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1.
Oecologia ; 193(1): 67-75, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32306117

RESUMO

The extent to which migratory bats forage at stopover sites or while in migratory flight is poorly understood. Endogenous fat stores have lower δ13C values relative to the dietary substrates from which they were synthesized, and so, the fed versus fasted state of bats should be discernable by comparing their breath δ13C at capture to that after a known period of fasting. We captured silver-haired bats (Lasionycteris noctivagans) at a stopover site at Long Point, Ontario, Canada, during spring and fall migration. We collected breath samples at capture and after fasting in captivity for 12 h, providing a fasted-state δ13C value corresponding to metabolism of fat stores. We also collected and weighed fecal pellets produced while in captivity. Breath δ13C values at capture were positively correlated with mass of feces produced. During spring migration, δ13C values of breath CO2 at capture were low and similar to fasting values, but increased with date consistent with increased foraging at stopover and reliance on exogenous dietary nutrients as the season progressed. The opposite temporal pattern was found during fall migration. Our findings suggest that bats forage during migratory stopover when environmental conditions permit despite potential time trade-offs between feeding and travel, and the energy savings resulting from torpor during roosting. This study provides insight into the eco-physiology of bat migration and shows the importance of foraging habitat for migratory bats.


Assuntos
Quirópteros , Torpor , Migração Animal , Animais , Dióxido de Carbono , Ontário , Estações do Ano
3.
Sci Total Environ ; 719: 137215, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32126403

RESUMO

Knowledge of the location, physical attributes and impacts of obstacles on river connectivity is a requirement for any mitigating action aimed at restoring the connectivity of a river system. Here, we present a study that recorded the numbers and physical diversity of obstacles in 10 river catchments in Ireland, together with the impact these structures had on overall river connectivity. A total of 372 obstacles were recorded, 3 of these were dams, and the remainder were low-head weirs/sluices, obstacles associated with road or rail crossings of rivers and natural structures. The degree of fragmentation was estimated in each catchment by calculating obstacle density and the Dendritic Connectivity Index (DCI). DCI scores were calculated for 4 native Irish fish species with different life-histories, namely diadromous (Atlantic salmon, sea trout, European eel, sea lamprey) and potamodromous (brown trout). Obstacle density ranged between 1.2 and 0.02 obstacles/km of river. Six of the 10 catchments had at least one obstacle located on the mainstem river at least 5 km from its mouth/confluence. These 6 catchments typically had the lowest connectivity scores for diadromous species and ranged between 0.6 and 44.1 (a fully connected river would receive a maximum score of 100). While there was no significant correlation between obstacle density and the DCI score for diadromous fish, a significant negative correlation was detected between obstacle density and the DCI score for potamodromous brown trout. Here, we highlight the merit of these obstacle assessments and associated challenges for decision-making relating to prioritisation of obstacles for removal or modification.


Assuntos
Migração Animal , Animais , Enguias , Irlanda , Lampreias , Rios , Salmão , Truta
4.
Ecol Lett ; 23(5): 881-890, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32212213

RESUMO

The long-distance migrations by marine fishes are difficult to track by field observation. Here, we propose a new method to track such migrations using stable nitrogen isotopic composition at the base of the food web (δ15 NBase ), which can be estimated by using compound-specific isotope analysis. δ15 NBase exclusively reflects the δ15 N of nitrate in the ocean at a regional scale and is not affected by the trophic position of sampled organisms. In other words, δ15 NBase allows for direct comparison of isotope ratios between proxy organisms of the isoscape and the target migratory animal. We initially constructed a δ15 NBase isoscape in the northern North Pacific by bulk and compound-specific isotope analyses of copepods (n = 360 and 24, respectively), and then we determined retrospective δ15 NBase values of spawning chum salmon (Oncorhynchus keta) from their vertebral centra (10 sections from each of two salmon). We then estimated the migration routes of chum salmon during their skeletal growth by using a state-space model. Our isotope tracking method successfully reproduced a known chum salmon migration route between the Okhotsk and Bering seas, and our findings suggest the presence of a new migration route to the Bering Sea Shelf during a later growth stage.


