从细胞色素b部分序列探讨石斑鱼属的分子系统发育关系

石斑鱼的分类在学术界尚存在很多争议。本文采用PCR技术,测定了分布于中国的点带石斑鱼(Epinepheluscoioiaes)、青石斑鱼(E.awoara)、六带石斑鱼(E.sexfasciatus)、褐石斑鱼(E.brunneus),长棘石斑鱼(E.longispinis),吻斑石斑鱼(E.spilotoceps),巨石斑鱼(E.tauvina)以及石斑鱼亚科侧牙鲈属的侧牙鲈(Variola louti)的线粒体细胞色素b基因402bp的序列,结合GenBank提供的7种中国无记录的石斑鱼:青铜石斑鱼(E.aeneus)、海丰石斑鱼(E.haifensis)、犬牙石斑鱼(E.caninus)、东大西洋石斑鱼(E.marginatus)、白斑石斑鱼(E.multinotatus)、德氏石斑鱼(E.drummondhayi)、淡点石斑鱼(E.labriformis),把这14种石斑鱼作为内群,对他们的序列组成和结构特点进行了分析;并以同为科(Serranidae)、石斑鱼亚科(Epinephelinae)的侧牙鲈属(Variola)的侧牙鲈作外群,分别用MP法、NJ法对内、外群构建了分子系统树,结果表明:(1)14种石斑鱼402bp的mtDNA Cytb部分序列的碱基组成上,A+T的含量为53.6%高于G+C含量(46.4%),序列中转换颠换比为4.78,没有突变饱和;(2)青石斑鱼与六带石斑鱼、点带石斑鱼与巨石斑鱼、长棘石斑鱼与吻斑石斑鱼分别聚在一起,与形态分类结果一致;(3)系统树中,大西洋与太平洋种类各枝交替汇合,表明石斑鱼的Cytb序列有严格的保守性,也可能是协同进化的结果;(4)揭示在良种选配或遗传管理时,避免居于同枝的石斑鱼混交,将大西洋种类与太平洋种类杂交可能是遗传改良的一种途径。       

Molecular phylogenetic relationship of Epinephelus based on sequences of mtDNA Cty b

The mtDNA Cyt b gene was sequenced partially for Variola louti of Serranidae, Epinephelinae and seven endemic species of groupers—Epinephelus awoara, E. brunneus, E. coioides, E. longispinis, E. sexfasciatus, E. spilotoceps and E. tauvina in China. The seven endemic species and other seven foreign species of groupers—E. aeneus, E. caninus, E. drummondhayi, E. haifensis, E. labriformis, E. marginatus and E. multinotatus from the GenBank were combined and analysed as ingroup, while Variola louti was used as outgroup. We compared the 420 bp sequences of Cyt b among the 15 species and constructed two types of molecular phylogenetic trees with maximum parsimony method (MP) and neighbor-joining method (NJ) respectively. The results were as follows: (1) As to the base composition of mtDNA Cyt b sequence (402 bp) of 14 species of Epinephelus, the content of (A + T) was 53.6%, higher than that of (G + C) (46.4%). The transition/transversion ratio was 4.78 with no mutation saturation. (2) The cluster relationships between E. awoara and E. sexfasciatus, E. coioides and E. tauvina, E. longispinis and E. spilotoceps were consistent with phenotypes in taxonomy. (3) In the phylogenetic tree, the species in the Atlantic Ocean were associated closely with those in the Pacific Ocean, which suggested that the Cyt b sequences of Epinephelus were highly conserved. This may be attributed to the coordinate evolution. (4) In wel1-bred mating or heredity management, mating Epinephelus of the same branch should be avoided. It is likely to be an effective way to mate the species of the Atlantic Ocean with those of the Pacific Ocean to improve the inheritance species.     

