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The rotifer fauna of Africa has been studied for >100 years, but there has been no recent synthesis. We compiled data from 265 publications that reported information on African rotifers. Our dataset yielded information on the distribution of 765 taxa from ~1850 separate sites; these included both natural and artificial habitats such as lakes, ponds, puddles, oases, artificial systems, rivers and wetlands. A heat map of predicted rotifer biodiversity indicated that the greatest diversity should be present in the sub-Saharan region including a large hotspot in Mali and several smaller ones scattered in that region. Lakes Kariba, Tanganyika and Malawi showed high-predicted diversity, but surprisingly, Lake Victoria had lower diversity than expected. Two regions showed unusually high-predicted diversity: northwestern Algeria extending into Morocco and Egypt. Equatorial Africa is rich in habitats well suited for rotifers, yet their predicted biodiversity seems low. Latitude and elevation were negatively correlated with richness, while permanent water source and littoral zone were positively correlated according to generalized linear modeling results. Partial RDA analyses showed significant correlations among several environmental features and species occurrences. It is clear that more survey work remains to be done to achieve a better understanding of African rotifers.

Our understanding of the ecological drivers that control community structure of benthic rotifers is poorly known. By reviewing 21 papers on freshwater benthic rotifers we compiled an inventory of an additional 258 species, 27 genera, and six families not previously listed in the review of benthic, lotic rotifers by Ricci and Balsamo (Freshw Biol 44:15–28, 2000). This raises the number of reported benthic species to 416, ~ 23% of all rotifers. Using selected papers within our dataset we tested two hypotheses: (1) Within lakes of different trophic state benthic rotifer communities differ in their species composition and (2) because rotifer trophi types reflect strong specificity for certain foods, there is a difference in the distribution of trophi types in lakes of different trophic state. We found that the trophic state of water bodies influences species composition of benthic rotifers, but there was no significant difference in the distribution of their trophi types. To aid in understanding community assembly of benthic rotifers, we provide a list of knowledge gaps that future studies could address.

Rotifers that engage in cyclical parthenogenesis produce two types of eggs: subitaneous eggs that hatch as clonal females and meiotic eggs that hatch as haploid males, or if fertilized, as females after a period of diapause (resting eggs). The ultrastructure of resting eggshells is known for some motile species, but there are limited data on subitaneous eggshells, and no data on any eggshells of sessile rotifers. Here, we investigated the ultrastructure of the subitaneous eggshell of the sessile rotifer Stephanoceros millsii and its potential origins of secretion, the maternal vitellarium and embryonic integument. We also explored secretory activity in the larval and adult integuments to determine whether activity changes during ontogeny. The eggshell consists of a single layer with two sublayers: an external granular sublayer apparently derived from the maternal vitellarium, and an internal flocculent sublayer secreted by the embryonic integument that may form a hatching membrane or glycocalyx. Secretory activity remains high in both the larva and adult and appears to be the source of the thickening glycocalyx. Altogether, the subitaneous eggshell of S. millsii is the thinnest among monogonont rotifers. Thin eggshells may have evolved in response to the added protection provided by the mother's extracorporeal tube.

Desert springs are critical for wildlife and human subsistence, but poorly studied. The springs in the northern Chihuahuan Desert region of Mexico are no exception. While groundwater overexploitation and other anthropogenic activities have endangered these waters, little is known about their water quality or biodiversity. We monitored five springs on a monthly basis for one year, and two others sporadically, to determine their physicochemical characteristics and to study rotifer community composition as an assessment of biodiversity. Seasonal variation in temperature, dissolved oxygen (DO), and conductivity was observed in the five springs. DO was occasionally below the criterion for aquatic life (

Although the theoretical underpinnings of habitat selection by marine invertebrate larvae have been well studied, this theory has been neglected for freshwater sessile rotifers. To study how substratum selection affects larval fitness, we developed a dynamic model to examine influences of three elements of larval life (survival, substratum acceptance, substratum encounter probability) and substratum-dependent reproductive success in adults. Monte Carlo simulation models were run using an initial cohort of larvae. Our Basic Model assessed fitness as simply settling on a substratum using only the larval elements and revealed statistically greatest fitness when swimming speed decreased with age and when substratum preference was constant or exhibited mid-age competence. The Reproductive Model assessed fitness (mean number of offspring adult−1) as a function of substratum. We compared reproduction on neutral substrata to substrata where quality varied and separately as a function of adult population density: coloniality (synergism) versus competition. The model showed fitness was statistically greatest when larval swimming speed decreased with age and when coloniality increased reproduction. We also explored conditions where populations of planktonic adults could survive. The model is applicable to sessile organisms and may be modified to examine other life history activities including selection of mates, prey, or territory.

Small birefringent concretions have been reported in rotifers for over a century and often hypothesized as energy sources. Here, we provide an update on their distribution in superorder Gnesiotrocha and the first data on their ultrastructure. Within Gnesiotrocha, these birefringent bodies (BRB) are known from at least ten species of Collothecaceae and 14 species of Flosculariaceae, both of which include planktonic and sessile species. Among sessile species, the predator Acyclus inquietus contains a single BRB that has been described as starch-like. We examined larvae of A. inquietus with transmission electron microscopy and revealed the BRB to have an irregular, electron-dense margin that surrounds a speckled core. The core appears mostly amorphous, but contains numerous, very small electron-dense spots and thin electron-dense fibers; there is no evidence of any crystalline lattice. The intestinal lumen contains smaller concretions that are probably the result of BRB metabolism. The thin epithelium contains abundant electron-dense granules but relatively few organelles. We hypothesize that the BRB is a unique form of extracellular glycogen that functions as an energy source in larvae for their dispersal and metamorphosis. In adult A. inquietus, the BRB may provide energy permitting reproduction when prey are no longer available.