Assuntos
Aminoácidos , Peixes , Migração Animal , Animais , Oceanos e Mares , Estudos Retrospectivos , Salmão
5.
Nat Commun ; 11(1): 671, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-32015346

RESUMO

Dingoes are wild canids living in Australia, originating from domestic dogs. They have lived isolated from both the wild and the domestic ancestor, making them a unique model for studying feralization. Here, we sequence the genomes of 10 dingoes and 2 New Guinea Singing Dogs. Phylogenetic and demographic analyses show that dingoes originate from dogs in southern East Asia, which migrated via Island Southeast Asia to reach Australia around 8300 years ago, and subsequently diverged into a genetically distinct population. Selection analysis identifies 50 positively selected genes enriched in digestion and metabolism, indicating a diet change during feralization of dingoes. Thirteen of these genes have shifted allele frequencies compared to dogs but not compared to wolves. Functional assays show that an A-to-G mutation in ARHGEF7 decreases the endogenous expression, suggesting behavioral adaptations related to the transitions in environment. Our results indicate that the feralization of the dingo induced positive selection on genomic regions correlated to neurodevelopment, metabolism and reproduction, in adaptation to a wild environment.


Assuntos
Canidae/classificação , Canidae/genética , Genômica , Filogenia , Migração Animal , Animais , Ásia Sudeste , Austrália , DNA Mitocondrial/análise , Cães/classificação , Cães/genética , Variação Genética , Genética Populacional , Genoma Mitocondrial , Nova Guiné , Polimorfismo de Nucleotídeo Único , Fatores de Troca de Nucleotídeo Guanina Rho/genética , Lobos/classificação , Lobos/genética
6.
PLoS One ; 15(1): e0227302, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32004321

RESUMO

Over the centuries, the geographical distribution of brown bear (Ursus arctos) across the Iberian Peninsula has been decreasing, with the species currently confined to North Iberia. The Cantabrian brown bear population is one of the smallest in Europe and is structured into two subpopulations, positioned along an east-west axis. Given the current critically endangered status of this population, it is essential to have a clear picture of its within-population genetic patterns and processes. We use a set of three molecular markers (mitochondrial DNA, autosomal microsatellites and sex markers) to clarify the genetic origins and assess the migration patterns and gene flow of the Cantabrian brown bear population. Our results reveal the presence of two different mitochondrial (matrilineal) haplotypes in the Cantabrian population, both belonging to European brown bear clade 1a. The two haplotypes are geographically structured between Eastern (haplotype CanE) and Western Cantabrian (haplotype CanW) subpopulations, which is consistent with the genetic structure previously identified using nuclear markers. Additionally, we show that CanE is closer to the historical Pyrenean (Pyr) haplotype than to CanW. Despite strong structuring at the levels of mtDNA and nuclear loci, there is evidence of bidirectional gene flow and admixture among subpopulations. Gene flow is asymmetrical and significantly more intense from the Eastern to the Western Cantabrian subpopulation. In fact, we only detected first generation male migrants from the Eastern to the Western Cantabrian subpopulation. These results suggest more intense migration from the smaller and more vulnerable Eastern Cantabrian subpopulation towards the larger and more stable Western Cantabrian subpopulation. These new insights are relevant for assessments of on-going conservation measures, namely the role of dispersal corridors and enhanced connectivity. We discuss the importance of complementary conservation measures, such as human-wildlife conflict mitigation and habitat improvement, for the conservation of a viable Cantabrian brown bear population.


Assuntos
Migração Animal , Espécies em Perigo de Extinção/tendências , Haplótipos , Dinâmica Populacional/tendências , Ursidae/genética , Animais , DNA Mitocondrial/genética , DNA Mitocondrial/isolamento & purificação , Feminino , Fluxo Gênico , Loci Gênicos , Masculino , Repetições de Microssatélites/genética , Espanha
7.
PLoS One ; 15(2): e0226089, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049995