Molecular phylogenetic relationship of Epinephelus based on sequences of mtDNA Cty b

The mtDNA Cyt b gene was sequenced partially for Variola louti of Serranidae, Epinephelinae and seven endemic species of groupers—Epinephelus awoara, E. brunneus, E. coioides, E. longispinis, E. sexfasciatus, E. spilotoceps and E. tauvina in China. The seven endemic species and other seven foreign species of groupers—E. aeneus, E. caninus, E. drummondhayi, E. haifensis, E. labriformis, E. marginatus and E. multinotatus from the GenBank were combined and analysed as ingroup, while Variola louti was used as outgroup. We compared the 420 bp sequences of Cyt b among the 15 species and constructed two types of molecular phylogenetic trees with maximum parsimony method (MP) and neighbor-joining method (NJ) respectively. The results were as follows: (1) As to the base composition of mtDNA Cyt b sequence (402 bp) of 14 species of Epinephelus, the content of (A + T) was 53.6%, higher than that of (G + C) (46.4%). The transition/transversion ratio was 4.78 with no mutation saturation. (2) The cluster relationships between E. awoara and E. sexfasciatus, E. coioides and E. tauvina, E. longispinis and E. spilotoceps were consistent with phenotypes in taxonomy. (3) In the phylogenetic tree, the species in the Atlantic Ocean were associated closely with those in the Pacific Ocean, which suggested that the Cyt b sequences of Epinephelus were highly conserved. This may be attributed to the coordinate evolution. (4) In wel1-bred mating or heredity management, mating Epinephelus of the same branch should be avoided. It is likely to be an effective way to mate the species of the Atlantic Ocean with those of the Pacific Ocean to improve the inheritance species. __________ Translated from Acta Hydrobiologica Sinica, 2006, 30(4): 432–438 [译自: 水生生物学报]     

9种石斑鱼遗传多样性和系统发生关系的微卫星分析

利用实验室克隆的13个青石斑鱼微卫星分子标记, 对中国南海海域9种石斑鱼(青石斑鱼、蜂巢石斑鱼、鲑点石斑鱼、黑边石斑鱼、鞍带石斑鱼、赤点石斑鱼、七带石斑鱼、斜带石斑鱼和棕点石斑鱼)进行了遗传多样性和系统发生关系的分析。研究结果显示, 13个微卫星标记共检测到了84个等位基因, 9种石斑鱼中的平均等位基因数、平均多态信息含量(PIC)、平均观测杂合度(Ho)、平均期望杂合度(He)和平均Hardy-Weinberg遗传偏离指数(D)分别在2.69~5.38、0.1976~0.4267、0.4615~0.6239、0.3510~0.4754和0.1097~0.2836之间变动, 说明9种石斑鱼的遗传多样性都处于中等水平。用NJ法进行聚类分析的结果将9种石斑鱼分为3个支系：斜带石斑鱼、棕点石斑鱼和鞍带石斑鱼为第1支; 青石斑鱼、赤点石斑鱼和七带石斑鱼为第2支系; 蜂巢石斑鱼、黑边石斑鱼和鲑点石斑鱼为第3支系, 该支系与第2支系的关系较近。本研究支持将宽额鲈(鞍带石斑鱼)归入石斑鱼属。     

Description of Pseudorhabdosynochus shenzhenensis n. sp. (Monogenea: Diplectanidae) and redescription of P. serrani Yamaguti, 1953 from Epinephelus coioides off Dapeng Bay, Shenzhen, China

One new species of diplectanid, Pseudorhabdosynochus shenzhenensis n. sp., is reported and described from the marine fish Epinephelus coioides off Nan'ao, Shenzhen, China. It can be differentiated from previously described species of the same genus by features of the haptoral and vaginal hard-parts. A second species, P. serrani Yamaguti, 1953, originally described from Serranus sp. from the western Pacific Ocean off the Celebes (now called Sulawesi), is redescribed based on new material from E. coioides.     

Origin, diversification, and historical biogeography of the genus Trachurus (Perciformes: Carangidae)

We addressed phylogenetic relationships in the genus Trachurus using cytochrome b gene and D-loop sequences. The trees showed five groups: (1) the Southwest Pacific species (T. japonicus, T. novaezelandiae, and T. declivis); (2) The Mediterranean Sea and Eastern Atlantic species (T. mediterraneus); (3) The Atlantic Ocean species (T. lathami and T. trecae); (4) Eastern Atlantic species (T. trachurus and T. capensis); and (5) a group of highly mobile pelagic species, two from the Eastern Pacific (T. symmetricus and T. murphyi) and one from the Eastern Atlantic (T. picturatus). The phylogeny based on Cyt b, supports the molecular clock hypothesis and our results agree with the reported fossil indicating that the origin of this genus occur when the Thetys Sea closed (around 18.4 MYA). In addition, a very slow neutral substitution rate is reported identified only two periods of maximum diversification: the first occurring between 18.4 and 15.0 MYA and the second between 8.4 MYA and present day.     

