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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Revisão sistemática e ontogenética dos materiais cranianos atribuídos ao gênero Mariliasuchus (Crocodyliformes, Notosuchia) e suas implicações taxonômicas e paleobiológicas / Sistematic and ontogenetic review of the cranial materials assigned to the genus Mariliasuchus (Crocodyliformes, Notosuchia) and its taxonomic and palaeobiological implications

Augusta, Bruno Gonçalves 22 November 2013 (has links)
Mariliasuchus amarali Carvalho & Bertini 1999 é um crocodilomorfo Notosuchia do Cretáceo da Bacia Bauru. Este táxon possui um registro fóssil relativamente comum, e diversos espécimes (incluindo animais juvenis) são conhecidos. Portanto, ele representa um dos poucos táxons fósseis que permitem uma análise ontogenética, e seu desenvolvimento foi comparado com o do gênero Caiman (incluindo C. latirostris, C. crocodilus e C. yacare), um crocodilomorfo atual de ampla distribuição pela América do Sul. Foram empregadas as seguintes metodologias para comparação das trajetórias ontogenéticas dos táxons fóssil e atual: descrição qualitativa, morfometria linear e morfometria geométrica. Os dados obtidos destacaram trajetórias ontogenéticas comuns aos dois táxons, que foram interpretadas como o resultado de um padrão plesiomórfico aos Crocodyliformes, e distintas trajetórias ontogenéticas que foram relacionadas, principalmente, a diferentes adaptações ecomorfológicas. A ocorrência de tendências ontogenéticas como a manutenção de uma fenestra supratemporal de grandes proporções ao longo da ontogenia, a expansão anterior do articular e do côndilo mandibular do quadrado, o aumento na espessura da camada de esmalte dentário e a alometria positiva das fenestras infratemporal e mandibular sugerem que Mariliasuchus amarali aumentava gradativamente seu controle e capacidade de processamento alimentar ao longo de seu desenvolvimento. A análise ontogenética também mostrou fortes evidências de que o espécime UFRJ-DG 56-R, interpretado por Nobre et al. (2007a) como uma nova espécie dentro do gênero Mariliasuchus (M. robustus), é na verdade um indivíduo de M. amarali em avançado estágio de desenvolvimento e não uma nova espécie. O espécime MZSP-PV 760 é descrito pela primeira vez no presente trabalho. Suas características anatômicas sugerem que o mesmo não é um indivíduo juvenil de Mariliasuchus, como pensado anteriormente, mas parece estar relacionado ao clado que inclui ambos M. amarali e Adamantinasuchus navae (outro crocodilomorfo da Bacia Bauru). MZSP-PV 760 representa o mais jovem crocodilomorfo pós-embrionário já descrito para o Cretáceo de Gondwana. Uma reanálise da dentição altamente heterodonte em M. amarali mostrou a ocorrência de um novo morfótipo dentário (pré-molariforme), descrito pela primeira vez no presente trabalho. Uma coroa de cada morfótipo dentário foi extraída do espécime MZSP-PV 813 para análise da microanatomia do esmalte dentário e do padrão de organização dos cristais de esmalte, descritos pela primeira vez para um Notosuchia. A descrição de um novo morfótipo