CONSERVATION BIOLOGY, Issue 6 2001
Jinliang Wang
This procedure is intended to increase population size without introducing exogenous genes into the managed population. Previous work examining the genetic effects of a single generation of supportive breeding has shown that although a successful program increases the census population size, it may reduce the genetically effective population size and thereby induce excessive inbreeding and loss of genetic variation. We expand and generalize previous analyses of supportive breeding and consider the effects of multiple generations of supportive breeding on rates of inbreeding and genetic drift. We derived recurrence equations for the inbreeding coefficient and coancestry, and thereby equations for inbreeding and variance effective sizes, under three models for selecting captive breeders: at random, preferentially among those born in captivity, and preferentially among those born in the wild. Numerical examples indicate that supportive breeding, when carried out successfully over multiple generations, may increase not only the census but also the effective size of the supported population as a whole. If supportive breeding does not result in a substantial and continuous increase of the census size of the breeding population, however, it might be genetically harmful because of elevated rates of inbreeding and genetic drift. Resumen: La práctica de apoyar poblaciones silvestres débiles mediante la captura de una fracción de los individuos silvestres, su cautiverio para la reproducción y la liberación a su descendencia en habitas naturales para que convivan con organismos silvestres se conoce como reproducción de apoyo y se ha empleado ampliamente en la biología de la conservación y en el manejo de pesca y vida silvestre. Este procedimiento tiene la intención de incrementar el tamaño de la población sin introducir genes exógenos en la población bajo manejo. Trabajos previos sobre los efectos genéticos de una sola generación de reproducción de apoyo muestran que, aunque un programa exitoso incrementa el tamaño poblacional, puede reducir la población genéticamente efectivae inducir así un exceso de consanguinidad y pérdida de variación genética. Expandimos y generalizamos análisis previos de la reproducción de apoyo y consideramos los efectos de múltiples generaciones de reproducción de soporte en las tasas de consanguinidad y de deriva génica. Derivamos ecuaciones de recurrencia para el coeficiente de consanguinidad y de coancestría, y por tanto ecuaciones de tamaños efectivos de consanguinidad y de varianza, para tres modelos de selección de reproductores en cautiverio : aleatoria, preferentemente entre los nacidos en cautiverio y preferentemente entre los nacidos en libertad. Los ejemplos numéricos indican que la reproducción de apoyo, cuando es exitosa en múltiples generaciones, puede ser favorable para el incremento no solo del tamaño, sino del tamaño efectivo de la población soportada en su conjunto. Sin embargo, si la reproducción de soporte no resulta en un incremento sustancial y continuo del tamaño de la población, puede ser genéticamente dañina debido a las altas tasas de consanguinidad y de deriva genética. [source]

Prescribed Burning to Restore Mixed-Oak Communities in Southern Ohio: Effects on Breeding- Bird Populations

CONSERVATION BIOLOGY, Issue 5 2001
Vanessa L. Artman
We studied the effects of repeated burning (1,4 years of annual burning) and recovery (1 year after burning,) on the breeding bird community. Burning resulted in incremental but temporary reductions in the availability of leaf litter, shrubs, and saplings, but it did not affect trees, snags, or understory vegetation cover. Of 30 bird species monitored, 4 were affected negatively and 2 were affected positively by burning. Population densities of Ovenbirds ( Seiurus aurocapillus), Worm-eating Warblers ( Helmitheros vermivorus), and Hooded Warblers ( Wilsonia citrina) declined incrementally in response to repeated burning and did not recover within 1 year after burning, suggesting a lag time in response to the changes in habitat conditions. Densities of Northern Cardinals ( Cardinalis cardinalis) fluctuated among years in the control units, but remained low in the burned units. Densities of American Robins ( Turdus migratorius) and Eastern Wood-Pewees ( Contopus virens) increased in response to burning, but these increases were apparent only after several years of repeated burning. In general, burning resulted in short-term reductions in the suitability of habitat for ground- and low-shrub-nesting birds, but it improved habitat for ground- and aerial-foraging birds. Overall, there were no changes in the composition of the breeding-bird community. Total breeding bird population levels were also unaffected by burning. Our results suggest that prescribed burning applied on a long-term basis or across large spatial scales is likely to have adverse effects on ground- and low-shrub-nesting bird species, but other changes in the composition of the breeding-bird community are likely to be minimal as long as the closed-canopy forest structure is maintained within the context of prescribed burning. Resumen: Se está reintroduciendo fuego artificialmente en los bosque del sur de Ohio para determinar su efectividad para restaurar y mantener comunidades de bosques mixtos de encino ( Quercus spp.). Estudiamos los efectos de quemas repetidas (1,4 años de quema anual,) y de recuperación (1 año después de la quema) sobre la comunidad de aves reproductivas. La quema resultó en reducciones temporales en la disponibilidad de hojarasca, arbustos y renuevos, pero no afectó a los árboles, tocones o la cubierta vegetal del sotobosque. De 30 especies de aves monitoredas, 4 fueron afectadas negativamente por la quema y 2 fueron afectadas positivamente. Las densidades de población de Seiurus aurocapillus, de Helmitheros vermivorus y de Wilsonia citrina declinaron incrementalmente en respuesta a quemas repetidas y no se recuperaron en un año después de la quema, sugiriendo un retraso en el tiempo de respuesta a los cambios en las condiciones del hábitat. Las densidades de Cardinalis cardinalis fluctuaron entre años en las unidades control, pero permanecieron bajas en las unidades quemadas. Las densidades de Turdus migratorius y de Contopus virens aumentaron en respuesta a la quema, pero estos incrementos fueron evidentes sólo hasta varios años después de quemas repetidas. En general, en el corto plazo la quema resultó en reducciones en la calidad del hábitat para aves que anidan sobre el suelo y en arbustos bajos, pero mejoró el hábitat para aves que forrajean en el suelo y el aire. En general, no hubo cambios en la composición de la comunidad de aves reproductivas. Los niveles totales de poblaciones de aves reproductivas tampoco fueron afectados por la quema. Nuestros resultados sugieren la posibilidad de que la quema prescrita aplicada a largo plazo o en escalas espaciales grandes tenga efectos adversos sobre especies de aves que anidan sobre el suelo y en arbustos bajos, pero la posibilidad de cambios en la composición de la comunidad de aves reproductivas es mínima. [source]

