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1.
Int J Parasitol ; 54(7): 357-366, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38460721

RESUMO

Parasites are a key driving force behind many ecological and evolutionary processes. Prevalence and diversity of parasites, as well as their effects on hosts, are not uniform across host species. As such, the potential parasite spillover between species can significantly influence outcomes of interspecific interactions. We screened two species of Luscinia nightingales for haemosporidian blood parasites (Plasmodium, Leucocytozoon and Haemoproteus) along an approximately 3000 km transect in Europe, incorporating areas of host distant allopatry, close allopatry and sympatry. We found significant differences in infection rates between the two host species, with common nightingales having much lower parasite prevalence than thrush nightingales (36.7% versus 83.8%). This disparity was mostly driven by Haemoproteus prevalence, which was significantly higher in thrush nightingales while common nightingales had a small, but significantly higher, Plasmodium prevalence. Furthermore, we found no effect of proximity to the contact zone on infection rate in either host species. Despite having lower infection prevalence, common nightingales were infected with a significantly higher diversity of parasite lineages than thrush nightingales, and lineage assemblages differed considerably between the two species, even in sympatry. This pattern was mostly driven by the large diversity of comparatively rare lineages, while the most abundant lineages were shared between the two host species. This suggests that, despite the close evolutionary relationships between the two nightingales, there are significant differences in parasite prevalence and diversity, regardless of the distance from the contact zone. This suggests that spillover of haemosporidian blood parasites is unlikely to contribute towards interspecific interactions in this system.


Assuntos
Haemosporida , Simpatria , Animais , Prevalência , Haemosporida/classificação , Haemosporida/isolamento & purificação , Haemosporida/genética , Infecções Protozoárias em Animais/epidemiologia , Infecções Protozoárias em Animais/parasitologia , Doenças das Aves/parasitologia , Doenças das Aves/epidemiologia , Interações Hospedeiro-Parasita , Especificidade de Hospedeiro , Europa (Continente)/epidemiologia , Passeriformes/parasitologia
2.
Ecol Lett ; 25(10): 2203-2216, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36082485

RESUMO

Macrophysiological research is vital to our understanding of mechanisms underpinning global life history variation and adaptation to diverse environments. Here, we examined latitudinal and elevational variation in a key substrate of energy metabolism and an emerging physiological component of pace-of-life syndromes, blood glucose concentration. Our data, collected from 61 European temperate and 99 Afrotropical passerine species, revealed that baseline blood glucose increases with both latitude and elevation, whereas blood glucose stress response shows divergent directions, being stronger at low latitudes and high elevations. Low baseline glucose in tropical birds, compared to their temperate counterparts, was mainly explained by their low fecundity, consistent with the slow pace-of-life syndrome in the tropics. In contrast, elevational variation in this trait was decoupled from fecundity, implying a unique montane pace-of-life syndrome combining slow-paced life histories with fast-paced physiology. The observed patterns suggest that pace-of-life syndromes do not evolve along the single fast-slow axis.


Assuntos
Características de História de Vida , Passeriformes , Altitude , Animais , Glicemia , Metabolismo Energético , Fertilidade
3.
Proc Biol Sci ; 289(1970): 20212404, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35259984

RESUMO

Tropical bird species are characterized by a comparatively slow pace of life, being predictably different from their temperate zone counterparts in their investments in growth, survival and reproduction. In birds, the development of functional plumage is often considered energetically demanding investment, with consequences on individual fitness and survival. However, current knowledge of interspecific variation in feather growth patterns is mostly based on species of the northern temperate zone. We evaluated patterns in tail feather growth rates (FGR) and feather quality (stress-induced fault bar occurrence; FBO), using 1518 individuals of 167 species and 39 passerine families inhabiting Afrotropical and northern temperate zones. We detected a clear difference in feather traits between species breeding in the temperate and tropical zones, with the latter having significantly slower FGR and three times higher FBO. Moreover, trans-Saharan latitudinal migrants resembled temperate zone residents in that they exhibited a comparatively fast FGR and low FBO, despite sharing moulting environments with tropical species. Our results reveal convergent latitudinal shifts in feather growth investments (latitudinal syndrome) across unrelated passerine families and underscore the importance of breeding latitude in determining cross-species variation in key avian life-history traits.