Assessment of genetic diversity and phylogenetic relationship among grouper species Epinephelus spp. from the Saudi waters of the Arabian Gulf

Understanding of fish genetic characterization plays a vital role in the conservation and utilization of fish genetic resources of grouper species. The present study was carried out to assess the genetic diversity and phylogenetic relationships in five grouper species, Epinephelus spp. from eastern Saudi Arabian coast using two molecular marker systems, inter simple sequence repeat (ISSR) and microsatellite (SSR) markers. In total, 219 individuals grouper specimens (Epinephelus tauvina, E. coioides, E. bleekeri, E. malabaricus, and E. areolatus) were genotyped with 10 ISSR and 11 SSR selected primers. The ISSR produced 94 DNA fragments, of which 44 were polymorphic with an average of 2.13 fragment per primer. While SSR primers generated 107 alleles, all of them were polymorphic with an average 9.72 per primer. ISSR and SSR techniques demonstrated a high level of gene diversity and genetic distances illustrated by UPGMA dendrograms among the grouper species. The results proved that the SSR markers were highly informative and efficient in detecting genetic variability and relationships of the Epinephelus spp.     

西太平洋沿海石斑鱼属鱼类DNA条形码及分子系统进化研究

研究测定了分布于西太平洋沿海的35种石斑鱼属鱼类共142个个体线粒体基因COⅠ及核基因TMO-4C4标记序列,基于最大似然法与贝叶斯法构建分析了石斑鱼类分子系统进化关系.同时,探讨了COⅠ基因作为DNA条形码在石斑鱼属鱼类物种鉴定中的有效性问题.结果显示:35种石斑鱼属鱼类COⅠ同源序列为636 bp,编码212个氨基...     

Detection of species-specific long VNTRs in mitochondrial control region and their application to identifying sympatric Hong Kong grouper (Epinephelus akaara) and yellow grouper (Epinephelus awoara)

Length variation and heteroplasmy were observed in PCR products of the first half of mtDNA control region of both Hong Kong grouper (Epinephelus akaara) and yellow grouper (Epinephelus awoara). DNA sequencing unveiled the phenomena were caused by the presence of species-specific long variable number tandem repeats (VNTRs). This is the first report on the mtDNA VNTRs and their heteroplasmy in groupers. Moreover, these VNTRs are also the longest such structure found in teleost fish. Thereafter, we designed two species-specific PCR reverse primers according to the 3' end sequences of the VNTRs and successfully established assays for the identification of these two sympatric grouper species.     

Hierarchical analyses of genetic variation of samples from breeding and feeding grounds confirm the genetic partitioning of northwest Atlantic and South Atlantic populations of swordfish (Xiphias gladius L.)

In species with high migratory potential, the genetic signal revealing population differentiation is often obscured by population admixture. To our knowledge, the explicit comparison of genetic samples from known spawning and feeding areas has not been conducted for any highly migratory pelagic fish species. This study examines the geographic heterogeneity of swordfish mitochondrial DNA (mtDNA) lineages within the Atlantic Ocean using 330 base pairs of sequence of the control region from 480 individuals. Hierarchical analyses of sequence variation were conducted to test whether samples from areas identified as the corresponding spawning and feeding grounds for the northwest (NW) Atlantic (Caribbean and Georges Banks-US northeast) and the South Atlantic (Brazil-Uruguay and Gulf of Guinea), were more closely related to each other than to samples from any other region, including the Mediterranean Sea, the Indian Ocean, and the Pacific Ocean. Phylogeographic analyses reveal that swordfish mtDNA phylogeny is characterized by incomplete lineage sorting and secondary contact of two highly divergent clades. However, despite this complex phylogenetic signature, results from an analysis of nucleotide diversity and from an analysis of molecular variance (AMOVA) were for the most part concordant and indicate that NW Atlantic and South Atlantic swordfish belong to separate populations. The mtDNA distinctiveness of NW Atlantic and South Atlantic swordfish populations is indicative of philopatric behavior in swordfish towards breeding and feeding areas.     

