Pairs Of Sibling Species Research Articles

Geometric morphometrics for the taxonomy of 11 species of Anopheles (Nyssorhynchus) mosquitoes.

The subgenus Anopheles (Nyssorhynchus) (Diptera: Culicidae) includes the primary vectors of Plasmodium spp. in Colombia. Most adult females of this subgenus are difficult to identify in the field using the available keys. With the objective of further investigating the discriminatory power of modern morphometrics, both landmark-based and outline-based approaches were explored using the wing venation geometry of 11 Anopheles (Nyssorhynchus) species. Wing shape was able to separate the closest species of the subgenus. When the 11 species were analysed together, validated classification scores on average 5.3-8.6 times higher than those expected by chance were observed. These scores computed from the total sample of 11 species were not satisfactory for the recognition of Anopheles benarrochi B, Anopheles oswaldoi s.l. and Anopheles strodei. These sibling species were captured in sympatry. To improve the identification power of the morphometric tool, it was necessary to analyse these species separately from the remaining species. The best classification scores were obtained using a combination of 12 landmarks collected not only on the intersections of wing veins, but also on spots. An outline approach also gave excellent reclassification scores. Another pair of sibling species, collected in allopatry, Anopheles nuneztovari and Anopheles rangeli, also showed high classification scores.

Patterns of acoustic and morphometric variation in species of genus Tettigettalna (Hemiptera: Cicadidae): Sympatric populations show unexpected differences

Tettigettalna (Hemiptera: Cicadidae) is a genus of small sized cicadas occurring in south-western Europe, which consists of a complex of sibling species that are morphologically difficult to distinguish from each other but their calling songs can be used as the main character for their identification. These sibling species may sometimes occur in sympatry, therefore, this genus is a suitable model for addressing questions on isolation mechanisms and recognition processes. For this study, we selected T. argentata (the species with the broadest distribution) and the three other species of Tettigettalna (T. mariae, T. estrellae and T. josei) that are known to occur in sympatry with T. argentata at some locations in their distribution ranges. Thus, the present study investigates calling song and variation in external morphology in selected sympatric and allopatric populations of four species of Tettigettalna in order to determine whether there are patterns in population divergence that provide evidence of species recognition and reproductive isolation. The interspecific analysis of the calling songs showed that most time domain variables are species-specific although an overlap was found between the maximum and minimum values in T. argentata and T. mariae populations for four time domain variables. When only sympatric popu- lations of T. argentata and T. mariae are compared, time domain variables show less variation leading to a reduced overlap between this pair of sibling species. The morphometric variables showed low interspecific variability and did not allow a complete separation of the four species, both in allopatric and sympatric populations. Sympatric populations of both T. argentata and T. mariae showed lower frequencies and bigger general body sizes than the allopatric ones. The pattern of variation found does not correspond to the pattern expected in species undergoing character displacement.

A world revision of the bee fly tribe Usiini (Diptera, Bombyliidae) Part 2: Usia sensu stricto

This is the second part of a world revision of the genera Usia Latreille and Parageron Paramonov, of the tribe Usiini Becker, and covers the pale-haired species, the Usia sensu stricto group. Usia sensu stricto as defined here contains 24 species of which 16 species fall into two monophyletic groups, the U. lata group with 10 species and the U. florea group with six species. Eight species cannot be placed in either of these two groups, four of them form two pairs of sibling species while the remaining four species have no clear affinities. Of the 25 formerly available names that belong in Usia sensu stricto, U. putilla Becker stat. rev., previously synonymised under U. angustifrons, is reinstated as a full species. U. sicula Egger syn. nov., is synonymised under U. manca Loew, U. anus Becker syn. nov., is synonymised under U. vestita Macquart and U. claripennis Macquart syn. nov., is synonymised under U. atrata (Fabricius). Usia vicina Macquart, formerly placed as a synonym of U. atrata, is shown to be a junior synonym of U. aenea Rossi. Five new species are described, U. anatoliensis sp. nov., U. annetteae sp. nov., U. greatheadi sp. nov., U. maghrebensis sp. nov. and U. cornigera sp. nov. Both the male and female genitalia are illustrated in detail for 21 species, female only in the cases of U. calva Loew and U. notata Loew and male only for U. incognita Paramonov.

