Glossary Plant Breeding

Ecological Niche. The place occupied by a species in the community structure which it is
part of.
Ecological Regions. Specific areas where crop plants originated. Six such ecological
regions have been documented by Harlan (1992); these are: (1) Mediterranean, (2)
Savanna, (3) Tropical low lands/coastals, (4) Tropical highlands, (5) Tropical forests,
and (6) Temperate woodlands. In these regions, wheat and barley, corn and rice, apple
and grapes, potato, sugarcane and coconut, and apple and oranges, respectively are
supposed to be originated.
Ecospecies. A group of ecotypes capable of interbreeding without any adverse effect on
the fitness of offspring.
Ecosphere. Also called biosphere; the largest and most nearly self-sufficient biological
system. It includes all the earth’s living organisms interacting with the physical
environment as a whole to maintain a steady-state system intermediate in the flow of
energy between the input of the sun and the thermal sink of space. Steady state
implies a self-adjusting equilibrium or balanced condition relatively immune to at
least small-scale disturbances.
Ecosystem (Tansley 1935). Also called ecological system; the interaction between or
functioning together of the community and the non-living environment.
Ecotypes. The locally adapted populations having optima and limits of tolerance
(adjusted to local conditions) of species with wide geographical ranges. It may also be
defined as a local race with genotypes adapted to a particular restricted habitat as a
result of natural selection. Ecotypes may be the result of factor compensation.
Compensation along gradients of temperature, light or other factors may involve
genetic races (with or without morphological manifestations) or physiological
acclimation without a genetic change(s).
Effective Breeding Population. The number of breeding individuals of a population,
contributing to the gene pool of the next generation.
Egg. The female gamete or germ cell. It gives rise to the zygote after getting fertilised
with a sperm.
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