dentário representa uma inesperada adição para uma já complexa condição heterodonte em M. amarali, corroborando com a hipótese de OConnor et al. (2010) de que os Notosuchia podem ter ocupado nichos ecológicos e ecomorfoespaços, durante o Cretáceo do Gondwana, tão complexos quanto os de mamíferos. / Mariliasuchus amarali Carvalho & Bertini 1999 is a notosuchian crocodyliform from the Cretaceous of Bauru Basin (Brazil). This taxon has a fossil record that is relatively common, and several specimens (including juveniles) are known. Therefore, it represents one of the few fossil taxa that allows an ontogenetic approach, and its development was compared with the genus Caiman (including C. latirostris, C. crocodilus and C. yacare), a widespread South American crocodyliform. I used the following methodologies for the comparison of the ontogenetic trajectories of the fossil and living taxa: qualitative description, traditional morphometrics and geometric morphometrics. The data highlighted common ontogenetic trajectories that were interpreted as the result of a plesiomorphic pattern for Crocodyliformes, and distinct ontogenetic trajectories that were related mainly to different ecomorphological adaptations. The occurrence of ontogenetic trends as the retention of a large supratemporal fenestra along the ontogenetic development, the anterior expansion of the articular and the articular condyle of the quadrate, the thickening of the enamel cap in the teeth crowns, and the positive allometry of both infratemporal and mandibular fenestrae, suggest that Mariliasuchus amarali gradually increased its control and capacity of food processing along its ontogeny. The ontogenetic analysis also provided compeling evidence that specimen UFRJ-DG 56-R, interpreted by Nobre et al. (2007a) as a new species of the genus Mariliasuchus (M. robustus), is actually an individual of M. amarali in an advanced stage of development rather than a new species. Specimen MZSP-PV 760 is described for the first time here. Its anatomical characteristics suggest that this individual is not a juvenile specimen of Mariliasuchus amarali, as previously thought, but rather appears to be related to the clade that includes both M. amarali and Adamantinasuchus navae (another Bauru Basin crocodyliform). MZSP-PV 760 represents the youngest post-hatchling crocodyliform described for the Cretaceous of Gondwana. A reevaluation of the highly heterodont dentition of M. amarali showed the occurrence of a new tooth morphotype (premolariform), described here for the first time. A crown from each tooth morphotype was extracted from the specimen MZSP-PV 813 to perform an analysis of the enamel microanatomy and organizational patterns of enamel crystallities, described for the first time within Notosuchia. The description of a new tooth morphotype represents an unexpected addition to an already complex heterodont condition in M. amarali, adding to OConnor et al.s (2010) hypothesis that Notosuchia could have filled complex niches and ecomorphospaces during the Cretaceous of Gondwana similar to the ones occupied by mammals.
52