Endemism of subterranean Diacyclops in Korea and Japan, with descriptions of seven new species of the languidoides-group and redescriptions of D. brevifurcus Ishida, 2006 and D. suoensis Ito, 1954 (Crustacea, Copepoda, Cyclopoida).

Copepods have been poorly studied in subterranean habitats in Korea. Previous records have indicated mostly the presence of species already described from Japan, with very few endemic elements. This commonality has usually been explained by repeated dispersal across the land bridges that connected the two countries several times during the Pleistocene glacial cycles. However, the Korean Peninsula is known for pockets of Cambrian and Ordovician carbonate rocks, with more than 1,000 caves already having been explored. The relative isolation of these carbonate pockets makes for an enormous speciation potential, and the development of a high level of short-range endemism of subterranean copepods should be expected. Representatives of the genus Diacyclops Kiefer, 1927 are here investigated from a range of subterranean habitats in South Korea, with comparative material sampled from central Honshu in Japan. Morphological analyses of microcharacters, many of which are used in cyclopoid taxonomy for the first time herein, reveal high diversity in both countries. No subterranean species is found in common, although the existence of four sibling species pairs in Korea and Japan may be indicative of relatively recent speciation. We describe seven new stygobiotic species, including three from Korea (Diacyclops hanguk sp. n., Diacyclops leeae sp. n., and Diacyclops parasuoensis sp. n.) and four from Japan (Diacyclops hisuta sp. n., Diacyclops ishidai sp. n., Diacyclops parahanguk sp. n., and Diacyclops pseudosuoensis sp. n.). Diacyclops hanguk, Diacyclops parasuoensis, Diacyclops ishidai, and Diacyclops parahanguk are described from newly collected material, while the other three new species are proposed for specimens previously identified as other, widely distributed species. Diacyclops brevifurcus Ishida, 2006 is redescribed from the holotype female, and Diacyclops suoensis Ito, 1954 is redescribed from material newly collected near the ancient Lake Biwa in Japan. This research provides evidence for the importance of subterranean habitats as reservoirs of biodiversity, and also demonstrates the inadequacy of current morphological methods of identifying closely related species of copepods. The disproportionately high diversity discovered around Lake Biwa provides further evidence in support of the hypothesis about the role of ancient lakes as biodiversity pumps for subterranean habitats. A key to the East Asian species of the languidoides-group is provided.

Relative geographic range of sibling species of host damselflies does not reliably predict differential parasitism by water mites

BackgroundOne of the main challenges in evolutionary parasitology is to determine the factors that explain variation among host species in parasitism. In this study, we addressed whether host phylogeny or ecology was important in determining host species use by water mites. Parasitism (prevalence and intensity) by Arrenurus water mites was examined in relation to geographic distribution of host damselflies from sibling species pairs. In addition, the likelihood of putative mite species parasitizing both species of a host species pair was explored.ResultsA total of 1162 damselflies were examined for water mites across four sites in Southeastern Ontario. These damselflies represent ten species (five closely related host species pairs) in the Coenagrionidae. Only two of the five species pairs showed near significant or significant differences in prevalence of infection by mites. In one of those species comparisons, it was the less widespread host that had higher water mite prevalence and in the other species comparison, the less widespread host species had lower water mite prevalence. Only one of the five pairs showed a significant difference in intensity of infection; intensity was higher in the species with a smaller geographic distribution. Based on the COI barcode, there were nine water mite clades (OTU) infecting these ten host species. Three Arrenurus OTUs may be host monospecific, four OTUs were specific to a given host species pair, and two OTUs infected at least three host species. Host species in each species pairs tend to share at least one of the Arrenurus OTU. No striking differences in mite species diversity were found among species in any species pair. Finally, the Arrenurus examined in this study appear to be ecological specialists, restricted to a particular type of habitat, parasitizing few to many of the host species present in that site or habitat.ConclusionsAlthough differences in levels of parasitism by water mites exist for some closely related hosts species, no such differences were found between other related host species. Differences in geographic range of related host species does not reliably explain differential levels of parasitism by water mites.