RESUMO

There is a growing need to understand how species respond to habitat changes and the potential key role played by natal dispersal in population dynamics, structure and gene flow. However, few studies have explored differences in this process between conspecifics living in natural habitats and those inhabiting landscapes highly transformed by humans, such as cities. Here, we investigate how individual traits and social characteristics can influence the natal dispersal decisions of burrowing owls (Athene cunicularia) living in urban and rural areas, as well as the consequences in terms of reproductive success and apparent survival. We found short dispersal movements among individuals, with differences between urban and rural birds (i.e., the former covering shorter distances than the latter), maybe because of the higher conspecific density of urban compared to rural areas. Moreover, we found that urban and rural females as well as bold individuals (i.e., individuals with shorter flight initiation distance) exhibited longer dispersal distances than their counterparts. These dispersal decisions have effects on individual fitness. Individuals traveling longer distances increased their reproductive prospects (productivity during the first breeding attempt, and long term productivity). However, the apparent survival of females decreased when they dispersed farther from their natal territory. Although further research is needed to properly understand the ecological and evolutionary consequences of dispersal patterns in transformed habitats, our results provide information about the drivers and the consequences of the restricted natal movements of this species, which may explain its population structuring through restricted gene flow between and within urban and rural areas.


Assuntos
Migração Animal/fisiologia , Pradaria , Personalidade/fisiologia , Dinâmica Populacional , População Rural , Estrigiformes/fisiologia , População Urbana , Animais , Argentina , Cruzamento , Feminino , Expectativa de Vida , Masculino , Reprodução/fisiologia , Fatores Sexuais
8.
Gene ; 737: 144478, 2020 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-32061762

RESUMO

Different types of fish taxa generally seem to present diverse phylogeographic structures and show different responses to environmental changes. In southern China, however, a large number of phylogeographic studies have been employed for small and/or benthic fish species, while phylogeographic patterns of larger and migratory species are not well understood. In this study, we chose Megalobrama terminalis, an endemic cyprinid from Southern China with a median size and relatively high migratory potential as a candidate to explore the phylogeographic structure and to seek the relevant driving forces using a multilocus approach (two mitochondrial markers and three nuclear markers). Our results show that M. terminalis exhibits three mtDNA genetic groups, each presenting genetic structure to the local geography, but the differentiation level was much weaker than that of small and/or benthic fish species reported in earlier studies. Nuclear loci did not observe pronounced genetic group subdivision, but did examine noteworthy genetic differentiation between the Hainan Island population and the mainland populations. Divergence time estimation and demographic analyses suggest that sea-level changes associated with the Late Pleistocene glacial cycles have exerted pronounced effects on the divergence of the three groups and the expansion of M. terminalis populations. Above all, our study provides important knowledge that can be used to improve monitoring programs and develop a conservation strategy for this endemic organism.


Assuntos
Migração Animal , Cyprinidae/genética , Filogeografia , Animais , Mudança Climática , Cyprinidae/fisiologia , DNA Mitocondrial/genética , Água Doce , Oceanos e Mares
10.
Nat Commun ; 11(1): 801, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32071295

RESUMO

Migration is a widespread response of birds to seasonally varying climates. As seasonality is particularly pronounced during interglacial periods, this raises the question of the significance of bird migration during past periods with different patterns of seasonality. Here, we apply a mechanistic model to climate reconstructions to simulate the past 50,000 years of bird migration worldwide, a period encompassing the transition between the last glacial period and the current interglacial. Our results indicate that bird migration was also a prevalent phenomenon during the last ice age, almost as much as today, suggesting that it has been continually important throughout the glacial cycles of recent Earth history. We find however regional variations, with increasing migratory activity in the Americas, which is not mirrored in the Old World. These results highlight the strong flexibility of the global bird migration system and offer a baseline in the context of on-going anthropogenic climate change.


Assuntos
Migração Animal/fisiologia , Aves/fisiologia , Mudança Climática , Animais , Biodiversidade , Planeta Terra , Ecologia , Camada de Gelo , Modelos Biológicos , Estações do Ano
11.
J Environ Manage ; 255: 109875, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32063321