Rotifers are diverse and abundant aquatic micrometazoans that rely on their ciliated apical end (corona) for locomotion and feeding. In order Collothecaceae, which includes mostly sessile species, larval rotifers go through a complex metamorphosis after settlement wherein they replace their corona with an unusual cup-shaped head that functions exclusively in food capture. This new head, called the infundibulum, consists of morphological elaborations such as lobes or tentacles that develop precociously in the larval stage; in adults they function in ambush and sit-and-wait predation. Here, we provide evidence from brightfield and transmission electron microscopy that the infundibulum of collothecid rotifers is derived from the larval foregut and not the larval corona, suggesting that the adult head of collothecids is a morphological novelty and therefore not homologous with the rotifer corona as classically defined. The wide variety of morphologies of the infundibulum suggests that selection to maximize foraging may have driven the evolution of head form in these sessile species, and that future studies of collothecid rotifers should consider the infundibulum as a unique form of food-collection device that is evolutionarily distinct from the rotifer corona.

While separated by large expanses of dry terrain unsuitable for aquatic biota, aridland waters possess high biodiversity. How aquatic micrometazoans disperse to, and colonize, these isolated ephemeral habitats are not well understood. We used a multi‐faceted approach including wind tunnel and rehydration experiments, and next‐generation sequencing to assess potential movement of diapausing propagules of aquatic invertebrates by anemochory across regional scales (102–105 km). Wind tunnel experiments using dry playa sediments with added micrometazoan propagules demonstrated that after entrainment by saltation and downwind transport, propagules could be subsequently rehydrated and were viable. Further, rehydration of fallen natural dust yielded micrometazoans, including rotifers, gastrotrichs, microcrustaceans, and nematodes. Using conserved DNA primers, we identified > 3300 eukaryotic Operational Taxonomic Units (excluding fungi) in the dust including some taxa found in rehydration experiments. Thus, we provide strong evidence that anemochory can disperse micrometazoans among isolated, ephemeral ecosystems in North American deserts and likely elsewhere.

We assessed the zooplankton assemblages in four temperate shallow waterbodies differing in macrophyte coverage and alternative states: transparent vs. turbid. The main objectives of this study were: (i) to determine the horizontal assemblage of zooplankton in structurally different habitats; (ii) to examine the role of fish, macroinvertebrates and environmental conditions in the observed zooplankton assemblage patterns; and (iii) to evaluate the zooplankton-macroinvertebrate-fish food web interactions in pelagial and littoral zone in transparent vs. turbid lakes. Abiotic factors and food resources, as well as zooplankton assemblage did not show significant difference along the gradient of habitat complexity, but exhibited pronounced variability among these waterbodies. Selected lakes contained nutrient levels that can undergo or were shifted into turbid state. Two waterbodies showed hysteresis: at similar nutrient conditions one remained transparent with macrophytes, while other shifted in its turbid state with increased phytoplankton biomass, and reduced population of planktonic crustaceans. Rotifers contributed mainly to the metazooplankton diversity and abundance. The results suggested that total phosphorous and phytoplankton were the main drivers in turbid waterbodies, and biotic interactions governed structuring of zooplankton assemblage in transparent waterbodies. Habitats of submerged and floating-leaved macrophytes do not appear to a secure refuge for zooplankton against predation. On the other hand, sediment in the vegetated and non-vegetated littoral zone functioned as an effective shelter. According to our results, zooplankton underwent strong predation pressure by macroinvertebrates and small-sized fish in the littoral and by larger-sized fish in pelagial, with alteration related to ecosystem peculiarities. Based on an applied ecological network model, zooplankters were equally vulnerable to predation in both the pelagial and littoral zones, and these biotic interactions were main factors for zooplankton homogenous horizontal distribution. These results suggest that zooplankton organisms play important role in the matter cycling and resilience of the food webs to environmental alterations.

We developed a simple method to culture two sessile rotifers, Limnias ceratophylli and Limnias melicerta, which should be applicable to other sessile species, and examined effect of the concentration of Chlorella vulgaris on population growth of these species. Limnias ceratophylli had higher population abundances at higher food levels. For both species, intrinsic rate of increase (r), derived from population growth study, varied from 0.12 to 0.16 day−1. Differences in r varied depending on food level for L. ceratophylli, but not for L. melicerta. Both species had little mortality during 2–3 weeks and thereafter survivorship declined until 5–7 weeks depending on food concentration. Mean life expectancy at birth for L. ceratophylli and L. melicerta was 29–34 days and 28–33 days, respectively. Generation time was shorter for L. ceratophylli. Gross and net reproductive rates were higher for L. ceratophylli. For both species, increase in food density resulted in significant decrease of average lifespan and life expectancy at birth. Gross reproductive rate and rate of population increase of both species were not significantly affected by food density. Generation time was significantly affected due to increase in algal food only for L. ceratophylli but not for L. melicerta.

