Trophic Segregation of Small Carnivorans (Carnivora: Mustelidae and Mephitidae) from the Southern Cone of South America

Remarkable adaptations in the Carnivora have evolved as a way of dealing with feeding competition, accentuating hypocarnivorous or hypercarnivorous morphotypes. The Carnivora is a highly successful order with 47 living species in South America. Their history in South America is recent, and includes few lineages that arrived before the Panamanian bridge was completed (procyonids), and others that arrived later (felids, mephitids). Here, we evaluated the trophic segregation of small carnivorans (Conepatus chinga, Galictus cuja, Lontra provocax, Lyncodon patagonicus, and the introduced Neovison vison) from southern South America, using a geometric morphometric approach, i.e., Principal Component and Canonical Variate Analysis, to study shape variations and t-tests to study size variation. We also performed Canonical Phylogenetic Ordination to study the association between shape, size, diet, and phylogeny. We identified C. chinga as the most hypocarnivorous member of the guild, G. cuja, L. patagonicus, and N. vison as hypercarnivores, with L. provocax in an intermediate position. Semiaquatic habits segregate Lontra provocax, and partially N. vison, from other species. Significant differences in size were observed between all species pairs, except C. chinga and N. vison. Phylogeny accounts for a very important part of morphological variance, with cladogenetic events between mustelids and mephitids responsible for almost 55 % of it. The small carnivoran guild of southern South America is represented by species adapted to different feeding strategies, with C. chinga and L. provocax preying mainly on invertebrates, G. cuja and L. patagonicus specifically on small vertebrates, and the non-native N. vison with a highly diverse diet.     

Contribution to the taxonomy of Gryllus Linnaeus, 1758 in South America: Part I: Redescription of Gryllus argentinus Saussure, 1874 (Orthoptera,Grylloidea, Gryllidae)

The genus Gryllus includes 82 described species that occur in America from Canada to Argentina as well as in several areas of Africa, Europe and Asia. There are 12 species in South America, which were described in the nineteenth century based on a small number of samples and inconsistent characters such as body coloration and external morphology. The aim of this article is to redescribe Gryllus argentinus Saussure, 1874 collected in the urban areas of Pelotas, Capão do Leão and Rio Grande, in the state of Rio Grande do Sul, southern Brazil, highlighting phallic sclerites, calling song and body morphometry. We designate the lectotype male, provide a combination of diagnostic characteristics and discuss the taxonomic situation of South American Gryllus species.     

Environment and space as drivers of variation in skull shape in two widely distributed South‐American Tayassuidae,Pecari tajacu and Tayassu pecari (Mammalia: Cetartiodactyla)

The influence of the environment on the geographical variation of morphological traits has been recognized in a number of taxa. Pecari tajacu and Tayassu pecari are ideal models to investigate intraspecific geographic variation in skull because of their wide and heterogeneous geographical distribution in South America. We used geometric morphometric procedures to examine the geographical variation in skull shape of 294 adult specimens of these species from 134 localities. We quantified to what extent skull shape variation was explained by environment, skull size and geographical space using variation partitioning analysis. We detected a strong pattern of geographic variation for P. tajacu skull shape, but not for T. pecari. The environment seems to be the major selective force that drives skull shape variation in both species. Nevertheless, other spatially structured processes (e.g. genetic drift, gene flow) might also have affected variation in the skull shape of the more widespread species P. tajacu. Allometric relationships might reflect the biomechanical constraints that are thought to be strong enough to limit size‐related changes in T. pecari skull shape.     

