A cerebellar substrate for cognition evolved multiple times independently in mammals.

Given that complex behavior evolved multiple times independently in different lineages, a crucial question is whether these independent evolutionary events coincided with modifications to common neural systems. To test this question in mammals, we investigate the lateral cerebellum, a neurobiological system that is novel to mammals, and is associated with higher cognitive functions. We map the evolutionary diversification of the mammalian cerebellum and find that relative volumetric changes of the lateral cerebellar hemispheres (independent of cerebellar size) are correlated with measures of domain-general cognition in primates, and are characterized by a combination of parallel and convergent shifts towards similar levels of expansion in distantly related mammalian lineages. Results suggest that multiple independent evolutionary occurrences of increased behavioral complexity in mammals may at least partly be explained by selection on a common neural system, the cerebellum, which may have been subject to multiple independent neurodevelopmental remodeling events during mammalian evolution.

Examining the role of components of Slc11a1 (Nramp1) in the susceptibility of New Zealand sea lions (Phocarctos hookeri) to disease.

The New Zealand sea lion (NZSL, Phocarctos hookeri) is a Threatened marine mammal with a restricted distribution and a small, declining, population size. The species is susceptible to bacterial pathogens, having suffered three mass mortality events since 1998. Understanding the genetic factors linked to this susceptibility is important in mitigating population decline. The gene solute carrier family 11 member a1 (Slc11a1) plays an important role in mammalian resistance or susceptibility to a wide range of bacterial pathogens. At present, Slc11a1 has not been characterised in many taxa, and despite its known roles in mediating the effects of infectious disease agents, has not been examined as a candidate gene in susceptibility or resistance in any wild population of conservation concern. Here we examine components of Slc11a1 in NZSLs and identify: i) a polymorphic nucleotide in the promoter region; ii) putative shared transcription factor binding motifs between canids and NZSLs; and iii) a conserved polymorphic microsatellite in the first intron of Slc11a1, which together suggest conservation of Slc11a1 gene structure in otariids. At the promoter polymorphism, we demonstrate a shift away from normal allele frequency distributions and an increased likelihood of death from infectious causes with one allelic variant. While this increased likelihood is not statistically significant, lack of significance is potentially due to the complexity of genetic susceptibility to disease in wild populations. Our preliminary data highlight the potential significance of this gene in disease resistance in wild populations; further exploration of Slc11a1 will aid the understanding of susceptibility to infection in mammalian species of conservation significance.

Occupancy dynamics of South American sea-lions in Brazilian haul-outs / Dinâmica de ocupação do leão-marinho-do-sul no Brasil

Along the Brazilian coast only two haul-outs of South American sea lions (Otaria flavescens) are known: Ilha dos Lobos and Molhe Leste, both located in the southernmost state of Brazil, Rio Grande do Sul. Most sea lions observed in these haul-outs are adult and sub-adult males. It is supposed that the species' presence in these areas is due to food supply and absence of parental assistance by males. This study analysed the use of these haul-outs by O. flavescens between 1993 and 2002 based on counting data of observed individuals. Bayesian generalised linear mixed models were used to evaluate differences in abundance between areas, long term trends and seasonal patterns. Results showed that for O. flavescens abundance had a long term trend of increased average occupancy over the study period, with seasonal variation reaching the highest within-year value in August (Ilha dos Lobos) and October (Molhe Leste). The novel application of this powerful statistical modelling approach resulted in a useful tool to quantify occupancy dynamic.

Ao longo da costa do Brasil apenas duas colônias não-reprodutivas de leões-marinhos-do-sul (Otaria flavescens) são conhecidas: Ilha dos Lobos e Molhe Leste, ambas localizadas no estado do Rio Grande do Sul. A maioria dos leões-marinhos observados nestas colônias são machos adultos e sub-adultos. Supõe-se que a presença da espécie nestas áreas está relacionada ao forrageamento e a ausência de cuidado parental pelos machos. Este estudo analisou a dinâmica de ocupação e abundância de O. flavescens nas colônias não-reprodutivas entre 1993 e 2002, baseado em uma série temporal de dados de contagens de indivíduos. Modelos lineares generalizados mistos Bayesianos foram usados para avaliar diferença na abundância entre áreas, tendência de uso em longo prazo e padrões sazonais. Os resultados mostram que a abundância de O. flavescens variou sazonalmente, atingindo pico intra-anual em agosto (Ilha dos Lobos) e outubro (Molhe Leste), acompanhado de um aumento da ocupação média dos refúgios ao longo do período de estudo. A nova aplicação desta poderosa forma de modelagem estatística mostrou-se útil para quantificar a dinâmica de ocupação.