Members of the sessile rotifer species Cupelopagis vorax are unusual ambush predators that live permanently attached to submerged freshwater plants. Previous light microscopical research has revealed several uncommon features in this species including a stellate‐patterned integument and an expansive foregut region called the proventriculus. In this study, we apply transmission electron microscopy to explore the ultrastructure of both the integument and foregut to determine how they differ from other rotifers. Our results reveal that the integument is covered by a thick glycocalyx and is patterned with tubercles that originate from the intracytoplasmic lamina (ICL) within the syncytial epidermis. The ICL forms an apical layer within the syncytium, is electron dense and mostly amorphous, and forms tubercles up to 2.3 μm; these tubercles probably account for the patterned appearance of the integument and are similar to what has been found in other gnesiotrochan rotifers. The basal cytoplasm is highly granular and contains two types of membrane‐bound vesicles: large ovoid vesicles (320–411 nm) with amorphous, opaque contents, and secretory bulbs (110–264 nm) with electron‐lucent cores and occasionally electron‐dense contents. Only the secretory bulbs were observed to form connections to the apical plasmalemma, and so are probably exocytotic. Internally, the proventriculus is a large distensible sack that connects the anterior pharyngeal tube to the posterior mastax. The proventricular epithelium is a thin syncytium mostly covered with a dense glycocalyx and a strong brush border of microvilli underlain by a thin terminal web. The cytoplasm contains few organelles and there is no evidence that it is either secretory or has features (e.g., ICL) that might aid in maceration. We hypothesize that the thick glycocalyx might serve a protective function against the movements of live prey and/or against enzymes released from the rotifer's gastric glands that become regurgitated during feeding.

Long-term research (LTR) can provide insights into rotifer ecology that are not possible from short-term studies or experiments. However, such studies have become rarer in recent years due to budgetary constraints. This review examined 5023 published articles about rotifers to determine the number, location and types of LTR studies that had been undertaken. Forty-four articles reported the results of studies that spanned more than 10 years. Of these, most focused on the impacts of climate change, acidification/liming and eutrophication/recovery on waterbodies and soils. However, some investigated ecosystem function, especially in relation to the effects of invasive species or the development of cost effective and comparable sampling techniques. The types of sites examined in these LTR studies included lakes and reservoirs, rivers, lagoons, seas and estuaries and soils, with the lengths of LTR records ranging from 10 to 82 years. Although their geographical locations ranged from North and South America to Asia, the Middle East and Europe, no studies were found from Africa, Australia or Antarctica. This review explores the role of LTR in quantifying the effects of environmental change and highlights gaps in existing knowledge.

1. Dry, ephemeral, desert wetlands are major sources of windblown sediment, as well as repositories for diapausing stages (propagules) of aquatic invertebrates. Zooplankton propagules are of the same size range as sand and dust grains. They can be deflated and transported in windstorm events. This study provides the evidence that dust storms aid in dispersal of microinvertebrate propagules via anemochory (aeolian transport). 2. We monitored 91 windstorms at six sites in the southwestern U.S. over a 17-year period. The primary study site was located in El Paso, Texas in the northern Chihuahuan Desert. Additional samples were collected from the Southern High Plains region. Dust carried by these events was collected and rehydrated to hatch viable propagules transported with it. 3. Using samples collected over a six-year period, 21 m above the ground which included 59 storm events, we tested the hypothesis that transport of propagules is correlated with storm intensity by monitoring meteorological conditions such as storm duration, wind direction, wind speed, and PM(10) (fine dust concentration). An air quality monitoring site located adjacent to the dust samplers provided quantitative hourly measurements. 4. Rehydration results from all events showed that ciliates were found in 92% of the samples, rotifers in 81%, branchiopods in 29%, ostracods in 4%, nematodes in 13%, gastrotrichs in 16%, and tardigrades in 3%. Overall, four bdelloid and 11 monogonont rotifer species were identified from rehydrated windblown dust samples. 5. PCA results indicated gastrotrichs, branchiopods, nematodes, tardigrades, and monogonont rotifer occurrence positively correlated with PM(10) and dust event duration. Bdelloid rotifers were correlated with amount of sediment deposited. NMDS showed a significant relationship between PM(10) and occurrence of some taxa. Zero-inflated, general linear models with mixed-effects indicated significant relationships with bdelloid and nematode transport and PM(10). 6. Thus, windstorms with high particulate matter concentration and long duration are more likely to transport microinvertebrate diapausing stages in drylands.

