Use of noninvasive ‘bug-eggs’ to enable comparative inferences on genetic mating system with and without parental information: A study in a cattle egret colony

Colonial waterbirds such as herons, egrets and spoonbills exhibit ecological characteristics that could have promoted the evolution of conspecific brood parasitism and extra-pair copulation. However, an adequate characterization of the genetic mating systems of this avian group has been hindered by the lack of samples of elusive candidate parents which precluded conducting conventional parentage allocation tests. Here, we investigate the genetic mating system of the invasive cattle egret using hematophagous insects contained in fake eggs to collect blood from incubating adults in a wild breeding colony. We tested a protocol with a previously unused Neotropical Triatominae, Panstrongylus megistus, obtained blood samples from males and females in 31 nests built on trees, drew blood from 89 nestlings at those nests, and genotyped all samples at 14 microsatellite loci, including six new species-specific loci. We comparatively addressed the performance of parentage allocation versus kinship classification of nestlings to infer the genetic mating system of cattle egrets. In line with previous behavioral observations, we found evidence in support of a non-monogamous genetic mating system, including extra-pair paternity (EPP) and conspecific brood parasitism (CBP). Parentage allocation tests detected a higher percentage of nests with alternative reproductive tactics (EPP: 61.7%; CBP: 64.5%) than the kinship classification method (EPP: 50.0%; CBP: 43.3%). Overall, these results indicate that rates of alternative reproductive tactics inferred in the absence of parental genetic information could be underestimated and should be interpreted with caution. This study highlights the importance of incorporating samples from candidate parents to adequately determine the genetic mating system of a species. We expand knowledge on the reproductive tactics of colonial waterbirds, contributing novel data on the genetic mating system of the cattle egret, valuable for the design of management strategies for this invasive bird.Fil: Miño, Carolina Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Dantas de Souza, Elaine. Universidade Federal do São Carlos; BrasilFil: Moralez-Silva, Emmanuel. Universidade Federal do São Carlos; BrasilFil: Valdes, Talita Alvarenga. Universidade Federal do São Carlos; BrasilFil: Cortiço Corrêa Rodrigues, Vera Lúcia. Superintendencia de Controle de Endemias; BrasilFil: Del Lama, Sílvia Nassif. Universidade Federal do São Carlos; Brasi

Colonization of Brazil by the cattle egret (Bubulcus ibis) revealed by mitochondrial DNA

The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θ) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample

Colonization of Brazil by the cattle egret (Bubulcus ibis) revealed by mitochondrial DNA

The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θs) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample

Sistemas de acasalamento e biologia reprodutiva em aves aquáticas neotropicais

The present paper reviews the published information on the mating systems and reproductive biology of Neotropical waterbirds. Thirty-four scientific articles were included, which were divided into two main themes: �mating systems� (10 articles) and �reproductive biology� (24 articles). Extra-pair copulation and/ or fertilization were reported to occur in 60% of the Neotropical species investigated, while monogamy was reported in 22%, bigamy in 11% and nest parasitism in 11%. General aspects of reproductive biology of 30 species were more extensively reviewed, of which 20 were seabirds and 10 were lacustrine species. Aspects most frequently described were reproductive chronology (73% of species), clutch size (80%) and reproductive success defined by the number of hatched eggs (73%). Only one species in Sulidae (Sula leucogaster) and one in Threskiornithidae (Eudocimus rubber) were studied for both, mating system and reproduction. A global analysis of the available data revealed that seabirds and Ciconiiformes birds were most intensively studied in terms of reproductive biology, while their mating systems remain largely uninvestigatedUma revisão sobre sistemas de acasalamento e aspectos gerais da biologia reprodutiva em aves aquáticas neotropicais foi desenvolvida para avaliar o conjunto de publicações na literatura e nortear estudos futuros nesse grupo. Foram analisados 34 artigos científicos, classificados em dois temas principais: �sistemas de acasalamento� (10) e �biologia reprodutiva� (24). Sistemas de acasalamento foram estudados em nove espécies de aves neotropicais, pertencentes a quatro famílias: Anatidae, Diomedeidae, Sulidae e Threskiornithidae. Em 56% das espécies foram reportadas cópulas e/ou fertilização extra-par, em 22% monogamia, em 11% bigamia e em 11% parasitismo de ninho. Dados gerais de biologia reprodutiva foram levantados em 30 espécies neotropicais, sendo 20 de aves marinhas e 10 de aves lacustres. Os três enfoques mais comuns encontrados nesses estudos foram cronologia reprodutiva (73% das espécies), tamanho das ninhadas em número de ovos (80%) e sucesso reprodutivo avaliado pelo número de ovos eclodidos (73%). Apenas uma espécie da família Sulidae (Sula leucogaster) e uma da Threskiornithidae (Eudocimus ruber) foram estudadas sob os dois enfoques. Uma análise conjunta dos dados levantados revelou que as aves marinhas e os Ciconiiformes têm sido extensivamente estudados quanto às características reprodutivas gerais, porém seus sistemas de acasalamento não foram ainda bem investigados.Se realizó una revisión bibliográfica sobre sistemas de apareamiento y biología reproductiva de aves acuáticas neotropicales para recopilar información sobre la literatura actualizada y para direccionar futuros estudios en este grupo. Treinta y cuatro artículos científicos fueron analizados y clasificados de acuerdo con sus temas principales: �sistemas de apareamiento� (10) y �biología reproductiva� (24). En 60% de las publicaciones sobre espécies neotropicales, fueron registrados eventos de cópula extra-par y/o de fertilización extra-pareja; en 22% fue observada monogamia; en 11% bigamia y en 11% parasitismo de nido. Características generales de la reproducción fueron descritas para 30 especies, siendo 20 aves marinas y 10 especies lacustres. Las características más comúnmente descritas en las especies analizadas fueron: cronología reproductiva (73%), tamaño de la nidada (80%) y éxito reproductivo de los pichones definido por el porcentaje de huevos que eclosionaron (73%). Solamente una especie de la familia Sulidae (Sula leucogaster) y una de la familia Threskiornithidae (Eudocimus ruber), fueron estudiados en ambos aspectos (sistema de apareamiento y biología). Un análisis global de los datos reveló que diversos aspectos de la biología reproductiva han sido intensivamente estudiados en las aves marinas y los Ciconiformes, mientras que sus sistemas de apareamiento no fueron aún bien estudiados

