| 1. |
- Sköld, Helen Nilsson, et al.
(författare)
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Hormonal regulation of female nuptial coloration in a fish.
- 2008
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Ingår i: Hormones and behavior. - : Elsevier BV. - 1095-6867 .- 0018-506X. ; 54:4, s. 549-56
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Tidskriftsartikel (refereegranskat)abstract
- Physiological color change in camouflage and mating is widespread among fishes, but little is known about the regulation of such temporal changes in nuptial coloration and particularly concerning female coloration. To better understand regulation of nuptial coloration we investigated physiological color change in female two-spotted gobies (Gobiusculus flavescens). Females of this species develop an orange belly that acts as an ornament. The orange color is caused by the color of the gonads combined with the chromathophore based pigmentation and transparency of the skin. Often during courtship and female-female competition, a rapid increase in orange coloration, in combination with lighter sides and back that increases skin and body transparency, gives the belly an intense 'glowing' appearance. To understand how this increased orange coloration can be regulated we analysed chromatic and transparency effects of neurohumoral agents on abdominal skin biopsies in vitro. We found prolactin and alpha-melanocyte stimulating hormone (MSH) to increase orange coloration of the skin. By contrast, melatonin and noradrenaline increased skin transparency, but had a negative effect on orange coloration. However, mixtures of melatonin and MSH, or melatonin and prolactin, increased both orange coloration and transparency. This effect mimics the chromatic 'glow' effect that commonly takes place during courtship and intra sexual aggression. Notably, not only epidermal chromatophores but also internal chromatophores lining the peritoneum responded to hormone treatments. There were no chromatic effects of the sex steroids 17beta-estradiol, testosterone or 11-ketotestosterone. We hypothesize that similar modulation of nuptial coloration by multiple hormones may be widespread in nature.
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| 2. |
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| 3. |
- Koch, Kamilla, et al.
(författare)
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Morphological differences in the ovary of Libellulidae (Odonata)
- 2009
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Ingår i: International Journal of Odonatology. - Oxford : Taylor & Francis. - 1388-7890 .- 2159-6719. ; 12:1, s. 147-156
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Tidskriftsartikel (refereegranskat)abstract
- All female Odonata have been assumed to produce oocytes continuously during their mature life span. However, a recent study of ovariole orientation and development led to the suggestion that Libellulidae are divided into two groups of species, one with continuous, the other with stepwise oocyte production. To find more evidence of this division, we compared the size variation and growth within the vitellarium of the ovary, studying oocytes, and follicle cells. We found that morphological characters discriminate between the two ovary types in eight of the 10 investigated species. In both types we found an increase in all measurements from the anterior to the posterior end of the vitellarium. The increase in oocyte width and follicle cell length was significantly higher in species with a continuous oocyte production. We also noted that follicle cells may have more than one nucleus and that their number can vary during vitellogenesis. Our study confirmed the hypotheses that two different ovary types exist in Libellulidae. The two species not fitting into this grouping could be an artefact of small samp le size due to intraspecific phenotypic plasticity, or else there might be more than two ovary groups, or even a continuum. We could not offer an explanation as to how the process of stepwise oocyte production differs from continuous based production on morphological characters.
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| 4. |
- Nakano, Hiroaki, 1977, et al.
(författare)
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Developmental Studies of Xenoturbella
- 2008
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Ingår i: Journal of Morphology. - 0362-2525. ; 269, s. 1477-1478
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Schneider, Nicole, et al.
(författare)
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Influence and value of different water regimes on avian species richness in arid inland Australia
- 2009
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Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 18:2, s. 457-471
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Tidskriftsartikel (refereegranskat)abstract
- Riparian habitats in arid landscapes are recognised for their structurally diverse vegetation and diverse bird species assemblages. In the extensive semi-arid and arid centre of Australia, riparian woodland habitats are impacted by pastoral land-use which may negatively influence vegetation structure and avian species composition. However, pastoralism has promoted the establishment of artificial water bodies, so that additional riparian vegetation may occur in the landscape. In this study, we surveyed the importance of different water regimes (i.e. artificial lakes, natural waterholes, desert sites) together with their associated vegetation on avian species richness in north-western New South Wales, Australia. Our results show that bird species richness was highest at water locations, in particular at artificial lakes. Avian species richness was negatively associated with distance to water bodies, both in desert vegetation types and in the riparian vegetation type along dry creeks. Moreover, riparian habitats supported larger avian assemblages and especially those of sedentary bird species compared to the surrounding shrub-steppe landscape. This indicates that artificial water bodies may be of significance for arid zone bird species and might gain in importance with changing water availabilities due to climatic changes.