Assuntos
Muda , Passeriformes , Animais , Cruzamento , Plumas , Humanos , Reprodução
4.
Ecol Evol ; 12(2): e8497, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35222943

RESUMO

Haemosporidians are among the most common parasites of birds and often negatively impact host fitness. A multitude of biotic and abiotic factors influence these associations, but the magnitude of these factors can differ by spatial scales (i.e., local, regional and global). Consequently, to better understand global and regional drivers of avian-haemosporidian associations, it is key to investigate these associations at smaller (local) spatial scales. Thus, here, we explore the effect of abiotic variables (e.g., temperature, forest structure, and anthropogenic disturbances) on haemosporidian prevalence and host-parasite networks on a horizontal spatial scale, comparing four fragmented forests and five localities within a continuous forest in Papua New Guinea. Additionally, we investigate if prevalence and host-parasite networks differ between the canopy and the understory (vertical stratification) in one forest patch. We found that the majority of Haemosporidian infections were caused by the genus Haemoproteus and that avian-haemosporidian networks were more specialized in continuous forests. At the community level, only forest greenness was negatively associated with Haemoproteus infections, while the effects of abiotic variables on parasite prevalence differed between bird species. Haemoproteus prevalence levels were significantly higher in the canopy, and an opposite trend was observed for Plasmodium. This implies that birds experience distinct parasite pressures depending on the stratum they inhabit, likely driven by vector community differences. These three-dimensional spatial analyses of avian-haemosporidians at horizontal and vertical scales suggest that the effect of abiotic variables on haemosporidian infections are species specific, so that factors influencing community-level infections are primarily driven by host community composition.

5.
Oecologia ; 196(2): 373-387, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33963450

RESUMO

Plant and animal populations can adapt to prolonged environmental changes if they have sufficient genetic variation in important phenological traits. The genetic regulation of annual cycles can be studied either via candidate genes or through the decomposition of phenotypic variance by quantitative genetics. Here, we combined both approaches to study the timing of migration in a long-distance migrant, the collared flycatcher (Ficedula albicollis). We found that none of the four studied candidate genes (CLOCK, NPAS2, ADCYAP1 and CREB1) had any consistent effect on the timing of six annual cycle stages of geolocator-tracked individuals. This negative result was confirmed by direct observations of males arriving in spring to the breeding site over four consecutive years. Although male spring arrival date was significantly repeatable (R = 0.24 ± 0.08 SE), most was attributable to permanent environmental effects, while the additive genetic variance and heritability were very low (h2 = 0.03 ± 0.17 SE). This low value constrains species evolutionary adaptation, and our study adds to warnings that such populations may be threatened, e.g. by ongoing climate change.


Assuntos
Passeriformes , Aves Canoras , Migração Animal , Animais , Evolução Biológica , Masculino , Estações do Ano
6.
Ecol Evol ; 10(13): 6512-6524, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32724529

RESUMO

Coevolutionary processes that drive the patterns of host-parasite associations can be deduced through congruence analysis of their phylogenies. Feather lice and their avian hosts have previously been used as typical model systems for congruence analysis; however, such analyses are strongly biased toward nonpasserine hosts in the temperate zone. Further, in the Afrotropical region especially, cospeciation studies of lice and birds are entirely missing. This work supplements knowledge of host-parasite associations in lice using cospeciation analysis of feather lice (genus Myrsidea and the Brueelia complex) and their avian hosts in the tropical rainforests of Cameroon. Our analysis revealed a limited number of cospeciation events in both parasite groups. The parasite-host associations in both louse groups were predominantly shaped by host switching. Despite a general dissimilarity in phylogeny for the parasites and hosts, we found significant congruence in host-parasite distance matrices, mainly driven by associations between Brueelia lice and passerine species of the Waxbill (Estrildidae) family, and Myrsidea lice and their Bulbul (Pycnonotidae) host species. As such, our study supports the importance of complex biotic interactions in tropical environments.