Da variabilidade morfológica à diversidade taxonômica em Proboscoida (Cnidaria, Hydrozoa): inferências filogenéticas e morfométricas para a delimitação de linhagens / From morphological variability to taxonomic diversity in Proboscoida (Cnidaria, Hydrozoa): phylogenetic and morphometric inferences for lineages delimitation

Cunha, Amanda Ferreira e 27 April 2016 (has links)
A variabilidade morfológica é comum em vários táxons marinhos, e os membros de Cnidaria Medusozoa se destacam por expressar a variabilidade em diferentes níveis, especialmente considerando as diferentes fases do ciclo de vida. Entretanto, muitos problemas taxonômicos surgem a partir das dificuldades em interpretar os níveis de variação, já que variações intraespecíficas muitas vezes são interpretadas de forma imprecisa como interespecíficas, e vice-versa. Neste estudo, revisamos os padrões de variação morfológica em Cnidaria Medusozoa, avaliando sua influência na taxonomia e diversidade do grupo. Seguindo essa abordagem, investigamos as relações filogenéticas da subordem Proboscoida, testando a relevância dos caracteres morfológicos diagnósticos tradicionais para a delimitação de linhagens em vários níveis taxonômicos. Além disso, avaliamos os seus padrões de variação morfológica, contrastando dados morfométricos e filogenéticos. Ficou claro que a variação intraespecífica em Medusozoa está frequentemente correlacionada com a variação interespecífica, e existe sobreposição entre os diferentes níveis. Igualmente, mostramos que a diversidade de espécies em Medusozoa está imprecisamente estimada, e existe ainda um grande potencial para a descoberta de espécies crípticas em Hydrozoa. Isso foi comprovado em Proboscoida, já que seus padrões filogenéticos mostraram que vários grupos não são monofiléticos, incluindo a família Clytiidae, os gêneros Campanularia, Clytia, Obelia e Laomedea, e as espécies Orthopyxis integra, Clytia gracilis e Obelia dichotoma. Da mesma forma, vários caracteres diagnósticos tradicionais resultaram não informativos para a delimitação de espécies e gêneros. Por outro lado, encontramos padrões morfométricos consistentes entre caracteres investigados em diferentes níveis de comparação. Dentre eles, tamanho e forma da hidroteca, espessura do perissarco, assim como número e altura das cúspides da hidroteca corroboraram a delimitação de várias linhagens. Nosso estudo demonstrou a importância das análises que combinam dados morfométricos e filogenéticos, especialmente quando a amplitude de variação dos caracteres morfológicos é detalhadamente comparada e investigada. Estudos em Hydrozoa, assim como Medusozoa e outros táxons marinhos se beneficiarão dessa abordagem, estabelecendo espécies válidas bem fundamentadas, e aprimorando nossas estimativas sobre a diversidade de espécies no ambiente marinho / Morphological variability is common in several marine taxa, and members of Cnidaria Medusozoa are noticeable for expressing variability in many different levels, especially in different phases of the life cycle. However, difficulties in interpreting the levels of variation have posed many taxonomic problems, since intraspecific variations are often misinterpreted as interspecific variations, and vice-versa. In this study, we reassessed patterns of morphological variation in Cnidaria Medusozoa to evaluate their influence on the taxonomy and diversity of the group. Following this approach, we investigated the phylogenetic relationships in the suborder Proboscoida, testing the relevance of traditional morphological diagnostic characters for delimiting lineages in several taxonomic levels. Also, we evaluated their patterns of morphological variation, contrasting morphometric and phylogenetic data. It is clear that in Medusozoa intraspecific variation often parallels interspecific variation, and there is overlap between the different levels. In addition, we show that species diversity in Medusozoa is probably misestimated, and there is still a great potential for the discovery of cryptic species in Hydrozoa. This is true for Proboscoida, since their phylogenetic patterns showed that several groups are not monophyletic, including the family Clytiidae, the genera Campanularia, Clytia, Obelia and Laomedea, and the species Orthopyxis integra, Clytia gracilis and Obelia dichotoma. Similarly, several traditional diagnostic characters were shown not be informative for the delimitation of species and genera. On the other hand, we found consistent morphometric patterns among characters investigated at different levels of comparison. Among them, size and shape of hydrotheca, perisarc thickness, as well as number and height of hydrothecal cusps, supported the delimitation of several lineages. Our results showed the importance of analyses combining phylogenetic and morphometric data, especially when the ranges of variation of morphological characters are compared and investigated in detail. Studies on Hydrozoa, as well as Medusozoa and other marine taxa will benefit from this approach, establishing well grounded valid species and refining our assessments of marine species diversity
53

Revisão sistemática e ontogenética dos materiais cranianos atribuídos ao gênero Mariliasuchus (Crocodyliformes, Notosuchia) e suas implicações taxonômicas e paleobiológicas / Sistematic and ontogenetic review of the cranial materials assigned to the genus Mariliasuchus (Crocodyliformes, Notosuchia) and its taxonomic and palaeobiological implications