Mitochondrial DNA analysis reveals hidden genetic diversity in captive populations of the threatened American crocodile (Crocodylus acutus) in Colombia

Identification of units within species worthy of separate management consideration is an important area within conservation. Mitochondrial DNA (mtDNA) surveys can potentially contribute to this by identifying phylogenetic and population structure below the species level. The American crocodile (Crocodylus acutus) is broadly distributed throughout the Neotropics. Its numbers have been reduced severely with the species threatened throughout much of its distribution. In Colombia, the release of individuals from commercial captive populations has emerged as a possible conservation strategy that could contribute to species recovery. However, no studies have addressed levels of genetic differentiation or diversity within C. acutus in Colombia, thus complicating conservation and management decisions. Here, sequence variation was studied in mtDNA cytochrome b and cytochrome oxidase I gene sequences in three Colombian captive populations of C. acutus. Two distinct lineages were identified: C. acutus‐I, corresponding to haplotypes from Colombia and closely related Central American haplotypes; and C. acutus‐II, corresponding to all remaining haplotypes from Colombia. Comparison with findings from other studies indicates the presence of a single “northern” lineage (corresponding to C. acutus‐I) distributed from North America (southern Florida), through Central America and into northern South America. The absence of C. acutus‐II haplotypes from North and Central America indicates that the C. acutus‐II lineage probably represents a separate South American lineage. There appears to be sufficient divergence between lineages to suggest that they could represent two distinct evolutionary units. We suggest that this differentiation needs to be recognized for conservation purposes because it clearly contributes to the overall genetic diversity of the species. All Colombian captive populations included in this study contained a mixture of representatives of both lineages. As such, we recommend against the use of captive‐bred individuals for conservation strategies until further genetic information is available.     

Denning ecology of Molina's hog-nosed skunk in a farmland area in the Pampas grassland of Argentina

This paper reports the very first data on the denning habits of the little-studied Molina’s hog-nosed skunk (Conepatus chinga). We identified and characterized 240 (males: n = 92, females: n = 148) den sites used by nine radio-tracked skunks from November 2002 to October 2003 and from December 2005 to October 2007. Most dens were found in underground burrows and we found no variation in dimensions of den entrances across seasons. On average, 24.1% of the den sites were reused by C. chinga. Den sites were not homogeneously distributed within an animal's home range, being the density in core areas greater than in proximity to the borders of home ranges. C. chinga selected specific habitat characteristics for their den sites, such as high shrub and grass cover. Accordingly, the habitats preferred by skunks were native grasslands and pastures. Also, C. chinga preferred den sites located close to fences, roads, and grass patches. We argue that these preferences for den sites may provide two, not mutually exclusive, advantages: access to consistent and predictable sources of food, and protection from predators. Our results suggest that availability of semi-natural grassland and pasture areas may favor the conservation of C. chinga in the human-modified landscapes of the Pampas.     

The role of exotic mammals in the diet of native carnivores from South America

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The biogeography of Gunnera L.: vicariance and dispersal

Aim The genus Gunnera is distributed in South America, Africa and the Australasian region, a few species reaching Hawaii and southern Mexico in the North. A cladogram was used to (1) discuss the biogeography of Gunnera and (2) subsequently compare this biogeographical pattern with the geological history of continents and the patterns reported for other Southern Hemisphere organisms. Location Africa, northern South America, southern South America, Tasmania, New Zealand, New Guinea/Malaya, Hawaii, North America, Antarctica. Methods A phylogenetic analysis of twenty‐six species of Gunnera combining morphological characters and new as well as published sequences of the ITS region, rbcL and the rps16 intron, was used to interpret the biogeographical patterns in Gunnera. Vicariance was applied in the first place and dispersal was only assumed as a second best explanation. Results The Uruguayan/Brazilian Gunnera herteri Osten (subgenus Ostenigunnera Mattfeld) is sister to the rest of the genus, followed sequentially upwards by the African G. perpensa L. (subgenus Gunnera), in turn sister to all other, American and Australasian, species. These are divided into two clades, one containing American/Hawaiian species, the other containing all Australasian species. Within the Australasian clade, G. macrophylla Blume (subgenus Pseudogunnera Schindler), occurring in New Guinea and Malaya, is sister to a clade including the species from New Zealand and Tasmania (subgenus Milligania Schindler). The southern South American subgenus Misandra Schindler is sister to a clade containing the remaining American, as well as the Hawaiian species (subgenus Panke Schindler). Within subgenus Panke, G. mexicana Brandegee, the only North American species in the genus, is sister to a clade wherein the Hawaiian species are basal to all south and central American taxa. Main conclusions According to the cladogram, South America appears in two places, suggesting an historical explanation for northern South America to be separate from southern South America. Following a well‐known biogeographical pattern of vicariance, Africa is the sister area to the combined southern South America/Australasian clade. Within the Australasian clade, New Zealand is more closely related to New Guinea/Malaya than to southern South America, a pattern found in other plant cladograms, contradictory to some of the patterns supported by animal clades and by the geological hypothesis, respectively. The position of the Tasmanian G. cordifolia, nested within the New Zealand clade indicates dispersal of this species to Tasmania. The position of G. mexicana, the only North American species, as sister to the remaining species of subgenus Panke together with the subsequent sister relation between Hawaii and southern South America, may reflect a North American origin of Panke and a recolonization of South America from the north. This is in agreement with the early North American fossil record of Gunnera and the apparent young age of the South American clade.     