7.
Evolution ; 74(10): 2404-2418, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32385910

RESUMO

Many closely related populations are distinguished by variation in sexual signals and this variation is hypothesized to play an important role in reproductive isolation and speciation. Within populations, there is considerable evidence that sexual signals provide information about the incidence and severity of parasite infections, but it remains unclear if variation in parasite communities across space could play a role in initiating or maintaining sexual trait divergence. To test for variation in parasite-associated selection, we compared three barn swallow subspecies with divergent sexual signals. We found that parasite community structure and host tolerance to ecologically similar parasites varied between subspecies. Across subspecies we also found that different parasites were costly in terms of male survival and reproductive success. For each subspecies, the preferred sexual signal(s) were associated with the most costly local parasite(s), indicating that divergent signals are providing relevant information to females about local parasite communities. Across subspecies, the same traits were often associated with different parasites, indicating that parasite-sexual signal links are quite flexible and may evolve relatively quickly. This study provides evidence for (1) variation in parasite communities and (2) different parasite-sexual signal links among three closely related subspecies with divergent sexual signal traits, suggesting that parasites may play an important role in initiating and/or maintaining the divergence of sexual signals among these closely related, yet geographically isolated populations.


Assuntos
Aptidão Genética , Preferência de Acasalamento Animal , Pigmentação , Andorinhas/parasitologia , Animais , Feminino , Interações Hospedeiro-Parasita , Masculino , Reprodução , Especificidade da Espécie , Andorinhas/fisiologia , Cauda
8.
Mol Ecol ; 29(13): 2431-2448, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32470165

RESUMO

Exploration of interactions between hosts and parasitic symbionts is important for our understanding of the temporal and spatial distribution of organisms. For example, host colonization of new geographical regions may alter levels of infections and parasite specificity, and even allow hosts to escape from co-evolved parasites, consequently shaping spatial distributions and community structure of both host and parasite. Here we investigate the effect of host colonization of new regions and the elevational distribution of host-parasite associations between birds and their vector-transmitted haemosporidian blood parasites in two geological and geographical settings: mountains of New Guinea and the Canary Islands. Our results demonstrate that bird communities in younger regions have significantly lower levels of parasitism compared to those of older regions. Furthermore, host-parasite network analyses demonstrate that blood parasites may respond differently after arriving to a new region, through adaptations that allow for either expanding (Canary Islands) or retaining (New Guinea) their host niches. The spatial prevalence patterns along elevational gradients differed in the two regions, suggesting that region-specific biotic (e.g., host community) and abiotic factors (e.g., temperature) govern prevalence patterns. Our findings suggest that the spatiotemporal range dynamics in host-parasite systems are driven by multiple factors, but that host and parasite community compositions and colonization histories are of particular importance.


Assuntos
Aves/parasitologia , Haemosporida , Interações Hospedeiro-Parasita , Animais , Nova Guiné , Espanha , Análise Espaço-Temporal
9.
Sci Rep ; 8(1): 17878, 2018 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-30552359

RESUMO

Immune genes show remarkable levels of adaptive variation shaped by pathogen-mediated selection. Compared to humans, however, population polymorphism in animals has been understudied. To provide an insight into immunogenetic diversity in birds, we sequenced complete protein-coding regions of all Toll-like receptor (TLR) genes with direct orthology between mammals and birds (TLR3, TLR4, TLR5 and TLR7) in 110 domestic chickens from 25 breeds and compared their variability with a corresponding human dataset. Chicken TLRs (chTLRs) exhibit on average nine-times higher nucleotide diversity than human TLRs (hTLRs). Increased potentially functional non-synonymous variability is found in chTLR ligand-binding ectodomains. While we identified seven sites in chTLRs under positive selection and found evidence for convergence between alleles, no selection or convergence was detected in hTLRs. Up to six-times more alleles were identified in fowl (70 chTLR4 alleles vs. 11 hTLR4 alleles). In chTLRs, high numbers of alleles are shared between the breeds and the allelic frequencies are more equal than in hTLRs. These differences may have an important impact on infectious disease resistance and host-parasite co-evolution. Though adaptation through high genetic variation is typical for acquired immunity (e.g. MHC), our results show striking levels of intraspecific polymorphism also in poultry innate immune receptors.


Assuntos
Galinhas , Variação Genética , Receptores Toll-Like/genética , Animais , Frequência do Gene , Humanos , Análise de Sequência de DNA
10.
Ecol Evol ; 8(23): 12183-12192, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30598810