The diversity and biogeography of the Coleoptera of Churchill: insights from DNA barcoding.

BackgroundColeoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes (e.g., ca. 7400 species recorded in Canada), particularly of phytophagous and detritivorous species. However, incomplete sampling of northern habitats and a lack of taxonomic study of some families limits our understanding of biodiversity patterns in the Coleoptera. We conducted an intensive biodiversity survey from 2006–2010 at Churchill, Manitoba, Canada in order to quantify beetle species diversity in this model region, and to prepare a barcode library of beetles for sub-arctic biodiversity and ecological research. We employed DNA barcoding to provide estimates of provisional species diversity, including for families currently lacking taxonomic expertise, and to examine the guild structure, habitat distribution, and biogeography of beetles in the Churchill region.ResultsWe obtained DNA barcodes from 3203 specimens representing 302 species or provisional species (the latter quantitatively defined on the basis of Molecular Operational Taxonomic Units, MOTUs) in 31 families of Coleoptera. Of the 184 taxa identified to the level of a Linnaean species name, 170 (92.4%) corresponded to a single MOTU, four (2.2%) represented closely related sibling species pairs within a single MOTU, and ten (5.4%) were divided into two or more MOTUs suggestive of cryptic species. The most diverse families were the Dytiscidae (63 spp.), Staphylinidae (54 spp.), and Carabidae (52 spp.), although the accumulation curve for Staphylinidae suggests that considerable additional diversity remains to be sampled in this family. Most of the species present are predatory, with phytophagous, mycophagous, and saprophagous guilds being represented by fewer species. Most named species of Carabidae and Dytiscidae showed a significant bias toward open habitats (wet or dry). Forest habitats, particularly dry boreal forest, although limited in extent in the region, were undersampled.ConclusionsWe present an updated species list for this region as well as a species-level DNA barcode reference library. This resource will facilitate future work, such as biomonitoring and the study of the ecology and distribution of larvae.

Higher gregarine parasitism often in sibling species of host damselflies with smaller geographical distributions

1. This study investigated inter‐specific variation in parasitism by gregarines (Eugregarinorida: Actinocephalidae), among sibling species of damselflies (Odonata: Zygoptera), in relation to relative size of geographical ranges of host species.2. Gregarines are considered generalist parasites, particularly for taxonomically related host species collected at the same sites or area. Prevalence and median intensity of gregarine parasitism was obtained for 1338 adult damselflies, representing 14 species (7 sibling species pairs) across 3 families within the suborder Zygoptera. Damselflies were collected at three local sites in Southeastern Ontario, during the same periods over the season.3. Five out of seven species pairs had significant differences in parasitism between sibling species. The less widespread host species was the more parasitised for three species pairs with significant differences in gregarine prevalence, and for two species pairs with differences in median intensity. The more widespread host had a higher intensity of infection as expected, in two species pairs.4. Future studies on ecological determinants of parasitism among related species should examine robust measures of abundance of species and representation of species regionally.