Spatio-temporal shifts in gradients of habitat quality for an opportunistic avian predator

ECOGRAPHY, Issue 2 2003
Fabrizio Sergio
We used the conceptual framework of the theory of natural selection to study breeding habitat preferences by an opportunistic avian predator, the black kite Milvus migrans. In Europe, black kite populations are mostly found near large networks of aquatic habitats, usually considered optimal for foraging and breeding. We hypothesized that proximity to wetlands could vary among individuals and affect their fitness, and thus be subject to natural selection. We tested the hypothesis first on a population on Lake Lugano (Italian pre-Alps) which has been monitored for nine years, and then on seven other populations, each studied for four,five years, located along a continuum of habitat from large water bodies to scarce aquatic habitat of any kind. In the Lake Lugano population, black kite abundance was negatively related to distance to the lake in all the nine years of study, consistent with long-term natural selection. There was evidence of ongoing directional selection on strategic nest location in three of the years, and evidence of stabilizing selection in two years. In eight of the nine years the trend was for a linear increase in fitness with increasing proximity to the lake. At the population level, results were consistent with adaptive habitat choice in relation to the previous year's spatial variation in fitness: higher associations between fitness and distance to the lake (i.e. higher selection gradients) resulted in higher density variations in the following year, in turn related to the availability of fish, the main local prey. The progressive decline of inland pairs and increase in the density of lakeshore pairs caused a directional long-term trend of declining mean distance to the lake. Breeding near aquatic habitats was associated with higher foraging success, and higher frequency and biomass of prey deliveries to offspring. There was weak evidence of selection in other populations. The inland-wetland gradient of habitat quality may have been affected by predation risk, as estimated by density of a major predator of adults and nestlings, the eagle owl Bubo bubo. Behavioral decisions at the level of the individual probably translated into population effects on density and distribution at various spatial scales. Populations in optimal habitats showed higher density and produced six times as many young per unit space as those in sub-optimal habitats. [source]

Assessment of the resistance of potato cultivars to Synchytrium endobioticum (Schilb.) Per. in Poland

EPPO BULLETIN, Issue 2 2008
J. Przetakiewicz
In Poland the Plant Breeding and Acclimatization Institute is responsible for officially assessing the resistance to Synchytrium endobioticum of domestic potato breeding lines and cultivars from other countries. Cultivation of potato cultivars in Poland requires confirmation of resistance to potato wart disease. The official assessment uses the modified Glynne-Lemmerzahl method (laboratory tests) and pot tests. The full cycle of assessment of resistance to wart disease requires 52 seed potatoes per variety/breeding line. Forty two tubers are used in laboratory tests. To complete the laboratory tests the next 10 tubers are grown in pot tests (in soil with winter sporangia) during the vegetation season. The final results for domestic breeding lines of potato are available after 3 years of investigation. For cultivars from other countries the authorization of resistance to S. endobioticum takes approximately one year. The Polish breeders (breeding lines) or the breeder's representative (cultivars from other countries) receive the certificate only for lines/cultivars with laboratory and field resistance to S. endobioticum. [source]

Cooperative Breeding and Group Structure in the Lake Tanganyika Cichlid Neolamprologus savoryi

ETHOLOGY, Issue 11 2005
Dik Heg
As yet, cooperative breeding has been described only for some fish species. However, evidence is accumulating that it is widespread among Lake Tanganyika cichlids. We studied the cooperative breeding system of the substrate breeding cichlid Neolamprologus savoryi. Breeding groups typically consisted of a large breeding male with one to four breeding females and three to 33 helpers (mean group size: 14.3 members). Group size was significantly related to breeding male and female body sizes, and larger males had more breeding females and larger sized male helpers. The size of the largest female in the group was positively related to the number and sizes of secondary breeding females and female helpers. In case of multiple breeding females, these females usually divided the group's territory into sub-territories, each with its own helpers (subgroups). Interspersed between groups, independent fish were detected defending an individual shelter (4.4% of all fish). In 9% of the groups no breeding female was present. All group members participated in territory defence and maintenance, and showed submissive behaviours to larger group members. As expected, the level of between-subgroup conflicts was high compared with the level of within-subgroup conflicts. We compare these results with data available from other cooperatively breeding fishes. [source]

Conditional transgene expression mediated by the mouse ,-actin locus

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 11 2007
Ulrike Jägle
Abstract Transgenic mice are an effective model to study gene function in vivo; however, position effects can complicate tissue-specific transgene analysis. To facilitate precise targeting of a transgenic construct into the mouse genome, we combined the Cre/lox and Flp/FRT recombination systems to allow for rapid transgene replacement and conditional transgene expression from the endogenous ,-actin locus. Flp/FRT recombination was used to rapidly exchange FRT-flanked transgene cassettes by recombinase-mediated cassette exchange in embryonic stem cells, while transgene expression can be activated in mice after Cre-mediated excision of a floxed STOP cassette. To validate our system, we analyzed the expression profile of an EGFP reporter gene after integration into the ,-actin locus and Cre-mediated excision of the floxed STOP cassette. Breeding of EGFP reporter mice with various Cre mouse lines resulted in the expected expression profiles, demonstrating the feasibility of the model to facilitate predictable and strong transgene expression in a spatially and temporally controlled manner. genesis 45:659,666, 2007. © 2007 Wiley-Liss, Inc. [source]

Of squeezers and skippers: factors determining the age at moult of immature African Penguins Spheniscus demersus in Namibia

IBIS, Issue 2 2005
JESSICA KEMPER
We used banding and resighting records of 391 African Penguins Spheniscus demersus banded as chicks and later resighted during immature moult to explain the roles of date of fledging and age at moult in determining the season of moult and its timing within the season. Breeding was continuous, but immature moult occurred mainly during spring and summer. Age at immature moult extended over 11 months, from 12 to 23 months after hatching. Birds that fledged during summer and early autumn generally moulted during the next moult season (squeezers), whereas birds that fledged in late autumn, winter and spring skipped the next moult season to moult only the following season (skippers). There was a significant relationship between age at moult and moult date, with young birds moulting later in the season than older birds. The age at moult of immature birds appears to be constrained by minimum age, moult seasonality and plumage wear. Birds that fledged over nearly 2 years moult during one season. Counts of moulting immature African Penguins have not been used to estimate year-class strength and post-fledging survival owing to the wide range of ages at immature moult. Our results provide the means of assigning recruits to specific age groups. [source]

