Diversity, Adaptation and Change in Ecosystems

Biodiversity and Classification Scientists estimate that there are between 2 and 4.5 million different types of organisms on the planet. Likely there are / were many more. To organize, name and group these organisms based on similar characteristics, scientists use a system called taxonomy. Scientists estimate that there are between 2 and 4.5 million different types of organisms on the planet. Likely there are / were many more. To organize, name and group these organisms based on similar characteristics, scientists use a system called taxonomy.

Taxonomy – the science of classification according to presumed relationships among organisms. Taxonomy – the science of classification according to presumed relationships among organisms. Scientists use a hierarchical system, where organisms are classified in a series of smaller groups. Scientists use a hierarchical system, where organisms are classified in a series of smaller groups.

Hierarchical System Domain- Bacteria, Eukarya, Archea Domain- Bacteria, Eukarya, Archea Kingdom – Monera, Protista, Plantae, Fungi, Animalia Kingdom – Monera, Protista, Plantae, Fungi, Animalia Phylum – sub-groups of each kingdom Phylum – sub-groups of each kingdom Class Class Order Order Family Family Genus Genus Species – organisms that are very similar and can naturally interbreed to produce fertile offspring Species – organisms that are very similar and can naturally interbreed to produce fertile offspring Most General Most Specific

Binomial Nomenclature When organisms are assigned a scientific name, the name is given in two parts, Genus species, and the name is either written in italics or underlined. This system is called binomial nomenclature. When organisms are assigned a scientific name, the name is given in two parts, Genus species, and the name is either written in italics or underlined. This system is called binomial nomenclature. Genus name indicates organisms that are similar, and is always capitalized. Genus name indicates organisms that are similar, and is always capitalized. Species name indicates organisms that are different, and is written in lower case. Species name indicates organisms that are different, and is written in lower case. Ex. Canis lupiswolf Ex. Canis lupiswolf Canis domesticusdog Canis domesticusdog

The 5 Kingdoms Prokaryotae – includes the bacteria (eubacteria and archaebacteria (unicellular with no cell nucleus) Prokaryotae – includes the bacteria (eubacteria and archaebacteria (unicellular with no cell nucleus) Protista – includes single celled plants and animals and algae (unicellular with a nucleus) Protista – includes single celled plants and animals and algae (unicellular with a nucleus) Fungi – includes the mushrooms, yeasts, moulds (multicellular, decomposers) Fungi – includes the mushrooms, yeasts, moulds (multicellular, decomposers) Plantae – includes the trees, flowers, mosses and ferns (multicellular, photosynthesizers) Plantae – includes the trees, flowers, mosses and ferns (multicellular, photosynthesizers) Animalia – includes sponges, worms, crustaceans, insects, and mammals (multicellular and heterotrophic) Animalia – includes sponges, worms, crustaceans, insects, and mammals (multicellular and heterotrophic)

Naming some 2 – 5 million organisms presents a challenge to scientists. To overcome this challenge, dichotomous keys are used to identify and classify organisms based on their characteristics. Naming some 2 – 5 million organisms presents a challenge to scientists. To overcome this challenge, dichotomous keys are used to identify and classify organisms based on their characteristics. Dichotomous Key Dichotomous Key Dichotomous Key Dichotomous Key Scientists today believe that organisms changed over time. Scientists today believe that organisms changed over time.

Phylogeny the history of evolution of a species or group of organisms. This history, and the evolutionary relationships between organisms is often shown in a phylogenetic tree. the history of evolution of a species or group of organisms. This history, and the evolutionary relationships between organisms is often shown in a phylogenetic tree.

Evolution The theory that changes occur and can been seen in the inherited traits of a population from 1 generation to another

Evidence of Evolution – Fossils Paleontology (the study of fossils) has provided scientists with an historical record of organisms that once lived. Fossil evidence has also revealed a number of patterns: 1. In the past, the earth was home to species that are very different from those that exist today. 2. The complexity of living organisms seems to have increased from the past to the present in a systematic manner. 3. Living species and their fossil matches are found in the same geographical regions.