Xenarthrans -anteaters, sloths, and armadillos- have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. Have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become. Fil: Marques Santos, Paloma. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasil Fil: Bocchiglieri, Adriana. Universidade Federal de Sergipe; Brasil Fil: Garcia Chiarello, Adriano. Universidade de Sao Paulo; Brasil Fil: Pereira Paglia, Adriano. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasil Fil: Moreira, Adryelle. Amplo Engenharia e Gestão de Projetos ; Brasil Fil: Abba, Agustin Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina Fil: Paviolo, Agustin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentina Fil: Gatica, Ailin. Universidad Nacional de San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina Fil: Ochoa, Ana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina Fil: de Angelo, Carlos Daniel. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquimicas y Naturales. Instituto de Ciencias de la Tierra, Biodiversidad y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Ciencias de la Tierra, Biodiversidad y Ambiente.; Argentina Fil: Tellaeche, Cintia Gisele. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Centro de Estudios Ambientales Territoriales y Sociales; Argentina. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Varela, Diego Martin. 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; Argentina Fil: Vanderhoeven, Ezequiel Andres. Ministerio de Salud. Instituto Nacional de Medicina Tropical; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Caruso, María Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Administración de Parques Nacionales. Delegación Regional del Noroeste; Argentina Fil: Arrabal, Juan Pablo. Secretaria de Gobierno de Salud. Instituto Nacional de Medicina Tropical - Sede Puerto Iguazú Misiones; Argentina. Centro de Investigaciones del Bosque Atlántico; Argentina Fil: Iezzi, María Eugenia. 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; Argentina Fil: Di Bitetti, Mario Santiago. Centro de Investigaciones del Bosque Atlántico; Argentina. 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; Argentina Fil: Cruz, Paula Andrea. 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; Argentina. Centro de Investigaciones del Bosque Atlántico; Argentina Fil: Reppucci, Juan Ignacio. Administración de Parques Nacionales. Delegación Regional del Noroeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Benito Santamaria, Silvia. Centro de Investigaciones del Bosque Atlántico; Argentina. 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; Argentina Fil: Quiroga, Verónica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Di Blanco, Yamil Edgardo. 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; Argentina Fil: Marás, Gustavo Arnaldo. Administración de Parques Nacionales. Delegación Regional del Noroeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Camino, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Perovic, Pablo Gastón. Administración de Parques Nacionales. Delegación Regional del Noroeste; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Martínez Pardo, Julia. 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; Argentina Fil: Costa, Sebastián Andrés. 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; Argentina Fil: Pinheiro, Fabiana. Universidade Federal do Rio Grande do Sul; Brasil Fil: Volkmer de Castilho, Pedro. Universidade Federal de Santa Catarina; Brasil Fil: Bercê, William. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil Fil: Camara Assis, Julia. Universidade Estadual Paulista Julio de Mesquita Filho. Faculdade de Engenharia.; Brasil Fil: Rodrigues Tonetti, Vinicius. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil Fil: Alves Eigenheer, Milene. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil Fil: Chinem, Simonne. Universidade de Sao Paulo; Brasil Fil: Honda, Laura K.. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil Fil: Bergallo, Helena de Godoy. Universidade do Estado de Rio do Janeiro; Brasil Fil: Alberici, Vinicius. Universidade de Sao Paulo; Brasil Fil: Wallace, Robert. Wildlife Conservation Society; Estados Unidos Fil: Ribeiro, Milton Cezar. Universidade de Sao Paulo; Brasil Fil: Galetti, Mauro. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil

We present a survey of the literature documenting sexuality in monogonont rotifers, including reports of diapausing embryos (DEs), males, and/or hatchlings from dry sediments. Of 30 families, 27 possess species with documented occurrences of sex. Information on DEs is lacking in 41 genera. Of ~300 species with evidence of sexuality (~20% of ~1500 monogononts), only 172 had direct observations of DEs; in the others, DE production was inferred from observations of males and/or hatchlings. DEs are sufficiently widespread to affirm that their presence is plesiomorphic, however few DE characteristics show a phylogenetic signature. They differ widely in volume (~0.11–100 × 105 µm3) and have a varied surface morphology (smooth to highly structured and ornamented). Some species retain DEs within their bodies; others carry them, deposit them on or attach them to surfaces, or release them free into the water. To better understand the evolutionary forces that influence monogonont sexuality and DE biology, a more comprehensive and uniform reporting scheme is needed. To enhance information dissemination, we propose that new and existing data on sex in monogonont rotifers (DEs, males, and hatchlings from dry sediments) be placed in an Internet-based repository.

Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is by far the most extensively studied group of rotifers, is widely used in aquaculture, and is known to host a large amount of unresolved diversity. Here we collate a dataset of previously available and newly generated sequences of COI and ITS1 for 1273 isolates of the B. plicatilis complex and apply three approaches in DNA taxonomy (i.e. ABGD, PTP, and GMYC) to identify and provide support for the existence of 15 species within the complex. We used these results to explore phylogenetic signal in morphometric and ecological traits, and to understand correlation among the traits using phylogenetic comparative models. Our results support niche conservatism for some traits (e.g. body length) and phylogenetic plasticity for others (e.g. genome size).