RESUMO

Countries share responsibility for the management and conservation of migratory bird species. However, a limited understanding of population dynamics hampers the implementation of harvest and transboundary management. Age-ratios and population density can be useful indicators to assess population dynamics to improve management and conservation actions. Here, the dynamics of an Atlantic population of Common quail Coturnix coturnix, using 32,508 quail samples and 4814 hunter questionnaires over a 20-year period (1996-2016) served as a comparative study for examining age-ratio patterns related to different geographic zones, population density and weather parameters. Results show that age-ratios varied over zones and years, specifically age-ratio 1 (AR1), used as an index of late breeding attempts, varied from 0.1 to 0.21. Age-ratio 2 (AR2), a surrogate of central recruitment, varied from 0.16 to 0.66. Finally, age-ratio 3 (AR3), used as an indicator of the population's annual breeding success, varied from 3.69 to 6.68. Age-ratio is linked to internal and external factors (i.e. effect of rainfall, variations over time and density-dependent relationships) depicting how quail age groups make segregated migration in time and space. Quail age groups perform a complex pattern of migration because of entwined changes in abundance, migration routes and timing, influencing population connectivity and dynamics. Our findings highlight the relevance of citizen science and transboundary agreements to improve management and conservation measures of migrant species. Administrations and policy-makers in developed and developing countries must coordinate efforts to engage hunters in a participatory management systems to achieve sustainability.


Assuntos
Migração Animal , Coturnix , Animais , Ciência do Cidadão , Ecologia , Dinâmica Populacional , Estações do Ano
12.
Proc Natl Acad Sci U S A ; 117(6): 3006-3014, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31988130

RESUMO

With threats to nature becoming increasingly prominent, in order for biodiversity levels to persist, there is a critical need to improve implementation of conservation measures. In the oceans, the surveillance of fisheries is complex and inadequate, such that quantifying and locating nondeclared and illegal fisheries is persistently problematic. Given that these activities dramatically impact oceanic ecosystems, through overexploitation of fish stocks and bycatch of threatened species, innovative ways to monitor the oceans are urgently required. Here, we describe a concept of "Ocean Sentinel" using animals equipped with state-of-the-art loggers which monitor fisheries in remote areas. Albatrosses fitted with loggers detecting and locating the presence of vessels and transmitting the information immediately to authorities allowed an estimation of the proportion of nondeclared fishing vessels operating in national and international waters of the Southern Ocean. We found that in international waters, more than one-third of vessels had no Automatic Identification System operating; in national Exclusive Economic Zones (EEZs), this proportion was lower on average, but variable according to EEZ. Ocean Sentinel was also able to provide unpreceded information on the attraction of seabirds to vessels, giving access to crucial information for risk-assessment plans of threatened species. Attraction differed between species, age, and vessel activity. Fishing vessels attracted more birds than other vessels, and juveniles both encountered fewer vessels and showed a lower attraction to vessels than adults. This study shows that the development of technologies offers the potential of implementing conservation policies by using wide-ranging seabirds to patrol oceans.


Assuntos
Aves/fisiologia , Conservação dos Recursos Naturais/métodos , Monitoramento Ambiental , Pesqueiros/legislação & jurisprudência , Navios , Migração Animal/fisiologia , Animais , Biodiversidade , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Desenho de Equipamento , Navios/legislação & jurisprudência , Navios/estatística & dados numéricos
13.
Biol Lett ; 16(1): 20190797, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31964257

RESUMO

Thermal soaring birds extract energy from the atmosphere to achieve energetically low-cost movement. When encountering regions that are energetically costly to fly over, such as open seas, they should attempt to adjust the spatio-temporal pattern of their passage to maximize energy extraction from the atmosphere over these ecological barriers. We applied the concept of energy landscapes to investigate the spatio-temporal dynamics of energy availability over the open sea for soaring flight. We specifically investigated how the 'energy seascape' may shape age-specific sea-crossing behaviour of European honey buzzards, Pernis apivorus, over the Mediterranean Sea in autumn. We found uplift potential over the sea to be the main determinant of sea-crossing distance, rather than wind conditions. Considering this variable as a proxy for available energy over the sea, we constructed the energy seascape for the autumn migration season using 40 years of temperature data. Our results indicate that early-migrating adult buzzards are likely to encounter adverse energy subsidence over the Mediterranean, whereas late-migrating juveniles face less adverse flight conditions, and even conditions conducive to soaring flight. Our study provides evidence that the dynamics of the energy landscape can explain intra-specific variation in migratory behaviour also at sea.