Revision of the bathyal cusk-eels of the genus Bassogigas (Ophidiidae) with description of a new species from off Guam, west Pacific Ocean

The bathyal genus Bassogigas (Teleostei: Ophidiidae) is revised based on 25 specimens, 18 from the west Atlantic Ocean and seven from the Indo-west Pacific Ocean. One specimen, from off Guam, west Pacific Ocean, represents a new species, Walker's cusk eel Bassogigas walkeri. The other 24 specimens all belong to the type species, Gills cusk eel Bassogigas gillii. A comparison between the Atlantic and the Indo-west Pacific Ocean specimens of B. gillii showed no differences in meristic and morphometric characters, but in two of the Indo-west Pacific Ocean specimens the sagittal otolith varied somewhat from the remaining specimens. The two Bassogigas species differ in the length of the lateral line, the number of scales in the midline of the body, the form of the median basibranchial tooth patches and in the thickness of the otolith.     

Species of Pseudorhabdosynochus Yamaguti, 1958 (Monogenea: Diplectanidae) from Epinephelus fasciatus and E. merra (Perciformes: Serranidae) off New Caledonia and other parts of the Indo-Pacific Ocean, with a comparison of measurements of specimens prepared using different methods, and a description of P. caledonicus n. sp.

Species of Pseudorhabdosynochus were studied from fresh specimens collected from Epinephelus fasciatus and E. merra off New Caledonia, South Pacific, and specimens deposited in Museums. Experiments on two species demonstrated that the sclerotised hollow organs, such as the quadriloculate male copulatory organ and the vagina, may show differences in measurements of up to 50% when flattened. P. caledonicus n. sp. is described from E. fasciatus in New Caledonia, on which it is relatively rare; it is distinguished on the basis of the quadriloculate organ, which has a very thin anterior wall, the sclerotised parts of the vagina in form of a straight tube with a star-shaped lateral structure, and the squamodiscs composed of 11 open rows of rodlets. P. cupatus (Young, 1969) is redescribed from abundant material from E. fasciatus off New Caledonia (new geographical record) and compared with paratype specimens from Australia (from E. fasciatus and E. merra) and specimens from E. fasciatus in the Red Sea (both herein redescribed and figured); a specimen was also found on a slide from E. merra off Vanuatu. P. melanesiensis (Laird, 1958) is redescribed from material from E. merra off New Caledonia (new geographical record) and compared with type-specimens (herein redescribed and figured) from the same host off Vanuatu. The structure of the sclerotised vagina in P. cupatus and P. melanesiensis is very similar, with a thin-walled tube and a heavily sclerotised structure with three loculi. P. vagampullum (Young, 1969) is redescribed from the paratypes from E. merra from Australia, but was not found in New Caledonia; specimens included among its paratypes (from E. merra in Australia), but different, are herein attributed to Pseudorhabdosynochus sp. 3. P. lantauensis (Beverley-Burton & Suriano, 1981) is redescribed from the paratype specimens from E. longispinis off Hong-Kong. A specimen found among the paratypes of P. cupatus belongs to a different species, herein designated as Pseudorhabdosynochus sp. 1. Specimens from E. longispinis off Hong-Kong, previously attributed to P. cupatus, are attributed to another species, Pseudorhabdosynochus sp. 2. The three species P. cupatus, Pseudorhabdosynochus sp. 1 and Pseudorhabdosynochus sp. 2 have in common a 'lamellosquamodisc' composed of central telescopic lamellae and peripheral rows of rodlets; they can be distinguished by the shape of the sclerotised vagina and measurements of the haptoral hard-parts. Specimens from E. longispinis off Hong-Kong, previously attributed to P. vagampullum, probably belong to a different species. Consequently, after these modified determinations, P. cupatus parasitises only E. fasciatus and E. merra, and P. melanesiensis and P. vagampullum parasitise only E. merra. With their wide geographical distribution and different species of Pseudorhabdosynochus in different localities, E. fasciatus and E. merra appear to represent excellent models for investigating monogenean biogeography in the Indo-Pacific Ocean.     

Molecular phylogenetics and biogeography of transisthmian and amphi-Atlantic needlefishes (Belonidae: Strongylura and Tylosurus): perspectives on New World marine speciation