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| 6. |
- Uller, Tobias, 1977, et al.
(författare)
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Direct exposure to corticosterone during embryonic development influences behaviour in an ovoviviparous lizard
- 2006
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Ingår i: ETHOLOGY. - : Wiley. - 0179-1613 .- 1439-0310. ; 112:4, s. 390-397
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Tidskriftsartikel (refereegranskat)abstract
- It is becoming increasingly clear that conditions experienced during embryonic development can be of major importance for traits subsequent to parturition or hatching. For example, in mammals, offspring from stressed mothers show a variety of changes in behavioural, morphological, and life-history traits. The effects of maternal stress on trait development are believed to be mediated via transfer of glucocorticoids, the main hormones released during the stress response, from mother to offspring. However, also other physiological maternal responses during stress could be responsible for changes in offspring phenotype. We investigated the direct effects of corticosterone on offspring development, without other confounding factors related to increased maternal stress, by injection of corticosterone in eggs of the ovoviviparous lizard Lacerta vivipara. Corticosterone-manipulated offspring did not show impaired development, reduced body size or body condition at parturition. However, corticosterone-treated offspring showed altered anti-predator behaviour, as measured by the time required to emerge from shelter after a simulated predator attack. Differential steroid exposure during development, possibly mediated by maternal stress response, may explain some of the variation in behaviour among individuals in natural populations.
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| 7. |
- Antonelli, Alexandre, 1978
(författare)
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Have giant lobelias evolved several times independently? Life form shifts and historical biogeography of the cosmopolitan and highly diverse subfamily Lobelioideae (Campanulaceae)
- 2009
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Ingår i: BMC BIOLOGY. - : Springer Science and Business Media LLC. - 1741-7007. ; 7:82
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Tidskriftsartikel (refereegranskat)abstract
- Background: The tendency of animals and plants to independently develop similar features under similar evolutionary pressures - convergence - is a widespread phenomenon in nature. In plants, convergence has been suggested to explain the striking similarity in life form between the giant lobelioids (Campanulaceae, the bellflower family) of Africa and the Hawaiian Islands. Under this assumption these plants would have developed the giant habit from herbaceous ancestors independently, in much the same way as has been suggested for the giant senecios of Africa and the silversword alliance of Hawaii. Results: Phylogenetic analyses based on plastid (rbcL, trnL-F) and nuclear (internal transcribed spacer [ITS]) DNA sequences for 101 species in subfamily Lobelioideae demonstrate that the large lobelioids from eastern Africa the Hawaiian Islands, and also South America, French Polynesia and southeast Asia, form a strongly supported monophyletic group. Ancestral state reconstructions of life form and distribution, taking into account phylogenetic uncertainty, indicate their descent from a woody ancestor that was probably confined to Africa. Molecular dating analyses using Penalized Likelihood and Bayesian relaxed clock approaches, and combining multiple calibration points, estimate their first diversification at similar to 25-33 million years ago (Ma), shortly followed by several long-distance dispersal events that resulted in the current pantropical distribution. Conclusion: These results confidently show that lobelioid species, commonly called 'giant', are very closely related and have not developed their giant form from herbaceous ancestors independently. This study, which includes the hitherto largest taxon sampling for subfamily Lobelioideae, highlights the need for a broad phylogenetic framework for testing assumptions about morphological development in general, and convergent evolution in particular.