Assuntos
Migração Animal , Voo Animal , Animais , Aves , Mar Mediterrâneo , Vento
15.
Arch Virol ; 165(3): 643-659, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31925543

RESUMO

The Izumi plain in Kagoshima Prefecture, Japan, is an overwintering site for migratory ducks and endangered cranes. We have surveyed avian influenza viruses (AIVs) in this area since 2012 and isolated low-pathogenic AIVs (LPAIVs) of various subtypes every winter season. H3N8 LPAIVs were isolated during the 2012/13 and 2016/17 seasons, and H4N6 LPAIVs were isolated during the 2012/13 and 2013/14 seasons. In the 2017/18 season, one H3N8 and two H4N6 LPAIV strains were isolated from environmental water samples. Genetic and phylogenetic analysis for each gene segment from these H3N8 and H4N6 LPAIVs suggested that our isolates were genetic reassortants generated by intermixing between AIVs circulating not only in Eurasia but also in Africa and/or North America. Comparison of the genetic constellations of our three isolates with their counterparts isolated during previous seasons from the Izumi plain revealed a drastic transition in the genetic constellations of both subtypes. These findings emphasize the importance of continuous surveillance of AIVs on the Izumi plain.


Assuntos
Aves/virologia , Patos/virologia , Genoma Viral/genética , Vírus da Influenza A Subtipo H3N8/genética , Influenza Aviária/virologia , África , Sequência de Aminoácidos , Migração Animal , Animais , Animais Selvagens/virologia , Sequência de Bases , Europa (Continente) , Variação Genética/genética , Vírus da Influenza A Subtipo H3N8/isolamento & purificação , Japão , América do Norte , Filogenia , Recombinação Genética/genética , Análise de Sequência de RNA
16.
Sci Total Environ ; 705: 135773, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31972933

RESUMO

Anthropogenic structures in rivers are major threats for fish migration and effective mitigation is imperative given the worldwide expansion of such structures. Fish behaviour is strongly influenced by hydrodynamics, but little is known on the relation between hydraulics and fish fine scale-movement. We combined 3D Computational fluid dynamics modelling (CFD) with 2D and 3D fish positioning to investigate the relation between hydrodynamics and the downstream movement of Atlantic salmon smolts (Salmo salar). We show that fish use fine-scale flow velocity and turbulence as navigation cues of fine-scale movement behaviour. Tri-dimensional swimming speed and swimming direction can be explained by adjustments of fish to flow motion, which are linked to fish swimming mode. Fish diverge from the flow by swimming at speeds within or higher than their prolonged speeds (0.38-0.73 m s-1). Flow direction plays a pivotal role on fish swimming performance, with high upstream and downwards velocities impacting swimming the most. Turbulence is also influential, by benefiting swimming performance at low TKE (< 0.03 m2 s-2) or constraining it at higher levels. We show that fish behaviour is affected by interactions of several hydraulic variables that should be considered jointly.


Assuntos
Salmo salar , Migração Animal , Animais , Hidrodinâmica , Rios , Natação
17.
PLoS One ; 15(1): e0219335, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31940348

RESUMO

Species introduced outside their natural range threaten global biodiversity and despite greater awareness of invasive species risks at ports and airports, control measures in place only concern anthropogenic routes of dispersal. Here, we use the Harlequin ladybird, Harmonia axyridis, an invasive species which first established in the UK from continental Europe in 2004, to test whether records from 2004 and 2005 were associated with atmospheric events. We used the atmospheric- chemistry transport model SILAM to model the movement of this species from known distributions in continental Europe and tested whether the predicted atmospheric events were associated with the frequency of ladybird records in the UK. We show that the distribution of this species in the early years of its arrival does not provide substantial evidence for a purely anthropogenic introduction and show instead that atmospheric events can better explain this arrival event. Our results suggest that air flows which may assist dispersal over the English Channel are relatively frequent; ranging from once a week from Belgium and the Netherlands to 1-2 times a week from France over our study period. Given the frequency of these events, we demonstrate that atmospheric-assisted dispersal is a viable route for flying species to cross natural barriers.