Extensive variation at MHC DRB in the New Zealand sea lion (Phocarctos hookeri) provides evidence for balancing selection.

Marine mammals are often reported to possess reduced variation of major histocompatibility complex (MHC) genes compared with their terrestrial counterparts. We evaluated diversity at two MHC class II B genes, DQB and DRB, in the New Zealand sea lion (Phocarctos hookeri, NZSL) a species that has suffered high mortality owing to bacterial epizootics, using Sanger sequencing and haplotype reconstruction, together with next-generation sequencing. Despite this species' prolonged history of small population size and highly restricted distribution, we demonstrate extensive diversity at MHC DRB with 26 alleles, whereas MHC DQB is dimorphic. We identify four DRB codons, predicted to be involved in antigen binding, that are evolving under adaptive evolution. Our data suggest diversity at DRB may be maintained by balancing selection, consistent with the role of this locus as an antigen-binding region and the species' recent history of mass mortality during a series of bacterial epizootics. Phylogenetic analyses of DQB and DRB sequences from pinnipeds and other carnivores revealed significant allelic diversity, but little phylogenetic depth or structure among pinniped alleles; thus, we could neither confirm nor refute the possibility of trans-species polymorphism in this group. The phylogenetic pattern observed however, suggests some significant evolutionary constraint on these loci in the recent past, with the pattern consistent with that expected following an epizootic event. These data may help further elucidate some of the genetic factors underlying the unusually high susceptibility to bacterial infection of the threatened NZSL, and help us to better understand the extent and pattern of MHC diversity in pinnipeds.

Occupancy dynamics of South American sea-lions in Brazilian haul-outs.

Along the Brazilian coast only two haul-outs of South American sea lions (Otaria flavescens) are known: Ilha dos Lobos and Molhe Leste, both located in the southernmost state of Brazil, Rio Grande do Sul. Most sea lions observed in these haul-outs are adult and sub-adult males. It is supposed that the species' presence in these areas is due to food supply and absence of parental assistance by males. This study analysed the use of these haul-outs by O. flavescens between 1993 and 2002 based on counting data of observed individuals. Bayesian generalised linear mixed models were used to evaluate differences in abundance between areas, long term trends and seasonal patterns. Results showed that for O. flavescens abundance had a long term trend of increased average occupancy over the study period, with seasonal variation reaching the highest within-year value in August (Ilha dos Lobos) and October (Molhe Leste). The novel application of this powerful statistical modelling approach resulted in a useful tool to quantify occupancy dynamic.

Genital morphology of the male South American fur seal (Arctocephalus australis) and biological implications / Morfologia dos órgãos genitais do macho do Lobo marinho (Arctocephalus australis) e implicações biológicas

Male capacity for spreading genes to a great number of descendents and to determine population dynamics depend directly on the genital organs. Morphological studies in pinnipeds are scarce and the functional meaning of some characteristics has never been discussed. We hypothesized that Arctocephalus australis (A. australis) shows morphophysiological adaptations in order to guarantee the perpetuation of the species in the unique annual mating season. Seven males, dead from natural causes, had their genital organs collected and fixed for morphological description. Some features differ from other described mammalian males and are closely related to the biology and reproductive cycle of this species, as the scrotal epidermis, absence of glandular portion in the ductus deferens and spermatogenic epithelium suggest a recrudescent testis period. The corona glandis exhibits a singular arrangement: its erectile border looks like a formation of petals and its association with the os penis gives a "lily-flower" form to this region. We propose the name margo petaliformis to this particular erectile border of the corona glandis because of its similarity to a flower corola. The male genital organs of A. australis show morphological features compatible with adaptation to environment requirements and reproductive efficiency.(AU)