Sample collection and culture Aquatic plant samples were collected from habitats across the USA and a sediment sample from Australia (Tables S1.1, S1.2). Limnias melicerta and L. ceratophylli were identified and isolated from rehydrated sediments or by removing a piece of vegetation to which they were attached. Species identification was based on tube structure, shape of corona, antennae length, and the number of dorsal nodules [1]. Clonal lineages initiated from single females were cultured in modified MBL media [2] and fed a mixture of the algae Chlorella vulgaris Berijerinck, 1890 (The UTEX Culture Collection of Algae at the University of Texas at Austin [UTEX] strain 30) and Chlamydomonasreinhardtii Dangeard, 1888 (UTEX strain 90). Rotifers in this genus produce tubes of hardened secretions [3]; we added powdered carmine (Alfa Aesar, UK) to lab cultures to provide a supplementary matrix to aid tube construction and to increase their visibility in culture. Voucher specimens were deposited in the UTEP Biodiversity Collections at The University of Texas at El Paso (L. melicerta: UTEP:Zoo:43, 105-134; L. ceratophylli: UTEP:Zoo:32-42, UTEP:Zoo:52-61).Deposited specimens included approximately 10 individuals from each population preserved in 95% ethanol and 10 clonal individuals preserved in 4% buffered formalin for molecular analyses and identification, respectively. DNA Extraction and gene amplification DNA was extracted from one individual of each clonal lineage by adding 13 µl Chelex®-100 (Bio-Rad Laboratories, CA, USA) and incubating at 100°C for 10 min. DNA templates were stored at -80°C until used for amplification. Number of clonal lineages examined from each population is given in Tables S1.1 and S1.2. An approximate 630 bp portion of the cytochrome c oxidase subunit I (COI) gene was amplified using the primers LCO1490: 5' -GGTCAACAAATCATAAAGATATTGG-3' and HCO2198: 5'-TAAACTTCAGGGTGACCAAAAAATCA-3' [4]. The entire nuclear internal transcribed spacer region (ITS) was amplified using the primers ITS4: 5'-TCCTCCGCTTATTGATATGC-3' and ITS5: 5'-GGAAGTAAAAGTCGTAACAAGG-3' [5], and 865 bp of the 18S rRNA gene was amplified using primers 3F: 5’-GTTCGATTCCGGAGAGGG-3’ as modified by Giribet et al. [6] and primer 18Sbi: 5’-CTAGAGTCTCGTTCGTTATCGG-3’ as modified by Whiting et al. [7]. PCR reactions contained 10 µl of genomic DNA, 1 µl of each primer (500 ng/ µl), 22 µl HPLC grade sterile water, 1 µl GoTaq® G2 DNA Polymerase (Promega), 10 µl 5X PCR buffer B (10 mM MgCl2, pH 8.5) or 5X PCR buffer A (7.5 mM MgCl2, pH 8.5), followed by adding 5 µl dNTP mix (2.5 mM each of dATP, dCTP, dGTP, dTTP) at 80ºC. PCR cycles were run on a thermocycler (TECHNE TC-412) and consisted of an initial denaturation at 94ºC for 1 min, followed by denaturation at 94ºC for 1 min, annealing at 48ºC for 2 min and extension at 72ºC for 3 min for 35 cycles, and a final extension step at 72ºC for 7 min. To verify the size of amplification products we used electrophoresis, and we purified them using GENECLEAN® kits (MP Biomedicals, LLC) before sequencing. Sequencing was done at UTEP’s BBRC Genomic Analysis Core Facility on an Applied Biosystems 3130xl Genetic Analyzer using BigDye Terminator v3.1 Cycle Sequencing Kits (Applied Biosystems). GenBank accession numbers for all sequences obtained are given in Tables S1.1 (L. melicerta) and S1.2 (L. ceratophylli). The COI gene sequences of L. melicerta (accession number, KT870155.1) and L. ceratophylli(KT870157.1) from GenBank are not included in our analyses for two reasons. 1) The COI sequence of L. melicerta KT870155.1 is 330 bp, which was much shorter than COI sequences obtained in this study (623 bp). 2) The COI sequence of L. ceratophylli KT870157.1 grouped with cryptic species M of L. melicerta in phylogenetic analyses. Additional 18S rRNA sequences (L. melicerta: KM873599.1, L. ceratophylli: KM873598.1) and a COI sequence from L. melicerta (KT870154.1) were included from GenBank. Sinantherina socialis(Linneaus, 1758) and Ptygura pilula (Cubitt, 1872) were included as outgroups in phylogenetic analyses for the COI gene. Floscularia conifera (Hudson, 1886) andPtygura brachiata (Hudson, 1886) were used as outgroup taxa in phylogenetic analyses based on ITS region. For analysis of 18S rRNA sequences, we used Collotheca campanulata as the outgroup (Table S1.1). Genetic Diversity FinchTV v 1.4.0 [8] was used to check sequences manually, especially for potential double peaks in the ITS region sequences. The ITS region alignment was uploaded to the SeqPhase online tool (http://seqphase.mpg.de/seqphase/) to phase the sequences as described by Flot [9]. Contigs for all sequences were made using CAP 3 [10] and were aligned using MAFFT v 7 [11]. Mesquite v 3.2 [12] was used to manually check the alignments and to translate COI gene sequences to proteins. To measure substitution saturation, we used DAMBE v 6 [13]. Number of polymorphic sites, number of parsimony informative sites, number of haplotypes, haplotype diversity (h), and nucleotide diversity (π) were calculated using DnaSp v 5.10.01 [14], and uncorrected pairwise sequences distances ("p") were calculated in Mega v 7.0 [15]. A haplotype network was constructed using the median joining method in Network v 5.0.3 [16]. Species delimitation Models for sequence evolution were TPM2uF+I+G for the COI gene, TPM1uF+I for the ITS region, and JC for the 18S rRNA gene as determined using Jmodeltest2 [17,18] available at the Cipres Science Gateway 3.3 [19]. To