Piecing together an integrative taxonomic puzzle: microsatellite, wing shape and aedeagus length analyses of Bactrocera dorsalis s.l. (Diptera: Tephritidae) find no evidence of multiple lineages in a proposed contact zone along the Thai/Malay Peninsula

Bactrocera dorsalis (Hendel) and B. papayae Drew & Hancock represent a closely related sibling species pair for which the biological species limits are unclear; i.e. it is uncertain if they are truely two biological species, or one biological species which has been incorrectly split taxonomically. The geographical ranges of the two taxa are thought to abut or overlap on or around the Isthmus of Kra, a recognised biogeographic barrier located on the narrowest portion of the Thai Peninsula. We collected fresh material of B. dorsalis s.l. (i.e. B. dorsalis s.s.+ B. papayae) in a north–south transect down the Thai Peninsula, from areas regarded as being exclusively B. dorsalis s.s., across the Kra Isthmus, and into regions regarded as exclusively B. papayae. We carried out microsatellite analyses and took measurements of male genitalia and wing shape, both used previously to separate the taxa. No significant population structuring was found in the microsatellite analysis, consistent with one, predominantly panmictic population. Both morphological datasets showed consistent, clinal variation along the transect, without disjunction. No evidence supported historical vicariance driven by the Isthmus of Kra, and no dataset supported the current taxonomy of two species. Rather, within and across the area of range overlap or abutment between the two species, only continuous morphological and genetic variation was recorded. Recognition that morphological traits previously used to separate these taxa are continuous, and that there is no genetic evidence for population segregation in the region of suspected species overlap, is consistent with a growing body of literature that reports no evidence of biological differentiation between these taxa.

Extensive morphological divergence and rapid evolution of the larval neuromuscular junction in Drosophila

Although the complexity and circuitry of nervous systems undergo evolutionary change, we lack understanding of the general principles and specific mechanisms through which it occurs. The Drosophila larval neuromuscular junction (NMJ), which has been widely used for studies of synaptic development and function, is also an excellent system for studies of synaptic evolution because the genus spans >40 Myr of evolution and the same identified synapse can be examined across the entire phylogeny. We have now characterized morphology of the NMJ on muscle 4 (NMJ4) in >20 species of Drosophila. Although there is little variation within a species, NMJ morphology and complexity vary extensively between species. We find no significant correlation between NMJ phenotypes and phylogeny for the species examined, suggesting that drift alone cannot explain the phenotypic variation and that selection likely plays an important role. However, the nature of the selective pressure is still unclear because basic parameters of synaptic function remain uniform. Whatever the mechanism, NMJ morphology is evolving rapidly in comparison with other morphological features because NMJ phenotypes differ even between several sibling species pairs. The discovery of this unexpectedly extensive divergence in NMJ morphology among Drosophila species provides unique opportunities to investigate mechanisms that regulate synaptic growth; the interrelationships between synaptic morphology, neural function, and behavior; and the evolution of nervous systems and behavior in natural populations.

Divergent hormonal responses to social competition in closely related species of haplochromine cichlid fish

The diverse cichlid species flocks of the East African lakes provide a classical example of adaptive radiation. Territorial aggression is thought to influence the evolution of phenotypic diversity in this system. Most vertebrates mount hormonal (androgen, glucocorticoid) responses to a territorial challenge. These hormones, in turn, influence behavior and multiple aspects of physiology and morphology. Examining variation in competition-induced hormone secretion patterns is thus fundamental to an understanding of the mechanisms of phenotypic diversification. We test here the hypothesis that diversification in male aggression has been accompanied by differentiation in steroid hormone levels. We studied two pairs of sibling species from Lake Victoria belonging to the genera Pundamilia and Mbipia. The two genera are ecologically differentiated, while sibling species pairs differ mainly in male color patterns. We found that aggression directed toward conspecific males varied between species and across genera: Pundamilia nyererei males were more aggressive than Pundamilia pundamilia males, and Mbipia mbipi males were more aggressive than Mbipia lutea males. Males of both genera exhibited comparable attack rates during acute exposure to a novel conspecific intruder, while Mbipia males were more aggressive than Pundamilia males during continuous exposure to a conspecific rival, consistent with the genus difference in feeding ecology. Variation in aggressiveness between genera, but not between sibling species, was reflected in androgen levels. We further found that M. mbipi displayed lower levels of cortisol than M. lutea. Our results suggest that concerted divergence in hormones and behavior might play an important role in the rapid speciation of cichlid fishes.

