTRAINTS TO LIFE-HISTORY EVOLUTION IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII.

Life-history theory relies heavily on the hypothesis that genetic tradeoffs among the components of fitness constrain their independent evolution and joint maximization. Herein we show that selection on preadult development time in the pitcher-plant mosquito, Wyeomyia smithii, leads to a correlated response in cohort mean generation time but no correlated response in survivorship, fecundity, or cohort replacement rate. Lines selected for fast development achieve a higher capacity for increase (rc ) than lines selected for slow development, independently of larval density. These results imply that tradeoffs due to underlying antagonistic pleiotropy affecting growth, development, survivorship, and reproduction are not necessary constraints to life-history evolution. Previous work with W. smithii has shown a positive genetic correlation between development time and a general, genetically coordinated diapause syndrome. We propose that the observed nontradeoffs among the components of rc may be subsumed into an even more fundamental tradeoff between performance during the summer generations and synchronization of development and reproduction with the changing seasons. Consequently, critical tests of genetic tradeoffs as a constraint to the independent evolution or simultaneous optimization of fitness components may need to consider the seasonal context.