RESUMO

Human-induced climate change is expected to cause major biotic changes in species distributions and thereby including escalation of novel host-parasite associations. Closely related host species that come into secondary contact are especially likely to exchange parasites and pathogens. Both the Enemy Release Hypothesis (where invading hosts escape their original parasites) and the Novel Weapon Hypothesis (where invading hosts bring new parasites that have detrimental effects on native hosts) predict that the local host will be most likely to experience a disadvantage. However, few studies evaluate the occurrence of interspecific parasite transfer by performing wide-scale geographic sampling of pathogen lineages, both within and far from host contact zones. In this study, we investigate how haemosporidian (avian malaria) prevalence and lineage diversity vary in two, closely related species of passerine birds; the pied flycatcher Ficedula hypoleuca and the collared flycatcher F. albicollis in both allopatry and sympatry. We find that host species is generally a better predictor of parasite diversity than location, but both prevalence and diversity of parasites vary widely among populations of the same bird species. We also find a limited and unidirectional transfer of parasites from pied flycatchers to collared flycatchers in a recent contact zone. This study therefore rejects both the Enemy Release Hypothesis and the Novel Weapon Hypothesis and highlights the complexity and importance of studying host-parasite relationships in an era of global climate change and species range shifts.

11.
Ann Hum Biol ; 44(6): 537-545, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28502204

RESUMO

BACKGROUND: The origin of Western African pastoralism, represented today by the Fulani nomads, has been a highly debated issue for the past decades, and has not yet been conclusively resolved. AIM: This study focused on Alu polymorphisms in sedentary and nomadic populations across the African Sahel to investigate patterns of diversity that can complement the existing results and contribute to resolving issues concerning the origin of West African pastoralism. SUBJECTS AND METHODS: A new dataset of 21 Alu biallelic markers covering a substantial part of the African Sahel has been analysed jointly with several published North African populations. RESULTS: Interestingly, with regard to Alu variation, the relationship of Fulani pastoralists to North Africans is not as evident as was earlier revealed by studies of uniparental loci such as mtDNA and NRY. Alu insertions point rather to an affinity of Fulani pastoralists to Eastern Africans also leading a pastoral lifestyle. CONCLUSIONS: It is suggested that contemporary Fulani pastoralists might be descendants of an ancestral Eastern African population that, while crossing the Sahara in the Holocene, admixed slightly with a population of Eurasian (as evidenced by uniparental polymorphisms) ancestry. It seems that, in the Fulani pastoralists, Alu elements reflect more ancient genetic relationships than do uniparental genetic systems.


Assuntos
Elementos Alu/genética , Polimorfismo Genético/genética , Migrantes , África Subsaariana , Humanos
12.
Hum Biol ; 89(4): 281-302, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-30047317

RESUMO

The objective of this study was to provide deeper knowledge of the maternal genetic structure and demographic history of the human populations of the Sahel/Savannah belt, the extensive region lying between the Sahara and tropical rainforests, spanning from the Atlantic Ocean to the Red Sea coast. The study aimed to confirm or disconfirm archaeological and linguistic data indicating that the region's populations underwent diversification as a result of the spread of agropastoral food-producing subsistence lifestyles, over time dividing the region into separate areas of nomadic pastoralism, on the one hand, and sedentary farming, on the other. To perform both descriptive and coalescence analyses from the Sahel/Savannah belt's entire region, including western and eastern rather than just central populations studied previously, we generated a new mitochondrial DNA (mtDNA) data set not only having almost 2,000 samples (875 of which were newly collected) but also encompassing whole mtDNA D-loop segment rather than only the previously studied hypervariable segment 1. While comparing our analyses with previous results from the Lake Chad Basin (central Sahel/Savannah Belt), we found similar intrapopulation diversity measures (i.e., lower values in pastoralists than in farmers). However, the new data set pointed to significant differences in mating strategies between western and eastern pastoralists: our results suggest higher gene flow between the Arabic pastoralists and neighboring farmers in the eastern part than between the Fulani pastoralists and their sedentary neighbors in the western part of the Sahel/Savannah belt. The findings are discussed in light of archaeological and linguistic data, allowing us to postulate that the genetic differentiation of Fulani pastoralists from the common western African agropastoral gene pool occurred at around the same time as the arrival of the Arabic pastoralists to eastern Africa. However, it seems that while the process of divergence of the Fulani pastoralists in the west was accompanied by a loss of Fulani females to other populations, the Arab pastoralists' immigration to the Sahel/Savannah belt conversely resulted in some gain of local females into this Arab population.


