Bonato M.,Stellenbosch University |
Evans M.R.,Queen Mary, University of London |
Hasselquist D.,Ecology Building |
Sherley R.B.,University of Cape Town |
And 2 more authors.
Behavioral Ecology and Sociobiology | Year: 2013
One of the most important measures of offspring performance is growth rate, which is often traded off against another important survival trait, immune function. A particular feature of ostrich chicks maintained in farmed environments is that cohorts of chicks vary widely in size. As parents can have a profound effect on the phenotype and fitness of their offspring, we investigated whether chick growth and immune defence were related to variation in levels of immune defence in their genetic parents. As secondary sexual traits of sires could serve as indicators of male quality, and be used in female mating decisions, we also investigated whether chick growth rate and immune defence were related to male plumage and integumentary colouration. We found that offspring growth rates and humoral responses were related to the humoral responses of their parents, suggesting that at least some components of humoral immune capacity are heritable. The white colour of male ostrich feathers was correlated to the humoral response and growth rate of their offspring, suggesting that this visual cue involved in the male courtship display could serve as an important signal to females of male quality, thereby forming the basis of mate choice in this species. © 2013 Springer-Verlag Berlin Heidelberg.
Nilsson L.,Ecology Building |
De Jong A.,Swedish University of Agricultural Sciences |
Heinicke T.,Chausseestr.1 |
Sjoberg K.,Swedish University of Agricultural Sciences
Ornis Svecica | Year: 2010
In order to determine their breeding and moulting sites we fitted eight Taiga Bean Geese Anser fabalis fabalis and two Tundra Bean Geese A. f rossicus with satellite transmitters in 2007-2009 at their spring roosting sites at Umeå and Luleå, Sweden. Nine of these transmitters transferred GPS positions for 11 months. All positions were N-ENE of the catching sites. The Tundra Bean Geese migrated to Finnmark in Norway and neighbouring parts of Finland. The Taiga Bean. Geese migrated to sites near Övre Soppero (Sweden) and Kautokeino (Norway) in the west, through northern Finland, to Russian Karelia. Three of five Taiga Bean. Geese with, active transmitters flew to Novaya Zemlya to moult. Our results indicate that a significant proportion of the Taiga Bean Geese that migrate along the coast of northern Sweden in spring do not breed west of 20° E, and that many of them moult on Novaya Zemlya. The Tundra Bean Geese that pass through northern Sweden in spring belong to the Finnmark population that breeds slightly north, of the Taiga Bean Geese.
Pimentel C.,New University of Lisbon |
Santos M.,University of Lisbon |
Ferreira C.,New University of Lisbon |
Nilsson J.-A.,Ecology Building
Biological Journal of the Linnean Society | Year: 2012
The present study aimed to investigate the relationship between growth rate, final mass, and larval development, as well as how this relationship influences reproductive trade-offs, in the context of a gregarious life-style and the need to keep an optimal group size. We use as a model two sympatric populations of the pine processionary moth Thaumetopoea pityocampa, which occur in different seasons and thus experience different climatic conditions. Thaumetopoea pityocampa is a strictly gregarious caterpillar throughout the larval period, which occurs during winter in countries all over the Mediterranean Basin. However, in 1997, a population in which larval development occurs during the summer was discovered in Portugal, namely the summer population (SP), as opposed to the normal winter population (WP), which coexists in the same forest feeding on the same host during the winter. Both populations were monitored over 3years, with an assessment of the length of the larval period and its relationship with different climatic variables, final mass and adult size, egg size and number, colony size, and mortality at different life stages. The SP larval period was reduced as a result of development in the warmer part of the year, although it reached the same final mass and adult size as the WP. Despite an equal size at maturity, a trade-off between egg size and number was found between the two populations: SP produced less but bigger eggs than WP. This contrasts with the findings obtained in other Lepidoptera species, where development in colder environments leads to larger eggs at the expense of fecundity, but corroborates the trend found at a macro-geographical scale for T.pityocampa, with females from northern latitudes and a colder environment producing more (and smaller) eggs. The results demonstrate the importance of the number of eggs in cold environments as a result of an advantage of large colonies when gregarious caterpillars develop in such environments, and these findings are discussed in accordance with the major theories regarding size in animals. © 2011 The Linnean Society of London.
Kvist L.,University of Oulu |
Ponnikas S.,University of Oulu |
Belda E.J.,Polytechnic University of Valencia |
Encabo I.,University of Valencia |
And 7 more authors.