Morphological and genetic evidence for two evolutionarily significant units (ESUs) in the South American fur seal, <Emphasis Type="Italic">Arctocephalus gazella</Emphasis>

The South American fur seal (Arctocephalus australis) is widely distributed, occurring along both the Atlantic and the Pacific coasts of South America. Previous work suggests there may be more than one subspecies, highlighting the need for further study. Here, we combine traditional and geometric morphometric analysis of skull shape and size with genetic data to compare two populations of South American fur seals, one from Uruguay and one from Peru. As a control group we used material from the closely related species Arctocephalus gazella. Both techniques of morphometric analysis reveal pronounced geographic variation in size and shape of the skull, with Peruvian specimens (n = 102) being larger than Uruguayan skulls (n = 133) and significant shape differences concentrated in the rostral region. Similarly, seven highly polymorphic microsatellite loci reveal highly significant differences in allele frequency. Moreover, Bayesian analysis implemented using the program structure reveals two separate clusters corresponding perfectly to the two populations, with an assignment test correctly placing over 98% of specimens in their population of origin. This degree of differentiation for both genetic and morphological traits suggests complete and possibly prolonged isolation to the extent that we believe these populations should be considered distinct evolutionarily significant units.     

Ecogeographical variation in skull morphometry of howler monkeys (Primates: Atelidae)

Our aim is to identify ecomorphological adaptations in the skull shape of the South American howler monkeys (species of the genus Alouatta, Lacépède, 1799, Primates, Atelidae). Since Alouatta is relatively homogenous in feeding ecology, we expect skull shape variation to be relatively conservative across species. We used geometric morphometrics to quantify craniodental morphology in six species of Alouatta. Multivariate regression, two-block Partial Least Squares, and variation partitioning were used to test for the impact of taxonomy, sexual dimorphism, allometry, geography and climate on skull shape. We found morphological overlap among species and sexes, although some discrimination occurs between species living in seasonal environments as opposed to rain forest species. There was a negative latitudinal gradient in skull size across species, with size explaining 34% of total shape variance. Latitude and climate, though important, were secondary in explaining shape variance. Amazonian Alouatta are larger, have thinner molars, wide incisors, and proportionally larger neurocranium. Overall, the shape of southern species seem well adapted to cope with proportionally tougher food items, whereas Amazonian species seem better equipped to deal with a diet richer in fruits, as confirmed by independent field observations. The small size of Alouatta in the South is possibly linked to the effect of competition with the larger folivorous atelid Brachyteles.     

