Evolution of Biodiversity Chapters 5

Biodiversity is the variety of life on Earth and the essential interdependence of all living things Scientists have identified more than 1.4 million species. Tens of millions -- remain unknown The tremendous variety of life on Earth is made possible by complex interactions among all living things including micro-organisms.

Discussion What does biodiversity provide for humans?

Benefits of Biodiversity Vital economic natural resources Renewable Forests (plants, wildlife) Soils Fresh water (lakes, rivers) Wildlife and fisheries Rangeland Medicines Plants Jellyfish & sea anemones Nudibranchs Marine slugs Food Security and new food sources Grains, fruits, vegetables, meat, fish

Biodiversity Where is the biodiversity Everywhere Every continent and habitat has unique life forms Concentrated in the tropics Panama: > 500 species of breeding birds Arctic: 50-100 species Dense concentrations

Earth is home to a tremendous diversity of species There are 3 components of biodiversity Ecosystem diversity- the variety of ecosystems within a given region. Species diversity- the variety of species in a given ecosystem. Genetic diversity- the variety of genes within a given species.

3 components of biodiversity Diversity of genes Chihuahuas, beagles, and rottweilers are all the same species —but they're not the same because there is variety in their genes. Beagle Chihuahua Rottweilers

There are 3 components of biodiversity 2. Diversity of number of species For example, monkeys, dragonflies, and meadow beauties are all different species. Saki Monkey Golden Skimmer Meadow Beauty

There are 3 components of biodiversity 3. Variety of ecosystems Lakes, Ponds, and Rivers are all Freshwater Ecosystems. Rocky coast, Sand Dune, Estuary, Salt Marsh , Coral Reef are all Marine Ecosystems.

A Species is Species are a group of organisms that is distinct from other groups in terms of size, shape, behaviour or biochemical properties and that can interbreed to produce fertile viable offspring. Organisms are individual life forms. Populations are groups of the same species living in the same place at the same time. Communities are populations of different species that live in the same place at the same time and interact with each other.

Species Distribution Measuring biodiversity is difficult. Species diversity is the combination of richness and evenness in an area. Species richness- The number of species in a given area. Species evenness—is the relative distribution of individuals among the species present in a community. Biodiversity is lower in a community that has been disturbed by humans.

The Shannon Index of diversity

Evolution is the mechanism underlying biodiversity Evolution- a change in the genetic composition of a population over time. Microevolution- evolution below the species level. Macroevolution- Evolution which gives rise to new species or new genera, family, class or phyla.

Evolution: Creating Genetic diversity Change over time is the mechanism of Earth’s biodiversity. Understanding it can help scientists perceive how organisms will adapt to their environment and change over time is crucial with environmental health. Genes are physical locations on chromosomes within each cell of an organism and the complete set of genes in an individual is called its genotype. Genotype is the blueprint for all the genes one posses. And phenotype is the actual traits expressed in that individual. Mutation is the occasional mistake in the copying process that produces a random change. These mutations get passed on. Most mutations are detrimental but occasionally they change everything. Recombination is another way in which genetic diversity is created when chromosomes are duplicated during reproductive cell division and a piece of one breaks off and attaches to another chromosome. This just creates novel traits.

NATURAL SELECTION Artificial selection is when humans determine which individuals will breed to get a desired set of traits like in dogs. Natural selection is when the environment determines which individuals will survive and reproduce. Charles Darwin’s idea of natural selection can be summed up by; individuals produce an excess of offspring, not all offspring can survive, individuals differ in traits, traits are passed on, and differences in traits are associated with differences in the ability to survive and reproduce. Fitness is the ability to survive and reproduce and traits that improve and individuals fitness are called adaptations.

Darwin’s theory of evolution by natural selection Individuals produce an excess of offspring. Not all offspring can survive. Individuals differ in their traits. Differences in traits can be passed on from parents to offspring. Differences in traits are associated with differences in the ability to survive and reproduce.

Discussion What do you think are traits that species have that might enable them to survive better?

Evolution by Random Processes Mutation- occur randomly and can add to the genetic variation of a population. (Most mutations are bad.)

Genetic drift- change in the genetic composition of a population over time as a result of random mating.

Founder effect- a change in a population descended from a small number of colonizing individuals.

Bottleneck effect- a reduction in the genetic diversity of a population caused by a reduction in its size.

Evolution by random Processes Mutation Genetic Drift

Speciation Allopatric speciation- when new species are created by geographic or reproductive isolation.

Speciation Sympatric speciation- the evolution of one species into two species in the absence of geographic isolation, usually through the process of polyploidy, an increase in the number of sets of chromosomes. When species form populations that become reproductively isolation within the same geographic location. (Mating during different seasons)

Selection Natural selection takes a long time. It typically follows a bell shaped curve which means that an average of individuals will have one form and a few will have other forms. There are many ways that natural selection can affect the population. Directional selection- an environmental change that occurs gives an advantage to a variation on one end of the distribution and against the other. Stabilizing selection- selection for the average form and against the extremes. Disruptive selection- selection for the extremes and against the average.

The pace of evolution

Human Interference Genetic engineering- scientists can now copy genes from a species with a desirable trait such as rapid growth and insert these genes into another species now known as genetically modified organisms which can then pass those traits onto their offspring.

Evolution shapes ecological niches and determines species distributions Range of tolerance- all species have an optimal environment in which it performs well. The limit to the abiotic conditions they can tolerate is known as the range of tolerance. Fundamental niche- the ideal conditions for a species.

Niches Niche – the role of an organism in its habitat, or how it makes its living type of food I eat Who else eats you Whether you need to survive Realized niche- the range of abiotic and biotic conditions under which a species lives. This determines the species distribution, or areas of the world where it lives. Niche generalist- species that live under a wide range of conditions. Niche specialist- species that live only in specific habitats.

The Fossil Record Fossils- remains of organisms that have been preserved in rock. Much of what we know about evolution comes from the fossil record.

Edges of Ecosystems Edge- Ecotone- transitional zones at edges biological communities can interact when they come into contact at boundaries called edges. Ecotone- transitional zones at edges Abrupt edge- abrupt changes between communities with no edge community Mixed edges- species from both communities invade the ecotone and compete for resources