Genetic variation in the Afromontane tree Prunus africana,an endangered medicinal species

An understanding of the patterns of variation within and among populations of tropical trees is essential for devising optimum genetic management strategies for their conservation and sustainable utilization. Here, random amplified polymorphic DNA (RAPD) analysis was used to partition variation within and among 10 populations of the endangered Afromontane medicinal tree, Prunus africana, sampled from five countries across the geographical range of the species (Cameroon, Ethiopia, Kenya, Madagascar and Uganda). Analysis of molecular variance ( AMOVA ) employed 48 RAPD markers and revealed most variation among countries (66%, P < 0.001). However, variation among individuals within populations and among populations within Cameroon and Madagascar was also highly significant. Analysis of population product frequency data indicated Ugandan material to be more similar to populations from Cameroon than populations from Kenya and Ethiopia, while Malagash populations were most distinct. The implications of these findings for determining appropriate approaches for conservation of the species, particularly in Cameroon and Madagascar, are discussed.     

A reconsideration of the Lower Guinean species of Sericanthe (Rubiaceae,Coffeeae), with four new species from Cameroon and Gabon

The genus Sericanthe was established and its species were revised 30 years ago by one of the authors. Intensive recent botanical collecting in Lower Guinea (mainly southern Cameroon, Equatorial Guinea and Gabon) has made a reconsideration of species in this area necessary. Revision of the newly collected Lower Guinean herbarium specimens of Sericanthe (twice as many as were available at the time of the first revision) has brought four new species to light, namely S. gabonensis and S. mpassa from Gabon, S. lowryana from Cameroon and S. rabia from Cameroon and Gabon. Distributional data are much augmented, and distributional maps of all species from the area are provided. Four species were reported to be newly recorded for at least one country. The occurrence of the novelties in the main diversity centre of the genus is discussed in the context of the chorology of the entire genus Sericanthe. A first estimation of the conservation status for the new species is given. A synopsis of the genus Sericanthe in Lower Guinea with a taxonomic key is provided. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169 , 530–554.     

Testing Putative African Tropical Forest Refugia Using Chloroplast and Nuclear DNA Phylogeography

The location and definition of Pleistocene refugia for tropical forest assemblages remains controversial. Phylogeographic methods have been used successfully in temperate ecosystems to locate past forest refugia using genetic data that coincide with pollen core evidence, and in some cases provide the sole basis for their location. Here we present molecular phylogeographic data from nuclear and chloroplast loci for the forest tree Irvingia gabonensis, across the majority of its natural range, in Nigeria, Cameroon and Gabon. It is the first detailed phylogeographic study to posit the location of tropical forest refugia across this region of Africa. Using the same method of restriction fragment length polymorphism screening, 17 alleles were identified across five anonymous nuclear loci and two haplotypes at a single chloroplast locus. Analysis based on nuclear variation identified two genetically diverse, differentiated allelic clusters within the species range, one in southern Nigeria/western Cameroon and the other in southwestern Cameroon. Molecular data are consistent with a historical genetic contraction and bottleneck into these regions in the Pleistocene and/or Holocene, which has been followed by subsequent expansion. Both genetic refugia are located within areas previously suggested as forest refugia from biogeographic studies, supported by available pollen core data, and occur either side of the Sanaga River, a notable biogeographic divide for mammals (particularly primates). Other putative refugia in Gabon do not appear to have acted as genetic refugia for I. gabonensis, and Gabon was most likely recolonised from the SW Cameroon refugial source. In this study, nuclear loci were able to highlight significant phylogeographic structure across the range of a tropical African tree, whereas chloroplast analysis gave a much more limited picture. With the increased availability of sequence data for non-model species, the de novo development and further application of nuclear loci is strongly recommended for phylogeographic studies of plants.     

Genetic diversity,introgression and relationships among West/Central African cattle breeds