Species conservation on human-dominated landscapes: the case of crowned crane breeding and distribution outside protected areas in Uganda

AFRICAN JOURNAL OF ECOLOGY, Issue 1 2010
William Olupot
Abstract Species primarily dependent on habitats outside protected areas have to cope with the direct pressure of human utilization or harassment, and the indirect pressure of habitat modification. In Uganda, wetlands mainly used by cranes occur mostly outside protected areas. The country's wetlands are however under heavy modification, and this and other pressures are thought to have reduced crane populations to 10,30% of the number in the early 1970s. From January 2005 to January 2006, we assessed the status of crane breeding and distribution in the country. Breeding and foraging sites were assessed through a nationwide newspaper survey, and visits to wetlands. We established occurrence of 21 nests during the study period, and crane use of 27 out of 30 districts surveyed. Crane harassment and trapping were common during breeding, as was crop damage by cranes. This is the first attempt to show the distribution of crane breeding outside protected areas throughout the country. In addition to maintaining suitable breeding habitat, survival of cranes in Uganda lies in part in community engagement and punishing crimes related to hunting and destruction of nests. Résumé Les espèces qui dépendent principalement d'habitats situés en dehors des aires protégées doivent supporter la pression directe de l'utilisation ou du harassement humains, et la pression indirecte de la modification de l'habitat. En Ouganda, les zones humides que les grues fréquentent le plus souvent se trouvent en dehors des aires protégées. Les zones humides du pays subissent pourtant de lourdes modifications, et ceci, entre autres pressions, est censéêtre ce qui a causé la réduction des populations de grues à 10,30% de ce qu'elles étaient au début des années 1970. De janvier 2005 à janvier 2006, nous avons évalué le statut de la reproduction et de la distribution des grues dans le pays. Les sites de reproduction et de nourrissage ont étéévalués grâce à une étude dans tout le pays via les journaux, et à des visites des zones humides. Nous avons pu établir la présence de 21 nids au cours de l'étude, et la fréquentation par les grues de 27 des 30 districts étudiés. Le harassement et le piégeage des crues ont été fréquents pendant la reproduction, comme l'étaient les dommages causés aux cultures par les grues. Ceci est la première tentative pour montrer la distribution de la reproduction des grues dans le pays en dehors des aires protégées. En plus du maintien d'habitats favorables à la reproduction, la survie des grues en Ouganda repose en partie sur l'implication communautaire dans la conservation des grues et sur le renforcement des mesures de sanctions contre les crimes liés à la chasse et à la destruction des nids. [source]

Breeding patterns of Arvicanthis neumanni in central Tanzania

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2008
A. W. Massawe
Abstract The breeding pattern of the grass rat, Arvicanthis neumanni, was investigated in central Tanzania in 2002/2003. Nine hundred and forty-seven animals were captured in three age groups: juveniles, sub adults and adults. These age groups were present in the population for an extended duration, but there was an increase in the number of sexually active individuals and juveniles 2,3 months after the onset of the rains (December 2002,May 2003). A peak in reproductive activity occurred between January and April. Litter size ranged between 5.58 ± 0.42 and 6.1 ± 0.26 in two study sites. There were no significant differences in the number of embryos implanted in the right and left horns of the uterus of pregnant females (t22 = 0, P > 0.05 and t36 = 1.68, P > 0.05, respectively). Sex ratio of A. neumanni was not skewed to either males or females. Breeding was seasonal and seemed to be associated with seasonal variations in primary productivity, which relates to rainfall patterns. Résumé Le schéma de reproduction d'Arvicanthis neumanni a étéétudié dans le centre de la Tanzanie en 2002/2003. On a capturé 947 animaux appartenant à trois groupes d'âge : juvéniles, sub-adultes et adultes. Ces groupes d'âge étaient présents dans la population pendant une longue période, mais il y avait une augmentation du nombre d'individus sexuellement actifs et de juvéniles deux à trois mois après le début des pluies (décembre 2002-mai 2003). Il y eut un pic d'activité sexuelle entre janvier et avril. La taille des portées allait de 5.58 ± 0.42 à 6.1 ± 0.26 dans deux sites étudiés. Il n'y avait pas de différence significative du nombre d'embryons implantés dans les cornes droite et gauche de l'utérus des femelles (t22 = 0, P > 0.05 et t36 = 1.68, P > 0.05 respectivement). Le sex-ratio d'A. neumanni ne favorise ni les mâles, ni les femelles. La reproduction est saisonnière et semble associée aux variations saisonnières de la productivité primaire, liées, elles, aux chutes de pluie. [source]

Seasonal occurrence and local movements of the grey-headed (brown-necked) parrot Poicephalus fuscicollis suahelicus in southern Africa

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2003
Craig T. Symes
Abstract Seasonal movements of grey-headed (brown-necked) parrots were recorded in parts of its range and are likely a response to breeding and availability of specific food sources. Breeding occurred in the northern Kruger National Park and lowveld near the Mutale,Luvhuvhu river confluence from April to August. Aggregations and movements of birds occurred during the post-breeding season (August,December) in response to seasonally abundant food sources. In north-eastern South Africa, grey-headed parrots occurred at Levubu, following the breeding season and their arrival in the area was correlated with the availability of unripe Mabola Plum, Parinari curatellifolia fruit. Similar regional movements occurred in Zimbabwe, the Caprivi of northern Namibia and Zambia. During these movements, flocks of up to 50 individuals were observed, whilst during breeding months singletons and pairs were more frequently seen. This increased abundance in time and space suggests that seasonal migratory movements occur. Résumé Des déplacements saisonniers de perroquets Poicephalus robustus ont été relevés dans des parties de leur aire de répartition, et ils sont vraisemblablement une réponse aux besoins de la reproduction et à la disponibilité des sources de leur nourriture spécifique. La reproduction avait lieu d'avril à août dans le nord du Parc National Kruger et dans le lowveld près du confluent des rivières Mutale et Luvhuvhu. Des rassemblements et des déplacements d'oiseaux avaient lieu dans la saison qui suivait celle de la reproduction (août , décembre) en réponse à l'abondance saisonnière des sources de nourriture. Au nord-est de l'Afrique du Sud, ces perroquets se rencontraient à Levubu, après la saison de reproduction, et leur arrivée coïncidait à la disponibilité des prunes Mabola (Parinari curatellifolia) avant leur maturité. On constatait des déplacements régionaux saisonniers semblables au Zimbabwe, dans le Capríví au nord de la Namibie et en Zambie. Au cours de ces déplacements, on a observé des bandes qui peuvent compter jusqu'à 50 individus, alors que pendant les mois de reproduction, on voyait plus souvent des solitaires ou des couples. Cette abondance accrue à certains moments et à certains endroits suggère qu'il existe des migrations saisonnières. [source]