A capacidade do macho de espalhar seus genes a um grande número de descendentes e determinar a dinâmica populacional depende diretamente dos seus órgãos genitais. Estudos morfológicos em pinípedes são escassos e o significado funcional de algumas de suas características ecológicas ainda foi pouco discutido. Nossa hipótese é que Arctocephalus australis (A. australis) apresenta adaptações morfofisiológicas em seus órgãos genitais capazes de interagir com o meio e garantir a perpetuação da espécie que apresenta apenas uma época de acasalamento que ocorre uma vez a cada ano. Sete A. australis machos, mortos recentes por causas naturais, tiveram seus órgãos genitais coletados e fixados para a descrição macro, micro e ultraestrutural. Algumas características diferem de outros machos já descritos e estão intimamente relacionados com a biologia e ciclo reprodutivo da espécie, dentre elas podemos citar a alta queratinização da epiderme escrotal que pode se relacionar com as rotineiras lesões por atrito desta região nas pedras; a ausência da porção glandular do ducto deferente aqui descrita pela primeira vez, o epitélio espermatogênico sugere um período de testículo recrudescente. A glande apresenta um arranjo singular: a coroa da glande apresenta porção lateral de tecido esponjoso que são bordas livres com capacidade de intumescencia. O osso peniano se encontra no centro destas bordas e representa a extremidade mais distal do penis, levando consigo o óstio uretral externo. As bordas associadas ao osso peniano, dão uma forma de "Flor de lírio" a esta região. Utilizamos o nome margo petaliformis a margem erétil liliforme a particular morfologia da glande, pela sua semelhança a uma corola de flor. Os órgãos genitais masculinos de A. australis mostram características morfológicas compatíveis com uma adaptação aos requisitos ambientais e de eficiência reprodutiva.(AU)

Differentiating between Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) scats through analysis of faecal DNA.

We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.

The monophyletic origin of sea lions and fur seals (Carnivora; Otariidae) in the Southern Hemisphere.

The pinniped family Otariidae (sea lions and fur seals) is composed of 7 extant genera with 14 species. They are mainly distributed in the Southern Hemisphere, but the fossil record is only known from the Northern Hemisphere until Pliocene. To clarify the biological and zoogeographical events during their evolution, it is necessary to reconstruct a robust phylogenetic tree. However, phylogenetic relationships among otariids continue to be controversial, except for the basal position of the northern fur seal among the extant otariids. We reconstructed phylogenetic trees of otariids based on mitochondrial genomes and multiple nuclear genes (IRBP and type I STS markers). The monophyly of the otariids including both sea lions and fur seals in the Southern Hemisphere was strongly supported by both the mitochondrial and nuclear evidence. We propose a novel evolutionary and dispersal scenario of otariids based on this phylogenetic hypothesis, estimated divergence times, and fossil records. According to our results, the center of origin of the southern otariids is hypothesized to be the eastern South Pacific along the west coast of South America.

Ancient DNA analysis of the Japanese sea lion (Zalophus californianus japonicus Peters, 1866): preliminary results using mitochondrial control-region sequences.

In this study, we successfully extracted ancient DNA from skeletal remains of the Japanese sea lion-a species that is practically extinct-from archaeological sites and determined a partial sequence of its mitochondrial DNA control region. A molecular phylogenetic tree constructed by the neighbor-joining (NJ) method showed that the sequences from Japanese sea lions clustered together, with a high bootstrap value, and that this cluster was closest to the California sea lion cluster. The distinctly divergent cluster of Japanese sea lions reflected the morphological classification of these animals as a distinct species of the genus Zalophus; however, proximity to the California sea lion cluster simultaneously implied conformation with the traditional classification of these animals as a subspecies of Zalophus californianus. The average amount of nucleotide substitution between the Japanese and California sea lions was 7.02%. The Japanese and California sea lions were estimated to have diverged 2.2 million years ago, i.e., in the late Pliocene Epoch. This is the first report on a genetic analysis of the Japanese sea lion.