Assuntos
Agricultura/tendências , Arqueologia/métodos , População Negra/genética , DNA Mitocondrial/genética , África do Norte/epidemiologia , Árabes/genética , População Negra/história , Emigração e Imigração , Feminino , Fluxo Gênico/genética , Estruturas Genéticas , Genética Populacional , História Antiga , História Medieval , Humanos , Idioma , Polimorfismo de Nucleotídeo Único/genética , Migrantes
13.
Parasitol Res ; 115(1): 291-8, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26365667

RESUMO

Sedentary bird species are suitable model hosts for identifying potential vectors of avian blood parasites. We studied haemosporidian infections in the Tengmalm's Owl (Aegolius funereus) in the Ore Mountains of the Czech Republic using molecular detection methods. Sex of owl nestlings was scored using molecular sexing based on fragment analysis of PCR-amplified CHD1 introns. Observed infection prevalences in nestlings and adult owls were 51 and 86 %, respectively. Five parasite lineages were detected. Most of the infections comprised the Leucocytozoon AEFUN02 and STOCC06 lineages that probably refer to distinct Leucocytozoon species. Other lineages were detected only sporadically. Mixed infections were found in 49 % of samples. The main factor affecting the probability of infection was host age. No effect of individual sex on infection probability was evidenced. The youngest infected nestling was 12 days old. High parasite prevalence in the Tengmalm's Owl nestlings suggests that insect vectors must enter nest boxes to transmit parasites before fledging. Hence, we placed sticky insect traps into modified nest boxes, collected potential insect vectors, and examined them for the presence of haemosporidian parasites using molecular detection. We trapped 201 insects which were determined as biting midges from the Culicoides genus and two black fly species, Simulium (Nevermannia) vernum and Simulium (Eusimulium) angustipes. Six haemosporidian lineages were detected in the potential insect vectors, among which the Leucocytozoon lineage BT2 was common to the Tengmalm's Owl and the trapped insects. However, we have not detected the most frequently encountered Tengmalm's Owl Leucocytozoon lineages AEFUN02 and STOCC06 in insects.


Assuntos
Doenças das Aves/parasitologia , Haemosporida/isolamento & purificação , Insetos Vetores/parasitologia , Infecções Protozoárias em Animais/parasitologia , Estrigiformes/parasitologia , Fatores Etários , Animais , Doenças das Aves/epidemiologia , Doenças das Aves/transmissão , Ceratopogonidae/parasitologia , República Tcheca/epidemiologia , Feminino , Haemosporida/genética , Masculino , Reação em Cadeia da Polimerase , Prevalência , Infecções Protozoárias em Animais/epidemiologia , Infecções Protozoárias em Animais/transmissão , Fatores Sexuais , Simuliidae/parasitologia
14.
Ecology ; 96(10): 2726-36, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26649393

RESUMO

If offspring develop in adverse conditions, the maternal component of their phenotypic variation might increase due to the stronger dependence of offspring traits on parental investment. This should result in increased parental investment to individual offspring, as assumed by the model of optimal egg size. The opposite pattern, i.e., stronger dependence of offspring fitness on parental investment and consequently larger parental investment under good conditions is assumed by both the theory of differential allocation if attractive males provide material benefits, and reproductive compensation if they invest less into paternal care. Another influential idea is the Trivers-Willard model, which assumes sex-specific dependence of offspring fitness on parental investment. Here we tested these ideas by examining the effects of egg size on offspring fitness across many postnatal contexts in the Collared Flycatcher Ficedula albicollis. We employed a cross-fostering design that generated variation in egg size within nests and used brood means of fledgling mass as a functional measure of the quality of rearing conditions. Effects of egg size on three offspring traits, including lifetime reproductive success of recruits, were more pronounced in low-quality broods. These results support the assumption of the model of optimal egg size. Based on female preference for males providing material benefits, this pattern could support differential allocation, if attractive males invest less in paternal care, or reproductive compensation, if they invest more. By comparison, we did not find any evidence for sex specificity of fitness returns that might explain sex monomorphism of egg size in this species. The challenge for future studies will be the integration of components of parental investment and offspring fitness into their global measures and testing how the former affects the latter across gradients of postnatal conditions.


