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Following influenza infection, natural killer (NK) cells function as interim effectors by suppressing viral replication until CD8 T cells are activated, proliferate, and are mobilized within the respiratory tract. Thus, NK cells are an important first line of defense against influenza virus. Here, in a murine model of influenza, we show that virally-induced IL-15 facilitates the trafficking of NK cells into the lung airways. Blocking IL-15 delays NK cell entry to the site of infection and results in a disregulated control of early viral replication. By the same principle, viral control by NK cells can be therapeutically enhanced via intranasal administration of exogenous IL-15 in the early days post influenza infection. In addition to controlling early viral replication, this IL-15-induced mobilization of NK cells to the lung airways has important downstream consequences on adaptive responses. Primarily, depletion of responding NK1.1+ NK cells is associated with reduced immigration of influenza-specific CD8 T cells to the site of infection. Together this work suggests that local deposits of IL-15 in the lung airways regulate the coordinated innate and adaptive immune responses to influenza infection and may represent an important point of immune intervention.

The parthenogenetic triploid lizard Aspidoscelis neotesselata originated from a hybridization event between a female of diploid parthenogenetic Aspidoscelis tesselata (pattern class C) and a male of Aspidoscelis sexlineata viridis, and A. neotesselata is morphologically more similar to its maternal progenitor, A. tesselata. The geographic distribution of A. neotesselata is characterized by localized arrays of individuals located within a four-county area in southeastern Colorado, and postorigin divergence is visually evident in its four allopatric color pattern classes (A, B, C, and D). A fundamental pattern of morphological divergence was revealed by a multivariate partitioning of its four color pattern classes into two basic groups: an A group (pattern classes A and D) and a B group (pattern classes B and C). A problem introduced by this grouping is the incongruence between the multivariate similarity of pattern classes A and D and the closer geographic proximity of other color pattern classes to each of A and D. All four color-pattern classes of A. neotesselata had a modified triploid karyotype of 69 + 1 chromosomes (3n = 70). Electrophoretic assessment of 31 nuclear gene loci across the four color-pattern classes revealed postorigin genetic variation only at the mannose-6-phosphate isomerase (MPI) locus, but A. neotesselata had a remarkable heterozygosity of 71% based on these loci.

The Aspidoscelis cozumela complex of parthenogenetic lizards of the Yucatán Peninsula originated from hybridization between individuals of Aspidoscelis angusticeps (maternal) and Aspidoscelis deppii deppii (paternal) followed by postorigin clonal divergence. A previous report of histocompatibility between two members of the complex, Aspidoscelis maslini and Aspidoscelis cozumela, is reliable evidence that they share a single hybridization event. However, evidence from mitochondrial DNA and histoincompatibility has been used to conclude that another member of the complex, Aspidoscelis rodecki, originated from a separate hybridization event. Although future evidence might tip the balance in favor of a two-hybridization model, we provide examples where evidence from mtDNA and histoincompatibility probably led to incorrect predictions of the number of hybridization events in parthenogenetic Aspidoscelis. In this study, we compared correspondence between patterns of morphological and karyotypic divergence among A. cozumela, A. rodecki, and northern populations of A. maslini and progenitor species to two-hybridization and one-hybridization models. Although morphological and karyotypic patterns can be explained by either model, the most parsimonious alternative is a single hybridization event followed by postformational divergence. El complejo Aspidoscelis cozumela de lagartijas partenogenéticas de la Península de Yucatán se originó de la hibridación entre individuos de Aspidoscelis angusticeps (especie materna) y Aspidoscelis deppii deppii (especie paterna) seguida por una divergencia clonal postorigen. Un reporte previo de histocompatibilidad entre dos miembros de este complejo, Aspidoscelis maslini y Aspidoscelis cozumela, es una evidencia confiable de que ellos comparten un evento de hibridación único. Sin embargo, evidencia de ADN mitocondrial e histoincompatibilidad ha sido utilizada para concluir que otro miembro de este complejo, Aspidoscelis rodecki, se originó de un evento de hibridación separado. Aunque evidencias futuras podrían inclinar la balanza en favor de un modelo de dos-hibridaciones, proporcionamos ejemplos donde evidencias de ADN mitocondrial e histoincompatibilidad probablemente conducen a predicciones incorrectas del número de eventos de hibridación en Aspidoscelis partenogenéticos. En este estudio, comparamos correspondencia entre patrones de divergencia morfológica y cariotípica entre A. cozumela, A. rodecki, y poblaciones del norte de A. maslini y especies progenitoras de modelos de dos-hibridaciones y una-hibridación. Aunque patrones morfológicos y cariotípicos pueden ser explicados por cualquiera de estos dos modelos, la alternativa más parsimoniosa es un evento único de hibridación seguido de divergencia postformativa.