The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of West Maui, Hawaii: taxonomy, biogeography, and conservation

Species of the genus Mecyclothorax Sharp are taxonomically revised for West Maui, resulting in recognition of 27 species, 23 newly described: M. allostriatus, M. arcanus, M. badius, M. bartletti, M. ceteratus, M. clermontiae, M. curtimutinus, M. excavatus, M. exilioides, M. ferovipennis, M. filitarsis, M. geminatus, M. improcerus, M. kahalawaiae, M. lyratus, M. minimops, M. oppenheimeri, M. pallidus, M. platops, M. scapulatus, M. ustulatus, M. vicinus, and M. vulcanoides. Among the species are two pairs of cryptic sibling species best diagnosed by male and female genitalia. In the sibling species pair M. lyratus and M. arcanus, the former species is geographically restricted to Hanaula, an isolated southern massif in West Maui, whereas the latter is distributed on the main massif, Puu Kukui. Mecyclothorax scapulatus is also restricted to Hanaula supporting recognition of this massif as a distinct area of endemism within the Mauna Kahalawai mountain system. Species comprising a second sibling species pair, M. allostriatus and M. geminatus, exhibit a mosaic geographic distribution wherein each locality supports only one species, but the species distributions interdigitate among the various isolated localities from which the two species are known suggesting a more complicated speciation history. The genus Mecyclothorax is treated as part of an austral assemblage of genera classified as the tribe Moriomorphini (stat. n.). Species richness and endemism are compared among West Maui carabid beetles, land snails (Gastropoda), and Drosophilidae (Diptera). Carabid beetles with 46 species present in West Maui are less rich than the land snail fauna of 59 species and drosophilid fly fauna of 51 species. Over all genera, carabid beetles exhibit 87% species-level endemism to West Maui, with Mecyclothorax species 100% precinctive. Percentage endemism across all snail groups is somewhat lower – 73% – but among the more diverse snail families Achatinellidae and Amastridae, fraction endemism is similar to beetles, being 80% and 88% respectively. Drosophilidae exhibit much lower levels of endemism, with only 25% of West Maui species restricted to the volcano. Authochthonous speciation occurs at similar rates in all three groups, with species duration in all three groups estimated to be 0.2–0.3 Myr. The higher fraction endemism in beetles versus flies can be explained in part by absence of metathoracic flight wings in 48 of the 51 resident carabid species versus the retention of flight by the flies. Mecyclothorax species diversity peaks at 1200–1300 m elevation. This elevational zone supports closed canopy forest with a well-developed forest floor leaf litter microhabitat, enabling occupation by subarboreal trunk and moss inhabitants as well as terrestrial litter-inhabiting taxa. Mecyclothorax species are recorded in habitats ranging from 600m to the highest West Maui summit at 1760 m elevation. Their present-day persistence in this broad range of natural habitats makes them suitable subjects for habitat monitoring and continued biotic survey. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Acoustic niche partitioning in two cryptic sibling species of Chrysoperla green lacewings that must duet before mating

Cryptic species may seem identical to us, but not to each other. The Chrysoperla carnea group of green lacewings has species-specific substrate-borne duetting songs that maintain reproductive isolation among its cryptic species. We propose that sympatric species of the group will partition acoustic niche space so as to minimize mating mistakes. Sibling species pairs could therefore occupy abutting regions of acoustic space without hybridizing in nature. One species pair, Chrysoperla plorabunda and C. adamsi, are not only closest relatives, but are also the most acoustically similar among sympatric congeners. Using F1 hybrids as a surrogate taxon occupying acoustic space between the parents, we tested the hypothesis that this space cannot support an additional species. Focusing on a critical song feature, volley period, we confirm firstly that the hybrid song occupies unfilled signal space between the parents. Secondly, we show that song discrimination is strong between parents, but weaker between parents and hybrids. Thirdly, each parent has the ability to respond to the other’s signal in a narrow region of overlap. Finally, preference functions for hybrids broadly overlap those of parents. These acoustic tests confirm that a species of this intermediate song phenotype could not persist.

