This glossary is a FREE SERVICE to assist the student and enthusiast alike to get a better understanding of scientific terms, wildlife industry jargon and ecological concepts.
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dacite Fine-grained igneous rock (volcanic) consisting of feldspar (sodium and potassium aluminium silicate), quartz and amphibole (calcium, magnesium, iron, aluminium silicate)

danckwerts equation equation used to calculate grazing capacity based on veld condition and rainfall.

dassie/hyrax Small, stocky gregarious mammals of the Order Hyracoidea. They range in colour from light to dark brown. Please see Mod #7 Comp #2 of the Game Ranging Course for more information.

death rate the percentage of individuals in a population dying in a specified time interval

deciduous trees or shrubs that lose their leaves every year

decomposer an organism that obtains energy from the breakdown of dead organic matter to more simple substances; more precisely refers to bacteria and fungi

decreaser a grass species that is dominant in good veld, but is replaced by other species when the area is under- or over grazed.

defoliation plants loosing thier leaves

density dependent varying in relation to population density

density independent unaffected by population density

desiccation drying out, losing all moisture content

detrital From the word detritus, the term given to dead or decaying organic matter.

detrital food web The detrital food web involves consuming a dead animal for example, a vulture. The decomposing remains of the carcass become nutrients for the soil, thus returning the minerals back into the ground, possibly nitrates would be involved in the process.

detritivore an organism that feeds on dead organic matter; usually applies to detritus feeding organisms other than bacteria and fungi

dewclaw A vestigial digit that fails to contact the ground; the inside (first) digit in carnivores (cf false hooves of ungulates).

dextral right-handed or pertaining to the right

diamictite Sedimentary rock whose particles are completely unsorted by size, consisting of both very fine-grained and large particles; often deposited under glacial conditions

diapause a period of arrested growth and activity in which metabolism is greatly decreased; usually seasonal in nature and common among insects

diapirism Slow, upward movement of a less- dense mass of material through a denser medium (e.g. a hot air balloon)

diapsid Member of the group of reptiles characterised by two accessory openings in the skull behind each eye, to accommodate jaw muscles; includes all the Archosauria, as well as the ancestors of all modern lizards and snakes

diapsids Diapsid skull - having two openings in the skull behind eyes.

diatom a microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica. It is a type of plankton.

dicotyledon A plant with two seed leaves; the subclass of angiosperms containing most higher plants, Dicot. Short for dicotyledon.

dicroidium Generic name for the leaves of the extinct seed fern that has bifurcating fronds and was dominant during deposition of the Molteno Formation (Upper Triassic Period)

dicynodont Large and diverse group of mammal- like reptiles (therapsids) which lived from the middle Permian to the Late Triassic; these animals were the dominant land-living herbivores of the Permian Period and were characterised by a horny beak rather than many teeth

differentiation Processes by which crystals are separated from magma as it crystallises, resulting in the formation of layers of rocks of different mineral composition

digestibale energy energy made available to the animal through the digestion process

digestion process of fermentation and uptake of nutrients in the digestive system.

digit a finger or toe in mammals

digitigrade an animal that walks on its toes, characteristic of all dogs and cats

dikkop Southern African bird species,English name -Thickknee.

dimorphic A species that has two distinctly different body forms, most frequently due to different genders i.e sexual dimorphism. Eg. Humans are distinctly sexually dimorphic, zebra are not.

dimorphism The differences in appearance between males and females of the same species, such as in colour, shape, size, and structure, that are caused by the inheritance of one or the other sexual pattern in the genetic material

dinocephalian Diverse group of carnivorous and herbivorous mammal-like reptiles (therapsids) that lived during the Permian; they were the first large vertebrates to live on land, and formed an important component of the earliest therapsid faunas of South Africa and Russia

dioecious a plant species that has separate flowers for each sex, i.e. it has male flowers and female flowers

diorite Coarse-grained igneous rock (plutonic) consisting mainly of amphibole (calcium, aluminium, iron and magnesium silicate) and plagioclase (calcium, sodium, aluminium silicate)

diplopoda millipedes

diptera the order which includes flies

dispersal the spreading of seeds by wind, water, animals etc

dispersion distribution of organisms in a given area

displacement activity the performance of a behaviour pattern different from its normal functional context of behaviour

display a technique used by birds to send a signal to another bird by means of a pose, movement, sound, or combination of these, in order to get a particular response

distemper a viral disease causing flu-like synptoms in canids

distribution the area in which a given species is likely to be found

disturbed area an area that has been dug up, altered by man, or heavily overgrazed

diurnal active during the day

diversity difference, the range of species in a given area

dolerite Medium-grained igneous rock consisting of plagioclase (calcium aluminium silicate) and pyroxene (calcium, magnesium, iron silicate); occurs as dykes or sills

dolomite Mineral, calcium magnesium carbonate, or rock entirely comprising grains of this mineral

dome Uplift that is more or less circular in plan, with rock layers dipping away from its centre

dominance hierarchy a social system whereby animals of the same species are ranked, and behave accordingly

dominant a population possessing ecological dominance in a given community and thereby governing the type and abundance of other species in their community

donga hole of various dimensions usually due to the act of erosion

dormant the state of cessation of growth and suspended biological activity during which life is maintained

dorsal on or referring to the back

drift the term given to soils which develop from previously weathered material

dronksiekte (drunk disease) plant poisoning disease with symptoms of severe shivering in animals

dung the faeces or droppings of herbivores

duplex type of soil where a sandy topsoil overlies a swelling clay

dwarf medlar A non-indigenous member of the rose family (Rosaceae) that can cause rapid death upon ingestion. In African mammals this is known as gousiekte (quick sickness).

dyke Tabular intrusive rock that cuts across other rocks

dynamic constantly changing

dynamic equilibrium with reference to plants, a community where change is constant, but the effects are not cumulitive.

dystrophy pertains to a weakening, commonly associated with muscles.

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