Assuntos
Metabolismo Energético/fisiologia , Óvulo/fisiologia , Passeriformes/fisiologia , Animais , Tamanho Corporal , Comportamento Alimentar/fisiologia , Feminino , Aptidão Genética , Masculino , Modelos Biológicos , Comportamento de Nidação/fisiologia , Passeriformes/genética , Fatores Sexuais
15.
Mol Biol Evol ; 32(5): 1208-20, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25631927

RESUMO

Genomic features such as rate of recombination and differentiation have been suggested to play a role in species divergence. However, the relationship of these phenomena to functional organization of the genome in the context of reproductive isolation remains unexplored. Here, we examine genomic characteristics of the species boundaries between two house mouse subspecies (Mus musculus musculus/M. m. domesticus). These taxa form a narrow semipermeable zone of secondary contact across Central Europe. Due to the incomplete nature of reproductive isolation, gene flow in the zone varies across the genome. We present an analysis of genomic differentiation, rate of recombination, and functional composition of genes relative to varying amounts of introgression. We assessed introgression using 1,316 autosomal single nucleotide polymorphism markers, previously genotyped in hybrid populations from three transects. We found a significant relationship between amounts of introgression and both genomic differentiation and rate of recombination with genomic regions of reduced introgression associated with higher genomic differentiation and lower rates of recombination, and the opposite for genomic regions of extensive introgression. We also found a striking functional polarization of genes based on where they are expressed in the cell. Regions of elevated introgression exhibit a disproportionate number of genes involved in signal transduction functioning at the cell periphery, among which olfactory receptor genes were found to be the most prominent group. Conversely, genes expressed intracellularly and involved in DNA binding were the most prevalent in regions of reduced introgression. We hypothesize that functional organization of the genome is an important driver of species divergence.


Assuntos
Especiação Genética , Genoma , Isolamento Reprodutivo , Seleção Genética , Animais , Camundongos , Polimorfismo de Nucleotídeo Único , Especificidade da Espécie
16.
Evol Appl ; 7(6): 645-62, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25067948

RESUMO

Many reintroduction projects for conservation fail, and there are a large number of factors that may contribute to failure. Genetic analysis can be used to help stack the odds of a reintroduction in favour of success, by conducting assessment of source populations to evaluate the possibility of inbreeding and outbreeding depression and by conducting postrelease monitoring. In this study, we use a panel of 306 SNP (single nucleotide polymorphism) markers and 487-489 base pairs of mitochondrial DNA control region sequence data to examine 321 individuals from possible source populations of the Eurasian beaver for a reintroduction to Scotland. We use this information to reassess the phylogenetic history of the Eurasian beavers, to examine the genetic legacy of past reintroductions on the Eurasian landmass and to assess the future power of the genetic markers to conduct ongoing monitoring via parentage analysis and individual identification. We demonstrate the capacity of medium density genetic data (hundreds of SNPs) to provide information suitable for applied conservation and discuss the difficulty of balancing the need for high genetic diversity against phylogenetic best fit when choosing source population(s) for reintroduction.

17.
Mol Ecol ; 22(1): 215-28, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23116299

RESUMO

Across animal taxa, reproductive success is generally more variable and more strongly dependent upon body condition for males than for females; in such cases, parents able to produce offspring in above-average condition are predicted to produce sons, whereas parents unable to produce offspring in good condition should produce daughters. We tested this hypothesis in the collared flycatcher (Ficedula albicollis) by cross-fostering eggs among nests and using the condition of foster young that parents raised to fledging as a functional measure of their ability to produce fit offspring. As predicted, females raising heavier-than-average foster fledglings with their social mate initially produced male-biased primary sex ratios, whereas those raising lighter-than-average foster fledglings produced female-biased primary sex ratios. Females also produced male-biased clutches when mated to males with large secondary sexual characters (wing patches), and tended to produce male-biased clutches earlier within breeding seasons relative to females breeding later. However, females did not adjust the sex of individuals within their clutches; sex was distributed randomly with respect to egg size, laying order and paternity. Future research investigating the proximate mechanisms linking ecological contexts and the quality of offspring parents are able to produce with primary sex-ratio variation could provide fundamental insight into the evolution of context-dependent sex-ratio adjustment.