Genetics of male nuptial colour divergence between sympatric sister species of a Lake Victoria cichlid fish

The hypothesis of sympatric speciation by sexual selection has been contentious. Several recent theoretical models of sympatric speciation by disruptive sexual selection were tailored to apply to African cichlids. Most of this work concludes that the genetic architecture of female preference and male trait is a key determinant of the likelihood of disruptive sexual selection to result in speciation. We investigated the genetic architecture controlling male nuptial colouration in a sympatric sibling species pair of cichlid fish from Lake Victoria, which differ conspicuously in male colouration and female mating preferences for these. We estimated that the difference between the species in male nuptial red colouration is controlled by a minimum number of two to four genes with significant epistasis and dominance effects. Yellow colouration appears to be controlled by one gene with complete dominance. The two colours appear to be epistatically linked. Knowledge on how male colouration segregates in hybrid generations and on the number of genes controlling differences between species can help us assess whether assumptions made in simulation models of sympatric speciation by sexual selection are realistic. In the particular case of the two sister species that we studied a small number of genes causing major differences in male colouration may have facilitated the divergence in male colouration associated with speciation.

Gracilaria, subgénero Textoriella (Gracilariaceae, Rhodophyta) en el golfo de México y el Caribe mexicano

Four species of Gracilaria (Gracilariaceae, Rhodophyta) with textorii-type spermatangial conceptacles (subgenus Textoriella Yamamoto) are recorded for the Gulf of Mexico and the Mexican Caribbean: Gracilaria blodgettii, G. cervicornis, G. mammillaris, and G. tikvahiae. The general distribution of the subgenus for Central America, both Pacific and Atlantic, displays a disjunct pattern explainable based on the geologic vicariant events that interrupted the connection between Pacific and Atlantic at the Isthmuses of Panama (closed 3.1-2.8 million years ago), and Tehuantepec (southern Mexico, closed 4-3.5 million years ago). Gracilaria cuneata/G. crispata, and G. mammillaris (G. hayi)/G. veleroae are 2 pairs of sibling species, or sister taxa, that diverged as a result of the final emergence of the Isthmus, and of the same age as the Central American Isthmus itself.

Hybridization leads to host-use divergence in a polyphagous butterfly sibling species pair

Climate warming has lead to increased genetic introgression across a narrow hybrid zone separating the eastern and Canadian tiger swallowtails (Papilio glaucus and Papilio canadensis). This situation has led to the formation of an allochronically separated hybrid population with a delayed emerging phenotype or "late flight". Here, we assess how the recombination of the parental genomes that lead to this phenotype may have facilitated another major ecological shift, host-use divergence. We first contrast the ovipositional profiles of the late flight population to that of the parental species P. glaucus and P. canadensis. Subsequently we contrast the larval survival and growth of the late flight, a P. canadensis and a P. glaucus population, and a population from the northern edge of the hybrid zone on five hosts. Our results indicate that the ovipositional preference of this hybrid swarm is identical to that of the introgressing parental species, P. glaucus. Due to the absence of the preferred hosts of P. glaucus (Liriodendron tulipifera L. and Ptelea trifoliata L.) where the late flight occurs, this ovipositional pattern implies a functional specialization onto a secondary host of both parental species, Fraxinus americana L. In contrast, the larval host-use abilities represent a mixture of P. glaucus and P. canadensis, indicating divergence in larval host-use abilities has not taken place. However, high genetic variability (genetic coefficient of variation) is present for growth on F. americana in the late flight hybrid swarm and tradeoffs for larval performance on the preferred hosts of the parental species are evident; indicating a strong potential for future specialization in larval host-use abilities. This current scenario represents an instance where a shift in a major ecological trait, host use, is likely occurring as a byproduct of a shift in an unrelated trait (delayed emergence) leading to partial reproductive isolation.

