Unit A: Biological Unit A: Biological DiversityDiversity

Topic 1: Biological Diversity Topic 1: Biological Diversity and Survivaland Survival

VariationsVariations

Variations are differences between Variations are differences between organisms caused by genetic and organisms caused by genetic and environmental factors. A genetic environmental factors. A genetic difference could include being born with difference could include being born with gray eyes. An environmental factor gray eyes. An environmental factor could include height and nutrition. could include height and nutrition. Eating a poor diet will result in a shorter Eating a poor diet will result in a shorter person than if that same person ate a person than if that same person ate a healthy diet with protein and calcium.healthy diet with protein and calcium.

Variation Between SpeciesVariation Between Species

There is variation between species, There is variation between species, and within a species. Biological and within a species. Biological diversity is the number and variety of diversity is the number and variety of organisms in an area. The more organisms in an area. The more biological diversity in an area, the biological diversity in an area, the healthier the environment of this area.healthier the environment of this area.

A species is a single class of living A species is a single class of living things. Only members of the same things. Only members of the same species can reproduce healthy species can reproduce healthy offspring. offspring.

Variation Inside a SpeciesVariation Inside a Species

There may be variation inside a There may be variation inside a species (different breeds of dogs), species (different breeds of dogs), but as long as reproduction is but as long as reproduction is possible, the organisms belong to the possible, the organisms belong to the same species. same species.

A lion and tiger can, very rarely, A lion and tiger can, very rarely, produce offspring together; however, produce offspring together; however, the ‘liger’ cubs never live past three the ‘liger’ cubs never live past three months. Therefore lions and tigers months. Therefore lions and tigers are two different species.are two different species.

SpeciationSpeciation

Speciation is the process where one Speciation is the process where one group of one species, gradually group of one species, gradually adapts to its own habitat and adapts to its own habitat and becomes so different genetically, becomes so different genetically, that it becomes its own species. that it becomes its own species. Lions and tigers were once part of Lions and tigers were once part of the same species, but over time, and the same species, but over time, and through evolution, they have through evolution, they have diverged into two species.diverged into two species.

Variations and AdaptationsVariations and Adaptations

Variations occur all the time. Every Variations occur all the time. Every organism has their genetic material organism has their genetic material change randomly when they are change randomly when they are developing in the womb. A certain developing in the womb. A certain variation becomes common in a variation becomes common in a group or species when it helps the group or species when it helps the organism adapt to its environment. organism adapt to its environment. There are two kinds of adaptations:There are two kinds of adaptations:

Structural AdaptationsStructural Adaptations

I. Structural Adaptations – adaptations that I. Structural Adaptations – adaptations that are physical, resulting in changes to the are physical, resulting in changes to the bodily structure. An example would be the bodily structure. An example would be the adaptation of the polar bear to have white adaptation of the polar bear to have white fur, allowing polar bears to camouflage fur, allowing polar bears to camouflage themselves in snow. themselves in snow.

A human example would be our brains A human example would be our brains which have evolved to have large areas which have evolved to have large areas devoted to thinking and planning. This devoted to thinking and planning. This structural adaptation has allowed us to work structural adaptation has allowed us to work together and use tools. together and use tools.

Behavioural AdaptationsBehavioural Adaptations

II. Behavioural Adaptations – II. Behavioural Adaptations – Adaptations that change the way a Adaptations that change the way a species act. An example would be species act. An example would be the tendency to hunt in packs (lions, the tendency to hunt in packs (lions, wolves) or alone (shark, snakes).wolves) or alone (shark, snakes).

A human example would include A human example would include shivering when you are cold.shivering when you are cold.

Importance of VariationImportance of Variation

Variation is a good thing for survival. If Variation is a good thing for survival. If the members of a species are too the members of a species are too similar, than one catastrophe could similar, than one catastrophe could wipe out the entire species. In the wipe out the entire species. In the Middle Ages 1/3 the population of Middle Ages 1/3 the population of Europe and Asia died from the Bubonic Europe and Asia died from the Bubonic Plague. Had there been less variation in Plague. Had there been less variation in the human species, the entire human the human species, the entire human populations in these areas might have populations in these areas might have been wiped out.been wiped out.

Importance of VariationImportance of Variation

The same thing applies to different The same thing applies to different species. Because different species of species. Because different species of dinosaurs were similar genetically, dinosaurs were similar genetically, most of the species were wiped out most of the species were wiped out 60 million years ago.60 million years ago.

Diversity IndexDiversity Index

The diversity index is a measurement The diversity index is a measurement that measures the health of an that measures the health of an ecosystem. It compares the diversity ecosystem. It compares the diversity of the number of species (runs) in an of the number of species (runs) in an ecosystem with the # of organisms. ecosystem with the # of organisms. The more variety in kinds of species The more variety in kinds of species in an ecosystem, the higher the in an ecosystem, the higher the diversity index.diversity index.

DI = # of Runs / # of OrganismsDI = # of Runs / # of Organisms

Bottleneck EventsBottleneck Events

Catastrophic events Catastrophic events which can wipe out which can wipe out a a species/population.species/population.

One such event One such event occurred 70000 y.a. occurred 70000 y.a. Human species Human species reduced to 1000-reduced to 1000-10000.10000.

Survivors now Survivors now better suited to better suited to volcanic eruptions. volcanic eruptions.