Genetic diversity, introgression and relationships were studied in 521 individuals from 9 African Bos indicus and 3 Bos taurus cattle breeds in Cameroon and Nigeria using genotype information on 28 markers (16 microsatellite, 7 milk protein and 5 blood protein markers). The genotypes of 13 of the 16 microsatellite markers studied on three European (German Angus, German Simmental and German Yellow) and two Indian (Nelore and Ongole) breeds were used to assess the relationships between them and the African breeds. Diversity levels at microsatellite loci were higher in the zebu than in the taurine breeds and were generally similar for protein loci in the breeds in each group. Microsatellite allelic distribution displayed groups of alleles specific to the Indian zebu, African taurine and European taurine. The level of the Indian zebu genetic admixture proportions in the African zebus was higher than the African taurine and European taurine admixture proportions, and ranged from 58.1% to 74.0%. The African taurine breed, Muturu was free of Indian zebu genes while its counter Namchi was highly introgressed (30.2%). Phylogenic reconstruction and principal component analysis indicate close relationships among the zebu breeds in Cameroon and Nigeria and a large genetic divergence between the main cattle groups – African taurine, European taurine and Indian zebu, and a central position for the African zebus. The study presents the first comprehensive information on the hybrid composition of the individual cattle breeds of Cameroon and Nigeria and the genetic relationships existing among them and other breeds outside of Africa. Strong evidence supporting separate domestication events for the Bos species is also provided.     

Congruent phylogeographical patterns of eight tree species in Atlantic Central Africa provide insights into the past dynamics of forest cover

Cycles of Quaternary climatic change are assumed to be major drivers of African rainforest dynamics and evolution. However, most hypotheses on past vegetation dynamics relied on palaeobotanical records, an approach lacking spatial resolution, and on current patterns of species diversity and endemism, an approach confounding history and environmental determinism. In this context, a comparative phylogeographical study of rainforest species represents a complementary approach because Pleistocene climatic fluctuations may have left interpretable signatures in the patterns of genetic diversity within species. Using 1274 plastid DNA sequences from eight tree species (Afrostyrax kamerunensis, A. lepidophyllus, Erythrophleum suaveolens, Greenwayodendron suaveolens, Milicia excelsa, Santiria trimera, Scorodophloeus zenkeri and Symphonia globulifera) sampled in 50 populations of Atlantic Central Africa (ACA), we averaged divergence across species to produce the first map of the region synthesizing genetic distinctiveness and standardized divergence within and among localities. Significant congruence in divergence was detected mostly among five of the eight species and was stronger in the northern ACA. This pattern is compatible with a scenario of past forest fragmentation and recolonization whereby forests from eastern Cameroon and northeastern Gabon would have been more affected by past climatic change than those of western Cameroon (where one or more refugia would have occurred). By contrast, southern ACA (Gabon) displayed low congruence among species that may reflect less drastic past forest fragmentation or a more complex history of vegetation changes. Finally, we also highlight the potential impact of current environmental barriers on spatial genetic structures.     

Evaluating hybridization as a potential facilitator of successful cogongrass (Imperata cylindrica) invasion in Florida,USA

Interspecific hybridization is cited as one potential mechanism for increased invasiveness, particularly among some grass species. In the southeastern United States, the successful invasion of cogongrass (Imperata cylindrica) has sometimes been attributed to hybridization with the previously naturalized Imperata brasiliensis. This research aimed to determine whether genetic signals are consistent with these two species having experienced interspecific hybridization in Florida (USA), where it has been proposed that such an event facilitated cogongrass invasion across the region. Individuals of invasive I. cylindrica populations (n = 66) were sampled broadly from the state, and I. brasiliensis (n = 63) individuals were sampled from expertly identified and vouchered populations in Miami-Dade County. Genetic analysis utilized amplified fragment length polymorphisms in sampled individuals, and failed to detect significant genetic differentiation between the two species. Analysis of molecular variance partitioned the majority of detected variation within populations (86 %), while only 8 % was significantly partitioned between I. cylindrica and I. brasiliensis (F_ST = 0.135, P < 0.001). Both STRUCTURE analysis and principal coordinates analysis strongly indicated the presence of a single genetic group across the sampled populations. Hybrid analysis furthermore failed to support interspecific hybridization. Florida populations thus are suggested to share genetic parent material(s) and/or have experienced substantial admixture across the state. Therefore, this study suggests Imperata populations in South Florida that are currently considered to be I. brasiliensis are not genetically distinct from I. cylindrica, and regional cogongrass invasion likely was not facilitated by previously postulated interspecific hybridization.     

Genetic variation of Calycophyllum spruceanum in the Peruvian Amazon Basin, revealed by amplified fragment length polymorphism (AFLP) analysis

An understanding of the level, structure and origin of genetic variation within and among populations of tropical trees is essential for devising optimum management strategies for their sustainable utilization and conservation. Here, amplified fragment length polymorphism (AFLP) analysis was used to partition genetic variation within and among nine populations of the predominantly riverine tree, Calycophyllum spruceanum , sampled across a wide geographical range along river tributaries of the Peruvian Amazon Basin. Analysis of molecular variance ( AMOVA ) employed 65 AFLP markers and revealed most variation among individuals within populations (91%), although variation among populations was highly significant ( P < 0.001). Calculation of genetic distances and nested AMOVA indicated a degree of structuring among populations based on geographical proximity, although clustering did not depend on geographical distance alone. No firm evidence was obtained for unidirectional seed dispersal by water playing an important role in determining genetic structure over the geographical range sampled. Implications of data for optimising genetic management of the species are discussed and areas for further study identified.     