Bruno Gonçalves Augusta 22 November 2013 (has links)
Mariliasuchus amarali Carvalho & Bertini 1999 é um crocodilomorfo Notosuchia do Cretáceo da Bacia Bauru. Este táxon possui um registro fóssil relativamente comum, e diversos espécimes (incluindo animais juvenis) são conhecidos. Portanto, ele representa um dos poucos táxons fósseis que permitem uma análise ontogenética, e seu desenvolvimento foi comparado com o do gênero Caiman (incluindo C. latirostris, C. crocodilus e C. yacare), um crocodilomorfo atual de ampla distribuição pela América do Sul. Foram empregadas as seguintes metodologias para comparação das trajetórias ontogenéticas dos táxons fóssil e atual: descrição qualitativa, morfometria linear e morfometria geométrica. Os dados obtidos destacaram trajetórias ontogenéticas comuns aos dois táxons, que foram interpretadas como o resultado de um padrão plesiomórfico aos Crocodyliformes, e distintas trajetórias ontogenéticas que foram relacionadas, principalmente, a diferentes adaptações ecomorfológicas. A ocorrência de tendências ontogenéticas como a manutenção de uma fenestra supratemporal de grandes proporções ao longo da ontogenia, a expansão anterior do articular e do côndilo mandibular do quadrado, o aumento na espessura da camada de esmalte dentário e a alometria positiva das fenestras infratemporal e mandibular sugerem que Mariliasuchus amarali aumentava gradativamente seu controle e capacidade de processamento alimentar ao longo de seu desenvolvimento. A análise ontogenética também mostrou fortes evidências de que o espécime UFRJ-DG 56-R, interpretado por Nobre et al. (2007a) como uma nova espécie dentro do gênero Mariliasuchus (M. robustus), é na verdade um indivíduo de M. amarali em avançado estágio de desenvolvimento e não uma nova espécie. O espécime MZSP-PV 760 é descrito pela primeira vez no presente trabalho. Suas características anatômicas sugerem que o mesmo não é um indivíduo juvenil de Mariliasuchus, como pensado anteriormente, mas parece estar relacionado ao clado que inclui ambos M. amarali e Adamantinasuchus navae (outro crocodilomorfo da Bacia Bauru). MZSP-PV 760 representa o mais jovem crocodilomorfo pós-embrionário já descrito para o Cretáceo de Gondwana. Uma reanálise da dentição altamente heterodonte em M. amarali mostrou a ocorrência de um novo morfótipo dentário (pré-molariforme), descrito pela primeira vez no presente trabalho. Uma coroa de cada morfótipo dentário foi extraída do espécime MZSP-PV 813 para análise da microanatomia do esmalte dentário e do padrão de organização dos cristais de esmalte, descritos pela primeira vez para um Notosuchia. A descrição de um novo morfótipo dentário representa uma inesperada adição para uma já complexa condição heterodonte em M. amarali, corroborando com a hipótese de OConnor et al. (2010) de que os Notosuchia podem ter ocupado nichos ecológicos e ecomorfoespaços, durante o Cretáceo do Gondwana, tão complexos quanto os de mamíferos. / Mariliasuchus amarali Carvalho & Bertini 1999 is a notosuchian crocodyliform from the Cretaceous of Bauru Basin (Brazil). This taxon has a fossil record that is relatively common, and several specimens (including juveniles) are known. Therefore, it represents one of the few fossil taxa that allows an ontogenetic approach, and its development was compared with the genus Caiman (including C. latirostris, C. crocodilus and C. yacare), a widespread South American crocodyliform. I used the following methodologies for the comparison of the ontogenetic trajectories of the fossil and living taxa: qualitative description, traditional morphometrics and geometric morphometrics. The data highlighted common ontogenetic trajectories that were interpreted as the result of a plesiomorphic pattern for Crocodyliformes, and distinct ontogenetic trajectories that were related mainly to different ecomorphological adaptations. The occurrence of ontogenetic trends as the retention of a large supratemporal fenestra along the ontogenetic development, the anterior expansion of the articular and the articular condyle of the quadrate, the thickening of the enamel cap in the teeth crowns, and the positive allometry of both infratemporal and mandibular fenestrae, suggest that Mariliasuchus amarali gradually increased its control and capacity of food processing along its ontogeny. The ontogenetic analysis also provided compeling evidence that specimen UFRJ-DG 56-R, interpreted by Nobre et al. (2007a) as a new species of the genus Mariliasuchus (M. robustus), is actually an individual of M. amarali in an advanced stage of development rather than a new species. Specimen MZSP-PV 760 is described for the first time here. Its anatomical characteristics suggest that this individual is not a juvenile specimen of Mariliasuchus amarali, as previously thought, but rather appears to be related to the clade that includes both M. amarali and Adamantinasuchus navae (another Bauru Basin crocodyliform). MZSP-PV 760 represents the youngest post-hatchling crocodyliform described for the Cretaceous of Gondwana. A reevaluation of the highly heterodont dentition of M. amarali showed the occurrence of a new tooth morphotype (premolariform), described here for the first time. A crown from each tooth morphotype was extracted from the specimen MZSP-PV 813 to perform an analysis of the enamel microanatomy and organizational patterns of enamel crystallities, described for the first time within Notosuchia. The description of a new tooth morphotype represents an unexpected addition to an already complex heterodont condition in M. amarali, adding to OConnor et al.s (2010) hypothesis that Notosuchia could have filled complex niches and ecomorphospaces during the Cretaceous of Gondwana similar to the ones occupied by mammals.
54