construct the phylogenetic trees, Bayesian analysis was run for 107 generations with two parallel runs and a 25% burn in period using MrBayes v 3.2.6 on XSEDE high-throughput computing resources available at Cipres Science Gateway [19]. Phylogenetic analyses were implemented in BEAST and *BEAST [20] using GTR+I+G model of sequence evolution for the COI gene and GTR+I model for the ITS region. TPM2uF and TPM1uF models are not available in BEAST. However, both of these models are classified under the GTR model. Thus GTR was used in both instances. To determine the number of evolutionary entities (putative cryptic species), we used Generalized Mixed Yule Coalescent (GMYC, [21]), Poisson Tree Process (PTP, [22]), Automatic Barcoding Gap Discovery (ABGD, [23]), *BEAST v 1.8.3 [20], and Bayesian Species Delimitation (BSD) implemented in Bayesian Phylogenetics and Phylogeography software (BPP v 3.1, [24–26]). We used BEAST v 1.8.3 [20] to construct ultrametric trees and *BEAST v 1.8.3 [20] for species delimitation. Both analyses were run for the COI gene and ITS region sequences separately for 107 generations, with sampling every 1,000 generations. Tracer v 1.6.0 [27] was used to check the effective sample size (ESS>200) and to verify convergence. Consensus trees were obtained using TreeAnnotator v 1.8.3 with a 25% burn in. Ultrametric trees were used for species delimitation in single threshold and multiple threshold GMYC [28] (http://species.h-its.org/gmyc/, accessed June 12, 2018), Bayesian GMYC (bGMYC) [29] and PTP methods. bGMYC was run using the R package bGMYC v 1.0.2 for 100,000 iterations with sampling every 1,000 iterations. We ran PTP by uploading the ultrametric trees to the online tool available at http://species.h-its.org/ptp/(accessed June 12, 2018) andused default settings. ABGD delimitation was done by uploading the sequence alignment to the online tool available at wwwabi.snv.jussieu.fr/public/abgd/ under the default settings (accessed June 12, 2018). *BEAST v 1.8.3 [20] was run under assumptions regarding the number of species for both the COI gene and ITS region sequences. Lineages having posterior probabilities > 0.90 were retained in *BEAST analyses. To run BSD, the phylogenetic tree based on Bayesian inference was used as the guide tree, and we used the joint species delimitation and tree estimation method (unguided species delimitation) that does not rely on the topology of the guide tree. Isolation by Distance Geographic distance matrices were constructed using Geographic Distance Matrix Generator v 1.2.3 [30]. To test the correlation between genetic variation and geographic distances (log transformed; km) among populations, Mantel tests with 10,000 permutations were run using the R package ecodist v 1.2.9 [31]. Trophi morphology Trophi were prepared for scanning electron microscopy (SEM) by dissolving rotifer tissue in ~5% sodium hypochlorite, rinsing with deionized water 10-15 times, and air-drying on circular cover slips at room temperature [32]. Trophi were coated with gold/palladium using a Gatan 682 PECS sputter coater. SEM images were obtained at 20 kV using a Hitachi S-4800 system. Trophi were prepared for individuals from one clonal lineage from each examined population. We used a geometric morphometric approach to study variation in the shape and size of 92 trophi for L. melicerta and 60 trophi for L. ceratophylli among putative cryptic species. This method uses Cartesian coordinates for a set of anatomical landmarks [33]. SEM images were obtained from caudal and frontal views of the trophi. Using TPS series software [34], nine landmarks on the caudal view and 10 on the frontal view of the trophi were digitized (Fig 1). Configuration of landmarks were analyzed using Generalized Procrustes Analysis [33]. Trophi size was calculated as Centroid Size (CS): i.e., the square root of the sum of squared distances between landmarks and their centroid [35]. Variation in the shape of trophi based on landmarks was examined using Discriminant Analysis in SPSS v 24 [36]. Because trophi centroid size was not normally distributed, variation in size among putative cryptic species was tested using a non-parametric Kruskal-Wallis test, and between the two morphospecies using a non-parametric Man-Whitney U test implemented in SPSS v 24 [36]. References 1. Wallace RL, Kordbacheh A, Walsh EJ. Key to the currently recognized species of Limnias Schrank, 1803 (Rotifera, Monogononta, Gnesiotrocha, Flosculariidae). Zootaxa. 2018;4442: 307–318. doi.org/10.11646/zootaxa.4442.2.7. 2. Stemberger RS. A general approach to the culture of planktonic rotifers. Can J Fish Aquat Sci. 1981;38: 721–724. doi:10.1139/f81-095. 3. 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Although the most widely used key to the Rotifera subsumes six species of the sessile genus Limnias within two species groups (L. ceratophylli and L. melicerta), the original descriptions of these forms are sufficiently different to recognize them as distinct entities. We used these descriptions and all available literature on these species to develop dichotomous and formula keys to the six species based on easily recognizable morphological characters. As part of our review we added relevant ecological information from published sources, as well as our own data. We also discuss the need for additional observations of morphological, behavioral, life history, and genetic features to better understand the diversity of this widespread genus.