Phylogenetic relationships among New World and eastern Atlantic species in the belonid genera Strongylura and Tylosurus were hypothesized using 3689bp of nucleotide sequence; including the entire mitochondrial (mtDNA) ATP synthase 6 and 8 genes; partial cytochrome b; 12S and 16S ribosomal genes; and introns and exons, 2 and 3 of the nuclear-encoded creatine kinase B gene. Concordant mtDNA and nuclear genealogies permitted well-supported inference of species relationships within Strongylura and Tylosurus, and of the chronology of diversification in the two genera. Our phylogenetic hypothesis permitted an assessment of Rosen's [Syst. Zool. 24 (1975) 431] model of species diversification across the eastern Atlantic to eastern Pacific marine biogeographic track. The spatial predictions of the Rosen model were generally supported, but not the temporal predictions. Furthermore, long branches leading to terminal Belonidae indicated that many species have persisted for millions of years or that nucleotide substitution rates were elevated for some clades. Though heterogeneity of nucleotide substitution rate was indicated across some belonid lineages, molecular clock estimates were used to hypothesize biogeographic scenarios for Strongylura across the eastern Pacific and Atlantic region. Furthermore, use of a molecular clock indicated; that early diversification among contemporary Strongylura may have been initiated by changes in Atlantic Ocean circulation precipitated by closure of the Tethys Sea; and provided approximate dates for the isolation of the freshwater species on the American continents.     

Aspects of the reproductive biology of the grouper, Epinephelus tauvina (Forskål), in Kuwaiti waters

Gonad maturation in Epinephelus tauvina is examined over one annual reproductive cycle. The species has one major spawning period from April to May and this is associated with increasing water temperatures and relatively low salinity. The histological changes in the gonads in the female, male and transitional phase are examined, and oogenesis and spermatogenesis are described in five developmental stages. That E. tauvina is a protogynous hermaphrodite is confirmed, and sexual transition is found to occur in individuals 55–75 cm in length, and is related to spawning activity. Fecundity estimates for E. tauvina of length 35.1–62.3 cm ranged from 850 186 to 2 904 921.     

Comparative ultrastructural studies of the zona radiata of marine fish eggs in three genera in Perciformes

The eggs of Mugil cephalus were significantly larger than those of Epinephelus malabaricus , and E. coioides , while those of Sciaenops ocellatus were intermediate between E. coioides and M. cephalus . The distribution density of pores in the egg envelope of S. ocellatus was significantly different from that of E. malabaricus and E. coioides . The micropyle diameters were significantly different in the four species. The ultrastructure of the zona radiata surface, the distribution density of pores and the size of eggs were also useful characters for distinguishing among the four species, but the ultrastructural features of the micropyles were the most important of all for egg identification.     

中国南方海域4种石斑鱼的遗传多样性及分子系统发生关系的分析

对中国南方海域的青石斑鱼(Epinephelus awoara)、赤点石斑鱼(E.akaara)、橙点石斑鱼(E.bleekeri)及蜂巢石斑鱼(E.merra)进行了遗传多样性和分子系统发生关系的分析。对9个微卫星DNA标记的基因型测定结果进行计算,发现这4个地理分布重叠且形态相似的石斑鱼均具有较丰富的遗传多样性,其平均等位基因数、平均多态信息含量(PIC)、平均观测杂合度(Ho)及平均期望杂合度(He)的取值范围分别为(8.22±5.02)～(18.67±9.38)、(0.56±0.21)～(0.83±0.13)、(0.62±0.03)～(0.85±0.02)和(0.60±0.07)～(0.86±0.04)。经哈迪-温伯格平衡(HWE)检验,除橙点石斑鱼外,其他3种鱼的微卫星DNA位点都基本符合平衡。利用微卫星DNA标记和线粒体细胞色素b基因对这4种鱼重建的分子系统树均显示,青石斑鱼与赤点石斑鱼的亲缘关系较近。以微卫星DNA标记对所研究石斑鱼的全部个体进行贝叶斯聚类分析的结果表明,4个鱼物种之间的分化关系明确。     

基于16S rDNA部分序列探讨中国近海30种石斑鱼类的分子系统进化关系

石斑鱼因其种类繁多、分布广泛及缺乏显著的形体特征,使其系统分类的研究颇为困难。为探讨中国近海石斑鱼类的系统进化关系,通过PCR扩增获得了石斑鱼亚科(Epinephelinae)6属30个种类的线粒体16SrDNA基因片段序列。采用多个生物软件对序列变异和碱基组成进行分析,计算了Kimura2parameter遗传距离、转换/颠换比等遗传信息指数,并结合GenBank石斑鱼属的同源序列,以多纹长尾(Pronotogrammusmultifasciatus)和皮氏叫姑鱼(Johniusbelengerii)为外群构建NJ、MP和ML系统树。根据所得分子依据并结合形态学特征,推论如下:1)在本研究的30种石斑鱼中,鳃棘鲈属(Plectropomus)最先分化,并呈明显单系性;九棘鲈属(Cephalopholis)是一个单系群,并且较石斑鱼属(Epinephelus)原始;侧牙鲈属(Variola)的进化地位介于鳃棘鲈属与九棘鲈属之间;2)宽额鲈(Promicropslanceolatus)可以归入石斑鱼属,而驼背鲈(Cromileptesaltivelis)也与石斑鱼属有很近的亲缘关系,甚至可能是石斑鱼属内的特化类群;3)石斑鱼属内部存在两个平行进化的姐妹分支,分支内部的种类组成与地理分布无关,暗示了石斑鱼属早期的分化模式。     