Discerning hominid taxonomic variation in the southern Chinese, peninsular Southeast Asian, and Sundaic Pleistocene dental record

Avalos, Toby R. 01 August 2017 (has links)
Today’s highly endangered orangutan populations of Sumatra and Borneo offer but a glimpse into the taxonomic diversity and vast regional distribution enjoyed by orangutans and their great ape relatives in East Asia over the past 2.5 million years—a time when tropical forest pongine habitats stretched from Java to southern China. In addition to the giant terrestrial ape Gigantopithecus, other great ape genera have been proposed to have existed within this hominid community. The taxonomic diversity of this great ape faunal array is even further complicated when the purported presence of hominins at Early Pleistocene sites older than 1.85 Ma is considered. Highly acidic, the jungle floors of East Asia are notoriously bad at fossil preservation decomposing skeletal and dental evidence quickly. Fortunately, ph-neutral limestone caves have acted to offset these forces. The outcome of this peculiar taphonomy has left us with many teeth, but very little bone. With only unassociated fossil dentition to work with, modern geometric morphometrics offers scientists one of the few cutting-edge tools capable of systematically assessing this material reliably. This dissertation applies modern geometric morphometric statistical analysis to over two thousand fossil hominid teeth (Appendix A) from the Quaternary of southern China and Southeast Asia, which offers unique insight into the taxonomic diversity present in this sole Pleistocene great ape community. This study provides a much clearer understanding of the composition, paleoecology, and regional distribution of Pleistocene great ape communities of East Asia. Concordant with previous research, the main study and pilot study conducted in this dissertation showed Homo sapiens to always be morphologically and statistically distinct from extant and fossil orangutans. In turn, Pongo pygmaeus and Pongo abelii were continuously shown to be distinct from each other as well as from fossil Pongo groups. This investigation refutes hominin assignments for several teeth previously placed within early East Asian hominins (showing them to be orangutans instead) but supports the hominin status of the Jianshi upper third premolar. In combination with a published age of 1.95–2.15 million years (Ma), the hominin assignment reaffirmed here for the Jianshi dentition originally classified as human by Liu, Clarke, & Xing (2010) may offer a challenge to evolutionary models that recognize the 1.85 Ma Dmanisi hominins as the earliest hominins outside of Africa. This fact is often lost on most contemporary scientists due to their preoccupation with the 2.5 Ma Longgupo mandibular fragment, once thought to be a hominin but now assignable to an ape. Like the Jianshi upper third premolar, it is also based on a single specimen (in this case, a mandibular fragment). This dissertation supports the existence of Ciochon’s (2009) “mystery ape”. It refutes Schwartz et al., (1995) multiple Vietnamese Pongo taxa, including the proposed genus “Langsonia,” which is reassigned here to Pongo or the “mystery ape,” while placing Vietnamese fossil orangutans into either Pongo weidenreichi or Pongo devosi. Teeth from the Ralph von Koenigswald collection originally assigned to “Hemanthropus” were also determined to be representative of either the “mystery ape” or Pongo. Indeterminate “hominin” teeth were assignable to either Homo erectus, Homo sapiens, or Pongo only; no evidence was found for any other types of hominin species present in the collections examined for this study.
55

Evolution Of shape morphologic variation of the genus Undaria (Scleractinia, Agariciidae)

Rhodes, Kristopher J S 01 May 2010 (has links)
In this study, the corallite shapes of three species of the scleractinian genus Undaria from the Yague group, Dominican Republic, were examined through a period of time stretching from 6.4 mya to 3.4 mya, a total of 3.0 ma. Corallite shape was measured using 3 dimensional landmarks and manipulated using the well established procedures of geometric morphometrics. Differences in shape and size through time were examined using a variety of tools, including canonical variates analysis, principal components analysis, least squares regression, partial least squares regression, and a variety of evolutionary model fits. Evolutionary model fits were used to test three models against the shape and size variables: general random walk, which models a directional change through time; unbiased random walk, which models random change through time; and stasis, which models stability through time. Stasis is the most common parameter through time, supported in 9 of 15 (60%) of cases, while the unbiased random walk was supported 6 of 15 times. While there was a significant change in one species associated with environmental variables, those variables were also correlated with time and no causal relationship can be reached.
56