Phylum Rotifera (L., rota , wheel; L., ferre , possessing) comprises ~2500 species of small, aquatic animals with ciliated anterior end, resembling a rotating wheel. They are distinguished because the major clades (Seisonidea, Bdelloidea, and Monogononta) reproduce by obligate sexuality, obligate asexuality, and facultative sexuality, respectively. Bdelloidea is a unique case of persistence for millions of years and high species diversification without sexual reproduction. Monogononta have ability to reproduce both asexually and sexual reproduction, thus combining high proliferation rates with the advantages of recombination. Reproductive features of monogononts make them useful in ecotoxicology for rapid assessment of toxicity and as live food in aquaculture.

Microorganisms, including rotifers, are thought to be capable of long distance dispersal. Therefore, they should show little population genetic structure due to high gene flow. Nevertheless, substantial genetic structure has been reported among populations of many taxa. In rotifers, genetic studies have focused on planktonic taxa leaving sessile groups largely unexplored. Here, we used COI gene and ITS region sequences to study genetic structure and delimit cryptic species in two sessile species (Limnias melicerta [32 populations]; L. ceratophylli [21 populations]). Among populations, ITS region sequences were less variable as compared to those of the COI gene (ITS; L. melicerta: 0–3.1% and L. ceratophylli: 0–4.4%; COI; L. melicerta: 0–22.7% and L. ceratophylli: 0–21.7%). Moreover, L. melicerta and L. ceratophylli were not resolved in phylogenetic analyses based on ITS sequences. Thus, we used COI sequences for species delimitation. Bayesian Species Delimitation detected nine putative cryptic species within L. melicerta and four putative cryptic species for L. ceratophylli. The genetic distance in the COI gene was 0–15.4% within cryptic species of L. melicerta and 0.5–0.6% within cryptic species of L. ceratophylli. Among cryptic species, COI genetic distance ranged 8.1–21.9% for L. melicerta and 15.1–21.2% for L. ceratophylli. The correlation between geographic and genetic distance was weak or lacking; thus geographic isolation cannot be considered a strong driver of genetic variation. In addition, geometric morphometric analyses of trophi did not show significant variation among cryptic species. In this study we used a conservative approach for species delimitation, yet we were able to show that species diversity in these sessile rotifers is underestimated.

Jaws have evolved numerous times in the animal kingdom and they display a wide variety of structural, compositional, and functional characteristics that reflect their polyphyletic origins. Among soft-bodied invertebrates, jaws are known from annelids, chaetognaths, flatworms, gnathostomulids, micrognathozoans, mollusks, rotifers, and several ecdysozoans. Depending on the taxon, jaws may function in the capture of prey (e.g., chaetognaths and flatworms), processing of prey (e.g., gnathostomulids and onychophorans), or both (e.g., rotifers). Although structural diversity among invertebrates’ jaws is becoming better characterized with the use of electron microscopy, many details remain poorly described, including neuromuscular control, elemental composition, and physical characteristics, such as hardness and resistance to wear. Unfortunately, absence of relevant data has impeded understanding of their functional diversity and evolutionary origins. With this symposium, we bring together researchers of disparately jawed taxa to draw structural and mechanistic comparisons among species to determine their commonalities. Additionally, we show that rotifers’ jaws, which are perhaps the best-characterized jaws among invertebrates, are still enigmatic with regard to their origins and mechanics. Nevertheless, technologies such as energy dispersive X-ray spectroscopy (EDX) and 3D modeling are being used to characterize their chemical composition and to develop physical models that allow exploration of their mechanical properties, respectively. We predict that these methods can also be used to develop biomimetic and bioinspired constructs based on the full range of the complexity of jaws, and that such constructs also can be developed from other invertebrate taxa. These approaches may also shed light on common developmental and physiological processes that facilitate the evolution of invertebrates’ jaws.

ObjectiveIn postmenopausal black women in the Women's Health Initiative randomized trial, estrogen alone reduced breast cancers but its comprehensive influence on health outcomes in black women is unknown. Therefore, we examined this issue in the Women's Health Initiative overall and by African ancestry.MethodsA total of 1,616 black women with prior hysterectomy, including 1,061 with percent African ancestry determination, at 40 US centers were randomly assigned to conjugated equine estrogen (0.625 mg/d) or placebo for 7.2 years' (median) intervention with 13 years' cumulative follow-up. Coronary heart disease (CHD) and breast cancer were primary efficacy and safety outcomes, respectively. A global index also included stroke, colorectal cancer, hip fracture, pulmonary embolism, and death.ResultsBlack women in the estrogen-alone group compared with black women in the placebo group had fewer breast cancers (17 vs 40, hazard ratio [HR] 0.47, 95% CI 0.26-0.82). In women with more than 80% African ancestry, breast cancer HR was lower (0.32, 95% CI 0.12-0.86, trend P = 0.04 for ancestry effect). Most other outcomes including CHD, stroke, hip fracture, and the global index were null with estrogen use in black women; a global index effect was more favorable in younger black women (HR 0.65, 95% CI 0.43-0.98).ConclusionsIn black postmenopausal women with prior hysterectomy, estrogen alone significantly reduced breast cancer incidence with no adverse influence on CHD, venous thromboembolism, or all-cause mortality. Favorable estrogen-alone global index effects in younger black women warrant further study.

While ubiquitous, temporary waters vary greatly in geographic distribution, origin, size, connectivity, hydroperiod, and biological composition. However, all terminate as active habitats, transitioning into either dryness or ice, only to be restored when conditions improve. Hydroperiod in some temporary habitats is cyclical and predictable, while in others it is sporadic. Although the rotifer communities of temporary waters are subjected to unique selective pressures within their habitats, species share many of the same adaptive responses. Here, we review temporary waters and their rotiferan inhabitants, examining community composition, life history, and evolutionary strategies that allow rotifers to flourish in these fluctuating environments.

The freshwater littoral comprises a mosaic of habitats structured at several scales by a combination of hydrophyte architecture and physiology. Within this complex environment littoral invertebrates should distribute themselves to maximize fitness: that is, for sessile animals selection of permanent substrata is critical, while distribution of motile (periphytic) animals should follow predictions of Ideal Free Distribution theory. Here we explore the relationships between littoral rotifers and hydrophytes by conducting nestedness analyses on 10 published datasets (7 sessile; 3 periphytic); one dataset each of microcrustaceans and insects were included for comparison. We used four metrics to assess nestedness: mean matrix temperature (T); counts of discrepancy shifts and species segregation; and percent singletons. Six sessile rotifer datasets exhibited nestedness (T = 9.25–30.2°, supported by ≥2 null models; the other metrics varied widely). Our results indicate that distribution of sessile rotifers and periphytic insects was highly structured, but until more data is available little can be said about the distribution of the periphytic rotifer or microcrustacean community structure. Sessile rotifer species possessing idiosyncratic temperatures (T>T +1.5 SD) exhibited a trend toward a record of cosmopolitanism. Important idiosyncratic hydrophytes included Ceratophyllum, Chara, and Utricularia. Two of the three periphytic, rotifer datasets exhibited nestedness (T = 19.2°, 39.9°), but each was supported by only one of the four null models. The periphytic microcrustaceans did not show nestedness, while the insects did (T = 15.5°; supported by four null models). The three other metrics varied considerably among the periphytic datasets, showing no discernable pattern.

