This is a comprehensive and detailed note on Chapter 25 & 26 ; Biodiversity and interspecific interactions for Bot 161.
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Key terms 2 (Ecology)
Lecture 25&26
PART 1: Biodiversity and inter-specific interactions
What is ecology? What is biodiversity? What kinds of interactions exist between species?
What determines species distribution? What are biomes and macro-ecology?
Abiotic - non-living, e.g., "abiotic variables" refers to environmental conditions including climate and
soil type.
Alien species - a species is alien when it occurs outside of its native distribution (i.e., where it is not
indigenous) due to transport by humans, e.g., an Australian plant brought to South Africa by humans
is an alien.
Amensalism (-/0 or 0/-) - association between organisms of two different species in which one is
inhibited or destroyed and the other is unaffected. Not common, e.g., Penicillium secretes penicillin
(0), which kills various bacteria (-).
Biodiversity - (from “biological diversity”) refers to the variety of life on Earth at all its levels, from
genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that
sustain life.
Biosphere - all ecosystems; all parts of the planet where living organisms can be found.
Biotic - living, e.g., "biotic interactions" refer to interactions between living organisms.
Biome - is a large collection of flora and fauna occupying a major habitat.
The distribution of vegetation types as a function of mean annual temperature and precipitation.
, Community - a group of populations of different species living in the same area at the same time,
that may all potentially interact.
Community ecology - or synecology is the study of the interactions between species in communities
on many spatial and temporal scales, including the distribution, structure, abundance, demography,
and interactions between coexisting populations. The primary focus of community ecology is on the
interactions between populations as determined by specific genotypic and phenotypic
characteristics.
Competition (-/-) - refers to the rivalry between or among living things for territory, resources,
goods, mates, etc. It is one of the many symbiotic relationships occurring in nature. Same or
different members of species compete for resources, especially for limited natural resources. This is
an important topic in ecology, especially community ecology.
Ecosystem - a community and the physical factors with which it interacts.
Ecosystem diversity - deals with the variations in ecosystems within a geographical location and its
overall impact on human existence and the environment. Ecosystem diversity addresses the
combined characteristics of biotic properties (biodiversity) and abiotic properties (geodiversity).
Endangered species - is a species in danger of becoming extinct throughout all (or most) of its
distribution.
Endemic species - is an indigenous species that limited to a specific area, e.g., the Silver tree
(Leucadendron argenteum) is a western Cape endemic because it does not naturally occur anywhere
else.
Extinct species - no longer has any living individuals.
Food chain - a representation of the trophic links (i.e., feeding relationships) between individual
consumer species and the species being consumed.
Food web - a representation of all the trophic links within a community (i.e., a combination of all the
food chains within a community).
Fundamental niche - an organism free of interference from other species could use the full range of
conditions (biotic and abiotic) and resources in which it could survive and reproduce which is called
its fundamental niche.
Genetic diversity - is the total number of genetic characteristics in the genetic makeup of a species,
it ranges widely from the number of species to differences within species and can be attributed to
the span of survival for a species. It is distinguished from genetic variability, which describes the
tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to
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