Learning Objectives Herbivory Herbivory describes the consumption of plants by animals, and it is another interspecific relationship that affects populations. Unlike animals, plants cannot outrun predators or use mimicry to hide from hungry animals (with a few exceptions). Some plants have…
Learning Objective Biotic Interactions Biotic interactions refer to the relationships among organisms. They can be intraspecific (between members of the same species) or interspecific (between members of different species). When at least one of the interacting organisms is harmed, the relationship is called an antagonism. Trophic…
Populations typically do not live in isolation from other species. Populations that interact within a given area form a community. The organisms that form a community are found in habitats, physical environments where organisms live. However, only the biotic (living) components are considered part…
Populations are characterized by their population size (total number of individuals) and their population density (number of individuals per unit area). Counting all individuals in a population is the most accurate way to determine its size. However, this approach is…
Learning Objectives The logistic model of population growth, while valid in many natural populations and a useful model, is a simplification of real-world population dynamics. Implicit in the model is that the carrying capacity of the environment does not change,…
Learning Objectives Although life histories describe the way many characteristics of a population (such as their age structure) change over time in a general way, population ecologists make use of a variety of methods to model population dynamics mathematically. These…
Learning Objectives Life History Patterns Energy is required by all living organisms for their growth, maintenance, and reproduction; at the same time, energy is often a major limiting factor in determining an organism’s survival. Plants, for example, acquire energy from…
Learning Objectives Population Size and Density Populations are characterized by their population size (total number of individuals) and their population density (number of individuals per unit area). A population may have a large number of individuals that are distributed densely, or sparsely. There are…
Researchers study ecology at various levels. For example, at the organismal level, a scientist might be interested in the adaptations that enable individuals to live in specific habitats. These adaptations could be morphological (pertaining to the study of form or…
During embryogenesis (the development of the embryo), the proembryo develops into the embryo proper and finally into the mature embryo. The mature embryo is surrounded by the seed coat. Depending on the species, nutrient-rich endosperm may remain in the mature seed between the embryo and seed coat. The embryo consists…