Etude de la diversité trophique des poissons demoiselles (Perciformes, Pomacentridae) par l'examen des variations du squelette céphalique à partir de leur vie récifale

Frederich, Bruno 15 June 2009 (has links)
Les poissons demoiselles (Pomacentridae) représentent lune des familles les plus importantes des récifs coralliens ; du point de vue du nombre despèces (> 350) et de leur abondance. Malgré cette importance, très peu détudes ont abordé leur diversité trophique et morphologique. Comme la majorité des poissons coralliens, les demoiselles possèdent un cycle de vie complexe divisé en deux phases : (1) une phase larvaire pélagique et océanique potentiellement dispersive et (2) une phase juvénile et adulte sédentaire associée à lhabitat corallien. La fin du stade larvaire coïncide avec la colonisation du récif. Le milieu océanique offre un habitat relativement homogène pour toutes les larves de Pomacentridae et celles-ci se nourrissent exclusivement de copépodes planctoniques. Au contraire, le récif propose une grande variété dhabitats et de ressources alimentaires. Au cours de leur ontogénie, les demoiselles subissent donc un changement de mode de vie qui doit saccompagner de modifications morphologiques, physiologiques et comportementales pour optimiser leur survie dans chaque environnement. La présente thèse a pour premier objectif de tester lhypothèse selon laquelle la plus grande diversité trophique attendue au stade adulte saccompagne dune plus grande disparité (mesure de la diversité morphologique au sein dun taxon) que chez les larves. Répondre à cet objectif a nécessité dorganiser la recherche selon trois axes. Premièrement, Lanalyse des contenus stomacaux et des isotopes stables du carbone et de lazote chez treize espèces a permis de mettre en évidence trois comportements alimentaires : (1) les « pelagic feeders » qui se nourrissent presquexclusivement de copépodes planctoniques, (2) les « benthic feeders » qui sont des espèces principalement herbivores broutant des algues filamenteuses et (3) un groupe intermédiaire incluant des espèces qui se nourrissent en proportions variables dans le compartiment pélagique et benthique (ex : copépodes planctoniques et benthiques, petits invertébrés vagiles et sessiles, algues filamenteuses). La littérature signale en plus deux demoiselles spécialisées dans la consommation exclusive de polypes de coraux. Deuxièmement, une étude écomorphologique a caractérisé la diversité du squelette céphalique chez les adultes. Les variations de forme de quatre unités du squelette céphalique (le neurocrâne, lunité « suspensorium et opercule », la mandibule et le prémaxillaire) ont été explorées au moyen de la morphométrie géométrique chez quatorze espèces adultes montrant des régimes alimentaires différents. Les résultats révèlent un parallélisme entre la diversité du squelette céphalique et la diversité des régimes alimentaires présent au stade adulte. Dune manière générale, les demoiselles planctonophages possèdent des caractères squelettiques optimisant la prise de nourriture par aspiration (ex : hauts suspensoria et opercules, une large crête supraoccipitale, des mandibules courtes formant une petite bouche). Les espèces brouteuses montrent des pièces squelettiques plus robustes (ex : mandibules hautes et massives, hyomandibulaires larges). Parmi les espèces zooplanctonophages, Chromis viridis et C. acares montrent une morphologie céphalique assez divergente de celle des autres. Leurs caractéristiques squelettiques laissent supposer un mode de prise de nourriture où le poisson capture sa proie en nageant vers elle bouche ouverte (type « ram-suction feeder »). La dentition buccale nest pas toujours corrélée au régime alimentaire. Troisièmement, lontogénie post-colonisation et la variation du niveau de disparité squelettique ont été étudiées et comparées chez huit espèces représentant un échantillon complet de la diversité trophique de la famille. Après la colonisation, les demoiselles subissent des allométries de croissance importantes (40 à 87% des variations de forme). La disparité morphologique est plus grande au stade adulte quau stade de la colonisation pour chaque structure squelettique céphalique. Lensemble des paramètres développementaux étudiés ont subi des changements évolutifs. À la colonisation, les formes larvaires sont déjà spécifiques, probablement à cause de différences dans la durée de vie larvaire pélagique des espèces. Laugmentation de la disparité au cours du développement post-colonisation est essentiellement due à la divergence des patrons allométriques. La longueur des trajectoires ontogénétiques et les vitesses de développement apparaissent comme deux facteurs moins variables. Dune manière générale, peu de liens existent entre les données phylogénétiques ou écologiques (régime, durée de vie larvaire,) et les paramètres développementaux. La diversité du genre Dascyllus illustre des cas de gigantisme. Les méthodes de morphométrie géométrique montrent que les petites espèces et les espèces géantes partagent les mêmes trajectoires ontogénétiques pour le neurocrâne et la mandibule. Au sein de ce groupe, lapparition despèces de grande taille au cours de lévolution résulterait de processus hétérochroniques. La morphologie céphalique larvaire suggère une prise de nourriture de type « ram/suction feeding ». Chez toutes les espèces étudiées, les patrons allométriques révèlent une optimisation du système de prise de nourriture par aspiration au cours du développement. Les demoiselles acquièrent au cours de leur croissance des joues et de opercules proportionnellement plus hauts, une crête supraoccipitale plus grande, des mandibules plus courtes et un processus ascendant du prémaxillaire plus long. Chez les espèces herbivores, dautres changements de forme sont liés à lacquisition de capacités de morsure et de découpe. Par exemple, les mandibules et les suspensoria deviennent plus massifs.
57