Aspects of the feeding habits and reproductive biology of the Ghana mole-rat Cryptomys zechi (Rodentia, Bathyergidae)

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2002
S. Yeboah
Abstract The feeding habits and reproductive biology of the Ghana mole-rat, Cryptomys zechi (Matchie), were studied in a Guinea savanna woodland in Ghana. Both tunnel contents and stomach content analysis indicated that bulbs and tubers constituted the commonest and most preferred food items, although some animal food materials were also consumed. Five plant species, Urgenia altissima, Manihot utilisima, Curuligo sp., Oxalis corniculata and Archis hypogea, were the most popular plant food source. Breeding occurred during the rainy season (March,August) and was at its peak in July. There is evidence that the species is capable of producing two litters in a year. In a colony, reproduction is restricted to one female and one male. Males reached sexual maturity at a lower body weights (105 g) than females (155 g). Estimated mean litter size was 1.5 (range 1,2), the smallest among the bathergids. Available data on birth weights of three other species of social Cryptomys indicate that C. zechi has the highest birth weight, which is comparable to that of solitary bathyergids. Résumé On a étudié les habitudes alimentaires et la biologie de la reproduction du rat-taupe du Ghana, Cryptomys zechi (Matschie), dans une savane guinéenne arborée au Ghana. L'analyse du contenu des terriers et des estomacs indique que les bulbes et les tubercules constituent les aliments les plus fréquents et les plus appréciés, bien qu'ils mangent aussi un peu de matière animale. Cinq espèces végétales, Urgenia altissima, Manihot utilissima, Curuligo sp., Oxalis corniculata et Archis hypogeaétaient les sources de nourriture végétale les plus appréciées. L'accouplement a lieu pendant la saison des pluies (mars , août) et est à son maximum en juillet. Des preuves montrent que l'espèce peut produire deux nichées par an. Dans une colonie, la reproduction est limitée à un mâle et une femelle. Les mâles atteignent la maturité sexuelle à un poids inférieur (105 gr) à celui des femelles (155 gr). On a estimé que la taille moyenne d'une nichée était de 1,5 jeune (allant de 1 à 2), la plus petite chez les rats-taupes. Les données disponibles sur le poids à la naissance de trois autres espèces de Cryptomys sociaux indiquent que C. zechi a le poids le plus important à la naissance, comparable à celui des rats-taupes solitaires. [source]

Creating Wheat Germplasm for High Quality Breeding by Monosomic Backcrossing

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 10 2006
Yan-Mei Wang
Abstract By crossing bread wheat cultivar GC8901 with the 1D monosonic line of Xiaoyan No. 6 and backcrossing the offspring with the Xiaoyan No. 6 1D monosonic line for 5 years, high-molecular-weight glutenin subunits 1Dx5+1Dy10 from GC8901 have been transferred into wheat cultivar Xiaoyan No. 6. The BC5F1 offspring lines had been detected by using methods of cytology, marker, molecular marker and six elite single plants with high molecular-weight glutenin subunits: 1Ax1, 1Bx14+1By15, 1Dx5+1Dy10 were identified. Those lines have high-yield potential with better agronomic characters and have been used in high quality wheat breeding processes as well. (Managing editor: Li-Hui Zhao) [source]

Use of intrauterine devices (IUDs) for contraception in the common chimpanzee (Pan troglodytes)

JOURNAL OF MEDICAL PRIMATOLOGY, Issue 2 2000
Kenneth G. Gould
The common chimpanzee (Pan troglodytes) is a species phylogenetically very close to man. It was not many years ago that the captive population of chimpanzees (P. troglodytes) was considered at risk because of perceived problems with reproductive success. With the potential need for many individuals for research in a variety of areas, particularly in the areas of parasitic and viral infections, an NIH-funded program was established to promote the breeding of the species. That program, the ,National Chimpanzee Breeding and Research Program', was highly successful, so successful, in fact, that there is now a surplus of animals available for current research programs. This situation has prompted the use of intrauterine devices (IUDs) as a method of fertility control. Overall, this method is successful and associated with a failure (of pregnancy) rate similar to that reported in the human. Physical and logistic constraints, however, render the method less than ideal for situations where a pregnancy rate of zero is desired. [source]

Virus Resistance in Cereals: Sources of Resistance, Genetics and Breeding

JOURNAL OF PHYTOPATHOLOGY, Issue 9 2009
Frank Ordon
Abstract In cereals, soil-borne viruses transmitted by the plasmodiophorid Polymyxa graminis (e.g., Barley mild mosaic virus, Barley yellow mosaic virus or Soil-borne cereal mosaic virus), have increased in importance due to the increase of the acreage infested and because yield losses cannot be prevented by chemical measures. Due to global warming, it is also expected that insect transmitted viruses vectored by aphids (e.g., Barley yellow dwarf virus, Cereal yellow dwarf virus), leafhoppers (Wheat dwarf virus) or mites (e.g., Wheat streak mosaic virus), will become much more important even in cooler regions. The environmentally most sound and also most cost effective approach to prevent high yield losses caused by these viruses is breeding for resistance. Therefore, in contrast to other reviews on cereal viruses, this study briefly reviews present knowledge on cereal-infecting viruses and emphasizes especially the sources of resistance or tolerance to these viruses and their use in molecular breeding schemes. [source]

Breeding of Pleurotus florida (oyster mushroom) for phenotypic pigmentation and high yield potential

