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1

Reproductive strategies of the raccoon dog and the red fox in Finland

100%
Kauhala K.
Acta Theriologica
|
1996
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tom 41
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nr 1
Reproductive strategies of the raccoon dog Nyctereutes procyonaid.es (Gray, 1834) and the red fox Vulpes vulpes (Linnaeus, 1758) were studied in southern Finland in 1986-1995. Litter size and relative litter weight, body size, population status and ecology were compared. Although the body size is almost equal, diet rather similar and both raccoon dog and fox populations have been rather stable during the study period, the litter sizes and relative litter weights differ greatly. The mean litter size of the raccoon dog was 9.0 and that of the red fox 5.1. The mean relative litter weight was 18.3-24.0% for the raccoon dog and 10,4-12.5% for the red fox. Thus, raccoon dog females are able to invest relatively more in reproduction than the red fox. There are several features in the ecology and behaviour of these species which can explain the different strategies. First, vole cycles have a strong effect on red fox reproduction, but have only a week effect on the litter size of the raccoon dog. Second, the raccoon dog sleeps during harsh winters and females are in good condition in the breeding season regardless of the weather and food supply during the winter. The red fox is always active in winter when food availability may be low and moving in snow is energetically costly. Omnivory, the ability to accumulate large fat reserves and winter dormancy guarantee the good condition of raccoon dog females even in fluctuating environments by reducing the relative costs of reproduction. Third, raccoon dog pups are easy prey to other predators, and mortality during their first year is very high. If mortality rate before the reproductive age is high and independent of litter size, natural selection will favour large litters. Juvenile mortality among red foxes is lower, and it probably would increase in larger litters due to eg starvation.
2

Reproductive strategy of Nosema apis in honey bee workers with different life expectancies

100%
Czekonska K., Woyciechowski M.
Pszczelnicze Zeszyty Naukowe
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2000
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tom 44
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nr 2
3

Alternative strategies in the acquisition of home ranges by male pine martens in a high-density population

84%
Zalewski A.
Acta Theriologica
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2012
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tom 57
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nr 4
Two strategies of home range acquisition by male subadult pine martens (Martes martes) were described from a high-density population inhabiting Białowieża National Park. Four mother–offspring pairs were identified by genetic parentage assignments. Four subadult males showed two different strategies of home range acquisition: dispersal and sedentary. The dispersing males used an area 4–10 times larger than in sedentary subadult males. A sedentary subadult male used his natal area with his mother, and in the following mating season, this male left this area and established a home range that overlapped greatly with another unrelated female near the natal range. A similar high overlap between another subadult male and an unrelated adult female persisted for 3 years. After the death of this female, the male extended his range to overlap slightly with two to four other females. The sedentary strategy adopted by some subadult males may explain the great variation in spacing patterns of solitary mammals.
4

Effect of different reproductive strategies on colony development characteristics in Bombus terrestris L.

84%
Gosterit A.
Journal of Apicultural Science
|
2011
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tom 55
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nr 2
5
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Histological structure of the vagina in three clausiliid species of different reproductive strategies

84%
Szybiak K., Gabala E.
Folia Malacologica
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2012
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tom 20
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nr 1
6

Cranial ontogeny of Lutreolina crassicaudata (Didelphidae): a comparison with Didelphis albiventris

84%
Flores D. A., Giannini N. P., Abdala F.
Acta Theriologica
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2003
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tom 48
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nr 1
Metatherians experience the greatest developmental changes during extrauterine life. Following previous studies on Didelphis albiventris Lund, 1840, we examined the postweaning cranial allometry of size of the Neotropical marsupial Lutreolina cras- sicaudata (Desmerest, 1804). Our aim was to compare growth patterns of both species to identify traits particular to each species and traits common to both species. This may contribute toward identifying a common developmental plan for didelphids. We mea­sured 15 cranial variables in 32-43 specimens from just-weaned young to old adult. Total length of the skull was the estimator of overall size in least squares and reduced major axis regressions. The skull of Lutreolina crassicaudata grows at a rate slower than the overall change in size in its neurocranial components, palate, and postcanine rows, and it grows relatively faster in the rest of the splanchnocranium. This pattern closely resembles that of Didelphis albiventris, from which it differs mainly in the allometry of the muzzle. In both species, allometry explains most postweaning changes of the trophic apparatus on functional grounds, in relation to interspecific differences in diet. We hypothesize that most local allometric departures from a generalized didelphid plan would relate to main dietary trends.
7

Testing energy expenditure hypotheses: reallocation versus increased demand in Microtus pennsylvanicus

