This document discusses biodiversity at three levels - species diversity, genetic diversity, and ecosystem diversity. It notes that species diversity is highest near the equator and in coastal areas with warm sea surface temperatures. Throughout history there have been several mass extinction events that dramatically reduced biodiversity. Currently, the Holocene extinction caused by human activity is reducing biodiversity. The document outlines that each level of biodiversity influences the others, and loss at one level can impact the other levels. Maintaining biodiversity is important for sustaining ecosystem productivity and resilience against disasters.

1. Biodiversity
Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or
planet. Terrestrial biodiversity tends to be highest at low latitudes near the equator,[1]
which
seems to be the result of the warm climate and high primary productivity.[2]
Marine biodiversity
tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest
and in mid-latitudinal band in all oceans.[3]
Biodiversity generally tends to cluster in hotspots,[4]
and has been increasing through time[5][6]
but will likely slow in the future.[7]
Rapid environmental changes typically cause mass extinctions.[8][9][10]
One estimate is that <1%-
3% of the species that have existed on Earth are extant.[11]
Since life began on Earth, five major mass extinctions and several minor events have led to large
and sudden drops in biodiversity. The Phanerozoic eon (the last 540 million years) marked a
rapid growth in biodiversity via the Cambrian explosion—a period during which the majority of
multicellular phyla first appeared.[12]
The next 400 million years included repeated, massive
biodiversity losses classified as mass extinction events. In the Carboniferous, rainforest collapse
led to a great loss of plant and animal life.[13]
The Permian–Triassic extinction event, 251 million
years ago, was the worst; vertebrate recovery took 30 million years.[14]
The most recent, the
Cretaceous–Paleogene extinction event, occurred 65 million years ago and has often attracted
more attention than others because it resulted in the extinction of the dinosaurs.[15]
The period since the emergence of humans has displayed an ongoing biodiversity reduction and
an accompanying loss of genetic diversity. Named the Holocene extinction, the reduction is
caused primarily by human impacts, particularly habitat destruction. Conversely, biodiversity
impacts human health in a number of ways, both positively and negatively.[16]
Levels of Biodiversity
Scientists speak of three levels of biodiversity: a. Species diversity b. Genetic diversity
c. Ecosystem diversity.
In effect, these levels cannot be separated. Each is important, interacting with and influencing the
others. A change at one level can cause changes at the other levels
Species Diversity
In all shape and size (tiny organisms to huge one): includes bacteria, protozoan, fungi, flowering
plants, ants, beetles, butterflies, birds, reptiles and large animals.
Each species is a group of organisms with unique characteristics. An individual of a species can
reproduce successfully, creating a viable offspring, only with another member of the same
species. Still learning how many species exist and how they relate to each other and to their

2. physical environment. Cannot predict the precise ripple effects that the loss of one species will
have on others and on ecosystems.
Keystone species: Plays critical role in ecosystems they inhabit Affect the abundance and health
of many other species. Their loss from ecosystems directly endangers the success of other
species. Scientists estimate between 10 to 30 million species on Earth. Only about 1.75 million
have been named and catalogued.
Most of insects, fungi and microscopic creatures remain unidentified. Their existence is a
mystery.
Genetic Diversity
Every individual inherits genes from its parents and passes on to the next generation.
Biodiversity is more than the variety of species. Genetic diversity everywhere (songs, feather
colors, taste and texture). Genetic variation is extremely important to the survival of species.
Genetic variability, responsible for these different traits, interact with local environmental
conditions to determine the extent to which populations can adapt to environmental changes and
survive exposure to new diseases.
Isolated populations in small patches of habitat cut off from the surrounding environment tend to
have less genetic variation than populations in large, intact ecosystems. Therefore, those isolated
populations are more susceptible to extinction.
Ecosystem Diversity
Populations and non-living environmental components- such as water or minerals surrounding
them interact dynamically to form an ecosystem. It includes: predators consuming prey,
pollinators selecting flowers and species responding to physical processes such as heavy rain.
Plant and Animal communities make up many kinds of ecosystems (forest, wetlands, rangelands,
mountains, deserts, terrestrial ecosystems). Species are not evenly distributed.
Why is Biodiversity Important?
Biodiversity boosts ecosystem productivity where each species, no matter how small, all have
an important role to play.
For example,
A larger number of plant species means a greater variety of crops
Greater species diversity ensures natural sustainability for all life forms
Healthy ecosystems can better withstand and recover from a variety of disasters.
And so, while we dominate this planet, we still need to preserve the diversity in wildlife.