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2008
Jatinder Kaur
Abstract BACKGROUND: Cross-hybridisation is a technique for exchange of genetic material between two compatible nuclei to develop a recombinant genome with a probable expression for a desirable trait. This technique as an example of classical genetics has been applied in a heterothallic bifactorial/tetrapolar fungus Pleurotus florida. It has worked successfully during this study in a small number of experiments. RESULTS: Fruit bodies from the Pleurotus florida PAU-5 were allowed to shed their basidiospores on filter paper under aseptic conditions. Forty-nine monokaryons were isolated from three spore prints, namely Ja, Jb and K. Three hundred and fifty-six crosses were laid to result in five compatible reactions (PFJ4, PFJ9, PFJ11, PFJ13 and PFJ14). The fruit bodies of the hybrid dikaryon PFJ4 were found to show grey pigmentation. The hybrid dikaryons PFJ11 and PFJ14 grew faster in wheat straw substrate to take 39 and 41 days, respectively, for complete mycelial impregnation as compared to the parent, PAU-5 (48 days). The dikaryon PFJ11 out-yielded the parent by giving 34.2% biological efficiency compared to 29.8% for the parent. CONCLUSION: Through cross-hybridisation various changes at the genetic level are possible, showing altered phenotypic expression of the characters, such as change in fruiting efficiency and variability in fruit body characteristics (e.g., pileus shape and pigmentation). This technique can also be applied to other crops to improve their yield potential and bring about desirable phenotypic changes. Copyright © 2008 Society of Chemical Industry [source]

Breeding of Anopheles mosquitoes in irrigated areas of South Punjab, Pakistan

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2001
N. Herrel
Abstract. As part of investigations on potential linkages between irrigation and malaria transmission, all surface water bodies in and around three villages along an irrigation distributary in South Punjab, Pakistan, were surveyed for anopheline mosquito larvae (Diptera: Culicidae) from April 1999 to March 2000. Samples were characterized according to exposure to sunlight, substratum, presence of vegetation, fauna, inorganic matter and physical water condition (clear/turbid/foul). Also water temperature, dissolved oxygen (DO), electroconductivity (EC) and pH of sites were recorded. A total of 37 982 Anopheles larvae of six morphological types were collected from 2992 samples taken from irrigation/agricultural and village/domestic aquatic habitats. Anopheles subpictus Grassi sensu lato was by far the most abundant (74.3%), followed by An. culicifacies Giles s.l. (4.1%), An. stephensi Liston s.l. (2.6%), An. pulcherrimus Theobald (1.8%), An. peditaeniatus Leicester (0.3%) and An. nigerrimus Giles (0.1%). The four most abundant species were significantly associated with waterlogged fields and communal village drinking-water tanks. Habitat characteristics most correlated with occurrence of anophelines were the physical water condition and the absence/presence of fauna, particularly predators. Occurrence and abundance of Anopheles immatures were not significantly correlated with water temperature, DO, EC or pH. Malaria vectors of the Anopheles culicifacies complex occurred at relatively low densities, mainly in irrigated and waterlogged fields. In South Punjab, where rainfall is very low, it should be possible to reduce anopheline breeding through water management, as larvae develop mainly in water bodies that are directly or indirectly related to the extensive canal-irrigation system. [source]

Use of SSR markers to assess sexual vs. apomictic origin and ploidy level of breeding progeny derived from crosses of apple proliferation-resistant Malus sieboldii and its hybrids with Malus × domestica cultivars

PLANT BREEDING, Issue 5 2009
C. Bisognin
Abstract To obtain apple rootstocks resistant to apple proliferation and suitable to modern fruit growing, 24 cross-combinations were performed over a 5-year period using Malus sieboldii and its hybrids as donors of the resistance trait and standard apple rootstock Malus × domestica genotypes as donors of agronomic value. Breeding with these genotypes was achieved despite different degrees of apomixis and polyploidy. Sets of five to six locus-specific microsatellite markers were identified for characterizing each progeny. Supported by flow cytometry these markers were applied to infer mode of reproduction, genomic constitution and ploidy level. Microsatellites allele composition identical to the maternal parent was revealed in 1668 of 3032 seedlings indicating seed formation through apomixis. Complete genetic recombination was found in 398 seedlings. The remaining hybrids displayed a higher ploidy than that of the parental plants which was consistent with the fertilization of unreduced egg cells. Thus, for each cross-combination, microsatellite loci were identified which enabled a reliable prediction of the ploidy level. They can now be applied in routine screening to distinguish sexual from apomictic progeny. [source]

Update on Semen Technologies for Animal Breeding,

REPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2006
JM Morrell
Contents Despite the scale of the livestock breeding industry, where many millions of insemination doses are prepared each year, sperm preparation techniques are used infrequently in animal assisted reproduction compared with its human counterpart. However, some of the techniques used for human sperm preparation, for example, density gradient centrifugation, improve the quality of sperm preparations which is, in turn, reflected by an increased conception rate. The preparation technique separates motile spermatozoa with normal morphology and intact DNA from the total sperm population, leaving behind immature or senescent spermatozoa, morphologically abnormal ones and those with damaged DNA. Furthermore, the motile spermatozoa are removed from the seminal plasma which carries cells, cellular debris and reactive oxygen species, as well as pathogens. Gradient-prepared spermatozoa survive longer, either in liquid storage or when cryopreserved, and are free of bacteria and viral infectivity if prepared carefully. Preparation techniques such as density gradient centrifugation, or the simplified single layer centrifugation technique, have considerable potential for aiding sperm preparation from poor quality semen samples, such as may be obtained from unselected semen donors in captive breeding programmes, or from performance horses. Moreover, the removal of pathogens has important implications, both for disease control and for avoiding the use of antibiotics in semen extenders, which can be detrimental to sperm survival. [source]

Sex Identification of the Black Swan (Cygnus atratus) using the Locus-specific PCR and Implications for its Reproduction

REPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2005
P-J He
Contents Over the last 4,5 years the small captive population of black swans (Cygnus atratus) has consistently failed to reproduce at the Chengdu Research Base of Giant Panda Breeding. The probable cause was hypothesized to be an abnormal sex distribution of the population. The black swan is an example of a sexually monomorphic species. The locus-specific polymerase chain reaction (PCR) approach based on the chromo-helicase-DNA-binding 1 (CHD1) gene, was adopted for the sex determination of the black swans. For this purpose, F1, F2 and R primers were designed using the primerselect software for amplification of the CHD1 gene region. DNA agarose gel electrophoresis showed that the female control displayed two bands, whereas only a single band was found in the male control. Sequence analyses of all seven unknown sex black swans demonstrated the sex-specific DNA band for female. Therefore, it was inferred that all the individuals of the black swan population are females, which has resulted in unfertilized eggs and reproduction failure. This method can be extended to the sexing of other monomorphic avian species and will assist in the design of breeding projects. [source]