Assuntos
Besouros/fisiologia , Espécies Introduzidas/estatística & dados numéricos , Modelos Estatísticos , Vento , Migração Animal/fisiologia , Animais , Bélgica , França , Humanos , Método de Monte Carlo , Países Baixos , Reino Unido
18.
Proc Natl Acad Sci U S A ; 117(2): 1216-1222, 2020 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-31889001

RESUMO

Certain long-distance migratory animals, such as salmon and sea turtles, are thought to imprint on the magnetic field of their natal area and to use this information to help them return as adults. Despite a growing body of indirect support for such imprinting, direct experimental evidence thereof remains elusive. Here, using the fruit fly as a magnetoreceptive model organism, we demonstrate that exposure to a specific geographic magnetic field during a critical period of early development affected responses to a matching magnetic field gradient later in life. Specifically, hungry flies that had imprinted on a specific magnetic field from 1 of 3 widely separated geographic locations responded to the imprinted field, but not other magnetic fields, by moving downward, a geotactic behavior associated with foraging. This same behavior occurred spontaneously in the progeny of the next generation: female progeny moved downward in response to the field on which their parents had imprinted, whereas male progeny did so only in the presence of these females. These results represent experimental evidence that organisms can learn and remember a magnetic field to which they were exposed during a critical period of development. Although the function of the behavior is not known, one possibility is that imprinting on the magnetic field of a natal area assists flies and their offspring in recognizing locations likely to be favorable for foraging and reproduction.


Assuntos
Migração Animal/fisiologia , Drosophila/fisiologia , Campos Magnéticos , Animais , Feminino , Comportamento de Retorno ao Território Vital/fisiologia , Fixação Psicológica Instintiva/fisiologia , Masculino , Reprodução
19.
Ecol Lett ; 23(2): 316-325, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31800170

RESUMO

Increasing temperatures associated with climate change are predicted to cause reductions in body size, a key determinant of animal physiology and ecology. Using a four-decade specimen series of 70 716 individuals of 52 North American migratory bird species, we demonstrate that increasing annual summer temperature over the 40-year period predicts consistent reductions in body size across these diverse taxa. Concurrently, wing length - an index of body shape that impacts numerous aspects of avian ecology and behaviour - has consistently increased across species. Our findings suggest that warming-induced body size reduction is a general response to climate change, and reveal a similarly consistent and unexpected shift in body shape. We hypothesise that increasing wing length represents a compensatory adaptation to maintain migration as reductions in body size have increased the metabolic cost of flight. An improved understanding of warming-induced morphological changes is important for predicting biotic responses to global change.


Assuntos
Aves , Aquecimento Global , Migração Animal , Animais , Tamanho Corporal , Mudança Climática , Estações do Ano , Temperatura
20.
Gen Comp Endocrinol ; 285: 113250, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31445009

RESUMO

Seasonally breeding animals initiate gonadal recrudescence when mechanisms that suppress reproduction give way to mechanisms that stimulate it. However, knowledge of mechanistic changes in hormonal regulation during this transition is limited. Further, most studies of reproductive timing have focused on males, despite the critical role of females in determining breeding phenology. Closely related populations that live in the same environment but differ in reproductive timing provide an opportunity to examine differences in mechanisms during the transition from the pre-reproductive to reproductive state. We studied closely related migrant and resident populations of dark-eyed juncos (Junco hyemalis) that reside in the same environment in spring but differ in breeding phenology. Residents initiate breeding earlier than migrants, which do not breed until after they have migrated. To directly study differences in the hypothalamic mechanisms of reproduction, we captured 16 migrant and 13 resident females from the field on March 25-April 11. We quantified expression of mRNA transcripts and show that resident females had higher abundance of gonadotropin-releasing hormone transcripts than migrant females, indicating greater reproductive development in resident than migrant females living in the same environment. We also found higher transcript abundance of estrogen receptor and androgen receptor in migrant than resident females, suggesting that negative feedback may delay reproductive development in migrant females until after they migrate. These differences in hypothalamic mechanisms may help to explain differences in reproductive timing in populations that differ in migratory strategy.


Assuntos
Migração Animal/fisiologia , Sistemas Neurossecretores/metabolismo , Estações do Ano , Aves Canoras/fisiologia , Simpatria/fisiologia , Animais , Feminino , Hormônio Liberador de Gonadotropina/genética , Hormônio Liberador de Gonadotropina/metabolismo , Hipotálamo/metabolismo , Modelos Lineares , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
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