Ecology Exam II

A record of events relating to its growth, development, reproduction, and survival

-age and size at sexual maturity-amount and timing of reproduction-survival and mortality rates

-Individuals within a species show differentiation in life history traits-Differences may be due to genetic variation or environmental conditions-Generalizations about a species' life history traits can still be made

The overall pattern in the average timing and nature of life history events-determined by how an organism divides its time between growth, reproduction, and survival

-traits influenced by genetic variation are usually more similar within families than between them-Natural selection favours individuals whose life history traits result in their having a better chance of surviving and reproducing

-Theoretical Ideal: Life histories are optimal (maximization at fitness)-More realistic: histories are not necessarily perfectly adapted to maximize fitness, particularly when environmental conditions change

One genotype may result in different phenotypes in different environmental conditions-may produce a continuous range of growth rates or discrete types (morphs)-plasticity in life history traits can be a source of plasticity in other traits

Different body parts grow at different rates, which leads to different proportions

Single cell division: all prokaryotes and many protists-some multicellular organisms reproduce sexually and asexually (corals).

Benefits: Recombination promotes genetic variation, may provide protection against diseaseDisadvantages: Individual transmits only 1/2 its genome to the next generation. Population growth rate is slower

Gametes are of equal size

Gametes of different sizes. Usually egg is much larger and has more nutritional material-most multicellular organisms are anisogametic

Involve at least two distinct stages that may have different body forms and live in different environments-transition between stages may be abrupt

Abrupt transition in form from the larval to juvenile stage.-most vertebrates have simple life cycles without abrupt transitions-complex life cycles common in insects, marine invertebrates, amphibians, and some fish

Small offspring may experience the environment very differently than larger parents-parents and offspring can be subject to different selection pressures-about 80% of animal species undergo metamorphosis at some time in their life cycle