Social behavior in fission,fusion groups of red uakari monkeys (Cacajao calvus ucayalii)

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 12 2009
Mark Bowler
Abstract Primates living in large groups that divide to forage must have social systems compatible with this mode of living. Uakari monkeys (Cacajao spp.) live in large groups and exhibit a form of fission,fusion grouping, but their social organization is poorly understood. We present some of the first data on social behavior for this genus based on a study on Cacajao calvus ucayalii. They traveled in multimale multifemale groups of highly variable sizes, with bachelor units on the periphery. Adult males were affiliative, and adult females associated with more than one adult male. Adult females typically traveled with their dependent offspring and an older juvenile within the group. In parties of two or more males, individuals engaged in previously unreported display behaviors and acted together to aggressively chase other males. Breeding was seasonal, and mating occurred away from other group members. We speculate on the social organization of C. calvus ucayalii, in which dispersal may be bisexual and peripheral males are affiliative with one another. Affiliated males appear to cooperate in fighting and displaying to other males for access to females during the breeding season. Am. J. Primatol. 71:976,987, 2009. © 2009 Wiley-Liss, Inc. [source]

Scope of Process Patents in Farm Animal Breeding

THE JOURNAL OF WORLD INTELLECTUAL PROPERTY, Issue 3 2008
Morten Walløe Tvedt
The number of process patent applications concerning farm animal breeding is growing rapidly. Patent law is general in form and is seldom adapted to specific areas of innovation. It was initially created for the purpose of granting exclusive rights to technical inventions, and it was taken for granted that higher animals, food production and pharmaceuticals were too important for mankind to be included under exclusive private rights. Today, with patent law increasingly used in the animal sector, the question arises: how will the law apply to this particular field of innovation? The degree of legal uncertainty is particularly high because it is not clear how the courts of various countries will apply the general law to this particular field. Patent law has the potential to alter the existing legal conditions for competition and investments in the field of animal breeding, and thus merits greater attention among policy-makers, animal breeders and farmers. [source]

Osteological Examinations on the Budgerigar (Melopsittacus undulatus Shaw 1805) with Special Reference to Skeletal Alterations Conditioned by Breeding

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2009
T. Bartels
Summary The aims of this study were to examine the skeleton of domesticated budgerigars of phenotypically different breeding types, to describe the expression of skeletal changes and to discuss the results with special reference to the causes and effects of breed-conditioned alterations. Complete skeletons of 39 adult budgerigars of both sexes were the object of our research. The examinations demonstrated that almost all metrically sized skeleton dimensions of budgerigars of the exhibition type were increased significantly, compared with those of the non-exhibition type. Only for the scapula significant length differences between the budgerigars of both breeding types could not be verified. It can be stated that the measuring parameters ,occipital width', ,maxilla length', ,skull length' and ,prefrontal width' are suitable for the characterization of exhibition budgerigars. However, sexual dimorphisms could be verified in only three parameters (width of the pars symphysialis mandibulae, height of the skull, width of the skull within the range of the occiput). It has to be clarified in future studies to what extent the changes in the skeleton of budgerigars of the exhibition type have already had consequences for their flying ability, metabolism, health and well-being. [source]

Selective breeding for the hybrid striped bass (Morone chrysops, Rafinesque ×M. saxatilis, Walbaum) industry: status and perspectives

AQUACULTURE RESEARCH, Issue 4 2006
Amber F. Garber
Abstract The hybrid striped bass (HSB) farming industry has considerable potential for growth into domestic retail markets, but expansion of this industry is limited by high production costs that dictate high prices for HSB. It is widely recognized within the industry that selective breeding of an improved HSB will be required to increase production efficiency and reduce market prices. A National Program of Genetic Improvement and Selective Breeding for the HSB Industry has been initiated and some progress has been made toward domestication of the parent species of the hybrid. However, uncertainty remains as to which breeding procedures will most rapidly yield sustainable genetic gains in key production traits. This paper consolidates and reviews general information on the biology of temperate basses (genus Morone) relevant to selective breeding of improved HSB. The topics covered include control of reproduction, geographic distribution of stocks and population genetic variation. This is followed by a brief review of the current application of selective breeding techniques, including those based on molecular markers. Finally, we discuss potential avenues for genetic improvement of HSB in a selective breeding program. [source]

Management and Recovery Options for Ural River Beluga Sturgeon

CONSERVATION BIOLOGY, Issue 3 2010
PHAEDRA DOUKAKIS
caviar; CITES; criadero; Mar Caspio; puntos de referencia; sobrepesca Abstract:,Management of declining fisheries of anadromous species sometimes relies heavily on supplementation of populations with captive breeding, despite evidence that captive breeding can have negative consequences and may not address the root cause of decline. The beluga sturgeon (Huso huso), a species threatened by the market for black caviar and reductions in habitat quality, is managed through harvest control and hatchery supplementation, with an emphasis on the latter. We used yield per recruit and elasticity analyses to evaluate the population status and current levels of fishing and to identify the life-history stages that are the best targets for conservation of beluga of the Ural River. Harvest rates in recent years were four to five times higher than rates that would sustain population abundance. Sustainable rates of fishing mortality are similar to those for other long-lived marine species such as sharks and mammals. Yield per recruit, which is maximized if fish are first harvested at age 31 years, would be greatly enhanced by raising minimum size limits or reducing illegal take of subadults. Improving the survival of subadult and adult females would increase population productivity by 10 times that achieved by improving fecundity and survival from egg to age 1 year (i.e., hatchery supplementation). These results suggest that reducing mortality of subadults and adult wild fish is a more effective conservation strategy than hatchery supplementation. Because genetics is not factored into hatchery management practices, supplementation may even reduce the viability of the beluga sturgeon. Resumen:,El manejo de pesquerías de peces anádromos en declinación a veces depende estrechamente de la suplementación de poblaciones mediante la reproducción en cautiverio, no obstante la evidencia de que la reproducción en cautiverio puede tener consecuencias negativas y no abordar la causa principal de la declinación. El esturión beluga (Huso huso), una especie amenazada por el mercado de caviar negro y por reducciones en la calidad del hábitat, es manejado mediante el control de la cosecha y suplementación de poblaciones, con énfasis en esta. Utilizamos análisis de producción por recluta y de elasticidad para evaluar el estatus de la población y los niveles de pesca actuales y para identificar las etapas de la historia de vida que son los mejores blancos para la conservación del beluga en el Río Ural. Las tasas de cosecha en años recientes fueron cuatro a cinco veces mayores que las tasas que sustentarían la abundancia de la población. Las tasas sustentables de mortalidad por pesca son similares a las de otras especies marinas longevas como tiburones y mamíferos. La producción por recluta, que es maximizada si los peces son cosechados a la edad de 31 años, podría incrementar significativamente elevando los límites de talla mínima o reduciendo la captura ilegal de subadultos. La mejora de la supervivencia de hembras subadultas y adultas incrementaría la productividad de la población 10 veces más que la mejora obtenida incrementando la fecundidad y supervivencia de huevo a 1 año de edad (i. e., suplementación de poblaciones mediante reproducción en cautiverio). Estos resultados sugieren que la reducción de la mortalidad de peces silvestres subadultos y adultos es una mejor estrategia de conservación que la suplementación. Debido a que la genética no es considerada en las prácticas de manejo en los criaderos, la suplementación incluso puede reducir la viabilidad del esturión beluga. [source]