84%
Berteaux D.
Acta Theriologica
|
1998
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tom 43
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nr 1
I tested the "reallocation" and "increased demand" hypotheses of seasonal al­location of energy using female meadow voles Microtus pennsylvanicus (Ord, 1815). I quantified the daily energy expenditure of adult females by the doubly labelled water method, both in the summer (reproductive) and winter (non-reproductive) seasons. Females were studied in field enclosures and were neither pregnant nor lactating, which made it possible to quantify the effect of season on non-reproductive costs. These costs were 20.6% higher in winter than in summer (3.40 vs 2,82 kj x g-1 x day"1). Laboratory data found in the literature showed that the cost of milk synthesis averages 3.53 kJ x g_1 x day"1 Assuming that these costs can be translated to natural conditions, daily energy expenditure of lactating females in the field is 225% that of non-reproductive ones. According to these results, females seem to follow a mixed strategy of both reallocation and increased demand of energy, although the observed pattern of allocation is much closer to an increased demand model. I discuss the assumption that lactation costs measured in captive voles can be transposed to field conditions, and propose an index of reallocation of energy that describes the strategy used by individuals. This index should permit the placement of each new species studied along the continuum of strategies that probably exists in mammals.
8
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Geographical variation of reproductive strategy of Alinda biplicata (Gastropoda: Clausiliidae)

67%
Sulikowska-Drozd A., Maltz T. K.
Folia Malacologica
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2012
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tom 20
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nr 1
9

Gonad development and reproduction in the monoecious species Chlorophthalmus agassizi (Actinopterygii: Aulopiformes: Chlorophthalmidae) from the Sardinian waters (central-western Mediterranean)

67%
Cabiddu S., Follesa M. C., Porcu C., Cau A.
Acta Ichthyologica et Piscatoria
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2010
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tom 40
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nr 2
Background. The shortnose greeneye, Chlorophthalmus agassizi Bonaparte, 1840, is a species with a circumglobal distribution and is among the most abundant commercial fishes in some Mediterranean areas. The knowledge of the biology and ecology of this species is poor and geographically limited, then the aim of this study is to provide a contribution to the knowledge on the reproductive biology of this monoecious deep-sea fish in Sardinian waters. Materials and Methods. In this paper the morphology and the development of the gonads, the mean size at maturity, the monthly evolution in the percent frequency of the maturity stages, and of the indices related to reproduction of the shortnose greeneye were examined. Individuals were caught by trawls, between 270 and 504 m of depth in the Sardinian seas. Results. The ovarian pattern is of an asynchronous type, characterized by releasing of eggs in successive batches. Seven stages of development for the ovary and four for the testis were identified on the basis of macroscopic and histological features. The female portion is the most evident component and shows a later maturation than the male portion. The spawning period is unique and takes place from May to September. Conclusion. The identification of spawning period and the adopted reproductive strategy is essential to obtain a better understanding of its biology and a good management of its fisheries.
10

Variation of sexual and clonal reproduction in Eremosparton songoricum (Litv.) (Fabaceae) on drought in arid regions: an experimental approach

67%
Wang J.-C., Shi X., Yin L.-K., Zhang D.-Y.
Polish Journal of Ecology
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2012
|
tom 60
|
nr 1
Clonal plants combine sexual and clonal reproduction, which contribute differently to plant fitness. We investigated the consequence of natural selection on the two reproductive modes and the ecological factors that affect the reproductive modes of Eremosparton songoricum (Litv.) Vass. in order to understand the reproductive strategies of a clonal plant and the relationship between sexual and clonal reproduction. Morphological characteristics and biomass allocation patterns were m easured and compared at the clonal fragment level in two natural populations (riverside population A and hinterland population B) in the Gurbantunggut Desert, China. The flowering plant ratio, inflorescence number per plant, flower number per raceme, fruit number, mass of 100 seeds, root biomass, fruit biomass and ramet height were significantly higher, whereas fruit set, ramet density, rhizome biomass and length, and root number were significantly lower, in population A compared with those in population B. We estimated that the importance of clonal reproduction varies in two populations of E. songoricum, and the investment adjustment in the two reproductive modes may be based on cost required for each new plant to generate the more survival progeny in the plant life time.
11
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Egg retention in the clausiliid Balea (Pseudalinda) fallax (Rossmassler, 1836) from Roztocze (S. E. Poland)

67%
Sulikowska-Drozd A., Maltz T. K., Stachyra P.
Folia Malacologica
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2012
|
tom 20
|
nr 1
Adults of Balea fallax sampled monthly from the Roztocze Upland were dissected to examine the occurrence of uterine egg retention. Developing eggs were found in snails collected between May and August. In June more than 60% of the studied individuals were gravid, while in other months egg-retaining snails constituted less than 10% of the sample. The number of retained eggs ranged from 3 to 17 (mean 12.3) and was not related to the adult shell size. In June the majority of eggs contained shelled embryos (maximum shell size1.1 whorl). The reproduction mode of B. fallax is compared with those of other ovoviviparous clausiliids of Central Europe.
12
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Cases of hermaphroditism in the Ukrainian populations of Unionidae

67%
Yanovych L. M., Pampura M. M., Vasilieva L. A.
Folia Malacologica
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2012
|
tom 20
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nr 1
13

The reproductive system and germination in orchids

67%
Batygina T. B., Bragina E. A., Vasilyeva V. E.
Acta Biologica Cracoviensia. Series Botanica
|
2003
|
tom 45
|
nr 2
The peculiarities of seminal and vegetative multiplication in orchids are discussed. The main pathways of morphogenesis during the formation of the whole organism of orchids in natural conditions and in vitro culture are reviewed. Peculiarities of development and the role of the protocorm in the life cycle are pointed out. Special attention is paid to the phenomenon of polyembryony of orchids and their germination.
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