Webpages tagged with «life-history»
This project is investigating the reproductive response of Carabid beetles to changes in their environment's temperature. Some of these species have adapted to cold climates by slowing down their maturation and changing the timing of their reproduction. We now wish to know if these populations will be able to do the oposite in response to warming temperaters. The results may be used to make predictions about the implications of global warming on future distributions of these insects.
Plant reproductive success is depending on temperature and climate during growth season, pollinator availibility and visitation rate, and interactions among plants, e.g. competition for resources and facilitated pollinator attraction. Plants in alpine regions face even larger climatic constraints and may also suffer from pollination limitation because of decrease in available pollinators with altitude. By including abiotic conditions, mutualistic interactions (pollination) and population qualities in elevational gradient consisting of 21 populations of the obligate out-crossing, lateflowering species Leontodon autumnalis var. taraxaci (Mountain Hawkweed) I wish to find out which predictors explain the observed variance in reproductive success. The fieldwork was performed at southfacing slopes of Sandalsnut and Kvanjolnut, Finse, Ulvik municipality – Norway.
Surviving the winter is a special challenge for herbivorous aquatic invertebrates in the alpine region due to long period of ice cover and cessation of primary production. Daphnids that reproduce parthenogenetically during the summer, with 2-3 generation through July and August, solve that problem with depositing sexually produced resting eggs in the autumn. However, the species at Finse, Daphnia umbra, also has an alternative strategy. Instead of producing parthenogenetic or sexual eggs in the autumn, they start storing lipid droplets in the body cavity.
Dividing available resources between reproduction and different somatic processes in organisms is associated to trade-offs in each species life-history. The variability in cost responses in plants has been discussed upon the variability in environmental conditions. We established a field experiment at Sanddalsnuten with the alpine herb, Parnassia palustris L. in focus. The reproductive level was artificially manipulated to determine if there exists cost of reproduction in this species. The field experiments involved manipulations of temperature regime by using open top chambers (OTCs) to simulate a warmer climate, and manipulations of current level of reproductive investment by supplemental hand-pollination (increasing output) and bud removal (decreasing output). Growth, survival, and reproduction was then determined the next year and compared inside and outside the OTCs.
In ecology, although there is a demand for it, there are very few long time series. So, after finishing the fieldwork for my master thesis in 1995, I decided to keep 90 of the Geranium sylvaticum L. individuals and continue to follow them up on a yearly basis, looking at between year variations as well as long-term trends. Every summer since 1995 I have measured; investments in reproduction (number of flowers, number of fruits, fruit:flower ratio, number of seeds) and vegetative growth (number of stalks and the height, number of leaves).
Here we look at life-history adaptation in the arctic charr in a high mountain environment with a particular emphazis on its life history strategies. As this is a marginal environment with regard to the number and variability of degree-days (i.e. the temperature sum), and the length and variability of the feeding season, the charr must trade-off energetic requirements to growth and gonad allocation, and potentially adopt a bet-hedging strategy. Thus, alternative life-history strategies may evolve in such harsh environments as compared to the founder population which exists in a very divergent lowland environment.
Rates of growth and development in ectotherms depend largely on ambient temperature. Some species of ground beetles are known to become smaller at the adult stage and reproduce earlier in the season at higher altitudes. This is interpreted as a response to lower temperature and shorter growth season. Other life-history traits such as fecundity, egg size and age of maturation may also change over such climate gradients. However, little is known about the effects of change in length of the snow-free season compared to changes in summer temperature. To disentangle the effects of season length and temperature on key life-history traits in selected species of ground beetles, we will sample beetles along both altitude gradients (changing temperature) and east-west gradients (changing season length due to more winter precipitation, and thus later snow melt-off, at western sites).