Oceanographic barriers,divergence, and admixture: Phylogeography and taxonomy of two putative subspecies of short‐finned pilot whale

Genomic phylogeography plays an important role in describing evolutionary processes and their geographic, ecological, or cultural drivers. These drivers are often poorly understood in marine environments, which have fewer obvious barriers to mixing than terrestrial environments. Taxonomic uncertainty of some taxa (e.g., cetaceans), due to the difficulty in obtaining morphological data, can hamper our understanding of these processes. One such taxon, the short‐finned pilot whale, is recognized as a single global species but includes at least two distinct morphological forms described from stranding and drive hunting in Japan, the “Naisa” and “Shiho” forms. Using samples (n = 735) collected throughout their global range, we examine phylogeographic patterns of divergence by comparing mitogenomes and nuclear SNP loci. Our results suggest three types within the species: an Atlantic Ocean type, a western/central Pacific and Indian Ocean (Naisa) type, and an eastern Pacific Ocean and northern Japan (Shiho) type. mtDNA control region differentiation indicates these three types form two subspecies, separated by the East Pacific Barrier: Shiho short‐finned pilot whale, in the eastern Pacific Ocean and northern Japan, and Naisa short‐finned pilot whale, throughout the remainder of the species' distribution. Our data further indicate two diverging populations within the Naisa subspecies, in the Atlantic Ocean and western/central Pacific and Indian Oceans, separated by the Benguela Barrier off South Africa. This study reveals a process of divergence and speciation within a globally‐distributed, mobile marine predator, and indicates the importance of the East Pacific Barrier to this evolutionary process.     

线粒体基因及其Cyt b基因与昆虫分子系统学研究

由于mtDNA及其Cyt b基因独特的进化速率及遗传特性,已成为追溯母系起源和群体遗传分化可信的遗传标记,被广泛应用于研究动物起源和分化,揭示群体的遗传背景,阐释种间和种内的系统演化关系,研究种内多态性和地理分布的关系.对mtDNA及其Cyt b基因的分子特点及其在昆虫系统学研究中的应用进行综述.     

Shallow mtDNA coalescence in Atlantic pygmy angelfishes (genus Centropyge) indicates a recent invasion from the Indian Ocean

Pygmy angelfishes (genus Centropyge) are widespread and species-rich in the Indo-Pacific, but only three species are recognized in the Atlantic: Centropyge resplendens on the Mid-Atlantic Ridge, Centropyge argi in the Caribbean, and Centropyge aurantonotus in Brazil and the southern Caribbean. Atlantic species are distinguished only by color patterns and are very similar to Centropyge acanthops (Cac) in the western Indian Ocean, raising the possibility that pygmy angelfish recently invaded the Atlantic Ocean via southern Africa. To test this zoogeographic hypothesis, we compared a 454-bp segment of the mitochondrial DNA (mtDNA) control region among pygmy angelfishes of the subgenus Xiphypops, which includes the three Atlantic species, the Indian Ocean species, and an Indo-Pacific species [Centropyge fisheri (Cfi)]. The Indian Ocean species Cac is closest to the Atlantic species (d = 0.059) relative to Cfi (d = 0.077). The mtDNA genealogy indicates a colonization pathway from the Indian Ocean directly to the West Atlantic, followed by at least two waves of dispersal to the Mid-Atlantic Ridge. The gene tree for the three Atlantic species is polyphyletic, raising questions about taxonomic assignments based on color pattern. Mismatch distributions place Atlantic founder events and population expansions at about 250,000-500,000 years ago. Estimates of effective female population sizes from mismatch and coalescence analyses are consistent with founder events by tens of individuals in the western Atlantic, followed by expansions to several million individuals.