Systematics and evolution of the Jacchus group of marmosets (Platyrrhini)

Interspecific differentiation and geographic variation patterns in 39 skull traits of eastern Brazilian marmosets are analyzed. Eastern Callithrix taxa are distinct morphologically, and no evidence of intergradation among taxa is observed. Instead, there are sharp, stepped morphological boundaries among taxa, consistent with species‐level distinction. The morphological similarity cluster diagram obtained from Mahalanobis distances is different from available molecular trees, and the general picture emerging is that the eastern Callithrix taxa should be considered as good species arising recently in South American history. In particular, C. kuhlii is morphologically distinct from other marmoset taxa, including C. geoffroyi and C. penicillata, which were previously hypothesized to be the parental populations that formed C. kuhlii by hybridization. Furthermore, C. kuhlii populations from southeastern Bahia do not overlap morphologically with any C. penicillata population, including the upper São Francisco River populations that display skin colors and pelage patterns to some extent similar to true Kuhli's marmosets. There is a negative, though insignificant, correlation between the morphological distance matrix and a Mahalanobis distance matrix estimated from nine climatic variables, a pattern opposite to that expected under a parapatric speciation model. This result, together with the lack of clinal variation in skull traits, suggests that an allopatric model of speciation might best explain eastern marmoset diversification. Am J Phys Anthropol 2003. © 2002 Wiley‐Liss, Inc.     

Late Cenozoic diversification of the austral genus Lagenophora (Astereae,Asteraceae)

Lagenophora (Astereae, Asteraceae) has 14 species in New Zealand, Australia, Asia, southern South America, Gough Island and Tristan da Cunha. Phylogenetic relationships in Lagenophora were inferred using nuclear and plastid DNA regions. Reconstruction of spatio‐temporal evolution was estimated using parsimony, Bayesian inference and likelihood methods, a Bayesian relaxed molecular clock and ancestral area and habitat reconstructions. Our results support a narrow taxonomic concept of Lagenophora including only a core group of species with one clade diversifying in New Zealand and another in South America. The split between the New Zealand and South American Lagenophora dates from 11.2 Mya [6.1–17.4 95% highest posterior density (HPD)]. The inferred ancestral habitats were openings in beech forest and subalpine tussockland. The biogeographical analyses infer a complex ancestral area for Lagenophora involving New Zealand and southern South America. Thus, the estimated divergence times and biogeographical reconstructions provide circumstantial evidence that Antarctica may have served as a corridor for migration until the expansion of the continental ice during the late Cenozoic. The extant distribution of Lagenophora reflects a complex history that could also have involved direct long‐distance dispersal across southern oceans. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 177 , 78–95.     

Differences in diet and trophic interactions of Patagonian carnivores between areas with mostly native or exotic prey

The prey base for Patagonian carnivores has been altered greatly over the past 150 years due to widespread overgrazing by livestock, invasions by exotic wildlife, and hunting. On ranches in northern Patagonia carnivores consume mostly exotic species, and native herbivores are ecologically extinct in their role as prey. In this study we compare diets of the culpeo (Lycalopex culpaeus), chilla (L. griseus), puma (Puma concolor), Geoffroy's cat (Leopardus geoffroyi), colocolo (L. colocolo), and hog-nosed skunks (Conepatus chinga and C. humboldtii) in a reserve with a mostly native prey base to their diets on the ranches, and evaluate how differences in prey bases affect trophic interactions among carnivores. Carnivores in the reserve consumed mostly native prey. Dietary overlap among carnivores was not significant on the reserve, but was highly significant on the ranches. This homogenization of diets where densities of native species are reduced could lead to stronger negative interactions among carnivores, altering the composition of the carnivore assemblage to the detriment of the more specialized species. Study of carnivore diets may be a relatively quick way to evaluate the conservation status and ecological functionality of prey assemblages in Patagonia and other areas where these have been altered.     

Phylogenetic Relationships of Spider Monkeys (Ateles) Based on Mitochondrial DNA Variation