Landscape Context Moderates Edge Effects: Nesting Success of Wood Thrushes in Central New York

CONSERVATION BIOLOGY, Issue 5 2004
MELANIE J. L. DRISCOLL
We studied abundance and nesting success in Wood Thrushes (Hylocichla mustelina) breeding across a heterogeneous landscape in central New York from 1998 to 2000 to test the hypothesis that edge effects on nesting passerines are stronger in fragmented than contiguous landscapes. We monitored nests to estimate nesting success in edge and interior habitats in both fragmented and contiguously forested landscapes. In contiguous landscapes, daily survival rate did not differ between edge nests (0.963) and interior nests (0.968) (,2= 0.19, p = 0.66). In contrast, in fragmented landscapes, daily survival estimates were higher in interior (0.971) than edge (0.953) nests (,2= 3.1, p = 0.08). Our study supports the hypothesis that landscape composition moderates edge effects on actual nests of birds but does not determine the mechanisms causing these patterns. Resumen:,No obstante dos décadas de investigación sobre fragmentación de hábitat y efecto de borde sobre aves anidantes, aun se carece de información sobre el efecto de borde sobre el éxito de nidos naturales de aves migratorias neotropicales que se reproducen en pasajes heterogéneos. Estudiamos la abundancia y éxito de anidación de Hylocichla mustelina en un paisaje heterogéneo en el centro de New York de 1998 , 2000 para probar la hipótesis de que el efecto de borde sobre paserinas anidantes eran mayores en paisajes fragmentados que en continuos. Monitoreamos nidos para estimar el éxito en hábitats de borde y de interior en paisajes tanto con bosques continuos como discontinuos. En paisajes continuos, la tasa de supervivencia diaria no difirió entre nidos de borde (0.963) y nidos de interior (0.968) (,2= 0.19, p = 0.66). En contraste, en paisajes fragmentados, las estimaciones de supervivencia diaria fueron mayores en nidos del interior (0.971) que del borde (0.953) (,2= 3.1, p = 0.08). Nuestro estudio soporta la hipótesis de que la composición del paisaje modera los efectos de borde sobre nidos de aves, pero no determina los mecanismos que causan estos patrones. [source]

Genetic Effects of Multiple Generations of Supportive Breeding

Phylogenetic Reanalysis of the Saudi Gazelle and Its Implications for Conservation

CONSERVATION BIOLOGY, Issue 4 2001
Robert L. Hammond
The Saudi gazelle ( Gazella saudiya) was endemic to the Arabian peninsula but is now considered extinct in the wild and is potentially a candidate for captive breeding and reintroduction. Using 375 base pairs of mitochondrial DNA (mtDNA) cytochrome b gene derived from museum samples collected from the wild prior to the presumed extinction of this species, we show that G. saudiya is the sister taxon of the African dorcas gazelle ( G. dorcas). Reciprocal monophyly of G. saudiya mtDNA haplotypes with G. dorcas, coupled with morphological distinctiveness, suggests that it is an evolutionarily significant unit. These data indicate that captive populations identified previously as potential sources of G. saudiya for captive breeding appear incorrectly designated and are irrelevant to the conservation of G. saudiya. The polymerase chain reaction,restriction fragment length polymorphism ( PCR-RFLP) analysis of several private collections of living gazelles in Saudi Arabia provides no evidence for the survival of G. saudiya. We recommend that field surveys be undertaken to establish whether G. saudiya is indeed extinct in the wild and that other private collections within the Arabian peninsula be screened genetically. We urge caution when captive animals of unknown provenance are used to investigate the phylogenetics of cryptic species groups. Resumen: La identificación de poblaciones taxonómicamente apropiadas de especies en peligro para programas de reproducción en cautiverio y de reintroducción es fundamental para su éxito. La Gacela Saudi (Gazella saudiya) fue endémica a la península de Arabia pero ahora está considerada como extinta en su medio y es un candidato potencial para reproducción en cautiverio y reintroducción. Utilizando 375 pares de bases de ADN mitocondrial (ADNmt) del gene citocromo b derivados de muestras de museos colectadas en el medio silvestre antes de la extinción de la especie, mostramos que G. saudiya es el taxón hermano de la gacela dorcas africana (G. dorcas). La monofilia recíproca de haplotipos de ADNmt de G. saudiya con G. dorcas, aunado a diferencias morfológicas, sugiere que es una unidad evolutiva significativa. Estos datos indican que las poblaciones cautivas identificadas previamente como fuente potencial de G. saudiya para reproducción en cautiverio están incorrectamente identificadas y son irrelevantes para la conservación de G. saudiya. El análisis PCR-RFLP de varias colecciones privadas de gacelas vivas en Arabia Saudita no proporcionan evidencia para la supervivencia de G. saudiya. Recomendamos que se realicen muestreos en el campo para establecer si en efecto G. saudiya está extinta en su hábitat y que se examinen genéticamente las otras colecciones privadas en la península Arábiga. Recomendamos precaución cuando animales cautivos de origen desconocido son utilizados para investigar la filogenia de grupos de especies crípticas. [source]