Dating the Past Radioactive elements lose particles (and mass) as they decay at a constant rate (despite temperature, moisture or pressure). Radioactive decay can be used as an accurate a measure of the age of an object. The half-life of an object is the length of time it takes for half the sample to decay and become stable. By measuring the age of rock in which fossils are found, paleontologists can estimate the age of the fossils, creating a chronological evolutionary scale. Radioactive elements lose particles (and mass) as they decay at a constant rate (despite temperature, moisture or pressure). Radioactive decay can be used as an accurate a measure of the age of an object. The half-life of an object is the length of time it takes for half the sample to decay and become stable. By measuring the age of rock in which fossils are found, paleontologists can estimate the age of the fossils, creating a chronological evolutionary scale.

Biogeography Biogeography studies the distribution of different organisms on the surface of the earth. Over long periods of time, the Earth’s continents have shifted position, re-distributing living organisms. The continents can be matched up geographically and biologically. Some islands are far away from land and host a unique set of organisms. The evolutionary pressures and past of these isolated organisms can also be studied. Biogeography studies the distribution of different organisms on the surface of the earth. Over long periods of time, the Earth’s continents have shifted position, re-distributing living organisms. The continents can be matched up geographically and biologically. Some islands are far away from land and host a unique set of organisms. The evolutionary pressures and past of these isolated organisms can also be studied. Essentials of Geology : Chapter 2 : Animations Essentials of Geology : Chapter 2 : Animations Essentials of Geology : Chapter 2 : Animations Essentials of Geology : Chapter 2 : Animations Example: Pangea and the idea that similar organisms exist on 2 different continents (Bison in Northern Canada and Bison in Russia) Example: Pangea and the idea that similar organisms exist on 2 different continents (Bison in Northern Canada and Bison in Russia)

Anatomical Evidence Scientists can study similarities and differences in the anatomy of organisms and in their embryological development to determine ancestral links between organisms. Scientists can study similarities and differences in the anatomy of organisms and in their embryological development to determine ancestral links between organisms.

Homologous structures - features with similar structures, and different functions that indicate an evolutionary relationship between organisms. - Shows evolution from a common ancestor Ex. bat wing and human hand Ex. dolphin flipper and forelimb of a dog

Analogous structures – features with similar functions, but very different structures that indicate there is little evolutionary link between organisms. -Shows no common ancestor Ex. bat wing and butterfly wing Ex. bat wing and butterfly wing

Vestigial features rudimentary structures that have no clear function that may have once been important, but are evolving out of existence. rudimentary structures that have no clear function that may have once been important, but are evolving out of existence. Ex. Appendix & tailbone of humans, small foot found on some snakes Ex. Appendix & tailbone of humans, small foot found on some snakes

Biochemical Evidence Scientists believe that the amino acid sequences in proteins or related organisms are more similar than those in unrelated organisms. DNA sequences that make up different genes control the traits an organism will have. More similar organisms will have more similar DNA. Scientists believe that the amino acid sequences in proteins or related organisms are more similar than those in unrelated organisms. DNA sequences that make up different genes control the traits an organism will have. More similar organisms will have more similar DNA. –Ex. Monkeys and humans share about 94% of the same genetic information and about 90% of the same amino acids. Other examples are: waste products (nitrogenous waste), hormones, chromosomes Other examples are: waste products (nitrogenous waste), hormones, chromosomes

Theories of Evolution

Lamarck –Inheritance of Acquired Characteristics Lamark believed that organisms would desire to evolve and develop a certain trait that they required within a life time to survive and would lose un- necessary traits (‘Use-Disuse’ Theory). He also suggested that these traits could be passed down to offspring (Inheritance). Ex. if a giraffe needed along neck to reach food, the long neck would evolve as the giraffes spent many generations reaching for food. Lamark believed that organisms would desire to evolve and develop a certain trait that they required within a life time to survive and would lose un- necessary traits (‘Use-Disuse’ Theory). He also suggested that these traits could be passed down to offspring (Inheritance). Ex. if a giraffe needed along neck to reach food, the long neck would evolve as the giraffes spent many generations reaching for food.