Our goal was to determine phylogenetic relationships among geographically and taxonomically distinct haplotypes of spider monkeys (Ateles) based on DNA sequence variation for the mitochondrial DNA control region and cytochrome c oxidase subunit II gene. We obtained samples from most previously recognized subspecies of Ateles, ranging from Central America throughout the Amazon Basin, to determine phylogenetic relationships among racially recognized groups. Comparison of DNA sequences using both parsimony analysis and genetic distance analysis produced phylogenetic relationships that were very similar for each genetic region. We analyzed the phylograms produced, along with associated bootstrap support, confidence probabilities, and genetic distances between taxonomic groups, to identify four monophyletic species of Ateles: Ateles paniscus, composed of haplotypes from the northeastern Amazon Basin; A. belzebuth in the southern Amazon Basin; A. hybridus, located primarily along the Magdalena River valley of Colombia; and A. geoffroyi, which includes two former species: A. geoffroyi and A. fusciceps. This arrangement is contradictory to long-held taxonomies of Ateles based on pelage variation and is similar to a recent analysis based on craniodental variation. Results of this investigation suggest patterns of gene flow, evolutionary relationships, and speciation patterns that are more plausible than previous pelage-based taxonomies, which required seemingly impossible patterns of gene flow. Conservation efforts aimed at protecting Ateles, one of the Neotropics most endangered genera, will also benefit from the findings presented in this paper.     

Molecular Phylogeny of Tuco-Tucos, Genus Ctenomys (Rodentia: Octodontidae): Evaluation of the mendocinus Species Group and the Evolution of Asymmetric Sperm

The phylogenetic relationships among 23 individuals representing 14 species of underground hystricognath rodents of the genus Ctenomys were studied by analyzing variation of complete cytochrome b gene sequences. Maximum parsimony, neighbor joining, and maximum likelihood analyses were performed, using the octodontine genera Octodon and Tympanoctomys as outgroups. Our analyses support previous studies based on chromosomes and skull morphology that suggested a clade comprised of Argentinean and Uruguayan populations of C. rionegrensis. This clade is closely related to one comprised of C. flamarioni and the C. mendocinus species complex. Our analyses provide evidence that the symmetric sperm morph, which is common to other South American hystricognath rodents, is the plesiomorphic character state in Ctenomys and in Hystricognathi. Our analyses do not support the hypothesis that the sperm morphs define two major lineages of tuco-tuco species, because species with asymmetric sperm are diphyletic on the basis of cytochrome b sequences, and this morphology appears to have evolved twice in Ctenomys.     

Notes on the geographic distribution of howling monkeys in the marajó archipelago, pará, Brazil

I review the distribution of genus Alouattain the Marajó Archipelago based on geographic variation of pelage color patterns. Specific differences exist among the labeled specimens at Museu Paraense Emílio Goeldi, which are confirmed via new field information from wild populations. The animals from Marajó, Caviana, and Mexiana Islands possess color patterns of Alouatta belzebul,while Alouatta seniculusis confirmed as the species that inhabits Gurupá Island. The high variability of pelage coloration of the animals from Marajó, Caviana, and Mexiana Islands includes all phenotypes formerly designated as different subspecies. The howler populations from these three islands belong to the same subspecies as those populations that inhabit the region of Tucurui dam reservoir (area 4). Finally, it seems that, as also suggested by chromosome studies, A. belzebulprobably comprises different epiphenotypes without taxonomic validity.     

Multilocus molecular systematics and evolution in time and space of Calligrapha (Coleoptera: Chrysomelidae,Chrysomelinae)

Calligrapha (Coleoptera: Chrysomelidae) is a genus with species present in most of the American continent, from the Arctic polar circle to the Pampas in Argentina. In its current concept, the genus comprises some 80 species, but the diagnosis of the genus is problematic, based on a combination of potentially symplesiomorphic character states. In this study, we investigate the largest taxonomic sample of Calligrapha diversity to date (43 species) using a phylogenetic perspective based on more than 6000 molecular characters from eight genes (four mitochondrial and four nuclear) for a systematic evaluation of the genus. The analyses also include thirteen species in the closely related Zygospila (currently a subgenus of Zygogramma) to assist the systematic delimitation of Calligrapha. Partitioned and total evidence phylogenetic trees were additionally used for molecular clock analyses and dating based on standard mtDNA evolutionary rates, and for likelihood‐based inference of ancestral areas. Calligrapha and Zygospila are reciprocally paraphyletic, and our interpretation of taxonomic stability merges both taxa into a larger genus Calligrapha which plausibly originated in the dry steppes of southern North America in the Late Miocene. The genus includes a minimum of five strongly supported lineages which initially diversified in the Pliocene, fully congruent with expectations from morphology, but of uncertain mutual relationships. Only two of these lineages dispersed to South America: the group of C. polyspila right at the time of the final closure of the Isthmus of Panama in the Early Pliocene and the group of C. argus only in recent times, well in the Pleistocene. The most species‐rich lineage of Calligrapha, associated to trees and shrubs typical of riverine and lacustrine environments (as opposed to herbaceous steppe plants, generally Malvaceae and Asteraceae, for most other groups) diversified and spread in North America in the Late Pliocene. The ecological shift to a stable habitat spreading in the continent due to climate change is hypothesized as one possible explanation for the evolutionary success of this group.     