Identification, Distribution and Control of an Invasive Pest Ant, Paratrechina sp. (Hymenoptera: Formicidae), in Texas

Meyers, Jason 16 January 2010 (has links)
Invasive species are capable of causing considerable damage to natural ecosystems, agricultures and economies throughout the world. These invasive species must be identified and adequate control measures should be investigated to prevent and reduce the negative effects associated with exotic species. A recent introduction of an exotic ant, Paratrechina sp. nr. pubens, has caused tremendous economic and ecological damage to southern Texas. Morphometric and phylogenetic procedures were used to identify this pest ant, P. sp. nr. pubens, to Southern Texas. The populations in Texas were found to be slightly different but not discriminating from P. pubens populations described in previous literature. Analysis of the distribution and expansion of P. sp. nr. pubens found numerous geographically discrete populations and moderately expanding territories. These expansion rates were determined to be ~20 and ~30 m per mo for a neighborhood and industrial area, respectively. Several laboratory and field control strategies were implemented for control of this intensely pestiferous species. Dinotefuran exhibited high laboratory efficacy against P. sp. nr. pubens, while treatments using novaluron were inconclusive. The use of expanded-use Termidor� demonstrated trends in these data that suggest it as the treatment of choice. Other field treatments, such as Termidor and Top Choice�, Termidor and Advance Carpenter Ant BaitTM, and Transport� and Talstar� G, did not attain the success found in the expanded-use Termidor treatment. Most treatments examined were determined ineffective against high populations of P. sp. nr. pubens. Additional and more intensive population management regimes should be investigated. Abating further P. sp. nr. pubens population proliferation to other regions will only be realized from additional control research supplemented with state and federal interdiction policies.
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A Behavioral Analysis of Clovis Point Morphology Using Geometric Morphometrics