Demography of the California Condor: Implications for Reestablishment

CONSERVATION BIOLOGY, Issue 4 2000
Vicky J. Meretsky
The most prominent mortality factor was lead poisoning resulting from ingestion of bullet fragments in carcasses. Successful captive breeding has allowed many birds to be released to the wild since 1992, based originally on an assumption that exposure to lead could be prevented by food subsidy. The mortality of released birds, however, has generally exceeded levels needed for population stability calculated from simple population models. Collision with overhead wires was the most frequent cause of death in releases before 1994. Lead poisoning again surfaced as a problem starting in 1997 as older birds began feeding on carcasses outside the subsidy program. Although poisonings have been treated successfully by chelation therapy in recaptured birds, food subsidy is proving an ineffective solution to lead exposure. The best long-term solution appears to be either the creation of large reserves where hunting is prohibited or the restriction of hunting to nontoxic ammunition in release areas. Until sources of lead contamination are effectively countered, releases cannot be expected to result in viable populations. In addition, problems involving human-oriented behavior have resulted in the permanent removal of many released birds from the wild. The most promising reduction in human-oriented behavior has been achieved in one release of aversively conditioned, parent-reared birds. Rigorous evaluation of the factors reducing attraction to humans and human structures has been hampered by confounding of techniques in releases. Behavioral problems could be more quickly overcome by adoption of a comprehensive experimental approach. Resumen: Las poblaciones silvestres remanentes del cóndor de California (Gymnogyps californianus) de los anõs 80 exhibieron una disminución poblacional rápida debido a altas tasas de mortalidad de individuos adultos e inmaduros. El factor de mortalidad más prominente fue el envenenamiento por plomo ocasionado por la ingestión de fragmentos de municiones en cadáveres. La reproducción exitosa en cautiverio ha permitido muchas liberaciones en ambientes silvestres desde 1992, bajo el argumento de que la exposición al plomo puede ser prevenida mediante el subsidio de alimento. Sin embargo, la mortalidad de aves liberadas ha excedido generalmente los niveles necesarios para alcanzar una estabilidad poblacional calculada a partir de modelos poblacionales simples. Las colisiones con alambres en lo alto fueron la causa más frecuente de las muertes en liberaciones anteriores a 1994. A partir de 1997, el envenenamiento con plomo surgió una vez más como un problema, puesto que las aves de edad avanzada comenzaron a alimentarse de cadáveres fuera del programa de subsidio. A pesar de que el envenenamiento ha sido tratado exitosamente mediante terapia de quelación de las aves recapturadas, el subsidio de alimento ha probado ser una solución ineficaz contra la exposición al plomo. Las mejores soluciones de largo plazo aparentan ser la creación de reservas grandes donde la caza sea prohibida o se restrinja la caza a municiones no tóxicas en las áreas de liberación. Solo una vez que la contaminación por plomo sea contrarrestada efectivamente, no se podrá esperar que las liberaciones resulten en poblaciones viables. Además, los problemas de conductas orientadas hacia humanos ha resultado en la remoción permanente de muchas aves liberadas de zonas silvestres. La reducción más prometedora de conductas orientadas hacia humanos ha sido obtenida en una liberación de aves criadas por sus padres y condicionadas adversamente. La evaluación rigurosa de los factores que reducen la atracción hacia humanos y estructuras de humanos ha sido obstaculizada por la confusión de técnicas en las liberaciones. Los problemas de conducta podrían ser superados más rápidamente mediante la adopción de una estrategia experimental comprensiva. [source]

Optimal conservation planning for migratory animals: integrating demographic information across seasons

CONSERVATION LETTERS, Issue 3 2010
Justin Sheehy
Abstract Conservation strategies for migratory animals are typically based on ad-hoc or simple ranking methods and focus on a single period of the annual cycle. We use a density-dependent population model to examine one-time land purchase strategies for a migratory population with a breeding and wintering grounds. Under equal rates of habitat loss, we show that it is optimal to invest more, but never solely, in the habitat with the higher density dependence to habitat cost ratio. When there are two habitats that vary in quality within a season, the best strategy is to invest only in one habitat. Whether to purchase high- or low-quality habitat depends on the general life history of the species and the ratio of habitat quality to habitat cost. When carry-over effects are incorporated, it is almost always optimal to invest in high-quality habitat during the season that produces the carry-over effect. We apply this model to a threatened warbler population and show the optimal strategy is to purchase more breeding than wintering habitat despite the fact that breeding habitat is over ten times more expensive. Our model provides a framework for developing year-round conservation strategies for migratory animals and has important implications for long-term planning and management. [source]

Brain aromatase, 5,-reductase, and 5,-reductase change seasonally in wild male song sparrows: Relationship to aggressive and sexual behavior

DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2003
Kiran K. Soma
Abstract In many species, territoriality is expressed only during the breeding season, when plasma testosterone (T) is elevated. In contrast, in song sparrows (Melospiza melodia morphna), males are highly territorial during the breeding (spring) and nonbreeding (autumn) seasons, but not during molt (late summer). In autumn, plasma sex steroids are basal, and castration has no effect on aggression. However, inhibition of aromatase reduces nonbreeding aggression, suggesting that neural steroid metabolism may regulate aggressive behavior. In wild male song sparrows, we examined the neural distribution of aromatase mRNA and seasonal changes in the activities of aromatase, 5,-, and 5,-reductase, enzymes that convert T to 17,-estradiol, 5,-dihydrotestosterone (5,-DHT, a potent androgen), or 5,-DHT (an inactive metabolite), respectively. Enzyme activities were measured in the diencephalon, ventromedial telencephalon (vmTEL, which includes avian amygdala), caudomedial neostriatum (NCM), and the hippocampus of birds captured during spring, molt, or autumn. Aromatase and 5,-reductase changed seasonally in a region-specific manner. Aromatase in the diencephalon was higher in spring than in molt and autumn, similar to seasonal changes in male sexual behavior. Aromatase activity in the vmTEL was high in both spring and autumn but significantly reduced at molt, similar to seasonal changes in aggression. 5,-Reductase was not elevated during molt, suggesting that low aggression during molt is not a result of increased inactivation of androgens. These data highlight the relevance of neural steroid metabolism to the expression of natural behaviors by free-living animals. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 209,221, 2003 [source]