Assuntos
Comportamento de Nidação , Razão de Masculinidade , Comportamento Sexual Animal , Aves Canoras/fisiologia , Animais , Tamanho Corporal , Feminino , Masculino , Caracteres Sexuais
18.
Parasitol Res ; 112(2): 839-45, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23224608

RESUMO

The degree to which avian haemosporidian parasites can exploit different vectors as a definitive host has ecological implications for their transmission and biogeography. Studies targeting haemosporidian parasites using precise molecular detection methods are almost lacking in Central Europe, however. Here, we utilized PCR-based molecular methods to detect avian haemosporidians in insect vectors in the Czech Republic. Nine lineages of parasites belonging to three genera, Haemoproteus, Plasmodium, and Leucocytozoon, were detected in pooled samples of insect individuals, of which three lineages had not yet been discovered in previous studies. All three Leucocytozoon lineages were found exclusively in black flies, while five Haemoproteus lineages were found in biting midges. The most abundant insect species Culicoides kibunensis harbored three Haemoproteus lineages, and the second-most numerous species Culicoides segnis even four. The positive mosquitoes of Culex pipiens complex hosted two parasite lineages, one Plasmodium and one Haemoproteus, the latter of which, however, could suggest the aberrant development of this parasite in an unusual invertebrate host. The co-occurrence of Haemoproteus ROFI1 and TURDUS2 lineages in both insects and birds at the same study plot suggests a transmission of these lineages during breeding season of birds.


Assuntos
Ceratopogonidae/parasitologia , Culex/parasitologia , Haemosporida/classificação , Haemosporida/isolamento & purificação , Simuliidae/parasitologia , Animais , Aves/parasitologia , República Tcheca , DNA de Protozoário/genética , Feminino , Haemosporida/genética , Insetos , Reação em Cadeia da Polimerase
19.
Proc Biol Sci ; 279(1748): 4803-10, 2012 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-23055063

RESUMO

The house mouse hybrid zone (HMHZ) is a species barrier thought to be maintained by a balance between dispersal and natural selection against hybrids. While the HMHZ is characterized by frequency discontinuities for some sex chromosome markers, there is an unexpected large-scale regional introgression of a Y chromosome across the barrier, in defiance of Haldane's rule. Recent work suggests that a major force maintaining the species barrier acts through sperm traits. Here, we test whether the Y chromosome penetration of the species barrier acts through sperm traits by assessing sperm characteristics of wild-caught males directly in a field laboratory set up in a Y introgression region of the HMHZ, later calculating the hybrid index of each male using 1401 diagnostic single nucleotide polymorphisms (SNPs). We found that both sperm count (SC) and sperm velocity were significantly reduced across the natural spectrum of hybrids. However, SC was more than rescued in the presence of the invading Y. Our results imply an asymmetric advantage for Y chromosome introgression consistent with the observed large-scale introgression. We suggest that selection on sperm-related traits probably explains a large component of patterns observed in the natural hybrid zone, including the Y chromosome penetration.


Assuntos
Hibridização Genética , Camundongos/fisiologia , Espermatozoides/fisiologia , Cromossomo Y , Animais , Masculino , Modelos Genéticos , Fenótipo , Polimorfismo de Nucleotídeo Único , Seleção Genética , Especificidade da Espécie
20.
Mol Ecol ; 21(12): 3032-47, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22582810

RESUMO

Studies of a hybrid zone between two house mouse subspecies (Mus musculus musculus and M. m. domesticus) along with studies using laboratory crosses reveal a large role for the X chromosome and multiple autosomal regions in reproductive isolation as a consequence of disrupted epistasis in hybrids. One limitation of previous work has been that most of the identified genomic regions have been large. The goal here is to detect and characterize precise genomic regions underlying reproductive isolation. We surveyed 1401 markers evenly spaced across the genome in 679 mice collected from two different transects. Comparisons between transects provide a means for identifying common patterns that likely reflect intrinsic incompatibilities. We used a genomic cline approach to identify patterns that correspond to epistasis. From both transects, we identified contiguous regions on the X chromosome in which markers were inferred to be involved in epistatic interactions. We then searched for autosomal regions showing the same patterns and found they constitute about 5% of autosomal markers. We discovered substantial overlap between these candidate regions underlying reproductive isolation and QTL for hybrid sterility identified in laboratory crosses. Analysis of gene content in these regions suggests a key role for several mechanisms, including the regulation of transcription, sexual conflict and sexual selection operating at both the postmating prezygotic and postzygotic stages of reproductive isolation. Taken together, these results indicate that speciation in two recently diverged (c. 0.5 Ma) house mouse subspecies is complex, involving many genes dispersed throughout the genome and associated with distinct functions.


Assuntos
Epistasia Genética , Preferência de Acasalamento Animal , Camundongos/genética , Isolamento Reprodutivo , Cromossomo X/genética , Animais , Especiação Genética , Variação Genética , Hibridização Genética , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas
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