Taxonomic revision of Mecyclothorax Sharp (Coleoptera, Carabidae) of Hawaii Island: abundant genitalic variation in a nascent island radiation

The Hawaii Island fauna of Mecyclothorax Sharp, 1903 is taxonomically revised and found to comprise 30 species, 18 newly described: M. gagnei sp. n., M. nitidus sp. n., M. maunakukini sp. n., M. punakukini sp. n., M. kaukukini sp. n., M. perivariipes sp. n., M. aa sp. n., M. giffini sp. n., M. hephaestus sp. n., M. funebris sp. n., M. granulipennis sp. n., M. rufipennis sp. n., M. blackburnianus sp. n., M. swezeyi sp. n., M. sinuosus sp. n., M. williamsi sp. n., M. purpuripennis sp. n., and M. footei sp. n. New synonymies include: Mecyclothorax parvus Britton, 1948 = M. subunctus (Perkins), 1917; Thriscothorax munroi Perkins, 1937 = M. karschi (Blackburn), 1882; Thriscothorax gracilis Sharp, 1903 and Mecyclothorax proximus Britton, 1948 = M. konanus Sharp, 1903; Mecyclothorax terminalis Britton, 1948 = M. discedens (Sharp) 1903. Mecyclothorax vulcanus (Blackburn) was described from a mixed series, with the cryptic sibling species M. hephaestus newly described to correct the partial misidentification. Species delimitation for the highly variable M. konanus is achieved using a hierarchical analysis based on infraspecifically variable attributes. Extensive male genitalic variation is documented within M. konanus and M. deverilli (Blackburn), and also among the cryptic sibling species pair M. variipes (Blackburn) and M. perivariipes. The observed variation is consistent with various hypotheses of sexual selection, but not with the genitalic lock and key hypothesis. Areas of endemism are tentatively proposed based on the most restricted distributions of Hawaii Island Mecyclothorax, with various flanks of Mauna Kea and Mauna Loa volcanoes identified as distinctive areas. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Contrasting patterns in species boundaries and evolution of anemonefishes (Amphiprioninae, Pomacentridae) in the centre of marine biodiversity

Many species of coral reef fishes are distinguished by their colour patterns, but genetic studies have shown these are not always good predictors of genetic isolation and species boundaries. The genus Amphiprion comprises several species that have very similar colouration. Additionally, morphological characters are so variable, that sibling species can show a considerable overlap, making it difficult to differentiate them. In this study, we investigated the species boundaries between the sibling species pair A. ocellaris and A. percula (Subgenus Actinicola) and three closely related species of the subgenus Phalerebus ( A. akallopisos, A. perideraion, A. sandaracinos) by phylogenetic analysis of mitochondrial cytochrome b and control region sequences. These two subgenera show strong differences in their patterns of species boundaries. Within the A. ocellaris/ A. percula complex, five clades were found representing different geographic regions. Two major divergences both with genetic distances of 4–7% in cty b and 17–19% in the d-loop region indicate the presence of three instead of two deep evolutionary lineages. The species of the subgenus Phalerebus show three monophyletic clades, independent of the geographical location of origin, but concordant to the morphological species classification. The genetic distances between the Phalerebus species were 2–5% in cty b and 10–12% in the control region.