Glacial refugia and the phylogeography of Steller's sea lion (Eumatopias jubatus) in the North Pacific.

Mitochondrial DNA sequence data were used to examine the phylogeographic history of Steller's sea lions (Eumetopias jubatus) in relation to the presence of Plio-Pleistocene insular refugia. Cytochrome b and control region sequences from 336 Steller's sea lions reveal phylogenetic lineages associated with continental refugia south of the ice sheets in North America and Eurasia. Phylogenetic analysis suggests the genetic structure of E. jubatus is the result of Pleistocene glacial geology, which caused the elimination and subsequent reappearance of suitable rookery habitat during glacial and interglacial periods. The cyclic nature of geological change produced a series of independent population expansions, contractions and isolations that had analogous results on Steller's sea lions and other marine and terrestrial species. Our data show evidence of four glacial refugia in which populations of Steller's sea lions diverged. These events occurred from approximately 60,000 to 180,000 years BP and thus preceded the last glacial maximum.

Seroepidemiology of parapoxvirus infections in captive and free-ranging California sea lions Zalophus californianus.

Cutaneous nodular lesions caused by parapoxvirus infections are commonly observed in stranded pinnipeds following their arrival at rehabilitation facilities. An indirect enzyme-linked immunosorbent assay (ELISA) was developed and validated to determine exposure to parapoxviruses in California sea lions Zalophus californianus in captivity and in the wild. The diagnostic performance of this assay was evaluated using receiver-operating characteristic analysis. At a selected cut-off value, the calculated sensitivity was 100% (95% CI = 86 to 100%) and the specificity was 100% (95% CI = 87 to 100%). Analysis of sera collected from 26 affected sea lions during various stages of the disease revealed anti-parapoxvirus antibodies in all affected sea lions prior to the development of cutaneous pox lesions. This indicated that previous exposure to a parapoxvirus does not confer protection against clinical disease. In at least 7 cases, exposure to the virus occurred during hospitalization. Analysis of paired sera from 74 unaffected sea lions indicated subclinical infections in at least 3 animals. Finally, the prevalence of anti-parapoxviral antibodies in 761 free-ranging California sea lions captured and tested was 91% (95% CI = 89 to 93%). This indicated that infection with a parapoxvirus is a common occurrence in the wild and that the release of captive sea lions infected with parapoxvirus into the wild should not increase the risk of a parapoxvirus outbreak in free-ranging sea lions.

Common metastatic carcinoma of California sea lions (Zalophus californianus): evidence of genital origin and association with novel gammaherpesvirus.

Tissues from 10 adult California sea lions (Zalophus californianus, seven females and three males) that had metastatic carcinoma in sublumbar area lymph nodes were examined histologically. A distinctive epithelial proliferative lesion interpreted as intraepithelial neoplasia was found in genital tracts of all ten animals; in vagina (5/7), cervix (7/7), uterus (3/7), penis (3/3) and prepuce (3/3). Intraepithelial neoplasia closely resembled metastatic carcinomas and was directly contiguous with invasive carcinoma in one animal. Rare eosinophilic intranuclear inclusion bodies were found in penile and preputial intraepithelial neoplasia (one animal), cervical intraepithelial neoplasia (one animal), invasive cervical carcinoma (one animal) and metastatic carcinoma (two animals). Electron microscopic examination of tissues from two sea lions (one with intraepithelial neoplasia and one with metastatic carcinoma) demonstrated viral particles consistent with a herpesvirus. An immunohistochemical stain for the latent membrane protein of Epstein-Barr virus was positive in intraepithelial neoplasia in one sea lion. Herpesvirus DNA sequences were detected by consensus primer polymerase chain reaction (PCR) in metastatic carcinomas from all four sea lions from which unfixed tumor samples were available. Results of sequencing were consistent with a novel gammaherpesvirus in the genus Rhadinovirus. DNA extracted from the four metastatic carcinomas also was tested for papillomavirus by Southern blot and PCR with consensus papillomavirus primers; all samples were negative by both methods. These findings support the genital origin of the sea lion carcinoma and implicate a novel gammaherpesvirus as a possible cause.