A tale of two clades: Comparative study of Glyptodon Owen and Glyptotherium Osborn (Xenarthra,Cingulata, Glyptodontidae)

Glyptodon and Glyptotherium represent the most conspicuous taxa of late Neogene and Pleistocene glyptodonts in South America and North America, respectively. The earliest records of Glyptodon in South America are 1.07 Ma (late early Pleistocene, Calabrian), although the possibility that “Paraglyptodon uquiensis” represents a Pliocene specimen of Glyptodon cannot be rejected. Glyptotherium originated from South American ancestry in northern South America or Central America about 3.9 Ma (early late Pliocene, Zanclean) or earlier. The diversity of South American Glyptodon is currently under study, but preliminary evidence would indicate that no more than three species (G. munizi, G. elongatus and G. reticulatus) are valid, plus a possible new Andean species. In turn, according to the updated taxonomy proposed herein, Glyptotherium includes two chronospecies. The earliest species, Gl. texanum, differs only slightly from the latest species, Gl. cylindricum. The relationship of Glyptodon and Glyptotherium has been problematical since the discovery of the North American lineage, at first identified as various species of Glyptodon and later considered a separate genus. Glyptodon is recognized as a natural group and recent taxonomic and phylogenetic revisions place all North American glyptodontines into Glyptotherium. In this paper, we propose a detailed morphological comparison between the southern South American species of Glyptodon and Glyptotherium in order to identify diagnostic differences and potential synapomorphies. Both genera can be distinguished mainly by differences in the skull, mandible, dentition, dorsal carapace, and caudal armor, Glyptodon being somewhat larger than Glyptotherium. Both clades show a highly conservative evolution, which could be interpreted as an anagenesis. The scarce records of glyptodonts in Central America show more morphological affinity with Glyptotherium than with Glyptodon.     

Revision of Chaetodipus arenarius (Rodentia: Heteromyidae)

Chaetodipus arenarius is an endemic species of the Baja California Peninsula. It has undergone taxonomic changes in the last few years. Today, two species, C. arenarius and Chaetodipus dalquesti, are formally recognized with an unknown range for each. However, genetic analysis showed the possible presence of a third species. The objectives of this study were to use molecular data (cytochrome b and cytochrome c oxidase subunit III genes) to determine how many genetic groups are present in C. arenarius in the Baja California Peninsula; if these groups have morphological characteristics that could be used to distinguish them; if the genetic groups have limited distributions; identify taxonomic implications; and establish if there are any associations amongst genetic groups and different habitats. Bayesian inference, maximum parsimony, maximum likelihood, distance optimality criteria, and minimum spanning network indicated three monophyletic groups with high genetic differences (5.54–13.59%). These groups are morphologically diagnosable based on pelage and morphometric characters and geographical range. The three genetic groups correspond to three taxa previously described as subspecies or species. Based on our results, these should be considered to be different species: C. arenarius occupies the most extreme habitats with hot summers; C. dalquesti occupies the moistest coastal areas in the southern part of the peninsula, and Chaetodipus siccus is restricted by mountain ranges to the isolated Los Planes Basin and Cerralvo Island. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010.