Colonization of Brazil by the cattle egret (Bubulcus ibis) revealed by mitochondrial DNA

The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θs) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample

Inferred genetic mating system of the cattle egret.

<p>Inferences drew using the parental allocation approach with samples from incubating adults or the multiple methods’ approach in absence of parental information. Inferred genetic mating system (i. e., monogamy, CBP: conspecific brood parasitism, or EPP: extra-pair paternity) refers to whole nests rather than dyads. Symbol ‘/’ indicates that both behaviors were detected in nest. ‘Not inferred’ (nest #16) indicates that the multiple methods approach could not reach a final diagnosis for the full brood. Detailed results of parentage and kinship analyses for all nests are given in Tables C and D in S1 File, respectively.</p

Proportion of inferred genetic mating system in cattle egret nests and nestling-dyads.

<p>(A) Number of nests showing genetic evidence of monogamy, extra-pair paternity (EPP), conspecific brood parasitism (CBP) or of both behaviors, as inferred by application of the parentage allocation procedure or the multiple methods approach; (B) Number of nestling-dyads inferred to be product of monogamy, EPP or CBP by both methods.</p

Fake eggs and hematophagous insects used for blood collection of incubating cattle egret adults.

<p>Photograph showing: (A) Side view of fiberglass egg mimicking cattle egret egg (approximate dimensions: 45 mm length, 33 mm width) with holes through which the insect projects its proboscis; (B) Interior view of two halves of egg, which are attached with nut and bolt; (C) Fifth instar <i>Panstrongylus megistus</i> larva being removed from a fake-egg after having fed on an incubating cattle egret. Note the insect's engorged abdomen.</p

Summary of diversity statistics and power of set of markers used for relatedness analyses in cattle egret.

<p>Number of alleles (<i>Na</i>), observed heterozygosity (<i>Ho</i>), unbiased expected heterozygosity (<i>uHe</i>), Fixation Index (<i>F</i>_<i>IS</i>), probability values of tests for deviation from Hardy-Weinberg Equilibrium (<i>PHWE</i>), probability of excluding a parent-pair (<i>P</i>_<i>E</i>), probability of identity between siblings (<i>P</i>_{<i>ID-Sibs</i>}) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0183153#pone.0183153.ref054" target="_blank">54</a>]. Multilocus estimates (± standard errors) are given in last row. Parameters were estimated using sample of unrelated females (<i>n</i> = 31) and males (<i>n</i> = 31).</p

Rates of alternative reproductive tactics inferred in wild waterbirds.

<p>Percentages of nests with evidence of extra-pair paternity (EPP) or conspecific brood parasitism (CBP) inferred in waterbirds studied to date with molecular tools. Inferences were made either by applying the parental allocation approach [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0183153#pone.0183153.ref057" target="_blank">57</a>] or the multiple methods approach in the absence of parental information [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0183153#pone.0183153.ref011" target="_blank">11</a>].</p