Journal of Ornithology | Year: 2011
In the Iberian Peninsula, populations of two subspecies of the Reed Bunting Emberiza schoeniclus have become increasingly fragmented during the last decades when suitable habitats have been lost and/or the populations have gone extinct. Presently, both subspecies are endangered. We estimated the amount of genetic variation and population structure in order to define conservation units and management practices for these populations. We found that the subspecies lusitanica has clearly reduced genetic variation in nuclear and mitochondrial markers, has a drastically small effective population size and no genetic differentiation between populations. In contrast, the subspecies witherbyi is significantly structured, but the populations still hold large amounts of variation even though the effective population sizes are smaller than in the non-endangered subspecies schoeniclus. We suggest several management units for the Iberian populations. One unit includes subspecies lusitanica as a whole; the other three units are based on genetically differentiated populations of witherbyi. The most important genetic conservation measure in the case of lusitanica is to preserve the remaining habitats in order to at least maintain the present levels of gene flow. In the case of the three management units within witherbyi, the most urgent conservation measure is to improve the habitat quality to increase the population sizes. © 2011 Dt. Ornithologen-Gesellschaft e.V.
Neto J.M.,University of Porto |
Hansson B.,Ecology Building |
Hasselquist D.,Ecology Building
Behavioral Ecology and Sociobiology | Year: 2011
Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi's warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the 'local resource competition' hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within-female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg. © 2010 Springer-Verlag.
Pimentel C.,New University of Lisbon |
Ferreira C.,New University of Lisbon |
Nilsson J.,Ecology Building
Biological Journal of the Linnean Society | Year: 2010
The present study aimed to investigate how the impact of several factors linked to geography would shape life-history traits in a gregarious species, using the pine processionary moth (PPM) Thaumetopoea pityocampa as a model system. PPM has a wide geographical distribution over the Mediterranean Basin, and it is a strictly gregarious species throughout larval development, where the total reproductive output of each female forms a colony. We reviewed both published and unpublished data on PPM from all over its distribution in the Mediterranean Basin and extracted data on fecundity, egg size, egg parasitoid mortality, flight period, and development time. These life-history traits were then related to location, expressed as latitude and altitude, local average temperatures, and host tree species. We found that PPM fecundity increaseed with latitude, concomitant with an increase in the length of development and an earlier onset of adult flight. These results are the opposite of that found in other Lepidoptera species with a wide geographical distribution, as well as in insects in general. We propose that a large colony size in PPM is important at higher latitudes because this confers an advantage for thermoregulation and tent building in areas where larvae have to face harsher conditions during the winter, thus shifting the optimal trade-off between the number and size of eggs with latitude. However, host tree species also affected the relationship between egg number and size and the optimal outcome of these traits is likely a compromise between different selection pressures. © 2010 The Linnean Society of London.
Jephson T.,Ecology Building |
Carlsson P.,Ecology Building |
Fagerberg T.,Ecology Building
Estuarine, Coastal and Shelf Science | Year: 2012
The vertical positions of four dinoflagellate species in three 48 h periods in late summer in a Swedish fjord (the Gullmar Fjord) reflect changes to the depth of the halocline. During stable, stratified conditions, the chlorophyll a maximum exhibited a diurnal migration pattern, which was disrupted when the halocline was forced closer to the surface by the inflow of more saline water. While conditions were stable, all studied dinoflagellate species were most abundant below the halocline at 06:00 in contrast to the other times of the day when the highest cell concentrations were above the halocline, indicating diurnal vertical migration. However, when wind-induced inflow of more saline water forced the halocline closer to the surface, these patterns were disrupted and there was no sign of diurnal vertical migration. Despite this, there was a vertical heterogeneity in the distribution of dinoflagellates with Dinophysis spp. found mainly above the halocline, while Ceratium spp. also occurred in high cell numbers below the halocline. We acknowledge the importance of representative resolution when sampling in the field, both in time and concerning vertical resolution. © 2012 Elsevier Ltd.
PubMed | Ecology Building
Type: Journal Article | Journal: Trends in ecology & evolution | Year: 2011
Adaptive evolution in multicellular organisms is generally assumed to occur through natural selection acting differentially among the phenotypes programmed by sexually-generated zygotic genotypes. Under this view, only genetic changes in the gamete-zygote-germline-gamete cycle are considered relevant to the evolutionary process. Yet asexuality - production of progeny through proliferation of mitotic cell-lineages - is found in over one half of all eukaryotic phyla, and is likely to contribute to adaptive changes, as suggested by recent evidence from both animals and plants. Adaptive changes in mitotic lineages can be reconciled with contemporary evolutionary thought by fully abandoning the weismannian concept of individuality.