Zur Taxonomie, Lebensweise und parasitophyletischen Evidenz der Federlingsgattung Struthiolipeurus sensu lato (Insecta, Phthiraptera, Ischnocera)

On Taxonomy, Bionomic and Parasitophyletic Evidence of the Feather Louse Genus Struthiolipeurus sensu lato (Insecta, Phthiraptera, Ischnocera) The c. 80 Mill. years old ischnoceran chewing louse genus Struthiolipeurus s. l. parasitizing both Struthionidae (Africa) and Rheidae (South America) only is revised. Archolipeurus nov. gen. and Struthiolipeurus chilensis nov. spec. are described and illustrated. A. nandu, A. renschi, St. andinus, St. stresemanni and St. struthionis (incl. egg and larvae) are redescribed. Lectotypes are designated for both A. nandu and St. andinus. Except for the sibling species pair St. struthionis — St. stresemanni, all other species are clearly distinguished from each other by morphological characters. An abdominal organ of unknown function (may be a sensillus) is situated on each side of segments ii to viii. Data are given about some details of life cycles of St. struthionis: the importance of the functional unit of mandibles and asymmetric ventral preantennal region for host attachment, mating sequence (copulatory posture is subfeminal, timing of mating occurs for up to 18 h), life expectation apart from the host (25–26 d) and hyperparasitism by a mite. St. struthionis is found as a secondary colonizer on captive Rhea americana only. The hospital-geographical distribution is listed. Some problems regarding chewing lice material collected from wild versus captive birds are outlined. As indicated by two species of both Struthiolipeurus and Meinertzhageniella, Pterocnemia comprises two geographically isolated species: pennata in the southern area of South America, tarapacensis in the northern ones. Struthiolipeurus (and Archolipeurus) suggest a strong relationship between Struthionidae and Rheidae. This evidence is discussed in connection with the ostrich-rhea divergence (vicariant and dispersal hypothesis). Struthiolipeurus/Archolipeurus may have originated on a common palaeognathous ancestor in the mid-Cretaceous of the Southern Hemisphere. A key is provided for the identification of the species of Archolipeurus and Struthiolipeurus and for the genus Meinertzhageniella.

Differentiation in electrical pulse waveforms in a pair of sibling Dwarf Stonebashers, Pollimyrus castelnaui and P. marianne : possible mechanisms and functions (Mormyridae, Teleostei)

The recently discovered snoutfish Pollimyrus marianne is virtually indistinguishable from its vicariant sibling species P. castelnaui by general appearance, but well differentiated in the waveform of its communication signal, an electric organ discharge (EOD) of the pulse type. We here describe the differentiation in EOD waveform in detail, and also differences between the sexes in P. castelnaui . In an attempt to better understand how such strong differentiation is possible in an evolutionarily short time, we mathematically modelled the three successive electrical excitations at the level of the electrocytes that constitute an EOD by three Gaussians. By varying amplitudes, duration and relative delay times, all tri- and pentaphasic EOD waveforms observed in the two species are generated. We suggest that in speciation only slight quantitative modifications in the anatomy and physiology of the electrocytes were necessary to generate spectacular differentiation. Using a spontaneous choice paradigm in untrained fish, four out of four P. marianne , and two out of eight P. castelnaui showed a preference for conspecific rather than heterospecific playback EODs. The results suggest that EOD waveform differentiation was involved when their common ancestor differentiated into a pair of allopatric sibling species of Dwarf Stonebashers.

Phylogeny of diving beetles reveals a coevolutionary arms race between the sexes.

BackgroundDarwin illustrated his sexual selection theory with male and female morphology of diving beetles, but maintained a cooperative view of their interaction. Present theory suggests that instead sexual conflict should be a widespread evolutionary force driving both intersexual coevolutionary arms races and speciation.Methodology/Principal FindingsWe combined Bayesian phylogenetics, complete taxon sampling and a multi-gene approach to test the arms race scenario on a robust diving beetle phylogeny. As predicted, suction cups in males and modified dorsal surfaces in females showed a pronounced coevolutionary pattern. The female dorsal modifications impair the attachment ability of male suction cups, but each antagonistic novelty in females corresponds to counter-differentiation of suction cups in males.ConclusionsA recently diverged sibling species pair in Japan is possibly one consequence of this arms race and we suggest that future studies on hypoxia might reveal the key to the extraordinary selection for female counter-adaptations in diving beetles.