Genetic diversity and differentiation in Camellia reticulata (Theaceae) polyploid complex revealed by ISSR and ploidy

Camellia reticulata is a well-known ornamental and oil plant that is endemic to southwest China. This species shows three cell ploidies, i.e., diploidy, tetraploidy and hexaploidy. We made the first investigation of genetic diversity and differentiation of natural populations of C. reticulata, and 114 individuals from 6 populations were sampled. Cytogeography results showed that ploidy is invariable within populations and evenly distributed. A relatively high level of genetic diversity was found in C. reticulata, both at the species level (PPB = 88.89%; H = 0.2809; I = 0.4278) and at the population level (mean PPB = 42.13%; mean H = 0.14; mean I = 0.21). We found a relatively low degree of differentiation among ploidies (G(ST) = 0.2384; AMOVA = 10.26%) and a relatively high degree of differentiation among populations (G(CS) = 0.3807; AMOVA = 48.75%). The high genetic diversity can be explained by its biological character, wide distribution and ploidies, and the special genetic structure can be ascribed to polyploid origin from hybridization with different Camellia spp. This information will be useful for the introduction, conservation and further studies of C. reticulata and related species.     

Bayesian analysis of hybridization and introgression between the endangered european mink (Mustela lutreola) and the polecat (Mustela putorius)

Human-mediated global change will probably increase the rates of natural hybridization and genetic introgression between closely related species, and this will have major implications for conservation of the taxa involved. In this study, we analyse both mitochondrial and nuclear data to characterize ongoing hybridization and genetic introgression between two sympatric sister species of mustelids, the endangered European mink (Mustela lutreola) and the more abundant polecat (M. putorius). A total of 317 European mink, 114 polecats and 15 putative hybrid individuals were collected from different localities in Europe and genotyped with 13 microsatellite nuclear markers. Recently developed Bayesian methods for assigning individuals to populations and identifying admixture proportions were applied to the genetic data. To identify the direction of hybridization, we additionally sequenced mtDNA and Y chromosomes from 78 individuals and 29 males respectively. We found that both hybridization and genetic introgression occurred at low levels (3% and 0.9% respectively) and indicated that hybridization is asymmetric, as only pure polecat males mate with pure European mink females. Furthermore, backcrossing and genetic introgression was detected only from female first-generation (F1) hybrids of European mink to polecats. This latter result implies that Haldane's rule may apply. Our results suggest that hybridization and genetic introgression between the two species should be considered a rather uncommon event. However, the current low densities of European mink might be changing this trend.     

中华猕猴桃和美味猕猴桃自然居群遗传结构及其种间杂交渐渗

 利用9对SSR引物对中华猕猴桃（Actinidia chinensis）和美味猕猴桃（A. deliciosa）两近缘种的5个同域分布复合体和各自1个非同域分布居群进行了遗传多样性、居群遗传结构的分析以及种间杂交渐渗的探讨。结果表明：1）两物种共有等位基因比例高达81.13%,物种特有等位基因较少（中华猕猴桃：13.27%,美味猕猴桃：5.61%）,但共享等位基因表型频率在两近缘种间存在差异,而且与各同域复合体中两物种样本的交错程度或间距存在关联;2）两种猕猴桃均具有极高遗传多样性,美味猕猴桃的遗传多样性（H_o＝0 .749, PIC＝0.818）都略高于中华猕猴桃（H_o＝0.686,PIC＝0.799）;3）两猕 猴桃物种均具有较低的Nei’s居群遗传分化度,但AMOVA分析结果揭示种内异域居群间（F_ST=0.091 5）和同域复合体种间（F_ST=0.111 5）均存在一定程度的遗传分化;中华猕猴桃居群遗传分化（G_ST=0.086; F_ST=0.212 1）高于美味猕猴桃（G_ST= 0.080;F_ST=0.142 0）;4）同域分布复合体两物种间的遗传分化（G_ST=0.020）低于物种内异域居群间的遗传分化（中华猕猴桃：G_ST=0.086; 美味猕猴桃：G_ST=0.080）,同域复合体物种间的基因流（N_m＝7.89 -29.75）远远高于 同种异域居群间（中华猕猴桃：N_m =2.663; 美味猕猴桃：N_m=2.880）; 5）居群UPGMA聚类揭示在同一地域的居群优先聚类,个体聚类结果显示多数个体聚在各自居群组内,但各地理居群并不按地理距离的远近聚类,这与Mantel相关性检测所揭示的居群间遗传距离与地理距离没有显著性相关的结果一致。进一步分析表明两种猕猴桃的遗传多样性和居群遗传结构不仅受其广域分布、远交、晚期分化等生活史特性的影响,同时还与猕猴桃的染色体基数高 (x=29)、倍性复杂和种间杂交等因素密切相关,其中两种猕猴桃的共享祖先多态性和同域分布种间杂交基因渗透对两猕猴桃的居群遗传结构产生了重要影响。     

