Diversity, Adaptation and Change in Ecosystems
Selective Advantage?
Evolution The theory that changes occur and can been seen in the inherited traits of a population from 1 generation to another
Anatomical Evidence - Scientists can study similarities and differences in the anatomy of organisms and in their embryological development to determine ancestral links between organisms. Anatomical Evidence - 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
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). 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. 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
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).
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: Food source Food source 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.