Search results for "FECUNDITY"
showing 10 items of 104 documents
Transient and Permanent Experience with Fatty Acids Changes Drosophila melanogaster Preference and Fitness
2013
Food and host-preference relies on genetic adaptation and sensory experience. In vertebrates, experience with food-related cues during early development can change adult preference. This is also true in holometabolous insects, which undergo a drastic nervous system remodelling during their complete metamorphosis, but remains uncertain in Drosophila melanogaster. We have conditioned D. melanogaster with oleic (C18:1) and stearic (C18:0) acids, two common dietary fatty acids, respectively preferred by larvae and adult. Wild-type individuals exposed either during a transient period of development-from embryo to adult-or more permanently-during one to ten generation cycles-were affected by such…
Effects of temperature, salinity and food level on the life history traits of the marine rotifer Synchaera cecilia valentina, n. subsp.
1997
A strain of the marine rotifer Synchaeta cecilia valentina, n. subsp., isolated from the Hondo of Elche Spanish Mediterranean coastal lagoon at 22%o salinity, was cultured in the laboratory in 20 ml test tubes and fed with the alga Tetraselmis suecica. The effect of two temperatures (20 and 24°C), four salinities (20,25,30 and 37%o) and two food levels (15 000 and 25 000 cells ml-1) on the life history traits of this rotifer were studied in life tables performed with replicated individual cultures. Temper- ature and salinity had a significant negative effect (P < 0.001) on the average lifespan (LS) and on the number of offspring per female (RQ). The effect of food level on LS is unclear, wh…
COST OF REPRODUCTION IN THE WILD: MANIPULATION OF REPRODUCTIVE EFFORT IN THE BANK VOLE
2003
For three years, we manipulated litter size by adding or subtracting pups in eight wild populations of the bank vole, Clethrionomys glareolus, to examine reproductive costs and allocation of reproductive effort between offspring number and size. In general, litter enlargements did not increase the number of weanlings per mother and significantly decreased the size of weanlings. Reproductive effort and the breeding success of individuals varied within breeding seasons, but time of breeding and litter manipulation did not interact to affect reproductive trade-offs. Our 3-yr field experiment revealed that litter enlargements also reduced survival and fecundity of mothers. Small mammals have be…
Age-related effects of chronic hantavirus infection on female host fecundity.
2015
1. Pathogens often cause detrimental effects to their hosts and, consequently, may influence host population dynamics that may, in turn, feed back to pathogen transmission dynamics. Understanding fitness effects of pathogens upon animal host populations can help to predict the risks that zoonotic pathogens pose to humans. 2. Here we determine whether chronic infection by Puumala hantavirus (PUUV) affects important fitness-related traits, namely the probability of breeding, reproductive effort and mother and offspring condition, in the bank vole (Myodes glareolus). Using 9 years empirical data in a PUUV endemic area in Central Finland, we found differences between reproductive characteristic…
Dinosaurian survivorship schedules revisited: new insights from an age‐structured population model
2021
Little is known of dinosaur population biology due to insufficient information on age‐dependent fecundities and mortalities. So far, survivorship curves (SC) of only six dinosaurs (four tyrannosaurs, one ceratopsian, one hadrosaur) have been erected from bone assemblages of aged specimens. They indicate high survival throughout most of their life with presumably higher mortalities after hatching and increasing mortalities towards its end. However, none of these studies recognized that to infer a reliable SC for a taxon, the assemblage must preserve a stationary age distribution (i.e. one which is stable, with constant population size over time as overall fecundities match mortalities, herea…
Acid stress in respect to calcium and magnesium concentrations in the plasma of perch during maturation and spawning
1988
Plasma calcium and magnesium concentrations in perch,Perca fluviatilis, were monitored in an acid lake, Lake Iso Tenhetty (pH ∼5, Al concentrations 0.3–0.5 mg l-1) compared with a nearby reference lake, Lake Paijanne, in Southern Finland. The effect of acid stress could be noticed as 1/3 lower fecundity of perch in the acid lake. Plasma Ca concentrations were temporarily lower in the middle of the winter in the fish of the acid lake, and in April–May samples the situation was opposite. Plasma Mg concentration was also lower in the perch from the acid lake in midwinter months, when compared with the double as high values (∼3 mmol l-1) from the reference lake. Elevated level of plasma Mg have…
Reproductive, biochemical, physiological, and population responses in perch (Perca fluviatilisL.) and roach (Rutilus rutilusL.) downstream of two ele…
2001
Perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations in a state of late vitellogenesis were studied downstream of two pulp and paper mills and at upstream references in southern Lake Saimaa, Finland. The mills used elemental chlorine-free bleaching and activated sludge effluent treatment technologies. The exposure of fish to pulp mill effluents, as measured by concentrations of chlorophenolics in the bile and liver ethoxyresorufin-O-deethylase (EROD) activity, was low and almost similar to the references. Nevertheless, bile resin acid concentrations in exposed perch and roach (260-320 micrograms/ml) and bile beta-sitosterol concentrations in exposed roach (1.5-3.5 microgr…
Breaking the temperature-size rule: Thermal effects on growth, development and fecundity of a crustacean from temporary waters
2013
The temperature-size rule (TSR) is a well-established phenomenon to describe the growth response of ectotherms to temperature by which individuals maintained at low temperatures grow more slowly, but attain a larger size upon maturity. Although there are adaptive and non-adaptive theories about the plasticity of body size in response to temperature, these cannot be applied to all ectotherms, and little is known about the changes in growth and development rates through ontogeny. The ostracod species Heterocypris bosniaca, an inhabitant of freshwater temporary ponds, was used to examine the growth and development rates of its nine growth stages and female fecundity at four different temperatu…
Cadmium effects on development and reproduction of Oncopeltus fasciatus (Heteroptera: Lygaeidae)
2004
Newly hatched nymphs of the insect Oncopeltus fasciatus were exposed to various concentrations of CdCl2 administered in drinking water until the end of adult life. Significant nymphal mortalities were observed at concentrations above 30 mg Cd/l (corresponding to the LC50). The duration of the nymphal stages increased in proportion to the Cd concentration; at the lowest Cd concentration of 10 mg Cd/l, the median duration was significantly prolonged by one day, while at the highest concentration of 100 mg Cd/l it was increased by 10 days over the control group. The weight of newly emerged adults lineally decreased with Cd concentration, being reduced to half the weight of controls at 100 mg C…
Territorial defense, territory size, and population regulation.
2005
The carrying capacity of an environment is determined partly by how individuals compete over the available resources. To territorial animals, space is an important resource, leading to conflict over its use. We build a model where the carrying capacity for an organism in a given environment results from the evolution of territorial defense effort and the consequent space use. The same evolutionary process can yield two completely different modes of population regulation. Density dependence arises through expanding and shrinking territories if fecundity is low, breeding success increases gradually with territory size, and/or defense is cheap. By contrast, when fecundity is high, breeding suc…