Segers, Hendrik, De Smet, Willem H., Fontaneto, Diego, Hinz, Claus, Hussey, Charles, Michaloudi, Evangelia, Wallace, Robert L., Jersabek, Christian D. (2015): Period of public commentary begins on the revised proposal of species-group level names, and on the proposal of genus-group level names of the Candidate Part of List of Available Names (LAN) in the phylum Rotifera. European Journal of Taxonomy 165: 1-3, DOI: http://dx.doi.org/10.5852/ejt.2015.165

The introduction and establishment of arapaima (Arapaima gigas) in southeastern Peru and northwestern Bolivia is an example of a fish species that appears to be increasingly common and widespread in non-native portions of its range, but whose populations are on the decline within its native range. The arapaima is overfished and considered threatened throughout its native range in the Central Amazon. We gathered and examined data on the distribution of fish and wildlife in the Takana II Indigenous Territory in Bolivia, near the arapaima’s reported initial invasion zone in Peru. Results confirmed the presence of arapaima in several water bodies where local people have also reported a strong decline in native fish populations. Further south in the Takana I Indigenous Territory, monitoring of fisheries by local communities (2002-2008), including observations on arapaima catches, indicate that until 2008 arapaima had not been reported in the area. However in 2009, there were reports of arapaima in the Undumo stream. Our results demonstrate that since the first presence of arapaima in Bolivia at the beginning of the 1980s, it has steadily expanded its distribution. We propose actions to mitigate this situation by managing and controlling populations of this invasive and endangered species, as well as improving income for indigenous communities.

Ecological research is moving from a species-based to a functional-based approach to better understand the underlying principles that govern community dynamics. Studies of functional-based ecology, however, have been limited for zooplankton and particularly for rotifers. While rotifers show a variety of trophi types and coronal shapes, suggesting the importance of niche differentiation in their feeding strategy, relatively little is known of how this relates to rotifer dynamics. We used the guild ratio (GR′, a ratio of raptorial to microphagous species), an index based on a functional trait (i.e. feeding strategy), as a novel approach to rotifer dynamics. We extracted the seasonal GR′ by using seasonal trend decomposition and investigated similarities between study sites (Lake Washington, USA and Lake Caldonazzo, Italy) and its relation to cladocerans by cross-correlation analysis. Our study indicated that (i) raptorial and microphagous rotifers showed alternating dominance, and that raptorial rotifers and cladocerans had a synchronous pattern, (ii) the seasonal pattern of the GR′ was consistent across different sampling frequencies, and (iii) the GR′ was similar in both lakes. We interpreted these patterns as the general strength of the GR′: discernment of species–environment relationships and robustness across sampling regimes. The limitations of the GR′ (i.e. species identity is neglected, simplification of food preferences) can also be seen as its strong point: synthesis of multi-species patterns. In addition, the independence of GR′ from species-level identification and its potential to make use of datasets with infrequent sampling intervals and low taxon resolution could further support its innovative aspect.

The Chihuahuan Desert is known for its high biodiversity in both terrestrial and aquatic systems (Dinerstein et al. 2000, Souza et al. 2006). Endemism is pronounced in fishes (Minckley 1978) and springsnails (Hershler 1985); however, little is known regarding the distribution of many invertebrate groups. Dinger et al. 2005 recently surveyed the aquatic invertebrates in the diverse habitats at Cuatro Cienegas, Coahuila, Mexico, and noted the lack of taxonomic information for many insect groups in the region. Even less is known regarding the zooplankton of this and many other regions in the Chihuahuan Desert. Cosmopolitanism is assumed for many rotifers, including the monogonont Lecane bulla (Gosse 1851) (Koste 1978, Segers 1995). This species is characterized as one of the most eurytopic members of the Genus Lecane (Segers 1996), exhibits morphological variation, and is found in a variety of water sources worldwide. In his revision of the genus, Segers (1995) listed 11 species as synonyms with L. bulla but retained 3 recognized forms. More recently L. bulla goniata has been fully synonymized with L. bulla (Segers 2007). Because cryptic speciation is being detected with increasing frequency in rotifers (Gomez et al. 2002, Gomez 2005, Derry et al. 2003, Ortells et al. 2003, Gilbert & Walsh 2005, Suatoni et al. 2006, Schroder & Walsh 2007), we sampled sites from Chihuahuan Desert waters (U.S. and Mexico) to assess potential ecological and genetic differentiation of L. bulla.

This paper reviews several neutral models as possible mechanisms for simulating and explaining so-called “hollow curve distributions.” The models include simple random assignment, MacArthur's broken stick, Preston's lognor-mal (but as simulated by Sugihara), Fisher's logseries, and Hubbell's unified neutral theory of biodiversity and biogeog-raphy. Each model is fitted to data describing the distribution of genera over families in the phylum Rotifera.

(2008). Species composition and distribution of rotifers in Chihuahuan Desert waters of Mexico: is everything everywhere? SIL Proceedings, 1922-2010: Vol. 30, No. 1, pp. 73-76.