Guyana has a very distinctive herpetofauna. In this first ever detailed modern accounting, based on voucher specimens, we document the presence of 324 species of amphibians and reptiles in the country; 148 amphibians, 176 reptiles. Of these, we present species accounts for 317 species and color photographs of about 62% (Plates 1–40). At the rate that new species are being described and distributional records are being found for the first time, we suspect that at least 350 species will be documented in a few decades. The diverse herpetofauna includes 137 species of frogs and toads, 11 caecilians, 4 crocodylians, 4 amphisbaenians, 56 lizards, 97 snakes, and 15 turtles. Endemic species, which occur nowhere else in the world, comprise 15% of the herpetofauna. Most of the endemics are amphibians, comprising 27% of the amphibian fauna. Type localities (where the type specimens or scientific name-bearers of species were found) are located within Guyana for 24% of the herpetofauna, or 36% of the amphibians. This diverse fauna results from the geographic position of Guyana on the Guiana Shield and the isolated highlands or tepuis of the eastern part of the Pantepui Region, which are surrounded by lowland rainforest and savannas. Consequently, there is a mixture of local endemic species and widespread species characteristic of Amazonia and the Guianan Region. Although the size of this volume may mislead some people into thinking that a lot is known about the fauna of Guyana, the work has just begun. Many of the species are known from fewer than five individuals in scientific collections; for many the life history, distribution, ecology, and behavior remain poorly known; few resources in the country are devoted to developing such knowledge; and as far as we are aware, no other group of animals in the fauna of Guyana has been summarized in a volume such as this to document the biological resources. We briefly discuss aspects of biogeography, as reflected in samples collected at seven lowland sites (in rainforest, savanna, and mixed habitats below 500 m elevation) and three isolated highland sites (in montane forest and evergreen high-tepui forest above 1400 m elevation). Comparisons of these sites are preliminary because sampling of the local faunas remains incomplete. Nevertheless, it is certain that areas of about 2.5 km2 of lowland rainforest can support more than 130 species of amphibians and reptiles (perhaps actually more than 150), while many fewer species (fewer than 30 documented so far) occur in a comparable area of isolated highlands, where low temperatures, frequent cloudiness, and poor soils are relatively unfavorable for amphibians and reptiles. Furthermore, insufficient study has been done in upland sites of intermediate elevations, where lowland and highland faunas overlap significantly, although considerable work is being accomplished in Kaieteur National Park by other investigators. Comparisons of the faunas of the lowland and isolated highland sites showed that very few species occur in common in both the lowlands and isolated highlands; that those few are widespread lowland species that tolerate highland environments; that many endemic species (mostly amphibians) occur in the isolated highlands of the Pakaraima Mountains; and that each of the isolated highlands, lowland savannas, and lowland rainforests at these 10 sites have distinctive faunal elements. No two sites were identical in species composition. Much more work is needed to compare a variety of sites, and especially to incorporate upland sites of intermediate elevations in such comparisons. Five species of sea turtles utilize the limited areas of Atlantic coastal beaches to the northwest of Georgetown. All of these are listed by the International Union for the Conservation of Nature as being of global concern for long-term survival, mostly owing to human predation. The categories of Critically Endangered or Endangered are applied to four of the local sea turtles (80%). It is important to protect the few good nesting beaches for the sea turtles of Guyana. We have documented each of the species now known to comprise the herpetofauna of Guyana by citing specimens that exist in scientific collections, many of which were collected and identified by us and colleagues, including students of the University of Guyana (UG). We also re-identified many old museum specimens collected by others in the past (e.g., collections of William Beebe) and we used documented publications and collection records of colleagues, most of whom have been working more recently. We present dichotomous keys for identifying representatives of the species known to occur in Guyana, and we present brief annotated species accounts. The accounts provide the current scientific name, original name (with citation of the original description, which we personally examined in the literature), some outdated names used in the recent past, type specimens, type localities, general geographic distribution, examples of voucher specimens from Guyana, coloration in life (and often a color photograph), and comments pointing out interesting subjects for future research.

Guyana has a very distinctive herpetofauna. In this first ever detailed modern accounting, based on voucher specimens, the authors document the presence of 324 species of amphibians and reptiles in the country; 148 amphibians, 176 reptiles. They briefly discuss aspects of biogeography, as reflected in samples collected at seven lowland sites (in rainforest, savanna, and mixed habitats below 500 m elevation) and three isolated highland sites (in montane forest and evergreen high-tepui forest above 1,400 m elevation). Comparisons of the faunas of the lowland and isolated highland sites showed that very few species occur in common in both the lowlands and isolated highlands; that those few are widespread lowland species that tolerate highland environments; that many endemic species (mostly amphibians) occur in the isolated highlands of the Pakaraima Mountains; and that each of the isolated highlands, lowland savannas, and lowland rainforests at these 10 sites have distinctive faunal elements. No two sites were identical in species composition.

Karyotypes of many species of the genus Sceloporus support the generalization that there are no morphologically recognizable sex chromosomes in lizards; however, there is a marked sexual dimorphism in the karyotypes of Sceloporus jarrovi and Sceloporus poinsetti. During meiosis in males, whose diploid number of chromosomes is 31, preferential segregation of chromosomes from a trivalent results in heterogamety.