Smith, Heather Lynn 2010 December 1900 (has links)
This thesis presents an investigation into Paleoindian projectile-point morphology. A goal of this research is to determine if evidence of a normative cultural manufacturing protocol can be identified on Clovis projectile points which can then be used to address research questions concerning Clovis point variability, and ultimately, the spread of this tool-form across North America. This paper addresses obstacles to behavioral investigations of stone tool morphology such as the effects of resharpening and raw material type on tool shape. I argue that a culturally normative process of manufacture was maintained throughout the life-history of Clovis projectile points which translated into a specific shape maintained to the time of exhaustion and discard. As an analytical tool, this study utilizes the geometric morphometric method to retain the geometry of each artifact throughout analysis by focusing on spatial covariation among landmarks uniformly found on each tool. This thesis investigates variability in 123 fluted projectile points from 23 archaeological sites in North America which met criteria meant to control for security of context in the archaeological record. Principle components describing the shape-variability inherent in this data-set were generated using geometric morphometrics and multivariate statistical analyses were employed to identify major factors of variability. This research concluded that Clovis projectile-point shape was determined by normative cultural behavior maintained throughout the life of the artifact and not the result of raw material type or resharpening processes. Therefore, the projectile-point variability found to be geographically patterned provided evidence of Paleoindian movement and the spread of tool form. Multivariate analysis of variance determined that a regional trend in variability was present. The distribution of within-site variance suggested that artifacts from sites in the West were very homogeneous while artifacts from Eastern sites were more variable. The multivariate cluster and discriminant function analyses also demonstrated a closer affinity between artifacts in the Southwest and Northwest than either has with the Northeast. The similarities in projectile point morphology between the Southwest and Northwest regions suggest movement beginning with a Southwest point of origin from which Pleistocene peoples may have carried their fluted point technology north and east.
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Phylogeny and Biogeography of the Genus Capricornis (Artiodactyla: Bovidae) Based on Mitochondrial DNA Sequences and Cranial Morphometrics

Chang, Hsun-Cheng 27 June 2002 (has links)
The genus Capricornis Ogilby, 1837, is divided into three species and widely distributed in sourthern China, Tibet, Myanmar, IndoChinese peninsula, Malaysia peninsula, Sumatra, Japanese archipelagos and Taiwan. Using complete cytochrome b sequences (1140 bp) analyzes the genetic variation and phylogeny of genus Capricornis from Taiwan, Japan and Mainland China. Constructed by both distance and maximum parsimony methods, the phyloenetic tree distinguish the Capricornis to three clades: Formosan serow, Japanese serow, and Sumatran serow from mainland China. Formosan serow is more familiar with Sumatran serow than Japanese serow. Local populations of Formosan serow of Taiwan island and Japanese serow of the Japanese archipelagos are already differentiated. Serow and goral are apparently distinguishable. The results of Principal Component Analysis and Discriminant Analysis show that serows from Taiwan, Japan and mainland China and goral are apparently distinguishable at morphological characters. The variation of morphological analysis may be a good tool to identify serow and goral. From the paleogeology and fossil records of serow of Quaternary, we could infer that ancestors of serow from southwestern mountain of mainland China migrated to Taiwan island and Japanese archipelagos through the land bridge of east Asian islands to mainland China in the early Pleistocene caused by the glaciation of Quaternary, then separated from mainland of east Asia and speciation of serow occured in Taiwan island and Japanese archipelagos after the end of the glaciation of Quaternary.
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Predator induced defenses in prey with diverse predators

Garza, Mark Isaac 12 April 2006 (has links)
Phenotypic plasticity is an environmentally based change in phenotype and can be adaptive. Often, the change in an organism's phenotype is induced by the presence of a predator and serves as a defense against that predator. Defensive phenotypes are induced in freshwater physid snails in response to both crayfish and molluscivorous fish. Alternative morphologies are produced depending on which of these two predators snails are raised with, thus protecting them from each of these predators' unique mode of predation. Snails and other mollusks have been shown to produce thicker, differently shaped shells when found with predators relative to those found without predators. This production of thicker, differently shaped shells offers better protection against predators because of increased predator resistance. The first study in this thesis explores costs and limits to plasticity using the snailfish- crayfish system. I exposed juvenile physid snails (using a family structure) to either early or late shifts in predation regimes to assess whether developmental flexibility is equally possible early and late in development. Physid snails were observed to produce alternative defensive morphologies when raised in the presence of each of the two predators. All families responded similarly to the environment in which they were raised. Morphology was found to be heritable, but plasticity itself was not heritable. Morphology was found to become less flexible as snails progressed along their respective developmental pathways. In the second study, I raised physid snails with and without shell-crushing sunfish and examined the differences in shell thickness, shell mass, shell size and shell microstructural properties between the two treatment groups. Shells of snails raised with predators were found to be larger, thicker and more massive than those raised without predators, but differences in microstructure were found to be insignificant. I conclude that the observed shell thickening is accomplished by the snails' depositing more of the same material into their shells and not by producing a more complex shell composition.

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