Population genetic structure and hybridization patterns in the Mediterranean endemics Phlomis lychnitis and P. crinita (Lamiaceae)

BACKGROUND AND AIMS: The historical influence of gene flow and genetic drift after the last glacial phase of the Quaternary Period is reflected in current levels of genetic diversity and population structure of plant species. Moreover, hybridization after secondary contact might also affect population genetic diversity and structure. An assessment was made of the genetic variation and hybrid zone structure in Iberian populations of the Mediterranean Phlomis lychnitis and P. crinita, for which phylogenetic relationships are controversial, and hybridization and introgression are common. METHODS: Allozyme variation at 13 loci was analysed in 1723 individual plants sampled from 35 natural locations of P. lychnitis, P. crinita subsp. malacitana and P. crinita subsp. crinita in southern and eastern Spain. Standard genetic diversity parameters were calculated and patterns of genetic structure in each taxon were tested to fit the equilibrium between gene flow and genetic drift. Individual multilocus genotypes were subjected to Bayesian clustering analysis to estimate hybridization and introgression rates for both geographic regions. KEY RESULTS: Contrasting patterns in the distribution of genetic variation among the three taxa were found. Phlomis lychnitis showed no significant inbreeding, low genetic differentiation among populations and no evidence of isolation by distance. Phlomis crinita subsp. malacitana and P. crinita subsp. crinita showed high levels of genetic structure consistent with a pattern of gene flow-drift equilibrium. Higher instances of hybridization and introgression were detected in locations from southern Spain compared with locations from eastern Spain, matching unimodal and bimodal hybrid zones, respectively. CONCLUSIONS: High instances of historical gene flow, range expansion and altitudinal movement during the Quaternary Period, and lineage sorting can explain the diversity of patterns observed. The results suggest that P. lychnitis is the most differentiated lineage in the group; however, the relationship between the three taxa remains unclear.     

Genetic Diversity and Genetic Structure of an Endangered Species, Trillium tschonoskii

The genetic diversity and genetic structure of Trillium tschonoskii (Maxim) were investigated using amplified fragment length polymorphism markers. Eight primer combinations were carried out on 105 different individuals sampled from seven populations. Of the 619 discernible DNA fragments generated, 169 (27.3%) were polymorphic. The percentage of polymorphic bands within populations ranged from 4.52 to 10.50. Genetic diversity (H_E) within populations ranged from 0.0130 to 0.0379, averaging 0.0536 at the species level. Genetic differentiation among populations was detected based on Nei's genetic diversity analysis (53.03%) and analysis of molecular variance (AMOVA) (52.43%). AMOVA indicated significant genetic differentiation among populations (52.43% of the variance) and within populations (47.57% of the variance) (p < 0.0002). Gene flow was low (0.4429) among populations. Species breeding system and limited gene flow among populations are plausible reasons for the high genetic differentiation observed for this species. We propose an appropriate strategy for conserving the genetic resources of T. tschonoskii in China.     

Natural hybridisation between kermes (Quercus coccifera L.) and holm oaks (Q. ilex L.) revealed by microsatellite markers

Hybridisation between species of the genus Quercus is a common phenomenon as a result of weak reproductive isolation mechanisms between phylogenetically close species that frequently co-occur in mixed stands. In this study, we use microsatellite markers to analyse introgression between kermes ( Quercus coccifera L.) and holm ( Q. ilex L.) oak, two closely related taxa that frequently dominate the landscape in extensive areas in the Mediterranean region. All tested microsatellites amplified and were polymorphic in both kermes and holm oaks. Bayesian admixture analyses showed a good correspondence between each species and one of the two inferred genetic clusters. Five sampled individuals were a priori tentatively identified as hybrids on the basis of intermediate morphological characteristics, and it was confirmed that they also presented mixed genotypes. However, we also detected different levels of genetic introgression among morphologically pure individuals, suggesting that successful backcrossing and/or reduced phenotypic expression of genetic variance in certain individuals may have resulted in strong convergence towards a single species phenotype.     

