Animal Info - Glossary D

Deciduous
1. Relating to seasonal loss of leaves; 2. relating to teeth that are replaced by others.
Deciduous forest
A temperate or tropical forest with moderate rainfall and marked seasons. The trees usually shed their leaves during either cold or dry seasons.
Delayed implantation
The reproductive process whereby, after fertilization, the embryo divides a few times and then floats free in the uterus, without further development, for some time (that, depending on the animal, can include up to more than six months) before implanting on the uterine wall and resuming development.
Demersal
Dwelling at or near the bottom of a body of water.
Demographic
Related to the numbers and density of a population and to changes in the numbers and density.
Den
A shelter, natural or constructed, used for sleeping, for giving birth and raising young, and/or for providing shelter during winter.
Density dependence
The phenomenon by which the values of vital rates such as survivorship and fecundity depend on the density of the population.
Dentition
The number, kind, form and arrangement of teeth.
Desert
Areas of low rainfall, typically with sparse scrub or grassland vegetation, or without any vegetation.
Detritus
Loose material, such as rock fragments or organic particles, that results from disintegration, decay, or wearing away.
Dicotyledon
One of the classes of flowering plants, characterized by the presence of two seed leaves in the young plant, and by net-veined, often broad leaves, in mature plants. Includes deciduous trees.
Diel
Related to a 24-hour period that usually includes a day and the adjoining night.
Digit
A finger or toe.
Digitigrade
Relating to an animal that walks on its toes; as opposed to plantigrade.
Dimorphism
The occurrence of two distinct forms of structure, size, coloring, or other characteristic in a single species. "Sexual dimorphism" occurs where dimorphism exists between the male and female.
Dipterocarp forest
Dry-land tropical rain forest located in Southeast Asia that is characterized by dominance of the Dipterocarpaceae family of trees, which is the main timber family in the forests of Southeast Asia, and usually forms a high proportion of the emergent and main canopy strata of the forest. This type of forest is evergreen, hygrophilous in character, at least 30 m (100') high, and rich in thick-stemmed lianas and woody as well as herbaceous epiphytic growth. These forests are located in the non-seasonal humid zone stretching from Sumatra in the west, through the Malay archipelago, to New Guinea in the east. They comprise at least three-quarters of the forests of Southeast Asia. (Manokaran 1995)
Dispersal
Movement of an animal away from its previous home range. Often refers to the movement of a young animal away from the home range where it was born when it matures.
Display
Any conspicuous pattern of behavior that conveys information to others, usually to members of the same species; e.g. threat or courtship displays.
Distal
Farthest from the body.
Diurnal
Active during daylight hours.
Diversity - alpha
The number of species coexisting within a uniform habitat or a single community (this is the traditional concept of "species diversity").
Diversity - beta
As habitats change along a topographic or climatic gradient, new species are encountered as other species drop out, and this species turnover rate is termed "beta diversity" - a function of changing habitat. An example would be the rate at which the species composition of moss communities changes as you go higher on a mountain slope.
Diversity - gamma
The rate at which additional species are encountered as geographic replacements within a habitat type in different localities; i.e., the species turnover rate with distance between sites of similar habitat, or with expanding geographic areas.
DNA
DNA ("DeoxyriboNucleic Acid") is a long molecule in the shape of a double-stranded helix. It is a polymer (a molecule of similar repeating units which are linked together by a common bonding mechanism) made up of subunits known as nucleotides (which are made up of a phosphate, a sugar, and a base). In DNA, the sugar is deoxyribose. Four bases occur in DNA, and its sequence of paired bases constitute the genetic code of an organism. Particular segments of the DNA molecule constitute genes.
Dormant
Inactive for an extended period. For example, many bears are dormant for a period in winter. As opposed to animals which are hibernating, their pulse rate and body temperature do not decrease significantly.
Dorsal
On the upper or top side or surface; e.g. "dorsal fin".

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