Giraffe Evolution

Darwin – Natural Selection, Survival of the Fittest Darwin believed that there were many variations among organisms. Traits that were better adapted to survival and reproductive success, would be passed down to future generations (Inheritance). Darwin’s theory required that: Darwin believed that there were many variations among organisms. Traits that were better adapted to survival and reproductive success, would be passed down to future generations (Inheritance). Darwin’s theory required that:

Darwin’s theory required that: 1. Variations exist among organisms. 2. In a changing environment, specific variations were better adapted to survival than others. 3. Only those organisms that survive (and have the adaptive traits) will sexually reproduce. ‘Survival of the Fittest’ 4. The adaptive traits will be passed down to the offspring. 5. **Natural Selection always occurs, each trait has a chance to be passed on, but its likely the better trait would be passed

Sources of Variation Mutations – are random changes in the DNA sequence of a chromosome. Mutations may be: Mutations – are random changes in the DNA sequence of a chromosome. Mutations may be: –neutral – have no effect on an individual –harmful – hinder survival or reproductive success (selected against and may disappear) –beneficial – improve survival or reproductive success (selected for and accumulate) Example: Bacteria mutating to become resistant to drugs like antibiotics. Example: Bacteria mutating to become resistant to drugs like antibiotics. –Most biological diversity in organisms is due to mutations

Sexual Reproduction – involves the production of an organism from two different parents. The offspring inherits ½ the genetic characteristics of both parents, increasing variability. Sexual Reproduction – involves the production of an organism from two different parents. The offspring inherits ½ the genetic characteristics of both parents, increasing variability. –Each parent has two (different) copies of each gene, but only passes one copy to the offspring. –The copy that is inherited by the offspring is randomly determined. –Sexually reproducing organisms choose different mates giving rise to many different possible combinations (variation). –Sexual reproduction usually removes/masks abnormal/faulty genes

Asexual Reproduction – involves the production of an individual from one parent. The offspring is genetically identical to the parent. Asexual Reproduction – involves the production of an individual from one parent. The offspring is genetically identical to the parent. Example: Cloning Example: Cloning –Cloning decreases genetic diversity/variation and could possibly cause an unstable population.

Speciation and Evolution Speciation is the formation of a new species. It can occur by a step by step process known as allopatric speciation. Speciation is the formation of a new species. It can occur by a step by step process known as allopatric speciation. 1. A physical barrier separates a population into two isolated groups. 2. Environmental pressures on the two groups are very different causing the populations to evolve independently. 3. Over time the accumulated differences between populations become so extreme, the populations can no longer interbreed to produce fertile offspring. (They are two different species). Tutorial 24.1 Speciation Mechanisms Tutorial 24.1 Speciation Mechanisms

Theory of gradualism –speciation takes place very slowly. Due to Natural selection Theory of gradualism –speciation takes place very slowly. Due to Natural selection Theory of punctuated equilibrium – species evolve in bursts very rapidly, followed by longer periods of stability (little change). Again, due to natural selection Theory of punctuated equilibrium – species evolve in bursts very rapidly, followed by longer periods of stability (little change). Again, due to natural selection

Divergent evolution – the evolution into many different species. Divergent evolution – the evolution into many different species. –Due to different environmental pressures –Usually due to a barrier: Physical: island formation/wall/mountain/etc Physical: island formation/wall/mountain/etc Biological:pheromones/enemies Biological:pheromones/enemies Convergent evolution – the development of similar appearance, structure or behaviors in unrelated species due to similar environmental pressures. Convergent evolution – the development of similar appearance, structure or behaviors in unrelated species due to similar environmental pressures.