黑石顶南亚热带常绿阔叶林优势种群黄果厚壳桂的AFLP分析

以扩增片段长度多态性（AFLP）分析了黑石顶南亚热带常绿阔叶林优势种群黄果厚壳桂（Cryptocarya concinna)在三个不同群落类型中的遗传多态性及遗传结构,并比较了该3个种群间的遗传分,以4对AFLP选择引物组合产生了大量扩增表型带,用AMOVA、PHYLIP等软件分析计算了种群的遗传结构。结果表明黑石顶黄果厚0壳桂种群具有高的种群内遗传多态性、低的种群间遗传分析。并讨论了种群遗传变化与生境的关系。     

我国沿海缢蛏群体遗传结构的mtDNA-COⅠ分析

采集了我国沿海共计9个缢蛏(Sinonovacula constricta)地理群体的197个样本,分别是北部组群的3个群体:辽宁省庄河群体(ZH),天津市汉沽群体(HG),山东省海阳群体(HY);中部组群的3个群体:江苏省盐城群体(YC),上海市崇明县东滩群体(DT)和堡镇群体(BZ);以及南部组群的3个群体:浙江省宁波群体(NB),浙江省台州群体(TZ)以及福建省宁德群体(ND)。利用线粒体COⅠ标记分析了9个群体的遗传多样性和遗传分化。结果表明,在共计197个个体中检测到125个单倍型和96个变异位点,核苷酸多样性指数位于2.1764～7.4970之间,其中中部组群的群体遗传多样性指数最高。AMOVA分析结果显示,组间遗传变异量占总变异的80.27%,18.74%来自于群体内,只有0.99%来自于组内群体间。群体间遗传分化系数位于0.0219～0.8706之间,不同群体间具有一定的遗传分化,尤其是中部群体与其他群体间遗传分化值达到了0.8以上,为极高度分化。遗传距离和聚类结果显示,北部3群体和南部3群体首先聚在一起,之后与中部3群体聚类。     

MtDNA of Fulani nomads and their genetic relationships to neighboring sedentary populations

Despite the large size of the contemporary nomadic Fulani population (roughly 13 million people), the genetic diversity and degree of differentiation of Fulanis compared to other sub-Saharan populations remain unknown. We sampled four Fulani nomad populations (n = 186) in three countries of sub-Saharan Africa (Chad, Cameroon, and Burkina Faso) and analyzed sequences of the first hypervariable segment of the mitochondrial DNA. Most of the haplotypes belong to haplogroups of West African origin, such as L1b, L3b, L3d, L2b, L2c, and L2d (79.6% in total), which are all well represented in each of the four geographically separated samples. The haplogroups of Western Eurasian origin, such as J1b, U5, H, and V, were also detected but in rather low frequencies (8.1% in total). As in African hunter-gatherers (Pygmies and Khoisan) and some populations from central Tunisia (Kesra and Zriba), three of the Fulani nomad samples do not reveal significant negative values of Fu's selective neutrality test. The multidimensional scaling of FST genetic distances of related sub-Saharan populations and the analysis of molecular variance (AMOVA) show clear and close relationships between all pairs of the four Fulani nomad samples, irrespective of their geographic origin. The only group of nomadic Fulani that manifests some similarities with geographically related agricultural populations (from Guinea-Bissau and Nigeria) comes from Tcheboua in northern Cameroon.     

Evolutionary History of the Grey-Faced Sengi,Rhynchocyon udzungwensis,from Tanzania: A Molecular and Species Distribution Modelling Approach