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| 8. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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Pollination of the Lady's slipper orchid (Cypripedium calceolus) in Scandinavia - taxonomic and conservational aspects
- 2009
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 27:4, s. 266-273
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Tidskriftsartikel (refereegranskat)abstract
- The Lady's slipper orchid Cypripedium calceolus L. is considered one of the most beautiful orchids of Europe. Consequently, the species has suffered from over-collecting and is now critically endangered in many countries. Although pollination success is suspected to influence the long-term survival of Cypripedium calceolus, relatively little is known about the identity of its pollinators in mainland Sweden - a region that comprises the largest European populations. In order to identify which species pollinate eight representative populations in mainland Sweden, we observed and sampled visitors to flowers using a standardized protocol. Specimens were identified and any pollen smear found on their body was examined for the presence of Cypripedium pollen. Nine species were recognized as effective pollen vectors (Andrena cineraria, A. carantonica, A. haemorrohoa, A. helvola, A. nigroaenea, A. praecox, Colletes cunicularius, Lasioglossum fratellum and L. fulvicorne), four of them for the first time in Scandinavia. This is the first time that a species of Colletes is reported to carry pollen of Cypripedium in this region. All but one specimens were females. Our results suggest a taxonomically heterogeneous pollinator fauna for Cypripedium calceolus and are discussed in light of the management of this species.
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| 9. |
- Antonelli, Alexandre, 1978, et al.
(författare)
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Tracing the impact of the Andean uplift on Neotropical plant evolution
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 106:24, s. 9749-9754
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Tidskriftsartikel (refereegranskat)abstract
- Recent phylogenetic studies have revealed the major role played by the uplift of the Andes in the extraordinary diversification of the Neotropical flora. These studies, however, have typically considered the Andean uplift as a single, time-limited event fostering the evolution of highland elements. This contrasts with geological reconstructions indicating that the uplift occurred in discrete periods from west to east and that it affected different regions at different times. We introduce an approach for integrating Andean tectonics with biogeographic reconstructions of Neotropical plants, using the coffee family (Rubiaceae) as a model group. The distribution of this family spans highland and montane habitats as well as tropical lowlands of Central and South America, thus offering a unique opportunity to study the influence of the Andean uplift on the entire Neotropical flora. Our results suggest that the Rubiaceae originated in the Paleotropics and used the boreotropical connection to reach South America. The biogeographic patterns found corroborate the existence of a long-lasting dispersal barrier between the Northern and Central Andes, the "Western Andean Portal.'' The uplift of the Eastern Cordillera ended this barrier, allowing dispersal of boreotropical lineages to the South, but gave rise to a huge wetland system ("Lake Pebas'') in western Amazonia that prevented in situ speciation and floristic dispersal between the Andes and Amazonia for at least 6 million years. Here, we provide evidence of these events in plants.
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| 10. |
- Fritsch, Peter W., et al.
(författare)
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Taxonomic Implications of Morphological Variation in Cercis canadensis (Fabaceae) from Mexico and Adjacent Parts of Texas
- 2009
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Ingår i: Systematic Botany. - : American Society of Plant Taxonomists. - 0363-6445 .- 1548-2324. ; 34:3, s. 510-520
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Tidskriftsartikel (refereegranskat)abstract
- Taxonomic treatments recognize three varieties of Cercis canadensis: with variety canadensis, widespread throughout the eastern United States, and varieties texensis and mexicana, found east and west of the Pecos River in Texas, respectively. The distribution of Cercis continues southward into northeastern Mexico, but complex variation in leaf shape has confounded straightforward application of varietal names to the Mexican plants. To clarify the taxonomy of Cercis in Mexico, we conducted a morphometric analysis with 281 herbarium specimens, including a representative set of samples from Texas. Correlation and principal component analysis of 12 characters recovered two groups that correspond to the presence versus absence of branchlet pubescence. These groups are geographically distinct at the northern and southern extremes of the focus area but exhibit a large central region of overlap. No other discontinuities in character states were discovered to corroborate this division. Leaf shape varies continuously from ovate-acuminate at the northern and southern extremes to subreniform in the central region, suggesting clinal adaptation to the mesic versus xeric environments in which the plants occur. Based on our data, we apply the varietal epithets mexicana and, provisionally, texensis to Mexican C. canadensis with pubescent and glabrous branchlets, respectively, the latter based on geographic proximity to plants in Texas in the absence of definitive evidence on the phenotypic distinction between varieties canadensis and texensis.
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