Rhynchocyon udzungwensis is a recently described and poorly understood sengi (giant elephant-shrew) endemic to two small montane forests in Southern Tanzania, and surrounded in lower forests by R. cirnei reichardi. In this study, we investigate the molecular genetic relationship between R. udzungwensis and R. c. reichardi, and the possible role that shifting species distributions in response to climate fluctuations may have played in shaping their evolutionary history. Rhynchocyon udzungwensis and R. c. reichardi individuals were sampled from five localities for genetic analyses. Three mitochondrial and two nuclear loci were used to construct species trees for delimitation and to determine whether introgression was detectable either from ancient or ongoing hybridization. All species-tree results show R. udzungwensis and R. c. reichardi as distinct lineages, though mtDNA shows evidence of introgression in some populations. Nuclear loci of each species were monophyletic, implying introgression is exclusively historical. Because we found evidence of introgression, we used distribution data and species distribution modelling for present, glacial, and interglacial climate cycles to predict how shifting species distributions may have facilitated hybridization in some populations. Though interpretations are affected by the limited range of these species, a likely scenario is that the mtDNA introgression found in eastern mid-elevation populations was facilitated by low numbers of R. udzungwensis that expanded into lowland heavily occupied R. c. reichardi areas during interglacial climate cycles. These results imply that relationships within the genus Rhynchocyon may be confounded by porous species boundaries and introgression, even if species are not currently sympatric.     

Population structure and phylogeography of the short-tailed stingray, Dasyatis brevicaudata (Hutton 1875), in the Southern Hemisphere

There is accumulating evidence that the degree of vagility explains little of the extent of population subdivision found within elasmobranch species. Instead, patterns of gene flow in elasmobranchs appear more closely linked to the presence of dispersal barriers, either physical or biological. Here, we investigate the potential role of some of these isolating mechanisms in shaping the population structure of a member of the stingray family Dasyatidae (Dasyatis brevicaudata) at various scales (southern hemisphere vs. coastal New Zealand). Analyses of the mitochondrial DNA control region from 176 individuals revealed significant genetic structure between South Africa, Australia, and New Zealand populations (analysis of molecular variance [AMOVA], overall Ф(ST) = 0.67, P < 0.001), although New Zealand and Australia shared some haplotypes. Surprisingly, significant population differentiation was found among several coastal New Zealand locations (AMOVA, overall Ф(ST) = 0.05, P < 0.05). However, data did not support the genetic differentiation between individuals from an offshore breeding area and mainland individuals. Comparisons suggest that these stingrays exhibit similar levels of population differentiation as other coastal elasmobranchs, with high divergence across oceanic basins and lower differentiation along continuous coastal habitats. Differences in coastal population structuring in elasmobranch species studied to date may be attributed to species-specific preferences for coastal habitats, which may be linked to life history functions (e.g., feeding and pupping).     

Bidirectional mitochondrial introgression between Korean cobitid fish mediated by hybridogenetic hybrids

Genomic introgression through interspecific hybridization has been observed in some species of the freshwater fish family Cobitidae. Within this family, a Cobitis hankugensis–Iksookimia longicorpa diploid–triploid hybrid species complex on the Korean peninsula is unique in displaying hybridogenesis, a unisexual reproduction mode that allows hybrids to mediate the transfer of mitochondrial DNA (but not nuclear DNA) between the two parent species. However, populations of the parental species in the wild have never been examined for the potential effect of introgression on their genomes. To address the genetic consequences of unisexual hybridization on the parental species, we examined genetic structure of the two parental species, C. hankugensis and I. longicorpa, in three independent natural habitats where they coexist with their hybrid complex using DNA sequence data of one mitochondrial gene and three nuclear genes. We found that mitochondrial introgression between the two species was extensive in all the examined localities, while there was no evidence of nuclear introgression across the species boundary. This result indicates that the hybridogenetic individuals mediate mitochondrial introgression from one species to the other, producing mito‐nuclear mosaic genomes such as C. hankugensis nuclear genomes associated with I. longicorpa mitochondrial DNA and the reverse. The direction and degree of introgression varied among the three localities, but the underlying mechanisms for this observation proved elusive. Introgression might depend on which species serves as the predominant sperm or ovum donor or the environmental conditions of the localities. The present study suggests that introgressive hybridization between pure C. hankugensis and I. longicorpa species is highly likely where the two species co‐occur with hybridogenetic individuals, but the consequence of introgression could be variable due to the history and environmental characteristics of particular populations across the parental species’ ranges.     

Schistosoma intercalatum: an endangered species in Cameroon?

Despite the extremely wide distribution of both intermediate (snail) and definitive hosts, the species Schistosoma intercalatum has a highly restricted distribution in parts of West Africa (Cameroon, Equatorial Guinea, Gabon, Nigeria, Democratic Republic of Congo and S?o Tomé). Recent studies showed that the epidemiology of this species is very dynamic, including invasions and extinctions. This article reviews the epidemiology of S. intercalatum in Cameroon, where the species is endangered, and analyses its overall status in Africa. The possible reasons for the limited distribution of S. intercalatum are discussed.